smbXcli: add smbXcli_session infrastructure

[Samba/gebeck_regimport.git] / libcli / smb / smbXcli_base.c

/*
   Unix SMB/CIFS implementation.
   Infrastructure for async SMB client requests
   Copyright (C) Volker Lendecke 2008
   Copyright (C) Stefan Metzmacher 2011

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "system/network.h"
#include "../lib/async_req/async_sock.h"
#include "../lib/util/tevent_ntstatus.h"
#include "../lib/util/tevent_unix.h"
#include "lib/util/util_net.h"
#include "lib/util/dlinklist.h"
#include "../libcli/smb/smb_common.h"
#include "../libcli/smb/smb_seal.h"
#include "../libcli/smb/smb_signing.h"
#include "../libcli/smb/read_smb.h"
#include "smbXcli_base.h"
#include "librpc/ndr/libndr.h"

struct smbXcli_conn;
struct smbXcli_req;
struct smbXcli_session;

struct smbXcli_conn {
        int fd;
        struct sockaddr_storage local_ss;
        struct sockaddr_storage remote_ss;
        const char *remote_name;

        struct tevent_queue *outgoing;
        struct tevent_req **pending;
        struct tevent_req *read_smb_req;

        enum protocol_types protocol;
        bool allow_signing;
        bool desire_signing;
        bool mandatory_signing;

        /*
         * The incoming dispatch function should return:
         * - NT_STATUS_RETRY, if more incoming PDUs are expected.
         * - NT_STATUS_OK, if no more processing is desired, e.g.
         *                 the dispatch function called
         *                 tevent_req_done().
         * - All other return values disconnect the connection.
         */
        NTSTATUS (*dispatch_incoming)(struct smbXcli_conn *conn,
                                      TALLOC_CTX *tmp_mem,
                                      uint8_t *inbuf);

        struct {
                struct {
                        uint32_t capabilities;
                        uint32_t max_xmit;
                } client;

                struct {
                        uint32_t capabilities;
                        uint32_t max_xmit;
                        uint16_t max_mux;
                        uint16_t security_mode;
                        bool readbraw;
                        bool writebraw;
                        bool lockread;
                        bool writeunlock;
                        uint32_t session_key;
                        struct GUID guid;
                        DATA_BLOB gss_blob;
                        uint8_t challenge[8];
                        const char *workgroup;
                        const char *name;
                        int time_zone;
                        NTTIME system_time;
                } server;

                uint32_t capabilities;
                uint32_t max_xmit;

                uint16_t mid;

                struct smb_signing_state *signing;
                struct smb_trans_enc_state *trans_enc;
        } smb1;

        struct {
                struct {
                        uint16_t security_mode;
                        struct GUID guid;
                } client;

                struct {
                        uint32_t capabilities;
                        uint16_t security_mode;
                        struct GUID guid;
                        uint32_t max_trans_size;
                        uint32_t max_read_size;
                        uint32_t max_write_size;
                        NTTIME system_time;
                        NTTIME start_time;
                        DATA_BLOB gss_blob;
                } server;

                uint64_t mid;
                uint16_t cur_credits;
                uint16_t max_credits;
        } smb2;

        struct smbXcli_session *sessions;
};

struct smbXcli_session {
        struct smbXcli_session *prev, *next;
        struct smbXcli_conn *conn;

        struct {
                uint64_t session_id;
                uint16_t session_flags;
                DATA_BLOB signing_key;
                DATA_BLOB session_key;
                bool should_sign;
        } smb2;
};

struct smbXcli_req_state {
        struct tevent_context *ev;
        struct smbXcli_conn *conn;

        uint8_t length_hdr[4];

        bool one_way;

        uint8_t *inbuf;

        struct {
                /* Space for the header including the wct */
                uint8_t hdr[HDR_VWV];

                /*
                 * For normal requests, smb1cli_req_send chooses a mid.
                 * SecondaryV trans requests need to use the mid of the primary
                 * request, so we need a place to store it.
                 * Assume it is set if != 0.
                 */
                uint16_t mid;

                uint16_t *vwv;
                uint8_t bytecount_buf[2];

#define MAX_SMB_IOV 5
                /* length_hdr, hdr, words, byte_count, buffers */
                struct iovec iov[1 + 3 + MAX_SMB_IOV];
                int iov_count;

                uint32_t seqnum;
                struct tevent_req **chained_requests;

                uint8_t recv_cmd;
                NTSTATUS recv_status;
                /* always an array of 3 talloc elements */
                struct iovec *recv_iov;
        } smb1;

        struct {
                const uint8_t *fixed;
                uint16_t fixed_len;
                const uint8_t *dyn;
                uint32_t dyn_len;

                uint8_t hdr[64];
                uint8_t pad[7]; /* padding space for compounding */

                /* always an array of 3 talloc elements */
                struct iovec *recv_iov;

                uint16_t credit_charge;
        } smb2;
};

static int smbXcli_conn_destructor(struct smbXcli_conn *conn)
{
        /*
         * NT_STATUS_OK, means we do not notify the callers
         */
        smbXcli_conn_disconnect(conn, NT_STATUS_OK);

        while (conn->sessions) {
                conn->sessions->conn = NULL;
                DLIST_REMOVE(conn->sessions, conn->sessions);
        }

        if (conn->smb1.trans_enc) {
                common_free_encryption_state(&conn->smb1.trans_enc);
        }

        return 0;
}

struct smbXcli_conn *smbXcli_conn_create(TALLOC_CTX *mem_ctx,
                                         int fd,
                                         const char *remote_name,
                                         enum smb_signing_setting signing_state,
                                         uint32_t smb1_capabilities,
                                         struct GUID *client_guid)
{
        struct smbXcli_conn *conn = NULL;
        void *ss = NULL;
        struct sockaddr *sa = NULL;
        socklen_t sa_length;
        int ret;

        conn = talloc_zero(mem_ctx, struct smbXcli_conn);
        if (!conn) {
                return NULL;
        }

        conn->remote_name = talloc_strdup(conn, remote_name);
        if (conn->remote_name == NULL) {
                goto error;
        }

        conn->fd = fd;

        ss = (void *)&conn->local_ss;
        sa = (struct sockaddr *)ss;
        sa_length = sizeof(conn->local_ss);
        ret = getsockname(fd, sa, &sa_length);
        if (ret == -1) {
                goto error;
        }
        ss = (void *)&conn->remote_ss;
        sa = (struct sockaddr *)ss;
        sa_length = sizeof(conn->remote_ss);
        ret = getpeername(fd, sa, &sa_length);
        if (ret == -1) {
                goto error;
        }

        conn->outgoing = tevent_queue_create(conn, "smbXcli_outgoing");
        if (conn->outgoing == NULL) {
                goto error;
        }
        conn->pending = NULL;

        conn->protocol = PROTOCOL_NONE;

        switch (signing_state) {
        case SMB_SIGNING_OFF:
                /* never */
                conn->allow_signing = false;
                conn->desire_signing = false;
                conn->mandatory_signing = false;
                break;
        case SMB_SIGNING_DEFAULT:
        case SMB_SIGNING_IF_REQUIRED:
                /* if the server requires it */
                conn->allow_signing = true;
                conn->desire_signing = false;
                conn->mandatory_signing = false;
                break;
        case SMB_SIGNING_REQUIRED:
                /* always */
                conn->allow_signing = true;
                conn->desire_signing = true;
                conn->mandatory_signing = true;
                break;
        }

        conn->smb1.client.capabilities = smb1_capabilities;
        conn->smb1.client.max_xmit = UINT16_MAX;

        conn->smb1.capabilities = conn->smb1.client.capabilities;
        conn->smb1.max_xmit = 1024;

        conn->smb1.mid = 1;

        /* initialise signing */
        conn->smb1.signing = smb_signing_init(conn,
                                              conn->allow_signing,
                                              conn->desire_signing,
                                              conn->mandatory_signing);
        if (!conn->smb1.signing) {
                goto error;
        }

        conn->smb2.client.security_mode = SMB2_NEGOTIATE_SIGNING_ENABLED;
        if (conn->mandatory_signing) {
                conn->smb2.client.security_mode |= SMB2_NEGOTIATE_SIGNING_REQUIRED;
        }
        if (client_guid) {
                conn->smb2.client.guid = *client_guid;
        }

        conn->smb2.cur_credits = 1;
        conn->smb2.max_credits = 0;

        talloc_set_destructor(conn, smbXcli_conn_destructor);
        return conn;

 error:
        TALLOC_FREE(conn);
        return NULL;
}

bool smbXcli_conn_is_connected(struct smbXcli_conn *conn)
{
        if (conn == NULL) {
                return false;
        }

        if (conn->fd == -1) {
                return false;
        }

        return true;
}

enum protocol_types smbXcli_conn_protocol(struct smbXcli_conn *conn)
{
        return conn->protocol;
}

bool smbXcli_conn_use_unicode(struct smbXcli_conn *conn)
{
        if (conn->protocol >= PROTOCOL_SMB2_02) {
                return true;
        }

        if (conn->smb1.capabilities & CAP_UNICODE) {
                return true;
        }

        return false;
}

void smbXcli_conn_set_sockopt(struct smbXcli_conn *conn, const char *options)
{
        set_socket_options(conn->fd, options);
}

const struct sockaddr_storage *smbXcli_conn_local_sockaddr(struct smbXcli_conn *conn)
{
        return &conn->local_ss;
}

const struct sockaddr_storage *smbXcli_conn_remote_sockaddr(struct smbXcli_conn *conn)
{
        return &conn->remote_ss;
}

const char *smbXcli_conn_remote_name(struct smbXcli_conn *conn)
{
        return conn->remote_name;
}

uint16_t smbXcli_conn_max_requests(struct smbXcli_conn *conn)
{
        if (conn->protocol >= PROTOCOL_SMB2_02) {
                /*
                 * TODO...
                 */
                return 1;
        }

        return conn->smb1.server.max_mux;
}

NTTIME smbXcli_conn_server_system_time(struct smbXcli_conn *conn)
{
        if (conn->protocol >= PROTOCOL_SMB2_02) {
                return conn->smb2.server.system_time;
        }

        return conn->smb1.server.system_time;
}

const DATA_BLOB *smbXcli_conn_server_gss_blob(struct smbXcli_conn *conn)
{
        if (conn->protocol >= PROTOCOL_SMB2_02) {
                return &conn->smb2.server.gss_blob;
        }

        return &conn->smb1.server.gss_blob;
}

const struct GUID *smbXcli_conn_server_guid(struct smbXcli_conn *conn)
{
        if (conn->protocol >= PROTOCOL_SMB2_02) {
                return &conn->smb2.server.guid;
        }

        return &conn->smb1.server.guid;
}

uint32_t smb1cli_conn_capabilities(struct smbXcli_conn *conn)
{
        return conn->smb1.capabilities;
}

uint32_t smb1cli_conn_max_xmit(struct smbXcli_conn *conn)
{
        return conn->smb1.max_xmit;
}

uint32_t smb1cli_conn_server_session_key(struct smbXcli_conn *conn)
{
        return conn->smb1.server.session_key;
}

const uint8_t *smb1cli_conn_server_challenge(struct smbXcli_conn *conn)
{
        return conn->smb1.server.challenge;
}

uint16_t smb1cli_conn_server_security_mode(struct smbXcli_conn *conn)
{
        return conn->smb1.server.security_mode;
}

int smb1cli_conn_server_time_zone(struct smbXcli_conn *conn)
{
        return conn->smb1.server.time_zone;
}

bool smb1cli_conn_activate_signing(struct smbXcli_conn *conn,
                                   const DATA_BLOB user_session_key,
                                   const DATA_BLOB response)
{
        return smb_signing_activate(conn->smb1.signing,
                                    user_session_key,
                                    response);
}

bool smb1cli_conn_check_signing(struct smbXcli_conn *conn,
                                const uint8_t *buf, uint32_t seqnum)
{
        return smb_signing_check_pdu(conn->smb1.signing, buf, seqnum);
}

bool smb1cli_conn_signing_is_active(struct smbXcli_conn *conn)
{
        return smb_signing_is_active(conn->smb1.signing);
}

void smb1cli_conn_set_encryption(struct smbXcli_conn *conn,
                                 struct smb_trans_enc_state *es)
{
        /* Replace the old state, if any. */
        if (conn->smb1.trans_enc) {
                common_free_encryption_state(&conn->smb1.trans_enc);
        }
        conn->smb1.trans_enc = es;
}

bool smb1cli_conn_encryption_on(struct smbXcli_conn *conn)
{
        return common_encryption_on(conn->smb1.trans_enc);
}


static NTSTATUS smb1cli_pull_raw_error(const uint8_t *hdr)
{
        uint32_t flags2 = SVAL(hdr, HDR_FLG2);
        NTSTATUS status = NT_STATUS(IVAL(hdr, HDR_RCLS));

        if (NT_STATUS_IS_OK(status)) {
                return NT_STATUS_OK;
        }

        if (flags2 & FLAGS2_32_BIT_ERROR_CODES) {
                return status;
        }

        return NT_STATUS_DOS(CVAL(hdr, HDR_RCLS), SVAL(hdr, HDR_ERR));
}

/**
 * Is the SMB command able to hold an AND_X successor
 * @param[in] cmd       The SMB command in question
 * @retval Can we add a chained request after "cmd"?
 */
bool smb1cli_is_andx_req(uint8_t cmd)
{
        switch (cmd) {
        case SMBtconX:
        case SMBlockingX:
        case SMBopenX:
        case SMBreadX:
        case SMBwriteX:
        case SMBsesssetupX:
        case SMBulogoffX:
        case SMBntcreateX:
                return true;
                break;
        default:
                break;
        }

        return false;
}

static uint16_t smb1cli_alloc_mid(struct smbXcli_conn *conn)
{
        size_t num_pending = talloc_array_length(conn->pending);
        uint16_t result;

        while (true) {
                size_t i;

                result = conn->smb1.mid++;
                if ((result == 0) || (result == 0xffff)) {
                        continue;
                }

                for (i=0; i<num_pending; i++) {
                        if (result == smb1cli_req_mid(conn->pending[i])) {
                                break;
                        }
                }

                if (i == num_pending) {
                        return result;
                }
        }
}

void smbXcli_req_unset_pending(struct tevent_req *req)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        struct smbXcli_conn *conn = state->conn;
        size_t num_pending = talloc_array_length(conn->pending);
        size_t i;

        if (state->smb1.mid != 0) {
                /*
                 * This is a [nt]trans[2] request which waits
                 * for more than one reply.
                 */
                return;
        }

        talloc_set_destructor(req, NULL);

        if (num_pending == 1) {
                /*
                 * The pending read_smb tevent_req is a child of
                 * conn->pending. So if nothing is pending anymore, we need to
                 * delete the socket read fde.
                 */
                TALLOC_FREE(conn->pending);
                conn->read_smb_req = NULL;
                return;
        }

        for (i=0; i<num_pending; i++) {
                if (req == conn->pending[i]) {
                        break;
                }
        }
        if (i == num_pending) {
                /*
                 * Something's seriously broken. Just returning here is the
                 * right thing nevertheless, the point of this routine is to
                 * remove ourselves from conn->pending.
                 */
                return;
        }

        /*
         * Remove ourselves from the conn->pending array
         */
        for (; i < (num_pending - 1); i++) {
                conn->pending[i] = conn->pending[i+1];
        }

        /*
         * No NULL check here, we're shrinking by sizeof(void *), and
         * talloc_realloc just adjusts the size for this.
         */
        conn->pending = talloc_realloc(NULL, conn->pending, struct tevent_req *,
                                       num_pending - 1);
        return;
}

static int smbXcli_req_destructor(struct tevent_req *req)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        /*
         * Make sure we really remove it from
         * the pending array on destruction.
         */
        state->smb1.mid = 0;
        smbXcli_req_unset_pending(req);
        return 0;
}

static bool smbXcli_conn_receive_next(struct smbXcli_conn *conn);

bool smbXcli_req_set_pending(struct tevent_req *req)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        struct smbXcli_conn *conn;
        struct tevent_req **pending;
        size_t num_pending;

        conn = state->conn;

        if (!smbXcli_conn_is_connected(conn)) {
                return false;
        }

        num_pending = talloc_array_length(conn->pending);

        pending = talloc_realloc(conn, conn->pending, struct tevent_req *,
                                 num_pending+1);
        if (pending == NULL) {
                return false;
        }
        pending[num_pending] = req;
        conn->pending = pending;
        talloc_set_destructor(req, smbXcli_req_destructor);

        if (!smbXcli_conn_receive_next(conn)) {
                /*
                 * the caller should notify the current request
                 *
                 * And all other pending requests get notified
                 * by smbXcli_conn_disconnect().
                 */
                smbXcli_req_unset_pending(req);
                smbXcli_conn_disconnect(conn, NT_STATUS_NO_MEMORY);
                return false;
        }

        return true;
}

static void smbXcli_conn_received(struct tevent_req *subreq);

static bool smbXcli_conn_receive_next(struct smbXcli_conn *conn)
{
        size_t num_pending = talloc_array_length(conn->pending);
        struct tevent_req *req;
        struct smbXcli_req_state *state;

        if (conn->read_smb_req != NULL) {
                return true;
        }

        if (num_pending == 0) {
                if (conn->smb2.mid < UINT64_MAX) {
                        /* no more pending requests, so we are done for now */
                        return true;
                }

                /*
                 * If there are no more SMB2 requests possible,
                 * because we are out of message ids,
                 * we need to disconnect.
                 */
                smbXcli_conn_disconnect(conn, NT_STATUS_CONNECTION_ABORTED);
                return true;
        }

        req = conn->pending[0];
        state = tevent_req_data(req, struct smbXcli_req_state);

        /*
         * We're the first ones, add the read_smb request that waits for the
         * answer from the server
         */
        conn->read_smb_req = read_smb_send(conn->pending, state->ev, conn->fd);
        if (conn->read_smb_req == NULL) {
                return false;
        }
        tevent_req_set_callback(conn->read_smb_req, smbXcli_conn_received, conn);
        return true;
}

void smbXcli_conn_disconnect(struct smbXcli_conn *conn, NTSTATUS status)
{
        if (conn->fd != -1) {
                close(conn->fd);
        }
        conn->fd = -1;

        /*
         * Cancel all pending requests. We do not do a for-loop walking
         * conn->pending because that array changes in
         * smbXcli_req_unset_pending.
         */
        while (talloc_array_length(conn->pending) > 0) {
                struct tevent_req *req;
                struct smbXcli_req_state *state;
                struct tevent_req **chain;
                size_t num_chained;
                size_t i;

                req = conn->pending[0];
                state = tevent_req_data(req, struct smbXcli_req_state);

                if (state->smb1.chained_requests == NULL) {
                        /*
                         * We're dead. No point waiting for trans2
                         * replies.
                         */
                        state->smb1.mid = 0;

                        smbXcli_req_unset_pending(req);

                        if (NT_STATUS_IS_OK(status)) {
                                /* do not notify the callers */
                                continue;
                        }

                        /*
                         * we need to defer the callback, because we may notify
                         * more then one caller.
                         */
                        tevent_req_defer_callback(req, state->ev);
                        tevent_req_nterror(req, status);
                        continue;
                }

                chain = talloc_move(conn, &state->smb1.chained_requests);
                num_chained = talloc_array_length(chain);

                for (i=0; i<num_chained; i++) {
                        req = chain[i];
                        state = tevent_req_data(req, struct smbXcli_req_state);

                        /*
                         * We're dead. No point waiting for trans2
                         * replies.
                         */
                        state->smb1.mid = 0;

                        smbXcli_req_unset_pending(req);

                        if (NT_STATUS_IS_OK(status)) {
                                /* do not notify the callers */
                                continue;
                        }

                        /*
                         * we need to defer the callback, because we may notify
                         * more then one caller.
                         */
                        tevent_req_defer_callback(req, state->ev);
                        tevent_req_nterror(req, status);
                }
                TALLOC_FREE(chain);
        }
}

/*
 * Fetch a smb request's mid. Only valid after the request has been sent by
 * smb1cli_req_send().
 */
uint16_t smb1cli_req_mid(struct tevent_req *req)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        if (state->smb1.mid != 0) {
                return state->smb1.mid;
        }

        return SVAL(state->smb1.hdr, HDR_MID);
}

void smb1cli_req_set_mid(struct tevent_req *req, uint16_t mid)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        state->smb1.mid = mid;
}

uint32_t smb1cli_req_seqnum(struct tevent_req *req)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        return state->smb1.seqnum;
}

void smb1cli_req_set_seqnum(struct tevent_req *req, uint32_t seqnum)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        state->smb1.seqnum = seqnum;
}

static size_t smbXcli_iov_len(const struct iovec *iov, int count)
{
        size_t result = 0;
        int i;
        for (i=0; i<count; i++) {
                result += iov[i].iov_len;
        }
        return result;
}

static uint8_t *smbXcli_iov_concat(TALLOC_CTX *mem_ctx,
                                   const struct iovec *iov,
                                   int count)
{
        size_t len = smbXcli_iov_len(iov, count);
        size_t copied;
        uint8_t *buf;
        int i;

        buf = talloc_array(mem_ctx, uint8_t, len);
        if (buf == NULL) {
                return NULL;
        }
        copied = 0;
        for (i=0; i<count; i++) {
                memcpy(buf+copied, iov[i].iov_base, iov[i].iov_len);
                copied += iov[i].iov_len;
        }
        return buf;
}

static void smb1cli_req_flags(enum protocol_types protocol,
                              uint32_t smb1_capabilities,
                              uint8_t smb_command,
                              uint8_t additional_flags,
                              uint8_t clear_flags,
                              uint8_t *_flags,
                              uint16_t additional_flags2,
                              uint16_t clear_flags2,
                              uint16_t *_flags2)
{
        uint8_t flags = 0;
        uint16_t flags2 = 0;

        if (protocol >= PROTOCOL_LANMAN1) {
                flags |= FLAG_CASELESS_PATHNAMES;
                flags |= FLAG_CANONICAL_PATHNAMES;
        }

        if (protocol >= PROTOCOL_LANMAN2) {
                flags2 |= FLAGS2_LONG_PATH_COMPONENTS;
                flags2 |= FLAGS2_EXTENDED_ATTRIBUTES;
        }

        if (protocol >= PROTOCOL_NT1) {
                flags2 |= FLAGS2_IS_LONG_NAME;

                if (smb1_capabilities & CAP_UNICODE) {
                        flags2 |= FLAGS2_UNICODE_STRINGS;
                }
                if (smb1_capabilities & CAP_STATUS32) {
                        flags2 |= FLAGS2_32_BIT_ERROR_CODES;
                }
                if (smb1_capabilities & CAP_EXTENDED_SECURITY) {
                        flags2 |= FLAGS2_EXTENDED_SECURITY;
                }
        }

        flags |= additional_flags;
        flags &= ~clear_flags;
        flags2 |= additional_flags2;
        flags2 &= ~clear_flags2;

        *_flags = flags;
        *_flags2 = flags2;
}

struct tevent_req *smb1cli_req_create(TALLOC_CTX *mem_ctx,
                                      struct tevent_context *ev,
                                      struct smbXcli_conn *conn,
                                      uint8_t smb_command,
                                      uint8_t additional_flags,
                                      uint8_t clear_flags,
                                      uint16_t additional_flags2,
                                      uint16_t clear_flags2,
                                      uint32_t timeout_msec,
                                      uint32_t pid,
                                      uint16_t tid,
                                      uint16_t uid,
                                      uint8_t wct, uint16_t *vwv,
                                      int iov_count,
                                      struct iovec *bytes_iov)
{
        struct tevent_req *req;
        struct smbXcli_req_state *state;
        uint8_t flags = 0;
        uint16_t flags2 = 0;

        if (iov_count > MAX_SMB_IOV) {
                /*
                 * Should not happen :-)
                 */
                return NULL;
        }

        req = tevent_req_create(mem_ctx, &state,
                                struct smbXcli_req_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->conn = conn;

        state->smb1.recv_cmd = 0xFF;
        state->smb1.recv_status = NT_STATUS_INTERNAL_ERROR;
        state->smb1.recv_iov = talloc_zero_array(state, struct iovec, 3);
        if (state->smb1.recv_iov == NULL) {
                TALLOC_FREE(req);
                return NULL;
        }

        smb1cli_req_flags(conn->protocol,
                          conn->smb1.capabilities,
                          smb_command,
                          additional_flags,
                          clear_flags,
                          &flags,
                          additional_flags2,
                          clear_flags2,
                          &flags2);

        SIVAL(state->smb1.hdr, 0,           SMB_MAGIC);
        SCVAL(state->smb1.hdr, HDR_COM,     smb_command);
        SIVAL(state->smb1.hdr, HDR_RCLS,    NT_STATUS_V(NT_STATUS_OK));
        SCVAL(state->smb1.hdr, HDR_FLG,     flags);
        SSVAL(state->smb1.hdr, HDR_FLG2,    flags2);
        SSVAL(state->smb1.hdr, HDR_PIDHIGH, pid >> 16);
        SSVAL(state->smb1.hdr, HDR_TID,     tid);
        SSVAL(state->smb1.hdr, HDR_PID,     pid);
        SSVAL(state->smb1.hdr, HDR_UID,     uid);
        SSVAL(state->smb1.hdr, HDR_MID,     0); /* this comes later */
        SSVAL(state->smb1.hdr, HDR_WCT,     wct);

        state->smb1.vwv = vwv;

        SSVAL(state->smb1.bytecount_buf, 0, smbXcli_iov_len(bytes_iov, iov_count));

        state->smb1.iov[0].iov_base = (void *)state->length_hdr;
        state->smb1.iov[0].iov_len  = sizeof(state->length_hdr);
        state->smb1.iov[1].iov_base = (void *)state->smb1.hdr;
        state->smb1.iov[1].iov_len  = sizeof(state->smb1.hdr);
        state->smb1.iov[2].iov_base = (void *)state->smb1.vwv;
        state->smb1.iov[2].iov_len  = wct * sizeof(uint16_t);
        state->smb1.iov[3].iov_base = (void *)state->smb1.bytecount_buf;
        state->smb1.iov[3].iov_len  = sizeof(uint16_t);

        if (iov_count != 0) {
                memcpy(&state->smb1.iov[4], bytes_iov,
                       iov_count * sizeof(*bytes_iov));
        }
        state->smb1.iov_count = iov_count + 4;

        if (timeout_msec > 0) {
                struct timeval endtime;

                endtime = timeval_current_ofs_msec(timeout_msec);
                if (!tevent_req_set_endtime(req, ev, endtime)) {
                        return req;
                }
        }

        switch (smb_command) {
        case SMBtranss:
        case SMBtranss2:
        case SMBnttranss:
        case SMBntcancel:
                state->one_way = true;
                break;
        case SMBlockingX:
                if ((wct == 8) &&
                    (CVAL(vwv+3, 0) == LOCKING_ANDX_OPLOCK_RELEASE)) {
                        state->one_way = true;
                }
                break;
        }

        return req;
}

static NTSTATUS smb1cli_conn_signv(struct smbXcli_conn *conn,
                                   struct iovec *iov, int iov_count,
                                   uint32_t *seqnum)
{
        uint8_t *buf;

        /*
         * Obvious optimization: Make cli_calculate_sign_mac work with struct
         * iovec directly. MD5Update would do that just fine.
         */

        if (iov_count < 4) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[0].iov_len != NBT_HDR_SIZE) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[1].iov_len != (MIN_SMB_SIZE-sizeof(uint16_t))) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[2].iov_len > (0xFF * sizeof(uint16_t))) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[3].iov_len != sizeof(uint16_t)) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }

        buf = smbXcli_iov_concat(talloc_tos(), iov, iov_count);
        if (buf == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        *seqnum = smb_signing_next_seqnum(conn->smb1.signing, false);
        smb_signing_sign_pdu(conn->smb1.signing, buf, *seqnum);
        memcpy(iov[1].iov_base, buf+4, iov[1].iov_len);

        TALLOC_FREE(buf);
        return NT_STATUS_OK;
}

static void smb1cli_req_writev_done(struct tevent_req *subreq);
static NTSTATUS smb1cli_conn_dispatch_incoming(struct smbXcli_conn *conn,
                                               TALLOC_CTX *tmp_mem,
                                               uint8_t *inbuf);

static NTSTATUS smb1cli_req_writev_submit(struct tevent_req *req,
                                          struct smbXcli_req_state *state,
                                          struct iovec *iov, int iov_count)
{
        struct tevent_req *subreq;
        NTSTATUS status;
        uint16_t mid;

        if (!smbXcli_conn_is_connected(state->conn)) {
                return NT_STATUS_CONNECTION_DISCONNECTED;
        }

        if (state->conn->protocol > PROTOCOL_NT1) {
                return NT_STATUS_REVISION_MISMATCH;
        }

        if (iov_count < 4) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[0].iov_len != NBT_HDR_SIZE) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[1].iov_len != (MIN_SMB_SIZE-sizeof(uint16_t))) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[2].iov_len > (0xFF * sizeof(uint16_t))) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }
        if (iov[3].iov_len != sizeof(uint16_t)) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }

        if (state->smb1.mid != 0) {
                mid = state->smb1.mid;
        } else {
                mid = smb1cli_alloc_mid(state->conn);
        }
        SSVAL(iov[1].iov_base, HDR_MID, mid);

        _smb_setlen_nbt(iov[0].iov_base, smbXcli_iov_len(&iov[1], iov_count-1));

        status = smb1cli_conn_signv(state->conn, iov, iov_count,
                                    &state->smb1.seqnum);

        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        /*
         * If we supported multiple encrytion contexts
         * here we'd look up based on tid.
         */
        if (common_encryption_on(state->conn->smb1.trans_enc)) {
                char *buf, *enc_buf;

                buf = (char *)smbXcli_iov_concat(talloc_tos(), iov, iov_count);
                if (buf == NULL) {
                        return NT_STATUS_NO_MEMORY;
                }
                status = common_encrypt_buffer(state->conn->smb1.trans_enc,
                                               (char *)buf, &enc_buf);
                TALLOC_FREE(buf);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(0, ("Error in encrypting client message: %s\n",
                                  nt_errstr(status)));
                        return status;
                }
                buf = (char *)talloc_memdup(state, enc_buf,
                                            smb_len_nbt(enc_buf)+4);
                SAFE_FREE(enc_buf);
                if (buf == NULL) {
                        return NT_STATUS_NO_MEMORY;
                }
                iov[0].iov_base = (void *)buf;
                iov[0].iov_len = talloc_get_size(buf);
                iov_count = 1;
        }

        if (state->conn->dispatch_incoming == NULL) {
                state->conn->dispatch_incoming = smb1cli_conn_dispatch_incoming;
        }

        subreq = writev_send(state, state->ev, state->conn->outgoing,
                             state->conn->fd, false, iov, iov_count);
        if (subreq == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        tevent_req_set_callback(subreq, smb1cli_req_writev_done, req);
        return NT_STATUS_OK;
}

struct tevent_req *smb1cli_req_send(TALLOC_CTX *mem_ctx,
                                    struct tevent_context *ev,
                                    struct smbXcli_conn *conn,
                                    uint8_t smb_command,
                                    uint8_t additional_flags,
                                    uint8_t clear_flags,
                                    uint16_t additional_flags2,
                                    uint16_t clear_flags2,
                                    uint32_t timeout_msec,
                                    uint32_t pid,
                                    uint16_t tid,
                                    uint16_t uid,
                                    uint8_t wct, uint16_t *vwv,
                                    uint32_t num_bytes,
                                    const uint8_t *bytes)
{
        struct tevent_req *req;
        struct iovec iov;
        NTSTATUS status;

        iov.iov_base = discard_const_p(void, bytes);
        iov.iov_len = num_bytes;

        req = smb1cli_req_create(mem_ctx, ev, conn, smb_command,
                                 additional_flags, clear_flags,
                                 additional_flags2, clear_flags2,
                                 timeout_msec,
                                 pid, tid, uid,
                                 wct, vwv, 1, &iov);
        if (req == NULL) {
                return NULL;
        }
        if (!tevent_req_is_in_progress(req)) {
                return tevent_req_post(req, ev);
        }
        status = smb1cli_req_chain_submit(&req, 1);
        if (tevent_req_nterror(req, status)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void smb1cli_req_writev_done(struct tevent_req *subreq)
{
        struct tevent_req *req =
                tevent_req_callback_data(subreq,
                struct tevent_req);
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        ssize_t nwritten;
        int err;

        nwritten = writev_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (nwritten == -1) {
                NTSTATUS status = map_nt_error_from_unix_common(err);
                smbXcli_conn_disconnect(state->conn, status);
                return;
        }

        if (state->one_way) {
                state->inbuf = NULL;
                tevent_req_done(req);
                return;
        }

        if (!smbXcli_req_set_pending(req)) {
                tevent_req_nterror(req, NT_STATUS_NO_MEMORY);
                return;
        }
}

static void smbXcli_conn_received(struct tevent_req *subreq)
{
        struct smbXcli_conn *conn =
                tevent_req_callback_data(subreq,
                struct smbXcli_conn);
        TALLOC_CTX *frame = talloc_stackframe();
        NTSTATUS status;
        uint8_t *inbuf;
        ssize_t received;
        int err;

        if (subreq != conn->read_smb_req) {
                DEBUG(1, ("Internal error: cli_smb_received called with "
                          "unexpected subreq\n"));
                status = NT_STATUS_INTERNAL_ERROR;
                smbXcli_conn_disconnect(conn, status);
                TALLOC_FREE(frame);
                return;
        }
        conn->read_smb_req = NULL;

        received = read_smb_recv(subreq, frame, &inbuf, &err);
        TALLOC_FREE(subreq);
        if (received == -1) {
                status = map_nt_error_from_unix_common(err);
                smbXcli_conn_disconnect(conn, status);
                TALLOC_FREE(frame);
                return;
        }

        status = conn->dispatch_incoming(conn, frame, inbuf);
        TALLOC_FREE(frame);
        if (NT_STATUS_IS_OK(status)) {
                /*
                 * We should not do any more processing
                 * as the dispatch function called
                 * tevent_req_done().
                 */
                return;
        } else if (!NT_STATUS_EQUAL(status, NT_STATUS_RETRY)) {
                /*
                 * We got an error, so notify all pending requests
                 */
                smbXcli_conn_disconnect(conn, status);
                return;
        }

        /*
         * We got NT_STATUS_RETRY, so we may ask for a
         * next incoming pdu.
         */
        if (!smbXcli_conn_receive_next(conn)) {
                smbXcli_conn_disconnect(conn, NT_STATUS_NO_MEMORY);
        }
}

static NTSTATUS smb1cli_inbuf_parse_chain(uint8_t *buf, TALLOC_CTX *mem_ctx,
                                          struct iovec **piov, int *pnum_iov)
{
        struct iovec *iov;
        int num_iov;
        size_t buflen;
        size_t taken;
        size_t remaining;
        uint8_t *hdr;
        uint8_t cmd;
        uint32_t wct_ofs;

        buflen = smb_len_nbt(buf);
        taken = 0;

        hdr = buf + NBT_HDR_SIZE;

        if (buflen < MIN_SMB_SIZE) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        /*
         * This returns iovec elements in the following order:
         *
         * - SMB header
         *
         * - Parameter Block
         * - Data Block
         *
         * - Parameter Block
         * - Data Block
         *
         * - Parameter Block
         * - Data Block
         */
        num_iov = 1;

        iov = talloc_array(mem_ctx, struct iovec, num_iov);
        if (iov == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        iov[0].iov_base = hdr;
        iov[0].iov_len = HDR_WCT;
        taken += HDR_WCT;

        cmd = CVAL(hdr, HDR_COM);
        wct_ofs = HDR_WCT;

        while (true) {
                size_t len = buflen - taken;
                struct iovec *cur;
                struct iovec *iov_tmp;
                uint8_t wct;
                uint32_t bcc_ofs;
                uint16_t bcc;
                size_t needed;

                /*
                 * we need at least WCT and BCC
                 */
                needed = sizeof(uint8_t) + sizeof(uint16_t);
                if (len < needed) {
                        DEBUG(10, ("%s: %d bytes left, expected at least %d\n",
                                   __location__, (int)len, (int)needed));
                        goto inval;
                }

                /*
                 * Now we check if the specified words are there
                 */
                wct = CVAL(hdr, wct_ofs);
                needed += wct * sizeof(uint16_t);
                if (len < needed) {
                        DEBUG(10, ("%s: %d bytes left, expected at least %d\n",
                                   __location__, (int)len, (int)needed));
                        goto inval;
                }

                /*
                 * Now we check if the specified bytes are there
                 */
                bcc_ofs = wct_ofs + sizeof(uint8_t) + wct * sizeof(uint16_t);
                bcc = SVAL(hdr, bcc_ofs);
                needed += bcc * sizeof(uint8_t);
                if (len < needed) {
                        DEBUG(10, ("%s: %d bytes left, expected at least %d\n",
                                   __location__, (int)len, (int)needed));
                        goto inval;
                }

                /*
                 * we allocate 2 iovec structures for words and bytes
                 */
                iov_tmp = talloc_realloc(mem_ctx, iov, struct iovec,
                                         num_iov + 2);
                if (iov_tmp == NULL) {
                        TALLOC_FREE(iov);
                        return NT_STATUS_NO_MEMORY;
                }
                iov = iov_tmp;
                cur = &iov[num_iov];
                num_iov += 2;

                cur[0].iov_len = wct * sizeof(uint16_t);
                cur[0].iov_base = hdr + (wct_ofs + sizeof(uint8_t));
                cur[1].iov_len = bcc * sizeof(uint8_t);
                cur[1].iov_base = hdr + (bcc_ofs + sizeof(uint16_t));

                taken += needed;

                if (!smb1cli_is_andx_req(cmd)) {
                        /*
                         * If the current command does not have AndX chanining
                         * we are done.
                         */
                        break;
                }

                if (wct == 0 && bcc == 0) {
                        /*
                         * An empty response also ends the chain,
                         * most likely with an error.
                         */
                        break;
                }

                if (wct < 2) {
                        DEBUG(10, ("%s: wct[%d] < 2 for cmd[0x%02X]\n",
                                   __location__, (int)wct, (int)cmd));
                        goto inval;
                }
                cmd = CVAL(cur[0].iov_base, 0);
                if (cmd == 0xFF) {
                        /*
                         * If it is the end of the chain we are also done.
                         */
                        break;
                }
                wct_ofs = SVAL(cur[0].iov_base, 2);

                if (wct_ofs < taken) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }
                if (wct_ofs > buflen) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }

                /*
                 * we consumed everything up to the start of the next
                 * parameter block.
                 */
                taken = wct_ofs;
        }

        remaining = buflen - taken;

        if (remaining > 0 && num_iov >= 3) {
                /*
                 * The last DATA block gets the remaining
                 * bytes, this is needed to support
                 * CAP_LARGE_WRITEX and CAP_LARGE_READX.
                 */
                iov[num_iov-1].iov_len += remaining;
        }

        *piov = iov;
        *pnum_iov = num_iov;
        return NT_STATUS_OK;

inval:
        TALLOC_FREE(iov);
        return NT_STATUS_INVALID_NETWORK_RESPONSE;
}

static NTSTATUS smb1cli_conn_dispatch_incoming(struct smbXcli_conn *conn,
                                               TALLOC_CTX *tmp_mem,
                                               uint8_t *inbuf)
{
        struct tevent_req *req;
        struct smbXcli_req_state *state;
        NTSTATUS status;
        size_t num_pending;
        size_t i;
        uint8_t cmd;
        uint16_t mid;
        bool oplock_break;
        const uint8_t *inhdr = inbuf + NBT_HDR_SIZE;
        struct iovec *iov = NULL;
        int num_iov = 0;
        struct tevent_req **chain = NULL;
        size_t num_chained = 0;
        size_t num_responses = 0;

        if ((IVAL(inhdr, 0) != SMB_MAGIC) /* 0xFF"SMB" */
            && (SVAL(inhdr, 0) != 0x45ff)) /* 0xFF"E" */ {
                DEBUG(10, ("Got non-SMB PDU\n"));
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        /*
         * If we supported multiple encrytion contexts
         * here we'd look up based on tid.
         */
        if (common_encryption_on(conn->smb1.trans_enc)
            && (CVAL(inbuf, 0) == 0)) {
                uint16_t enc_ctx_num;

                status = get_enc_ctx_num(inbuf, &enc_ctx_num);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(10, ("get_enc_ctx_num returned %s\n",
                                   nt_errstr(status)));
                        return status;
                }

                if (enc_ctx_num != conn->smb1.trans_enc->enc_ctx_num) {
                        DEBUG(10, ("wrong enc_ctx %d, expected %d\n",
                                   enc_ctx_num,
                                   conn->smb1.trans_enc->enc_ctx_num));
                        return NT_STATUS_INVALID_HANDLE;
                }

                status = common_decrypt_buffer(conn->smb1.trans_enc,
                                               (char *)inbuf);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(10, ("common_decrypt_buffer returned %s\n",
                                   nt_errstr(status)));
                        return status;
                }
        }

        mid = SVAL(inhdr, HDR_MID);
        num_pending = talloc_array_length(conn->pending);

        for (i=0; i<num_pending; i++) {
                if (mid == smb1cli_req_mid(conn->pending[i])) {
                        break;
                }
        }
        if (i == num_pending) {
                /* Dump unexpected reply */
                return NT_STATUS_RETRY;
        }

        oplock_break = false;

        if (mid == 0xffff) {
                /*
                 * Paranoia checks that this is really an oplock break request.
                 */
                oplock_break = (smb_len_nbt(inbuf) == 51); /* hdr + 8 words */
                oplock_break &= ((CVAL(inhdr, HDR_FLG) & FLAG_REPLY) == 0);
                oplock_break &= (CVAL(inhdr, HDR_COM) == SMBlockingX);
                oplock_break &= (SVAL(inhdr, HDR_VWV+VWV(6)) == 0);
                oplock_break &= (SVAL(inhdr, HDR_VWV+VWV(7)) == 0);

                if (!oplock_break) {
                        /* Dump unexpected reply */
                        return NT_STATUS_RETRY;
                }
        }

        req = conn->pending[i];
        state = tevent_req_data(req, struct smbXcli_req_state);

        if (!oplock_break /* oplock breaks are not signed */
            && !smb_signing_check_pdu(conn->smb1.signing,
                                      inbuf, state->smb1.seqnum+1)) {
                DEBUG(10, ("cli_check_sign_mac failed\n"));
                return NT_STATUS_ACCESS_DENIED;
        }

        status = smb1cli_inbuf_parse_chain(inbuf, tmp_mem,
                                           &iov, &num_iov);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10,("smb1cli_inbuf_parse_chain - %s\n",
                          nt_errstr(status)));
                return status;
        }

        cmd = CVAL(inhdr, HDR_COM);
        status = smb1cli_pull_raw_error(inhdr);

        if (state->smb1.chained_requests == NULL) {
                if (num_iov != 3) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }

                smbXcli_req_unset_pending(req);

                state->smb1.recv_cmd = cmd;
                state->smb1.recv_status = status;
                state->inbuf = talloc_move(state->smb1.recv_iov, &inbuf);

                state->smb1.recv_iov[0] = iov[0];
                state->smb1.recv_iov[1] = iov[1];
                state->smb1.recv_iov[2] = iov[2];

                if (talloc_array_length(conn->pending) == 0) {
                        tevent_req_done(req);
                        return NT_STATUS_OK;
                }

                tevent_req_defer_callback(req, state->ev);
                tevent_req_done(req);
                return NT_STATUS_RETRY;
        }

        chain = talloc_move(tmp_mem, &state->smb1.chained_requests);
        num_chained = talloc_array_length(chain);
        num_responses = (num_iov - 1)/2;

        if (num_responses > num_chained) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        for (i=0; i<num_chained; i++) {
                size_t iov_idx = 1 + (i*2);
                struct iovec *cur = &iov[iov_idx];
                uint8_t *inbuf_ref;

                req = chain[i];
                state = tevent_req_data(req, struct smbXcli_req_state);

                smbXcli_req_unset_pending(req);

                /*
                 * as we finish multiple requests here
                 * we need to defer the callbacks as
                 * they could destroy our current stack state.
                 */
                tevent_req_defer_callback(req, state->ev);

                if (i >= num_responses) {
                        tevent_req_nterror(req, NT_STATUS_REQUEST_ABORTED);
                        continue;
                }

                state->smb1.recv_cmd = cmd;

                if (i == (num_responses - 1)) {
                        /*
                         * The last request in the chain gets the status
                         */
                        state->smb1.recv_status = status;
                } else {
                        cmd = CVAL(cur[0].iov_base, 0);
                        state->smb1.recv_status = NT_STATUS_OK;
                }

                state->inbuf = inbuf;

                /*
                 * Note: here we use talloc_reference() in a way
                 *       that does not expose it to the caller.
                 */
                inbuf_ref = talloc_reference(state->smb1.recv_iov, inbuf);
                if (tevent_req_nomem(inbuf_ref, req)) {
                        continue;
                }

                /* copy the related buffers */
                state->smb1.recv_iov[0] = iov[0];
                state->smb1.recv_iov[1] = cur[0];
                state->smb1.recv_iov[2] = cur[1];

                tevent_req_done(req);
        }

        return NT_STATUS_RETRY;
}

NTSTATUS smb1cli_req_recv(struct tevent_req *req,
                          TALLOC_CTX *mem_ctx,
                          struct iovec **piov,
                          uint8_t **phdr,
                          uint8_t *pwct,
                          uint16_t **pvwv,
                          uint32_t *pvwv_offset,
                          uint32_t *pnum_bytes,
                          uint8_t **pbytes,
                          uint32_t *pbytes_offset,
                          uint8_t **pinbuf,
                          const struct smb1cli_req_expected_response *expected,
                          size_t num_expected)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        NTSTATUS status = NT_STATUS_OK;
        struct iovec *recv_iov = NULL;
        uint8_t *hdr = NULL;
        uint8_t wct = 0;
        uint32_t vwv_offset = 0;
        uint16_t *vwv = NULL;
        uint32_t num_bytes = 0;
        uint32_t bytes_offset = 0;
        uint8_t *bytes = NULL;
        size_t i;
        bool found_status = false;
        bool found_size = false;

        if (piov != NULL) {
                *piov = NULL;
        }
        if (phdr != NULL) {
                *phdr = 0;
        }
        if (pwct != NULL) {
                *pwct = 0;
        }
        if (pvwv != NULL) {
                *pvwv = NULL;
        }
        if (pvwv_offset != NULL) {
                *pvwv_offset = 0;
        }
        if (pnum_bytes != NULL) {
                *pnum_bytes = 0;
        }
        if (pbytes != NULL) {
                *pbytes = NULL;
        }
        if (pbytes_offset != NULL) {
                *pbytes_offset = 0;
        }
        if (pinbuf != NULL) {
                *pinbuf = NULL;
        }

        if (state->inbuf != NULL) {
                recv_iov = state->smb1.recv_iov;
                hdr = (uint8_t *)recv_iov[0].iov_base;
                wct = recv_iov[1].iov_len/2;
                vwv = (uint16_t *)recv_iov[1].iov_base;
                vwv_offset = PTR_DIFF(vwv, hdr);
                num_bytes = recv_iov[2].iov_len;
                bytes = (uint8_t *)recv_iov[2].iov_base;
                bytes_offset = PTR_DIFF(bytes, hdr);
        }

        if (tevent_req_is_nterror(req, &status)) {
                for (i=0; i < num_expected; i++) {
                        if (NT_STATUS_EQUAL(status, expected[i].status)) {
                                found_status = true;
                                break;
                        }
                }

                if (found_status) {
                        return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
                }

                return status;
        }

        if (num_expected == 0) {
                found_status = true;
                found_size = true;
        }

        status = state->smb1.recv_status;

        for (i=0; i < num_expected; i++) {
                if (!NT_STATUS_EQUAL(status, expected[i].status)) {
                        continue;
                }

                found_status = true;
                if (expected[i].wct == 0) {
                        found_size = true;
                        break;
                }

                if (expected[i].wct == wct) {
                        found_size = true;
                        break;
                }
        }

        if (!found_status) {
                return status;
        }

        if (!found_size) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        if (piov != NULL) {
                *piov = talloc_move(mem_ctx, &recv_iov);
        }

        if (phdr != NULL) {
                *phdr = hdr;
        }
        if (pwct != NULL) {
                *pwct = wct;
        }
        if (pvwv != NULL) {
                *pvwv = vwv;
        }
        if (pvwv_offset != NULL) {
                *pvwv_offset = vwv_offset;
        }
        if (pnum_bytes != NULL) {
                *pnum_bytes = num_bytes;
        }
        if (pbytes != NULL) {
                *pbytes = bytes;
        }
        if (pbytes_offset != NULL) {
                *pbytes_offset = bytes_offset;
        }
        if (pinbuf != NULL) {
                *pinbuf = state->inbuf;
        }

        return status;
}

size_t smb1cli_req_wct_ofs(struct tevent_req **reqs, int num_reqs)
{
        size_t wct_ofs;
        int i;

        wct_ofs = HDR_WCT;

        for (i=0; i<num_reqs; i++) {
                struct smbXcli_req_state *state;
                state = tevent_req_data(reqs[i], struct smbXcli_req_state);
                wct_ofs += smbXcli_iov_len(state->smb1.iov+2,
                                           state->smb1.iov_count-2);
                wct_ofs = (wct_ofs + 3) & ~3;
        }
        return wct_ofs;
}

NTSTATUS smb1cli_req_chain_submit(struct tevent_req **reqs, int num_reqs)
{
        struct smbXcli_req_state *first_state =
                tevent_req_data(reqs[0],
                struct smbXcli_req_state);
        struct smbXcli_req_state *state;
        size_t wct_offset;
        size_t chain_padding = 0;
        int i, iovlen;
        struct iovec *iov = NULL;
        struct iovec *this_iov;
        NTSTATUS status;
        size_t nbt_len;

        if (num_reqs == 1) {
                return smb1cli_req_writev_submit(reqs[0], first_state,
                                                 first_state->smb1.iov,
                                                 first_state->smb1.iov_count);
        }

        iovlen = 0;
        for (i=0; i<num_reqs; i++) {
                if (!tevent_req_is_in_progress(reqs[i])) {
                        return NT_STATUS_INTERNAL_ERROR;
                }

                state = tevent_req_data(reqs[i], struct smbXcli_req_state);

                if (state->smb1.iov_count < 4) {
                        return NT_STATUS_INVALID_PARAMETER_MIX;
                }

                if (i == 0) {
                        /*
                         * The NBT and SMB header
                         */
                        iovlen += 2;
                } else {
                        /*
                         * Chain padding
                         */
                        iovlen += 1;
                }

                /*
                 * words and bytes
                 */
                iovlen += state->smb1.iov_count - 2;
        }

        iov = talloc_zero_array(first_state, struct iovec, iovlen);
        if (iov == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        first_state->smb1.chained_requests = (struct tevent_req **)talloc_memdup(
                first_state, reqs, sizeof(*reqs) * num_reqs);
        if (first_state->smb1.chained_requests == NULL) {
                TALLOC_FREE(iov);
                return NT_STATUS_NO_MEMORY;
        }

        wct_offset = HDR_WCT;
        this_iov = iov;

        for (i=0; i<num_reqs; i++) {
                size_t next_padding = 0;
                uint16_t *vwv;

                state = tevent_req_data(reqs[i], struct smbXcli_req_state);

                if (i < num_reqs-1) {
                        if (!smb1cli_is_andx_req(CVAL(state->smb1.hdr, HDR_COM))
                            || CVAL(state->smb1.hdr, HDR_WCT) < 2) {
                                TALLOC_FREE(iov);
                                TALLOC_FREE(first_state->smb1.chained_requests);
                                return NT_STATUS_INVALID_PARAMETER_MIX;
                        }
                }

                wct_offset += smbXcli_iov_len(state->smb1.iov+2,
                                              state->smb1.iov_count-2) + 1;
                if ((wct_offset % 4) != 0) {
                        next_padding = 4 - (wct_offset % 4);
                }
                wct_offset += next_padding;
                vwv = state->smb1.vwv;

                if (i < num_reqs-1) {
                        struct smbXcli_req_state *next_state =
                                tevent_req_data(reqs[i+1],
                                struct smbXcli_req_state);
                        SCVAL(vwv+0, 0, CVAL(next_state->smb1.hdr, HDR_COM));
                        SCVAL(vwv+0, 1, 0);
                        SSVAL(vwv+1, 0, wct_offset);
                } else if (smb1cli_is_andx_req(CVAL(state->smb1.hdr, HDR_COM))) {
                        /* properly end the chain */
                        SCVAL(vwv+0, 0, 0xff);
                        SCVAL(vwv+0, 1, 0xff);
                        SSVAL(vwv+1, 0, 0);
                }

                if (i == 0) {
                        /*
                         * The NBT and SMB header
                         */
                        this_iov[0] = state->smb1.iov[0];
                        this_iov[1] = state->smb1.iov[1];
                        this_iov += 2;
                } else {
                        /*
                         * This one is a bit subtle. We have to add
                         * chain_padding bytes between the requests, and we
                         * have to also include the wct field of the
                         * subsequent requests. We use the subsequent header
                         * for the padding, it contains the wct field in its
                         * last byte.
                         */
                        this_iov[0].iov_len = chain_padding+1;
                        this_iov[0].iov_base = (void *)&state->smb1.hdr[
                                sizeof(state->smb1.hdr) - this_iov[0].iov_len];
                        memset(this_iov[0].iov_base, 0, this_iov[0].iov_len-1);
                        this_iov += 1;
                }

                /*
                 * copy the words and bytes
                 */
                memcpy(this_iov, state->smb1.iov+2,
                       sizeof(struct iovec) * (state->smb1.iov_count-2));
                this_iov += state->smb1.iov_count - 2;
                chain_padding = next_padding;
        }

        nbt_len = smbXcli_iov_len(&iov[1], iovlen-1);
        if (nbt_len > first_state->conn->smb1.max_xmit) {
                TALLOC_FREE(iov);
                TALLOC_FREE(first_state->smb1.chained_requests);
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }

        status = smb1cli_req_writev_submit(reqs[0], first_state, iov, iovlen);
        if (!NT_STATUS_IS_OK(status)) {
                TALLOC_FREE(iov);
                TALLOC_FREE(first_state->smb1.chained_requests);
                return status;
        }

        return NT_STATUS_OK;
}

bool smbXcli_conn_has_async_calls(struct smbXcli_conn *conn)
{
        return ((tevent_queue_length(conn->outgoing) != 0)
                || (talloc_array_length(conn->pending) != 0));
}

uint32_t smb2cli_conn_server_capabilities(struct smbXcli_conn *conn)
{
        return conn->smb2.server.capabilities;
}

uint16_t smb2cli_conn_server_security_mode(struct smbXcli_conn *conn)
{
        return conn->smb2.server.security_mode;
}

uint32_t smb2cli_conn_max_trans_size(struct smbXcli_conn *conn)
{
        return conn->smb2.server.max_trans_size;
}

uint32_t smb2cli_conn_max_read_size(struct smbXcli_conn *conn)
{
        return conn->smb2.server.max_read_size;
}

uint32_t smb2cli_conn_max_write_size(struct smbXcli_conn *conn)
{
        return conn->smb2.server.max_write_size;
}

void smb2cli_conn_set_max_credits(struct smbXcli_conn *conn,
                                  uint16_t max_credits)
{
        conn->smb2.max_credits = max_credits;
}

struct tevent_req *smb2cli_req_create(TALLOC_CTX *mem_ctx,
                                      struct tevent_context *ev,
                                      struct smbXcli_conn *conn,
                                      uint16_t cmd,
                                      uint32_t additional_flags,
                                      uint32_t clear_flags,
                                      uint32_t timeout_msec,
                                      uint32_t pid,
                                      uint32_t tid,
                                      uint64_t uid,
                                      const uint8_t *fixed,
                                      uint16_t fixed_len,
                                      const uint8_t *dyn,
                                      uint32_t dyn_len)
{
        struct tevent_req *req;
        struct smbXcli_req_state *state;
        uint32_t flags = 0;

        req = tevent_req_create(mem_ctx, &state,
                                struct smbXcli_req_state);
        if (req == NULL) {
                return NULL;
        }

        state->ev = ev;
        state->conn = conn;

        state->smb2.recv_iov = talloc_zero_array(state, struct iovec, 3);
        if (state->smb2.recv_iov == NULL) {
                TALLOC_FREE(req);
                return NULL;
        }

        flags |= additional_flags;
        flags &= ~clear_flags;

        state->smb2.fixed = fixed;
        state->smb2.fixed_len = fixed_len;
        state->smb2.dyn = dyn;
        state->smb2.dyn_len = dyn_len;

        SIVAL(state->smb2.hdr, SMB2_HDR_PROTOCOL_ID,    SMB2_MAGIC);
        SSVAL(state->smb2.hdr, SMB2_HDR_LENGTH,         SMB2_HDR_BODY);
        SSVAL(state->smb2.hdr, SMB2_HDR_OPCODE,         cmd);
        SIVAL(state->smb2.hdr, SMB2_HDR_FLAGS,          flags);
        SIVAL(state->smb2.hdr, SMB2_HDR_PID,            pid);
        SIVAL(state->smb2.hdr, SMB2_HDR_TID,            tid);
        SBVAL(state->smb2.hdr, SMB2_HDR_SESSION_ID,     uid);

        switch (cmd) {
        case SMB2_OP_CANCEL:
                state->one_way = true;
                break;
        case SMB2_OP_BREAK:
                /*
                 * If this is a dummy request, it will have
                 * UINT64_MAX as message id.
                 * If we send on break acknowledgement,
                 * this gets overwritten later.
                 */
                SBVAL(state->smb2.hdr, SMB2_HDR_MESSAGE_ID, UINT64_MAX);
                break;
        }

        if (timeout_msec > 0) {
                struct timeval endtime;

                endtime = timeval_current_ofs_msec(timeout_msec);
                if (!tevent_req_set_endtime(req, ev, endtime)) {
                        return req;
                }
        }

        return req;
}

static void smb2cli_writev_done(struct tevent_req *subreq);
static NTSTATUS smb2cli_conn_dispatch_incoming(struct smbXcli_conn *conn,
                                               TALLOC_CTX *tmp_mem,
                                               uint8_t *inbuf);

NTSTATUS smb2cli_req_compound_submit(struct tevent_req **reqs,
                                     int num_reqs)
{
        struct smbXcli_req_state *state;
        struct tevent_req *subreq;
        struct iovec *iov;
        int i, num_iov, nbt_len;

        /*
         * 1 for the nbt length
         * per request: HDR, fixed, dyn, padding
         * -1 because the last one does not need padding
         */

        iov = talloc_array(reqs[0], struct iovec, 1 + 4*num_reqs - 1);
        if (iov == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        num_iov = 1;
        nbt_len = 0;

        for (i=0; i<num_reqs; i++) {
                size_t reqlen;
                bool ret;
                uint64_t avail;
                uint16_t charge;
                uint16_t credits;
                uint64_t mid;

                if (!tevent_req_is_in_progress(reqs[i])) {
                        return NT_STATUS_INTERNAL_ERROR;
                }

                state = tevent_req_data(reqs[i], struct smbXcli_req_state);

                if (!smbXcli_conn_is_connected(state->conn)) {
                        return NT_STATUS_CONNECTION_DISCONNECTED;
                }

                if ((state->conn->protocol != PROTOCOL_NONE) &&
                    (state->conn->protocol < PROTOCOL_SMB2_02)) {
                        return NT_STATUS_REVISION_MISMATCH;
                }

                avail = UINT64_MAX - state->conn->smb2.mid;
                if (avail < 1) {
                        return NT_STATUS_CONNECTION_ABORTED;
                }

                if (state->conn->smb2.server.capabilities & SMB2_CAP_LARGE_MTU) {
                        charge = (MAX(state->smb2.dyn_len, 1) - 1)/ 65536 + 1;
                } else {
                        charge = 1;
                }

                charge = MAX(state->smb2.credit_charge, charge);

                avail = MIN(avail, state->conn->smb2.cur_credits);
                if (avail < charge) {
                        return NT_STATUS_INTERNAL_ERROR;
                }

                credits = 0;
                if (state->conn->smb2.max_credits > state->conn->smb2.cur_credits) {
                        credits = state->conn->smb2.max_credits -
                                  state->conn->smb2.cur_credits;
                }
                if (state->conn->smb2.max_credits >= state->conn->smb2.cur_credits) {
                        credits += 1;
                }

                mid = state->conn->smb2.mid;
                state->conn->smb2.mid += charge;
                state->conn->smb2.cur_credits -= charge;

                if (state->conn->smb2.server.capabilities & SMB2_CAP_LARGE_MTU) {
                        SSVAL(state->smb2.hdr, SMB2_HDR_CREDIT_CHARGE, charge);
                }
                SSVAL(state->smb2.hdr, SMB2_HDR_CREDIT, credits);
                SBVAL(state->smb2.hdr, SMB2_HDR_MESSAGE_ID, mid);

                iov[num_iov].iov_base = state->smb2.hdr;
                iov[num_iov].iov_len  = sizeof(state->smb2.hdr);
                num_iov += 1;

                iov[num_iov].iov_base = discard_const(state->smb2.fixed);
                iov[num_iov].iov_len  = state->smb2.fixed_len;
                num_iov += 1;

                if (state->smb2.dyn != NULL) {
                        iov[num_iov].iov_base = discard_const(state->smb2.dyn);
                        iov[num_iov].iov_len  = state->smb2.dyn_len;
                        num_iov += 1;
                }

                reqlen  = sizeof(state->smb2.hdr);
                reqlen += state->smb2.fixed_len;
                reqlen += state->smb2.dyn_len;

                if (i < num_reqs-1) {
                        if ((reqlen % 8) > 0) {
                                uint8_t pad = 8 - (reqlen % 8);
                                iov[num_iov].iov_base = state->smb2.pad;
                                iov[num_iov].iov_len = pad;
                                num_iov += 1;
                                reqlen += pad;
                        }
                        SIVAL(state->smb2.hdr, SMB2_HDR_NEXT_COMMAND, reqlen);
                }
                nbt_len += reqlen;

                ret = smbXcli_req_set_pending(reqs[i]);
                if (!ret) {
                        return NT_STATUS_NO_MEMORY;
                }
        }

        /*
         * TODO: Do signing here
         */

        state = tevent_req_data(reqs[0], struct smbXcli_req_state);
        _smb_setlen_tcp(state->length_hdr, nbt_len);
        iov[0].iov_base = state->length_hdr;
        iov[0].iov_len  = sizeof(state->length_hdr);

        if (state->conn->dispatch_incoming == NULL) {
                state->conn->dispatch_incoming = smb2cli_conn_dispatch_incoming;
        }

        subreq = writev_send(state, state->ev, state->conn->outgoing,
                             state->conn->fd, false, iov, num_iov);
        if (subreq == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        tevent_req_set_callback(subreq, smb2cli_writev_done, reqs[0]);
        return NT_STATUS_OK;
}

void smb2cli_req_set_credit_charge(struct tevent_req *req, uint16_t charge)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);

        state->smb2.credit_charge = charge;
}

struct tevent_req *smb2cli_req_send(TALLOC_CTX *mem_ctx,
                                    struct tevent_context *ev,
                                    struct smbXcli_conn *conn,
                                    uint16_t cmd,
                                    uint32_t additional_flags,
                                    uint32_t clear_flags,
                                    uint32_t timeout_msec,
                                    uint32_t pid,
                                    uint32_t tid,
                                    uint64_t uid,
                                    const uint8_t *fixed,
                                    uint16_t fixed_len,
                                    const uint8_t *dyn,
                                    uint32_t dyn_len)
{
        struct tevent_req *req;
        NTSTATUS status;

        req = smb2cli_req_create(mem_ctx, ev, conn, cmd,
                                 additional_flags, clear_flags,
                                 timeout_msec,
                                 pid, tid, uid,
                                 fixed, fixed_len, dyn, dyn_len);
        if (req == NULL) {
                return NULL;
        }
        if (!tevent_req_is_in_progress(req)) {
                return tevent_req_post(req, ev);
        }
        status = smb2cli_req_compound_submit(&req, 1);
        if (tevent_req_nterror(req, status)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void smb2cli_writev_done(struct tevent_req *subreq)
{
        struct tevent_req *req =
                tevent_req_callback_data(subreq,
                struct tevent_req);
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        ssize_t nwritten;
        int err;

        nwritten = writev_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (nwritten == -1) {
                /* here, we need to notify all pending requests */
                NTSTATUS status = map_nt_error_from_unix_common(err);
                smbXcli_conn_disconnect(state->conn, status);
                return;
        }
}

static NTSTATUS smb2cli_inbuf_parse_compound(uint8_t *buf, TALLOC_CTX *mem_ctx,
                                             struct iovec **piov, int *pnum_iov)
{
        struct iovec *iov;
        int num_iov;
        size_t buflen;
        size_t taken;
        uint8_t *first_hdr;

        num_iov = 0;

        iov = talloc_array(mem_ctx, struct iovec, num_iov);
        if (iov == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        buflen = smb_len_tcp(buf);
        taken = 0;
        first_hdr = buf + NBT_HDR_SIZE;

        while (taken < buflen) {
                size_t len = buflen - taken;
                uint8_t *hdr = first_hdr + taken;
                struct iovec *cur;
                size_t full_size;
                size_t next_command_ofs;
                uint16_t body_size;
                struct iovec *iov_tmp;

                /*
                 * We need the header plus the body length field
                 */

                if (len < SMB2_HDR_BODY + 2) {
                        DEBUG(10, ("%d bytes left, expected at least %d\n",
                                   (int)len, SMB2_HDR_BODY));
                        goto inval;
                }
                if (IVAL(hdr, 0) != SMB2_MAGIC) {
                        DEBUG(10, ("Got non-SMB2 PDU: %x\n",
                                   IVAL(hdr, 0)));
                        goto inval;
                }
                if (SVAL(hdr, 4) != SMB2_HDR_BODY) {
                        DEBUG(10, ("Got HDR len %d, expected %d\n",
                                   SVAL(hdr, 4), SMB2_HDR_BODY));
                        goto inval;
                }

                full_size = len;
                next_command_ofs = IVAL(hdr, SMB2_HDR_NEXT_COMMAND);
                body_size = SVAL(hdr, SMB2_HDR_BODY);

                if (next_command_ofs != 0) {
                        if (next_command_ofs < (SMB2_HDR_BODY + 2)) {
                                goto inval;
                        }
                        if (next_command_ofs > full_size) {
                                goto inval;
                        }
                        full_size = next_command_ofs;
                }
                if (body_size < 2) {
                        goto inval;
                }
                body_size &= 0xfffe;

                if (body_size > (full_size - SMB2_HDR_BODY)) {
                        goto inval;
                }

                iov_tmp = talloc_realloc(mem_ctx, iov, struct iovec,
                                         num_iov + 3);
                if (iov_tmp == NULL) {
                        TALLOC_FREE(iov);
                        return NT_STATUS_NO_MEMORY;
                }
                iov = iov_tmp;
                cur = &iov[num_iov];
                num_iov += 3;

                cur[0].iov_base = hdr;
                cur[0].iov_len  = SMB2_HDR_BODY;
                cur[1].iov_base = hdr + SMB2_HDR_BODY;
                cur[1].iov_len  = body_size;
                cur[2].iov_base = hdr + SMB2_HDR_BODY + body_size;
                cur[2].iov_len  = full_size - (SMB2_HDR_BODY + body_size);

                taken += full_size;
        }

        *piov = iov;
        *pnum_iov = num_iov;
        return NT_STATUS_OK;

inval:
        TALLOC_FREE(iov);
        return NT_STATUS_INVALID_NETWORK_RESPONSE;
}

static struct tevent_req *smb2cli_conn_find_pending(struct smbXcli_conn *conn,
                                                    uint64_t mid)
{
        size_t num_pending = talloc_array_length(conn->pending);
        size_t i;

        for (i=0; i<num_pending; i++) {
                struct tevent_req *req = conn->pending[i];
                struct smbXcli_req_state *state =
                        tevent_req_data(req,
                        struct smbXcli_req_state);

                if (mid == BVAL(state->smb2.hdr, SMB2_HDR_MESSAGE_ID)) {
                        return req;
                }
        }
        return NULL;
}

static NTSTATUS smb2cli_conn_dispatch_incoming(struct smbXcli_conn *conn,
                                               TALLOC_CTX *tmp_mem,
                                               uint8_t *inbuf)
{
        struct tevent_req *req;
        struct smbXcli_req_state *state = NULL;
        struct iovec *iov;
        int i, num_iov;
        NTSTATUS status;
        bool defer = true;

        status = smb2cli_inbuf_parse_compound(inbuf, tmp_mem,
                                              &iov, &num_iov);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        for (i=0; i<num_iov; i+=3) {
                uint8_t *inbuf_ref = NULL;
                struct iovec *cur = &iov[i];
                uint8_t *inhdr = (uint8_t *)cur[0].iov_base;
                uint16_t opcode = SVAL(inhdr, SMB2_HDR_OPCODE);
                uint32_t flags = IVAL(inhdr, SMB2_HDR_FLAGS);
                uint64_t mid = BVAL(inhdr, SMB2_HDR_MESSAGE_ID);
                uint16_t req_opcode;
                uint16_t credits = SVAL(inhdr, SMB2_HDR_CREDIT);
                uint32_t new_credits;

                new_credits = conn->smb2.cur_credits;
                new_credits += credits;
                if (new_credits > UINT16_MAX) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }
                conn->smb2.cur_credits += credits;

                req = smb2cli_conn_find_pending(conn, mid);
                if (req == NULL) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }
                state = tevent_req_data(req, struct smbXcli_req_state);

                req_opcode = SVAL(state->smb2.hdr, SMB2_HDR_OPCODE);
                if (opcode != req_opcode) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }

                if (!(flags & SMB2_HDR_FLAG_REDIRECT)) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }

                status = NT_STATUS(IVAL(inhdr, SMB2_HDR_STATUS));
                if ((flags & SMB2_HDR_FLAG_ASYNC) &&
                    NT_STATUS_EQUAL(status, STATUS_PENDING)) {
                        uint32_t req_flags = IVAL(state->smb2.hdr, SMB2_HDR_FLAGS);
                        uint64_t async_id = BVAL(inhdr, SMB2_HDR_ASYNC_ID);

                        req_flags |= SMB2_HDR_FLAG_ASYNC;
                        SBVAL(state->smb2.hdr, SMB2_HDR_FLAGS, req_flags);
                        SBVAL(state->smb2.hdr, SMB2_HDR_ASYNC_ID, async_id);
                        continue;
                }

                smbXcli_req_unset_pending(req);

                /*
                 * There might be more than one response
                 * we need to defer the notifications
                 */
                if ((num_iov == 4) && (talloc_array_length(conn->pending) == 0)) {
                        defer = false;
                }

                if (defer) {
                        tevent_req_defer_callback(req, state->ev);
                }

                /*
                 * Note: here we use talloc_reference() in a way
                 *       that does not expose it to the caller.
                 */
                inbuf_ref = talloc_reference(state->smb2.recv_iov, inbuf);
                if (tevent_req_nomem(inbuf_ref, req)) {
                        continue;
                }

                /* copy the related buffers */
                state->smb2.recv_iov[0] = cur[0];
                state->smb2.recv_iov[1] = cur[1];
                state->smb2.recv_iov[2] = cur[2];

                tevent_req_done(req);
        }

        if (defer) {
                return NT_STATUS_RETRY;
        }

        return NT_STATUS_OK;
}

NTSTATUS smb2cli_req_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                          struct iovec **piov,
                          const struct smb2cli_req_expected_response *expected,
                          size_t num_expected)
{
        struct smbXcli_req_state *state =
                tevent_req_data(req,
                struct smbXcli_req_state);
        NTSTATUS status;
        size_t body_size;
        bool found_status = false;
        bool found_size = false;
        size_t i;

        if (piov != NULL) {
                *piov = NULL;
        }

        if (tevent_req_is_nterror(req, &status)) {
                for (i=0; i < num_expected; i++) {
                        if (NT_STATUS_EQUAL(status, expected[i].status)) {
                                found_status = true;
                                break;
                        }
                }

                if (found_status) {
                        return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
                }

                return status;
        }

        if (num_expected == 0) {
                found_status = true;
                found_size = true;
        }

        status = NT_STATUS(IVAL(state->smb2.recv_iov[0].iov_base, SMB2_HDR_STATUS));
        body_size = SVAL(state->smb2.recv_iov[1].iov_base, 0);

        for (i=0; i < num_expected; i++) {
                if (!NT_STATUS_EQUAL(status, expected[i].status)) {
                        continue;
                }

                found_status = true;
                if (expected[i].body_size == 0) {
                        found_size = true;
                        break;
                }

                if (expected[i].body_size == body_size) {
                        found_size = true;
                        break;
                }
        }

        if (!found_status) {
                return status;
        }

        if (!found_size) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        if (piov != NULL) {
                *piov = talloc_move(mem_ctx, &state->smb2.recv_iov);
        }

        return status;
}

static const struct {
        enum protocol_types proto;
        const char *smb1_name;
} smb1cli_prots[] = {
        {PROTOCOL_CORE,         "PC NETWORK PROGRAM 1.0"},
        {PROTOCOL_COREPLUS,     "MICROSOFT NETWORKS 1.03"},
        {PROTOCOL_LANMAN1,      "MICROSOFT NETWORKS 3.0"},
        {PROTOCOL_LANMAN1,      "LANMAN1.0"},
        {PROTOCOL_LANMAN2,      "LM1.2X002"},
        {PROTOCOL_LANMAN2,      "DOS LANMAN2.1"},
        {PROTOCOL_LANMAN2,      "LANMAN2.1"},
        {PROTOCOL_LANMAN2,      "Samba"},
        {PROTOCOL_NT1,          "NT LANMAN 1.0"},
        {PROTOCOL_NT1,          "NT LM 0.12"},
        {PROTOCOL_SMB2_02,      "SMB 2.002"},
        {PROTOCOL_SMB2_10,      "SMB 2.???"},
};

static const struct {
        enum protocol_types proto;
        uint16_t smb2_dialect;
} smb2cli_prots[] = {
        {PROTOCOL_SMB2_02,      SMB2_DIALECT_REVISION_202},
        {PROTOCOL_SMB2_10,      SMB2_DIALECT_REVISION_210},
        {PROTOCOL_SMB2_22,      SMB2_DIALECT_REVISION_222},
};

struct smbXcli_negprot_state {
        struct smbXcli_conn *conn;
        struct tevent_context *ev;
        uint32_t timeout_msec;
        enum protocol_types min_protocol;
        enum protocol_types max_protocol;

        struct {
                uint8_t fixed[36];
                uint8_t dyn[ARRAY_SIZE(smb2cli_prots)*2];
        } smb2;
};

static void smbXcli_negprot_invalid_done(struct tevent_req *subreq);
static struct tevent_req *smbXcli_negprot_smb1_subreq(struct smbXcli_negprot_state *state);
static void smbXcli_negprot_smb1_done(struct tevent_req *subreq);
static struct tevent_req *smbXcli_negprot_smb2_subreq(struct smbXcli_negprot_state *state);
static void smbXcli_negprot_smb2_done(struct tevent_req *subreq);
static NTSTATUS smbXcli_negprot_dispatch_incoming(struct smbXcli_conn *conn,
                                                  TALLOC_CTX *frame,
                                                  uint8_t *inbuf);

struct tevent_req *smbXcli_negprot_send(TALLOC_CTX *mem_ctx,
                                        struct tevent_context *ev,
                                        struct smbXcli_conn *conn,
                                        uint32_t timeout_msec,
                                        enum protocol_types min_protocol,
                                        enum protocol_types max_protocol)
{
        struct tevent_req *req, *subreq;
        struct smbXcli_negprot_state *state;

        req = tevent_req_create(mem_ctx, &state,
                                struct smbXcli_negprot_state);
        if (req == NULL) {
                return NULL;
        }
        state->conn = conn;
        state->ev = ev;
        state->timeout_msec = timeout_msec;
        state->min_protocol = min_protocol;
        state->max_protocol = max_protocol;

        if (min_protocol == PROTOCOL_NONE) {
                tevent_req_nterror(req, NT_STATUS_INVALID_PARAMETER_MIX);
                return tevent_req_post(req, ev);
        }

        if (max_protocol == PROTOCOL_NONE) {
                tevent_req_nterror(req, NT_STATUS_INVALID_PARAMETER_MIX);
                return tevent_req_post(req, ev);
        }

        if (min_protocol > max_protocol) {
                tevent_req_nterror(req, NT_STATUS_INVALID_PARAMETER_MIX);
                return tevent_req_post(req, ev);
        }

        if ((min_protocol < PROTOCOL_SMB2_02) &&
            (max_protocol < PROTOCOL_SMB2_02)) {
                /*
                 * SMB1 only...
                 */
                conn->dispatch_incoming = smb1cli_conn_dispatch_incoming;

                subreq = smbXcli_negprot_smb1_subreq(state);
                if (tevent_req_nomem(subreq, req)) {
                        return tevent_req_post(req, ev);
                }
                tevent_req_set_callback(subreq, smbXcli_negprot_smb1_done, req);
                return req;
        }

        if ((min_protocol >= PROTOCOL_SMB2_02) &&
            (max_protocol >= PROTOCOL_SMB2_02)) {
                /*
                 * SMB2 only...
                 */
                conn->dispatch_incoming = smb2cli_conn_dispatch_incoming;

                subreq = smbXcli_negprot_smb2_subreq(state);
                if (tevent_req_nomem(subreq, req)) {
                        return tevent_req_post(req, ev);
                }
                tevent_req_set_callback(subreq, smbXcli_negprot_smb2_done, req);
                return req;
        }

        /*
         * We send an SMB1 negprot with the SMB2 dialects
         * and expect a SMB1 or a SMB2 response.
         *
         * smbXcli_negprot_dispatch_incoming() will fix the
         * callback to match protocol of the response.
         */
        conn->dispatch_incoming = smbXcli_negprot_dispatch_incoming;

        subreq = smbXcli_negprot_smb1_subreq(state);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, smbXcli_negprot_invalid_done, req);
        return req;
}

static void smbXcli_negprot_invalid_done(struct tevent_req *subreq)
{
        struct tevent_req *req =
                tevent_req_callback_data(subreq,
                struct tevent_req);
        NTSTATUS status;

        /*
         * we just want the low level error
         */
        status = tevent_req_simple_recv_ntstatus(subreq);
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        /* this should never happen */
        tevent_req_nterror(req, NT_STATUS_INTERNAL_ERROR);
}

static struct tevent_req *smbXcli_negprot_smb1_subreq(struct smbXcli_negprot_state *state)
{
        size_t i;
        DATA_BLOB bytes = data_blob_null;
        uint8_t flags;
        uint16_t flags2;

        /* setup the protocol strings */
        for (i=0; i < ARRAY_SIZE(smb1cli_prots); i++) {
                uint8_t c = 2;
                bool ok;

                if (smb1cli_prots[i].proto < state->min_protocol) {
                        continue;
                }

                if (smb1cli_prots[i].proto > state->max_protocol) {
                        continue;
                }

                ok = data_blob_append(state, &bytes, &c, sizeof(c));
                if (!ok) {
                        return NULL;
                }

                /*
                 * We now it is already ascii and
                 * we want NULL termination.
                 */
                ok = data_blob_append(state, &bytes,
                                      smb1cli_prots[i].smb1_name,
                                      strlen(smb1cli_prots[i].smb1_name)+1);
                if (!ok) {
                        return NULL;
                }
        }

        smb1cli_req_flags(state->max_protocol,
                          state->conn->smb1.client.capabilities,
                          SMBnegprot,
                          0, 0, &flags,
                          0, 0, &flags2);

        return smb1cli_req_send(state, state->ev, state->conn,
                                SMBnegprot,
                                flags, ~flags,
                                flags2, ~flags2,
                                state->timeout_msec,
                                0xFFFE, 0, 0, /* pid, tid, uid */
                                0, NULL, /* wct, vwv */
                                bytes.length, bytes.data);
}

static void smbXcli_negprot_smb1_done(struct tevent_req *subreq)
{
        struct tevent_req *req =
                tevent_req_callback_data(subreq,
                struct tevent_req);
        struct smbXcli_negprot_state *state =
                tevent_req_data(req,
                struct smbXcli_negprot_state);
        struct smbXcli_conn *conn = state->conn;
        struct iovec *recv_iov = NULL;
        uint8_t *inhdr;
        uint8_t wct;
        uint16_t *vwv;
        uint32_t num_bytes;
        uint8_t *bytes;
        NTSTATUS status;
        uint16_t protnum;
        size_t i;
        size_t num_prots = 0;
        uint8_t flags;
        uint32_t client_capabilities = conn->smb1.client.capabilities;
        uint32_t both_capabilities;
        uint32_t server_capabilities = 0;
        uint32_t capabilities;
        uint32_t client_max_xmit = conn->smb1.client.max_xmit;
        uint32_t server_max_xmit = 0;
        uint32_t max_xmit;
        uint32_t server_max_mux = 0;
        uint16_t server_security_mode = 0;
        uint32_t server_session_key = 0;
        bool server_readbraw = false;
        bool server_writebraw = false;
        bool server_lockread = false;
        bool server_writeunlock = false;
        struct GUID server_guid = GUID_zero();
        DATA_BLOB server_gss_blob = data_blob_null;
        uint8_t server_challenge[8];
        char *server_workgroup = NULL;
        char *server_name = NULL;
        int server_time_zone = 0;
        NTTIME server_system_time = 0;
        static const struct smb1cli_req_expected_response expected[] = {
        {
                .status = NT_STATUS_OK,
                .wct = 0x11, /* NT1 */
        },
        {
                .status = NT_STATUS_OK,
                .wct = 0x0D, /* LM */
        },
        {
                .status = NT_STATUS_OK,
                .wct = 0x01, /* CORE */
        }
        };

        ZERO_STRUCT(server_challenge);

        status = smb1cli_req_recv(subreq, state,
                                  &recv_iov,
                                  &inhdr,
                                  &wct,
                                  &vwv,
                                  NULL, /* pvwv_offset */
                                  &num_bytes,
                                  &bytes,
                                  NULL, /* pbytes_offset */
                                  NULL, /* pinbuf */
                                  expected, ARRAY_SIZE(expected));
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        flags = CVAL(inhdr, HDR_FLG);

        protnum = SVAL(vwv, 0);

        for (i=0; i < ARRAY_SIZE(smb1cli_prots); i++) {
                if (smb1cli_prots[i].proto < state->min_protocol) {
                        continue;
                }

                if (smb1cli_prots[i].proto > state->max_protocol) {
                        continue;
                }

                if (protnum != num_prots) {
                        num_prots++;
                        continue;
                }

                conn->protocol = smb1cli_prots[i].proto;
                break;
        }

        if (conn->protocol == PROTOCOL_NONE) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        if ((conn->protocol < PROTOCOL_NT1) && conn->mandatory_signing) {
                DEBUG(0,("smbXcli_negprot: SMB signing is mandatory "
                         "and the selected protocol level doesn't support it.\n"));
                tevent_req_nterror(req, NT_STATUS_ACCESS_DENIED);
                return;
        }

        if (flags & FLAG_SUPPORT_LOCKREAD) {
                server_lockread = true;
                server_writeunlock = true;
        }

        if (conn->protocol >= PROTOCOL_NT1) {
                const char *client_signing = NULL;
                bool server_mandatory = false;
                bool server_allowed = false;
                const char *server_signing = NULL;
                bool ok;
                uint8_t key_len;

                if (wct != 0x11) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                /* NT protocol */
                server_security_mode = CVAL(vwv + 1, 0);
                server_max_mux = SVAL(vwv + 1, 1);
                server_max_xmit = IVAL(vwv + 3, 1);
                server_session_key = IVAL(vwv + 7, 1);
                server_time_zone = SVALS(vwv + 15, 1);
                server_time_zone *= 60;
                /* this time arrives in real GMT */
                server_system_time = BVAL(vwv + 11, 1);
                server_capabilities = IVAL(vwv + 9, 1);

                key_len = CVAL(vwv + 16, 1);

                if (server_capabilities & CAP_RAW_MODE) {
                        server_readbraw = true;
                        server_writebraw = true;
                }
                if (server_capabilities & CAP_LOCK_AND_READ) {
                        server_lockread = true;
                }

                if (server_capabilities & CAP_EXTENDED_SECURITY) {
                        DATA_BLOB blob1, blob2;

                        if (num_bytes < 16) {
                                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                                return;
                        }

                        blob1 = data_blob_const(bytes, 16);
                        status = GUID_from_data_blob(&blob1, &server_guid);
                        if (tevent_req_nterror(req, status)) {
                                return;
                        }

                        blob1 = data_blob_const(bytes+16, num_bytes-16);
                        blob2 = data_blob_dup_talloc(state, blob1);
                        if (blob1.length > 0 &&
                            tevent_req_nomem(blob2.data, req)) {
                                return;
                        }
                        server_gss_blob = blob2;
                } else {
                        DATA_BLOB blob1, blob2;

                        if (num_bytes < key_len) {
                                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                                return;
                        }

                        if (key_len != 0 && key_len != 8) {
                                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                                return;
                        }

                        if (key_len == 8) {
                                memcpy(server_challenge, bytes, 8);
                        }

                        blob1 = data_blob_const(bytes+key_len, num_bytes-key_len);
                        blob2 = data_blob_const(bytes+key_len, num_bytes-key_len);
                        if (blob1.length > 0) {
                                size_t len;

                                len = utf16_len_n(blob1.data,
                                                  blob1.length);
                                blob1.length = len;

                                ok = convert_string_talloc(state,
                                                           CH_UTF16LE,
                                                           CH_UNIX,
                                                           blob1.data,
                                                           blob1.length,
                                                           &server_workgroup,
                                                           &len);
                                if (!ok) {
                                        status = map_nt_error_from_unix_common(errno);
                                        tevent_req_nterror(req, status);
                                        return;
                                }
                        }

                        blob2.data += blob1.length;
                        blob2.length -= blob1.length;
                        if (blob2.length > 0) {
                                size_t len;

                                len = utf16_len_n(blob1.data,
                                                  blob1.length);
                                blob1.length = len;

                                ok = convert_string_talloc(state,
                                                           CH_UTF16LE,
                                                           CH_UNIX,
                                                           blob2.data,
                                                           blob2.length,
                                                           &server_name,
                                                           &len);
                                if (!ok) {
                                        status = map_nt_error_from_unix_common(errno);
                                        tevent_req_nterror(req, status);
                                        return;
                                }
                        }
                }

                client_signing = "disabled";
                if (conn->allow_signing) {
                        client_signing = "allowed";
                }
                if (conn->mandatory_signing) {
                        client_signing = "required";
                }

                server_signing = "not supported";
                if (server_security_mode & NEGOTIATE_SECURITY_SIGNATURES_ENABLED) {
                        server_signing = "supported";
                        server_allowed = true;
                }
                if (server_security_mode & NEGOTIATE_SECURITY_SIGNATURES_REQUIRED) {
                        server_signing = "required";
                        server_mandatory = true;
                }

                ok = smb_signing_set_negotiated(conn->smb1.signing,
                                                server_allowed,
                                                server_mandatory);
                if (!ok) {
                        DEBUG(1,("cli_negprot: SMB signing is required, "
                                 "but client[%s] and server[%s] mismatch\n",
                                 client_signing, server_signing));
                        tevent_req_nterror(req, NT_STATUS_ACCESS_DENIED);
                        return;
                }

        } else if (conn->protocol >= PROTOCOL_LANMAN1) {
                DATA_BLOB blob1;
                uint8_t key_len;
                time_t t;

                if (wct != 0x0D) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                server_security_mode = SVAL(vwv + 1, 0);
                server_max_xmit = SVAL(vwv + 2, 0);
                server_max_mux = SVAL(vwv + 3, 0);
                server_readbraw = ((SVAL(vwv + 5, 0) & 0x1) != 0);
                server_writebraw = ((SVAL(vwv + 5, 0) & 0x2) != 0);
                server_session_key = IVAL(vwv + 6, 0);
                server_time_zone = SVALS(vwv + 10, 0);
                server_time_zone *= 60;
                /* this time is converted to GMT by make_unix_date */
                t = pull_dos_date((const uint8_t *)(vwv + 8), server_time_zone);
                unix_to_nt_time(&server_system_time, t);
                key_len = SVAL(vwv + 11, 0);

                if (num_bytes < key_len) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                if (key_len != 0 && key_len != 8) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                if (key_len == 8) {
                        memcpy(server_challenge, bytes, 8);
                }

                blob1 = data_blob_const(bytes+key_len, num_bytes-key_len);
                if (blob1.length > 0) {
                        size_t len;
                        bool ok;

                        len = utf16_len_n(blob1.data,
                                          blob1.length);
                        blob1.length = len;

                        ok = convert_string_talloc(state,
                                                   CH_DOS,
                                                   CH_UNIX,
                                                   blob1.data,
                                                   blob1.length,
                                                   &server_workgroup,
                                                   &len);
                        if (!ok) {
                                status = map_nt_error_from_unix_common(errno);
                                tevent_req_nterror(req, status);
                                return;
                        }
                }

        } else {
                /* the old core protocol */
                server_time_zone = get_time_zone(time(NULL));
                server_max_xmit = 1024;
                server_max_mux = 1;
        }

        if (server_max_xmit < 1024) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        if (server_max_mux < 1) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        /*
         * Now calculate the negotiated capabilities
         * based on the mask for:
         * - client only flags
         * - flags used in both directions
         * - server only flags
         */
        both_capabilities = client_capabilities & server_capabilities;
        capabilities = client_capabilities & SMB_CAP_CLIENT_MASK;
        capabilities |= both_capabilities & SMB_CAP_BOTH_MASK;
        capabilities |= server_capabilities & SMB_CAP_SERVER_MASK;

        max_xmit = MIN(client_max_xmit, server_max_xmit);

        conn->smb1.server.capabilities = server_capabilities;
        conn->smb1.capabilities = capabilities;

        conn->smb1.server.max_xmit = server_max_xmit;
        conn->smb1.max_xmit = max_xmit;

        conn->smb1.server.max_mux = server_max_mux;

        conn->smb1.server.security_mode = server_security_mode;

        conn->smb1.server.readbraw = server_readbraw;
        conn->smb1.server.writebraw = server_writebraw;
        conn->smb1.server.lockread = server_lockread;
        conn->smb1.server.writeunlock = server_writeunlock;

        conn->smb1.server.session_key = server_session_key;

        talloc_steal(conn, server_gss_blob.data);
        conn->smb1.server.gss_blob = server_gss_blob;
        conn->smb1.server.guid = server_guid;
        memcpy(conn->smb1.server.challenge, server_challenge, 8);
        conn->smb1.server.workgroup = talloc_move(conn, &server_workgroup);
        conn->smb1.server.name = talloc_move(conn, &server_name);

        conn->smb1.server.time_zone = server_time_zone;
        conn->smb1.server.system_time = server_system_time;

        tevent_req_done(req);
}

static struct tevent_req *smbXcli_negprot_smb2_subreq(struct smbXcli_negprot_state *state)
{
        size_t i;
        uint8_t *buf;
        uint16_t dialect_count = 0;

        buf = state->smb2.dyn;
        for (i=0; i < ARRAY_SIZE(smb2cli_prots); i++) {
                if (smb2cli_prots[i].proto < state->min_protocol) {
                        continue;
                }

                if (smb2cli_prots[i].proto > state->max_protocol) {
                        continue;
                }

                SSVAL(buf, dialect_count*2, smb2cli_prots[i].smb2_dialect);
                dialect_count++;
        }

        buf = state->smb2.fixed;
        SSVAL(buf, 0, 36);
        SSVAL(buf, 2, dialect_count);
        SSVAL(buf, 4, state->conn->smb2.client.security_mode);
        SSVAL(buf, 6, 0);       /* Reserved */
        SSVAL(buf, 8, 0);       /* Capabilities */
        if (state->max_protocol >= PROTOCOL_SMB2_10) {
                NTSTATUS status;
                DATA_BLOB blob;

                status = GUID_to_ndr_blob(&state->conn->smb2.client.guid,
                                          state, &blob);
                if (!NT_STATUS_IS_OK(status)) {
                        return NULL;
                }
                memcpy(buf+12, blob.data, 16); /* ClientGuid */
        } else {
                memset(buf+12, 0, 16);  /* ClientGuid */
        }
        SBVAL(buf, 28, 0);      /* ClientStartTime */

        return smb2cli_req_send(state, state->ev,
                                state->conn, SMB2_OP_NEGPROT,
                                0, 0, /* flags */
                                state->timeout_msec,
                                0xFEFF, 0, 0, /* pid, tid, uid */
                                state->smb2.fixed, sizeof(state->smb2.fixed),
                                state->smb2.dyn, dialect_count*2);
}

static void smbXcli_negprot_smb2_done(struct tevent_req *subreq)
{
        struct tevent_req *req =
                tevent_req_callback_data(subreq,
                struct tevent_req);
        struct smbXcli_negprot_state *state =
                tevent_req_data(req,
                struct smbXcli_negprot_state);
        struct smbXcli_conn *conn = state->conn;
        size_t security_offset, security_length;
        DATA_BLOB blob;
        NTSTATUS status;
        struct iovec *iov;
        uint8_t *body;
        size_t i;
        uint16_t dialect_revision;
        static const struct smb2cli_req_expected_response expected[] = {
        {
                .status = NT_STATUS_OK,
                .body_size = 0x41
        }
        };

        status = smb2cli_req_recv(subreq, state, &iov,
                                  expected, ARRAY_SIZE(expected));
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        body = (uint8_t *)iov[1].iov_base;

        dialect_revision = SVAL(body, 4);

        for (i=0; i < ARRAY_SIZE(smb2cli_prots); i++) {
                if (smb2cli_prots[i].proto < state->min_protocol) {
                        continue;
                }

                if (smb2cli_prots[i].proto > state->max_protocol) {
                        continue;
                }

                if (smb2cli_prots[i].smb2_dialect != dialect_revision) {
                        continue;
                }

                conn->protocol = smb2cli_prots[i].proto;
                break;
        }

        if (conn->protocol == PROTOCOL_NONE) {
                if (state->min_protocol >= PROTOCOL_SMB2_02) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                if (dialect_revision != SMB2_DIALECT_REVISION_2FF) {
                        tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                        return;
                }

                /* make sure we do not loop forever */
                state->min_protocol = PROTOCOL_SMB2_02;

                /*
                 * send a SMB2 negprot, in order to negotiate
                 * the SMB2 dialect. This needs to use the
                 * message id 1.
                 */
                state->conn->smb2.mid = 1;
                subreq = smbXcli_negprot_smb2_subreq(state);
                if (tevent_req_nomem(subreq, req)) {
                        return;
                }
                tevent_req_set_callback(subreq, smbXcli_negprot_smb2_done, req);
                return;
        }

        conn->smb2.server.security_mode = SVAL(body, 2);

        blob = data_blob_const(body + 8, 16);
        status = GUID_from_data_blob(&blob, &conn->smb2.server.guid);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        conn->smb2.server.capabilities  = IVAL(body, 24);
        conn->smb2.server.max_trans_size= IVAL(body, 28);
        conn->smb2.server.max_read_size = IVAL(body, 32);
        conn->smb2.server.max_write_size= IVAL(body, 36);
        conn->smb2.server.system_time   = BVAL(body, 40);
        conn->smb2.server.start_time    = BVAL(body, 48);

        security_offset = SVAL(body, 56);
        security_length = SVAL(body, 58);

        if (security_offset != SMB2_HDR_BODY + iov[1].iov_len) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        if (security_length > iov[2].iov_len) {
                tevent_req_nterror(req, NT_STATUS_INVALID_NETWORK_RESPONSE);
                return;
        }

        conn->smb2.server.gss_blob = data_blob_talloc(conn,
                                                iov[2].iov_base,
                                                security_length);
        if (tevent_req_nomem(conn->smb2.server.gss_blob.data, req)) {
                return;
        }

        tevent_req_done(req);
}

static NTSTATUS smbXcli_negprot_dispatch_incoming(struct smbXcli_conn *conn,
                                                  TALLOC_CTX *tmp_mem,
                                                  uint8_t *inbuf)
{
        size_t num_pending = talloc_array_length(conn->pending);
        struct tevent_req *subreq;
        struct smbXcli_req_state *substate;
        struct tevent_req *req;
        struct smbXcli_negprot_state *state;
        uint32_t protocol_magic = IVAL(inbuf, 4);

        if (num_pending != 1) {
                return NT_STATUS_INTERNAL_ERROR;
        }

        subreq = conn->pending[0];
        substate = tevent_req_data(subreq, struct smbXcli_req_state);
        req = tevent_req_callback_data(subreq, struct tevent_req);
        state = tevent_req_data(req, struct smbXcli_negprot_state);

        switch (protocol_magic) {
        case SMB_MAGIC:
                tevent_req_set_callback(subreq, smbXcli_negprot_smb1_done, req);
                conn->dispatch_incoming = smb1cli_conn_dispatch_incoming;
                return smb1cli_conn_dispatch_incoming(conn, tmp_mem, inbuf);

        case SMB2_MAGIC:
                if (substate->smb2.recv_iov == NULL) {
                        /*
                         * For the SMB1 negprot we have move it.
                         */
                        substate->smb2.recv_iov = substate->smb1.recv_iov;
                        substate->smb1.recv_iov = NULL;
                }

                tevent_req_set_callback(subreq, smbXcli_negprot_smb2_done, req);
                conn->dispatch_incoming = smb2cli_conn_dispatch_incoming;
                return smb2cli_conn_dispatch_incoming(conn, tmp_mem, inbuf);
        }

        DEBUG(10, ("Got non-SMB PDU\n"));
        return NT_STATUS_INVALID_NETWORK_RESPONSE;
}

NTSTATUS smbXcli_negprot_recv(struct tevent_req *req)
{
        return tevent_req_simple_recv_ntstatus(req);
}

NTSTATUS smbXcli_negprot(struct smbXcli_conn *conn,
                         uint32_t timeout_msec,
                         enum protocol_types min_protocol,
                         enum protocol_types max_protocol)
{
        TALLOC_CTX *frame = talloc_stackframe();
        struct tevent_context *ev;
        struct tevent_req *req;
        NTSTATUS status = NT_STATUS_NO_MEMORY;
        bool ok;

        if (smbXcli_conn_has_async_calls(conn)) {
                /*
                 * Can't use sync call while an async call is in flight
                 */
                status = NT_STATUS_INVALID_PARAMETER_MIX;
                goto fail;
        }
        ev = tevent_context_init(frame);
        if (ev == NULL) {
                goto fail;
        }
        req = smbXcli_negprot_send(frame, ev, conn, timeout_msec,
                                   min_protocol, max_protocol);
        if (req == NULL) {
                goto fail;
        }
        ok = tevent_req_poll(req, ev);
        if (!ok) {
                status = map_nt_error_from_unix_common(errno);
                goto fail;
        }
        status = smbXcli_negprot_recv(req);
 fail:
        TALLOC_FREE(frame);
        return status;
}

static int smbXcli_session_destructor(struct smbXcli_session *session)
{
        if (session->conn == NULL) {
                return 0;
        }

        DLIST_REMOVE(session->conn->sessions, session);
        return 0;
}

struct smbXcli_session *smbXcli_session_create(TALLOC_CTX *mem_ctx,
                                               struct smbXcli_conn *conn)
{
        struct smbXcli_session *session;

        session = talloc_zero(mem_ctx, struct smbXcli_session);
        if (session == NULL) {
                return NULL;
        }
        talloc_set_destructor(session, smbXcli_session_destructor);

        DLIST_ADD_END(conn->sessions, session, struct smbXcli_session *);
        session->conn = conn;

        return session;
}

uint8_t smb2cli_session_security_mode(struct smbXcli_session *session)
{
        struct smbXcli_conn *conn = session->conn;
        uint8_t security_mode = 0;

        if (conn == NULL) {
                return security_mode;
        }

        security_mode = SMB2_NEGOTIATE_SIGNING_ENABLED;
        if (conn->mandatory_signing) {
                security_mode |= SMB2_NEGOTIATE_SIGNING_REQUIRED;
        }

        return security_mode;
}

uint64_t smb2cli_session_current_id(struct smbXcli_session *session)
{
        return session->smb2.session_id;
}

void smb2cli_session_set_id_and_flags(struct smbXcli_session *session,
                                      uint64_t session_id,
                                      uint16_t session_flags)
{
        session->smb2.session_id = session_id;
        session->smb2.session_flags = session_flags;
}

NTSTATUS smb2cli_session_update_session_key(struct smbXcli_session *session,
                                            const DATA_BLOB session_key,
                                            const struct iovec *recv_iov)
{
        struct smbXcli_conn *conn = session->conn;
        uint16_t no_sign_flags;
        DATA_BLOB signing_key;
        NTSTATUS status;

        if (conn == NULL) {
                return NT_STATUS_INVALID_PARAMETER_MIX;
        }

        no_sign_flags = SMB2_SESSION_FLAG_IS_GUEST | SMB2_SESSION_FLAG_IS_NULL;

        if (session->smb2.session_flags & no_sign_flags) {
                session->smb2.should_sign = false;
                return NT_STATUS_OK;
        }

        if (session->smb2.signing_key.length > 0) {
                signing_key = session->smb2.signing_key;
        } else {
                signing_key = session_key;
        }

        status = smb2_signing_check_pdu(signing_key, recv_iov, 3);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        session->smb2.session_key = data_blob_dup_talloc(session, session_key);
        if (session->smb2.session_key.data == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        if (session->smb2.signing_key.length > 0) {
                return NT_STATUS_OK;
        }

        session->smb2.signing_key = data_blob_dup_talloc(session, signing_key);
        if (session->smb2.signing_key.data == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        session->smb2.should_sign = false;

        if (conn->desire_signing) {
                session->smb2.should_sign = true;
        }

        if (conn->smb2.server.security_mode & SMB2_NEGOTIATE_SIGNING_REQUIRED) {
                session->smb2.should_sign = true;
        }

        return NT_STATUS_OK;
}