s4-dsdb: Modify the repl_meta_data behavior to allow Metadata change on attribute...

[Samba/gebeck_regimport.git] / source3 / libsmb / async_smb.c

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

   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 "libsmb/libsmb.h"
#include "../lib/async_req/async_sock.h"
#include "../lib/util/tevent_ntstatus.h"
#include "../lib/util/tevent_unix.h"
#include "async_smb.h"
#include "../libcli/smb/smb_seal.h"
#include "libsmb/nmblib.h"
#include "../libcli/smb/read_smb.h"

static NTSTATUS cli_pull_raw_error(const uint8_t *buf)
{
        const uint8_t *hdr = buf + NBT_HDR_SIZE;
        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));
}

/**
 * Figure out if there is an andx command behind the current one
 * @param[in] buf       The smb buffer to look at
 * @param[in] ofs       The offset to the wct field that is followed by the cmd
 * @retval Is there a command following?
 */

static bool have_andx_command(const char *buf, uint16_t ofs, uint8_t cmd)
{
        uint8_t wct;
        size_t buflen = talloc_get_size(buf);

        if (!is_andx_req(cmd)) {
                return false;
        }

        if ((ofs == buflen-1) || (ofs == buflen)) {
                return false;
        }

        wct = CVAL(buf, ofs);
        if (wct < 2) {
                /*
                 * Not enough space for the command and a following pointer
                 */
                return false;
        }
        return (CVAL(buf, ofs+1) != 0xff);
}

#define MAX_SMB_IOV 5

struct cli_smb_state {
        struct tevent_context *ev;
        struct cli_state *cli;
        uint8_t header[smb_wct+1]; /* Space for the header including the wct */

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

        uint16_t *vwv;
        uint8_t bytecount_buf[2];

        struct iovec iov[MAX_SMB_IOV+3];
        int iov_count;

        uint8_t *inbuf;
        uint32_t seqnum;
        int chain_num;
        int chain_length;
        struct tevent_req **chained_requests;

        bool one_way;
};

static uint16_t cli_alloc_mid(struct cli_state *cli)
{
        int num_pending = talloc_array_length(cli->conn.pending);
        uint16_t result;

        while (true) {
                int i;

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

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

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

void cli_smb_req_unset_pending(struct tevent_req *req)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        struct cli_state *cli = state->cli;
        int num_pending = talloc_array_length(cli->conn.pending);
        int i;

        if (state->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
                 * cli->pending. So if nothing is pending anymore, we need to
                 * delete the socket read fde.
                 */
                TALLOC_FREE(cli->conn.pending);
                cli->conn.read_smb_req = NULL;
                return;
        }

        for (i=0; i<num_pending; i++) {
                if (req == cli->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 cli->conn.pending.
                 */
                return;
        }

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

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

static int cli_smb_req_destructor(struct tevent_req *req)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        /*
         * Make sure we really remove it from
         * the pending array on destruction.
         */
        state->mid = 0;
        cli_smb_req_unset_pending(req);
        return 0;
}

static bool cli_state_receive_next(struct cli_state *cli);
static void cli_state_notify_pending(struct cli_state *cli, NTSTATUS status);

bool cli_smb_req_set_pending(struct tevent_req *req)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        struct cli_state *cli;
        struct tevent_req **pending;
        int num_pending;

        cli = state->cli;
        num_pending = talloc_array_length(cli->conn.pending);

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

        if (!cli_state_receive_next(cli)) {
                /*
                 * the caller should notify the current request
                 *
                 * And all other pending requests get notified
                 * by cli_state_notify_pending().
                 */
                cli_smb_req_unset_pending(req);
                cli_state_notify_pending(cli, NT_STATUS_NO_MEMORY);
                return false;
        }

        return true;
}

static void cli_smb_received(struct tevent_req *subreq);
static NTSTATUS cli_state_dispatch_smb1(struct cli_state *cli,
                                        TALLOC_CTX *frame,
                                        uint8_t *inbuf);

static bool cli_state_receive_next(struct cli_state *cli)
{
        size_t num_pending = talloc_array_length(cli->conn.pending);
        struct tevent_req *req;
        struct cli_smb_state *state;

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

        if (num_pending == 0) {
                return true;
        }

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

        cli->conn.dispatch_incoming = cli_state_dispatch_smb1;

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

static void cli_state_notify_pending(struct cli_state *cli, NTSTATUS status)
{
        cli_state_disconnect(cli);

        /*
         * Cancel all pending requests. We do not do a for-loop walking
         * cli->conn.pending because that array changes in
         * cli_smb_req_destructor().
         */
        while (talloc_array_length(cli->conn.pending) > 0) {
                struct tevent_req *req;
                struct cli_smb_state *state;

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

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

                cli_smb_req_unset_pending(req);

                /*
                 * 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);
        }
}

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

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

        return SVAL(state->header, smb_mid);
}

void cli_smb_req_set_mid(struct tevent_req *req, uint16_t mid)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        state->mid = mid;
}

uint32_t cli_smb_req_seqnum(struct tevent_req *req)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        return state->seqnum;
}

void cli_smb_req_set_seqnum(struct tevent_req *req, uint32_t seqnum)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        state->seqnum = seqnum;
}

static size_t 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 *iov_concat(TALLOC_CTX *mem_ctx, const struct iovec *iov,
                           int count)
{
        size_t len = 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;
}

struct tevent_req *cli_smb_req_create(TALLOC_CTX *mem_ctx,
                                      struct tevent_context *ev,
                                      struct cli_state *cli,
                                      uint8_t smb_command,
                                      uint8_t additional_flags,
                                      uint8_t wct, uint16_t *vwv,
                                      int iov_count,
                                      struct iovec *bytes_iov)
{
        struct tevent_req *result;
        struct cli_smb_state *state;
        struct timeval endtime;

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

        result = tevent_req_create(mem_ctx, &state, struct cli_smb_state);
        if (result == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->cli = cli;
        state->mid = 0;         /* Set to auto-choose in cli_smb_req_send */
        state->chain_num = 0;
        state->chained_requests = NULL;

        cli_setup_packet_buf(cli, (char *)state->header);
        SCVAL(state->header, smb_com, smb_command);
        SSVAL(state->header, smb_tid, cli->smb1.tid);
        SCVAL(state->header, smb_wct, wct);

        state->vwv = vwv;

        SSVAL(state->bytecount_buf, 0, iov_len(bytes_iov, iov_count));

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

        if (iov_count != 0) {
                memcpy(&state->iov[3], bytes_iov,
                       iov_count * sizeof(*bytes_iov));
        }
        state->iov_count = iov_count + 3;

        if (cli->timeout) {
                endtime = timeval_current_ofs_msec(cli->timeout);
                if (!tevent_req_set_endtime(result, ev, endtime)) {
                        return result;
                }
        }

        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 result;
}

static NTSTATUS cli_signv(struct cli_state *cli, struct iovec *iov, int 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 ((count <= 0) || (iov[0].iov_len < smb_wct)) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        buf = iov_concat(talloc_tos(), iov, count);
        if (buf == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        cli_calculate_sign_mac(cli, (char *)buf, seqnum);
        memcpy(iov[0].iov_base, buf, iov[0].iov_len);

        TALLOC_FREE(buf);
        return NT_STATUS_OK;
}

static void cli_smb_sent(struct tevent_req *subreq);

static NTSTATUS cli_smb_req_iov_send(struct tevent_req *req,
                                     struct cli_smb_state *state,
                                     struct iovec *iov, int iov_count)
{
        struct tevent_req *subreq;
        NTSTATUS status;

        if (!cli_state_is_connected(state->cli)) {
                return NT_STATUS_CONNECTION_DISCONNECTED;
        }

        if (iov[0].iov_len < smb_wct) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (state->mid != 0) {
                SSVAL(iov[0].iov_base, smb_mid, state->mid);
        } else {
                uint16_t mid = cli_alloc_mid(state->cli);
                SSVAL(iov[0].iov_base, smb_mid, mid);
        }

        smb_setlen_nbt((char *)iov[0].iov_base, iov_len(iov, iov_count) - 4);

        status = cli_signv(state->cli, iov, iov_count, &state->seqnum);

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

        if (cli_state_encryption_on(state->cli)) {
                char *buf, *enc_buf;

                buf = (char *)iov_concat(talloc_tos(), iov, iov_count);
                if (buf == NULL) {
                        return NT_STATUS_NO_MEMORY;
                }
                status = common_encrypt_buffer(state->cli->trans_enc_state,
                                               (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;
        }
        subreq = writev_send(state, state->ev, state->cli->conn.outgoing,
                             state->cli->conn.fd, false, iov, iov_count);
        if (subreq == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        tevent_req_set_callback(subreq, cli_smb_sent, req);
        return NT_STATUS_OK;
}

NTSTATUS cli_smb_req_send(struct tevent_req *req)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);

        if (!tevent_req_is_in_progress(req)) {
                return NT_STATUS_INTERNAL_ERROR;
        }

        return cli_smb_req_iov_send(req, state, state->iov, state->iov_count);
}

struct tevent_req *cli_smb_send(TALLOC_CTX *mem_ctx,
                                struct tevent_context *ev,
                                struct cli_state *cli,
                                uint8_t smb_command,
                                uint8_t additional_flags,
                                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 = cli_smb_req_create(mem_ctx, ev, cli, smb_command,
                                 additional_flags, wct, vwv, 1, &iov);
        if (req == NULL) {
                return NULL;
        }
        if (!tevent_req_is_in_progress(req)) {
                return tevent_req_post(req, ev);
        }
        status = cli_smb_req_send(req);
        if (!NT_STATUS_IS_OK(status)) {
                tevent_req_nterror(req, status);
                return tevent_req_post(req, ev);
        }
        return req;
}

static void cli_smb_sent(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_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);
                cli_state_notify_pending(state->cli, status);
                return;
        }

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

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

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

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

        received = read_smb_recv(subreq, frame, &inbuf, &err);
        TALLOC_FREE(subreq);
        cli->conn.read_smb_req = NULL;
        if (received == -1) {
                status = map_nt_error_from_unix_common(err);
                cli_state_notify_pending(cli, status);
                TALLOC_FREE(frame);
                return;
        }

        status = cli->conn.dispatch_incoming(cli, 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
                 */
                cli_state_notify_pending(cli, status);
                return;
        }

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

static NTSTATUS cli_state_dispatch_smb1(struct cli_state *cli,
                                        TALLOC_CTX *frame,
                                        uint8_t *inbuf)
{
        struct tevent_req *req;
        struct cli_smb_state *state;
        NTSTATUS status;
        int num_pending;
        int i;
        uint16_t mid;
        bool oplock_break;
        const uint8_t *inhdr = inbuf + NBT_HDR_SIZE;

        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 (cli_state_encryption_on(cli) && (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 != cli->trans_enc_state->enc_ctx_num) {
                        DEBUG(10, ("wrong enc_ctx %d, expected %d\n",
                                   enc_ctx_num,
                                   cli->trans_enc_state->enc_ctx_num));
                        return NT_STATUS_INVALID_HANDLE;
                }

                status = common_decrypt_buffer(cli->trans_enc_state,
                                               (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(cli->conn.pending);

        for (i=0; i<num_pending; i++) {
                if (mid == cli_smb_req_mid(cli->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 = cli->conn.pending[i];
        state = tevent_req_data(req, struct cli_smb_state);

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

        if (state->chained_requests != NULL) {
                struct tevent_req **chain = talloc_move(frame,
                                            &state->chained_requests);
                int num_chained = talloc_array_length(chain);

                /*
                 * We steal the inbuf to the chain,
                 * so that it will stay until all
                 * requests of the chain are finished.
                 *
                 * Each requests in the chain will
                 * hold a talloc reference to the chain.
                 * This way we do not expose the talloc_reference()
                 * behavior to the callers.
                 */
                talloc_steal(chain, inbuf);

                for (i=0; i<num_chained; i++) {
                        struct tevent_req **ref;

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

                        cli_smb_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);

                        ref = talloc_reference(state, chain);
                        if (tevent_req_nomem(ref, req)) {
                                continue;
                        }

                        state->inbuf = inbuf;
                        state->chain_num = i;
                        state->chain_length = num_chained;

                        tevent_req_done(req);
                }

                return NT_STATUS_RETRY;
        }

        cli_smb_req_unset_pending(req);

        state->inbuf = talloc_move(state, &inbuf);
        state->chain_num = 0;
        state->chain_length = 1;

        if (talloc_array_length(cli->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;
}

NTSTATUS cli_smb_recv(struct tevent_req *req,
                      TALLOC_CTX *mem_ctx, uint8_t **pinbuf,
                      uint8_t min_wct, uint8_t *pwct, uint16_t **pvwv,
                      uint32_t *pnum_bytes, uint8_t **pbytes)
{
        struct cli_smb_state *state = tevent_req_data(
                req, struct cli_smb_state);
        NTSTATUS status = NT_STATUS_OK;
        uint8_t cmd, wct;
        uint16_t num_bytes;
        size_t wct_ofs, bytes_offset;
        int i;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }

        if (state->inbuf == NULL) {
                if (min_wct != 0) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }
                if (pinbuf) {
                        *pinbuf = NULL;
                }
                if (pwct) {
                        *pwct = 0;
                }
                if (pvwv) {
                        *pvwv = NULL;
                }
                if (pnum_bytes) {
                        *pnum_bytes = 0;
                }
                if (pbytes) {
                        *pbytes = NULL;
                }
                /* This was a request without a reply */
                return NT_STATUS_OK;
        }

        wct_ofs = smb_wct;
        cmd = CVAL(state->inbuf, smb_com);

        for (i=0; i<state->chain_num; i++) {
                if (i < state->chain_num-1) {
                        if (cmd == 0xff) {
                                return NT_STATUS_REQUEST_ABORTED;
                        }
                        if (!is_andx_req(cmd)) {
                                return NT_STATUS_INVALID_NETWORK_RESPONSE;
                        }
                }

                if (!have_andx_command((char *)state->inbuf, wct_ofs, cmd)) {
                        /*
                         * This request was not completed because a previous
                         * request in the chain had received an error.
                         */
                        return NT_STATUS_REQUEST_ABORTED;
                }

                cmd = CVAL(state->inbuf, wct_ofs + 1);
                wct_ofs = SVAL(state->inbuf, wct_ofs + 3);

                /*
                 * Skip the all-present length field. No overflow, we've just
                 * put a 16-bit value into a size_t.
                 */
                wct_ofs += 4;

                if (wct_ofs+2 > talloc_get_size(state->inbuf)) {
                        return NT_STATUS_INVALID_NETWORK_RESPONSE;
                }
        }

        state->cli->raw_status = cli_pull_raw_error(state->inbuf);
        if (NT_STATUS_IS_DOS(state->cli->raw_status) &&
            state->cli->map_dos_errors) {
                uint8_t eclass = NT_STATUS_DOS_CLASS(state->cli->raw_status);
                uint16_t ecode = NT_STATUS_DOS_CODE(state->cli->raw_status);
                /*
                 * TODO: is it really a good idea to do a mapping here?
                 *
                 * The old cli_pull_error() also does it, so I do not change
                 * the behavior yet.
                 */
                status = dos_to_ntstatus(eclass, ecode);
        } else {
                status = state->cli->raw_status;
        }

        if (!have_andx_command((char *)state->inbuf, wct_ofs, cmd)) {

                if ((cmd == SMBsesssetupX)
                    && NT_STATUS_EQUAL(
                            status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
                        /*
                         * NT_STATUS_MORE_PROCESSING_REQUIRED is a
                         * valid return code for session setup
                         */
                        goto no_err;
                }

                if (NT_STATUS_IS_ERR(status)) {
                        /*
                         * The last command takes the error code. All
                         * further commands down the requested chain
                         * will get a NT_STATUS_REQUEST_ABORTED.
                         */
                        return status;
                }
        } else {
                /*
                 * Only the last request in the chain get the returned
                 * status.
                 */
                status = NT_STATUS_OK;
        }

no_err:

        wct = CVAL(state->inbuf, wct_ofs);
        bytes_offset = wct_ofs + 1 + wct * sizeof(uint16_t);
        num_bytes = SVAL(state->inbuf, bytes_offset);

        if (wct < min_wct) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        /*
         * wct_ofs is a 16-bit value plus 4, wct is a 8-bit value, num_bytes
         * is a 16-bit value. So bytes_offset being size_t should be far from
         * wrapping.
         */
        if ((bytes_offset + 2 > talloc_get_size(state->inbuf))
            || (bytes_offset > 0xffff)) {
                return NT_STATUS_INVALID_NETWORK_RESPONSE;
        }

        if (pwct != NULL) {
                *pwct = wct;
        }
        if (pvwv != NULL) {
                *pvwv = (uint16_t *)(state->inbuf + wct_ofs + 1);
        }
        if (pnum_bytes != NULL) {
                *pnum_bytes = num_bytes;
        }
        if (pbytes != NULL) {
                *pbytes = (uint8_t *)state->inbuf + bytes_offset + 2;
        }
        if ((mem_ctx != NULL) && (pinbuf != NULL)) {
                if (state->chain_num == state->chain_length-1) {
                        *pinbuf = talloc_move(mem_ctx, &state->inbuf);
                } else {
                        *pinbuf = state->inbuf;
                }
        }

        return status;
}

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

        wct_ofs = smb_wct - 4;

        for (i=0; i<num_reqs; i++) {
                struct cli_smb_state *state;
                state = tevent_req_data(reqs[i], struct cli_smb_state);
                wct_ofs += iov_len(state->iov+1, state->iov_count-1);
                wct_ofs = (wct_ofs + 3) & ~3;
        }
        return wct_ofs;
}

NTSTATUS cli_smb_chain_send(struct tevent_req **reqs, int num_reqs)
{
        struct cli_smb_state *first_state = tevent_req_data(
                reqs[0], struct cli_smb_state);
        struct cli_smb_state *last_state = tevent_req_data(
                reqs[num_reqs-1], struct cli_smb_state);
        struct cli_smb_state *state;
        size_t wct_offset;
        size_t chain_padding = 0;
        int i, iovlen;
        struct iovec *iov = NULL;
        struct iovec *this_iov;
        NTSTATUS status;

        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 cli_smb_state);
                iovlen += state->iov_count;
        }

        iov = talloc_array(last_state, struct iovec, iovlen);
        if (iov == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

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

        wct_offset = smb_wct - 4;
        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 cli_smb_state);

                if (i < num_reqs-1) {
                        if (!is_andx_req(CVAL(state->header, smb_com))
                            || CVAL(state->header, smb_wct) < 2) {
                                TALLOC_FREE(iov);
                                TALLOC_FREE(first_state->chained_requests);
                                return NT_STATUS_INVALID_PARAMETER;
                        }
                }

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

                if (i < num_reqs-1) {
                        struct cli_smb_state *next_state = tevent_req_data(
                                reqs[i+1], struct cli_smb_state);
                        SCVAL(vwv+0, 0, CVAL(next_state->header, smb_com));
                        SCVAL(vwv+0, 1, 0);
                        SSVAL(vwv+1, 0, wct_offset);
                } else if (is_andx_req(CVAL(state->header, smb_com))) {
                        /* properly end the chain */
                        SCVAL(vwv+0, 0, 0xff);
                        SCVAL(vwv+0, 1, 0xff);
                        SSVAL(vwv+1, 0, 0);
                }

                if (i == 0) {
                        this_iov[0] = state->iov[0];
                } 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->header[
                                sizeof(state->header) - this_iov[0].iov_len];
                        memset(this_iov[0].iov_base, 0, this_iov[0].iov_len-1);
                }
                memcpy(this_iov+1, state->iov+1,
                       sizeof(struct iovec) * (state->iov_count-1));
                this_iov += state->iov_count;
                chain_padding = next_padding;
        }

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

        for (i=0; i < (num_reqs - 1); i++) {
                state = tevent_req_data(reqs[i], struct cli_smb_state);

                state->seqnum = last_state->seqnum;
        }

        return NT_STATUS_OK;
}

bool cli_has_async_calls(struct cli_state *cli)
{
        return ((tevent_queue_length(cli->conn.outgoing) != 0)
                || (talloc_array_length(cli->conn.pending) != 0));
}