smbd: Remove "st" from struct open_symlink_err

[Samba.git] / lib / async_req / async_sock.c

/*
   Unix SMB/CIFS implementation.
   async socket syscalls
   Copyright (C) Volker Lendecke 2008

     ** NOTE! The following LGPL license applies to the async_sock
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

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

   This library 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
   Library General Public License for more details.

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

#include "replace.h"
#include "system/network.h"
#include "system/filesys.h"
#include <talloc.h>
#include <tevent.h>
#include "lib/async_req/async_sock.h"
#include "lib/util/iov_buf.h"
#include "lib/util/util_net.h"

/* Note: lib/util/ is currently GPL */
#include "lib/util/tevent_unix.h"
#include "lib/util/samba_util.h"

struct async_connect_state {
        int fd;
        struct tevent_fd *fde;
        int result;
        long old_sockflags;
        socklen_t address_len;
        struct sockaddr_storage address;

        void (*before_connect)(void *private_data);
        void (*after_connect)(void *private_data);
        void *private_data;
};

static void async_connect_cleanup(struct tevent_req *req,
                                  enum tevent_req_state req_state);
static void async_connect_connected(struct tevent_context *ev,
                                    struct tevent_fd *fde, uint16_t flags,
                                    void *priv);

/**
 * @brief async version of connect(2)
 * @param[in] mem_ctx   The memory context to hang the result off
 * @param[in] ev        The event context to work from
 * @param[in] fd        The socket to recv from
 * @param[in] address   Where to connect?
 * @param[in] address_len Length of *address
 * @retval The async request
 *
 * This function sets the socket into non-blocking state to be able to call
 * connect in an async state. This will be reset when the request is finished.
 */

struct tevent_req *async_connect_send(
        TALLOC_CTX *mem_ctx, struct tevent_context *ev, int fd,
        const struct sockaddr *address, socklen_t address_len,
        void (*before_connect)(void *private_data),
        void (*after_connect)(void *private_data),
        void *private_data)
{
        struct tevent_req *req;
        struct async_connect_state *state;
        int ret;

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

        /**
         * We have to set the socket to nonblocking for async connect(2). Keep
         * the old sockflags around.
         */

        state->fd = fd;
        state->before_connect = before_connect;
        state->after_connect = after_connect;
        state->private_data = private_data;

        state->old_sockflags = fcntl(fd, F_GETFL, 0);
        if (state->old_sockflags == -1) {
                tevent_req_error(req, errno);
                return tevent_req_post(req, ev);
        }

        tevent_req_set_cleanup_fn(req, async_connect_cleanup);

        state->address_len = address_len;
        if (address_len > sizeof(state->address)) {
                tevent_req_error(req, EINVAL);
                return tevent_req_post(req, ev);
        }
        memcpy(&state->address, address, address_len);

        ret = set_blocking(fd, false);
        if (ret == -1) {
                tevent_req_error(req, errno);
                return tevent_req_post(req, ev);
        }

        if (state->before_connect != NULL) {
                state->before_connect(state->private_data);
        }

        state->result = connect(fd, address, address_len);

        if (state->after_connect != NULL) {
                state->after_connect(state->private_data);
        }

        if (state->result == 0) {
                tevent_req_done(req);
                return tevent_req_post(req, ev);
        }

        /*
         * The only errno indicating that an initial connect is still
         * in flight is EINPROGRESS.
         *
         * This allows callers like open_socket_out_send() to reuse
         * fds and call us with an fd for which the connect is still
         * in flight. The proper thing to do for callers would be
         * closing the fd and starting from scratch with a fresh
         * socket.
         */

        if (errno != EINPROGRESS) {
                tevent_req_error(req, errno);
                return tevent_req_post(req, ev);
        }

        /*
         * Note for historic reasons TEVENT_FD_WRITE is not enough
         * to get notified for POLLERR or EPOLLHUP even if they
         * come together with POLLOUT. That means we need to
         * use TEVENT_FD_READ in addition until we have
         * TEVENT_FD_ERROR.
         */
        state->fde = tevent_add_fd(ev, state, fd,
                                   TEVENT_FD_ERROR|TEVENT_FD_WRITE,
                                   async_connect_connected, req);
        if (state->fde == NULL) {
                tevent_req_error(req, ENOMEM);
                return tevent_req_post(req, ev);
        }
        return req;
}

static void async_connect_cleanup(struct tevent_req *req,
                                  enum tevent_req_state req_state)
{
        struct async_connect_state *state =
                tevent_req_data(req, struct async_connect_state);

        TALLOC_FREE(state->fde);
        if (state->fd != -1) {
                int ret;

                ret = fcntl(state->fd, F_SETFL, state->old_sockflags);
                if (ret == -1) {
                        abort();
                }

                state->fd = -1;
        }
}

/**
 * fde event handler for connect(2)
 * @param[in] ev        The event context that sent us here
 * @param[in] fde       The file descriptor event associated with the connect
 * @param[in] flags     Indicate read/writeability of the socket
 * @param[in] priv      private data, "struct async_req *" in this case
 */

static void async_connect_connected(struct tevent_context *ev,
                                    struct tevent_fd *fde, uint16_t flags,
                                    void *priv)
{
        struct tevent_req *req = talloc_get_type_abort(
                priv, struct tevent_req);
        struct async_connect_state *state =
                tevent_req_data(req, struct async_connect_state);
        int ret;
        int socket_error = 0;
        socklen_t slen = sizeof(socket_error);

        ret = getsockopt(state->fd, SOL_SOCKET, SO_ERROR,
                         &socket_error, &slen);

        if (ret != 0) {
                /*
                 * According to Stevens this is the Solaris behaviour
                 * in case the connection encountered an error:
                 * getsockopt() fails, error is in errno
                 */
                tevent_req_error(req, errno);
                return;
        }

        if (socket_error != 0) {
                /*
                 * Berkeley derived implementations (including) Linux
                 * return the pending error via socket_error.
                 */
                tevent_req_error(req, socket_error);
                return;
        }

        tevent_req_done(req);
        return;
}

int async_connect_recv(struct tevent_req *req, int *perrno)
{
        int err = tevent_req_simple_recv_unix(req);

        if (err != 0) {
                *perrno = err;
                return -1;
        }

        return 0;
}

struct writev_state {
        struct tevent_context *ev;
        struct tevent_queue_entry *queue_entry;
        int fd;
        struct tevent_fd *fde;
        struct iovec *iov;
        int count;
        size_t total_size;
        uint16_t flags;
        bool err_on_readability;
};

static void writev_cleanup(struct tevent_req *req,
                           enum tevent_req_state req_state);
static bool writev_cancel(struct tevent_req *req);
static void writev_trigger(struct tevent_req *req, void *private_data);
static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
                           uint16_t flags, void *private_data);

struct tevent_req *writev_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
                               struct tevent_queue *queue, int fd,
                               bool err_on_readability,
                               struct iovec *iov, int count)
{
        struct tevent_req *req;
        struct writev_state *state;

        req = tevent_req_create(mem_ctx, &state, struct writev_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->fd = fd;
        state->total_size = 0;
        state->count = count;
        state->iov = (struct iovec *)talloc_memdup(
                state, iov, sizeof(struct iovec) * count);
        if (tevent_req_nomem(state->iov, req)) {
                return tevent_req_post(req, ev);
        }
        state->flags = TEVENT_FD_WRITE | TEVENT_FD_ERROR;
        if (err_on_readability) {
                state->flags |= TEVENT_FD_READ;
        }

        tevent_req_set_cleanup_fn(req, writev_cleanup);
        tevent_req_set_cancel_fn(req, writev_cancel);

        if (queue == NULL) {
                state->fde = tevent_add_fd(state->ev, state, state->fd,
                                    state->flags, writev_handler, req);
                if (tevent_req_nomem(state->fde, req)) {
                        return tevent_req_post(req, ev);
                }
                return req;
        }

        /*
         * writev_trigger tries a nonblocking write. If that succeeds,
         * we can't directly notify the callback to call
         * writev_recv. The callback would TALLOC_FREE(req) after
         * calling writev_recv even before writev_trigger can inspect
         * it for success.
         */
        tevent_req_defer_callback(req, ev);

        state->queue_entry = tevent_queue_add_optimize_empty(
                queue, ev, req, writev_trigger, NULL);
        if (tevent_req_nomem(state->queue_entry, req)) {
                return tevent_req_post(req, ev);
        }
        if (!tevent_req_is_in_progress(req)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void writev_cleanup(struct tevent_req *req,
                           enum tevent_req_state req_state)
{
        struct writev_state *state = tevent_req_data(req, struct writev_state);

        TALLOC_FREE(state->queue_entry);
        TALLOC_FREE(state->fde);
}

static bool writev_cancel(struct tevent_req *req)
{
        struct writev_state *state = tevent_req_data(req, struct writev_state);

        if (state->total_size > 0) {
                /*
                 * We've already started to write :-(
                 */
                return false;
        }

        TALLOC_FREE(state->queue_entry);
        TALLOC_FREE(state->fde);

        tevent_req_defer_callback(req, state->ev);
        tevent_req_error(req, ECANCELED);
        return true;
}

static void writev_do(struct tevent_req *req, struct writev_state *state)
{
        ssize_t written;
        bool ok;

        written = writev(state->fd, state->iov, state->count);
        if ((written == -1) &&
            ((errno == EINTR) ||
             (errno == EAGAIN) ||
             (errno == EWOULDBLOCK))) {
                /* retry after going through the tevent loop */
                return;
        }
        if (written == -1) {
                tevent_req_error(req, errno);
                return;
        }
        if (written == 0) {
                tevent_req_error(req, EPIPE);
                return;
        }
        state->total_size += written;

        ok = iov_advance(&state->iov, &state->count, written);
        if (!ok) {
                tevent_req_error(req, EIO);
                return;
        }

        if (state->count == 0) {
                tevent_req_done(req);
                return;
        }
}

static void writev_trigger(struct tevent_req *req, void *private_data)
{
        struct writev_state *state = tevent_req_data(req, struct writev_state);

        state->queue_entry = NULL;

        writev_do(req, state);
        if (!tevent_req_is_in_progress(req)) {
                return;
        }

        state->fde = tevent_add_fd(state->ev, state, state->fd, state->flags,
                            writev_handler, req);
        if (tevent_req_nomem(state->fde, req)) {
                return;
        }
}

static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
                           uint16_t flags, void *private_data)
{
        struct tevent_req *req = talloc_get_type_abort(
                private_data, struct tevent_req);
        struct writev_state *state =
                tevent_req_data(req, struct writev_state);

        if (flags & TEVENT_FD_ERROR) {
                /*
                 * There's an error, for legacy reasons
                 * we just use EPIPE instead of a more
                 * detailed error using
                 * samba_socket_poll_or_sock_error().
                 */
                tevent_req_error(req, EPIPE);
                return;
        }

        if (flags & TEVENT_FD_READ) {
                /* Readable and the caller wants an error on read. */
                tevent_req_error(req, EPIPE);
                return;
        }

        writev_do(req, state);
}

ssize_t writev_recv(struct tevent_req *req, int *perrno)
{
        struct writev_state *state =
                tevent_req_data(req, struct writev_state);
        ssize_t ret;

        if (tevent_req_is_unix_error(req, perrno)) {
                tevent_req_received(req);
                return -1;
        }
        ret = state->total_size;
        tevent_req_received(req);
        return ret;
}

struct read_packet_state {
        int fd;
        struct tevent_fd *fde;
        uint8_t *buf;
        size_t nread;
        ssize_t (*more)(uint8_t *buf, size_t buflen, void *private_data);
        void *private_data;
};

static void read_packet_cleanup(struct tevent_req *req,
                                 enum tevent_req_state req_state);
static void read_packet_handler(struct tevent_context *ev,
                                struct tevent_fd *fde,
                                uint16_t flags, void *private_data);

struct tevent_req *read_packet_send(TALLOC_CTX *mem_ctx,
                                    struct tevent_context *ev,
                                    int fd, size_t initial,
                                    ssize_t (*more)(uint8_t *buf,
                                                    size_t buflen,
                                                    void *private_data),
                                    void *private_data)
{
        struct tevent_req *req;
        struct read_packet_state *state;

        req = tevent_req_create(mem_ctx, &state, struct read_packet_state);
        if (req == NULL) {
                return NULL;
        }
        state->fd = fd;
        state->nread = 0;
        state->more = more;
        state->private_data = private_data;

        tevent_req_set_cleanup_fn(req, read_packet_cleanup);

        state->buf = talloc_array(state, uint8_t, initial);
        if (tevent_req_nomem(state->buf, req)) {
                return tevent_req_post(req, ev);
        }

        state->fde = tevent_add_fd(ev, state, fd,
                                   TEVENT_FD_READ, read_packet_handler,
                                   req);
        if (tevent_req_nomem(state->fde, req)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void read_packet_cleanup(struct tevent_req *req,
                           enum tevent_req_state req_state)
{
        struct read_packet_state *state =
                tevent_req_data(req, struct read_packet_state);

        TALLOC_FREE(state->fde);
}

static void read_packet_handler(struct tevent_context *ev,
                                struct tevent_fd *fde,
                                uint16_t flags, void *private_data)
{
        struct tevent_req *req = talloc_get_type_abort(
                private_data, struct tevent_req);
        struct read_packet_state *state =
                tevent_req_data(req, struct read_packet_state);
        size_t total = talloc_get_size(state->buf);
        ssize_t nread, more;
        uint8_t *tmp;

        nread = recv(state->fd, state->buf+state->nread, total-state->nread,
                     0);
        if ((nread == -1) && (errno == ENOTSOCK)) {
                nread = read(state->fd, state->buf+state->nread,
                             total-state->nread);
        }
        if ((nread == -1) && (errno == EINTR)) {
                /* retry */
                return;
        }
        if (nread == -1) {
                tevent_req_error(req, errno);
                return;
        }
        if (nread == 0) {
                tevent_req_error(req, EPIPE);
                return;
        }

        state->nread += nread;
        if (state->nread < total) {
                /* Come back later */
                return;
        }

        /*
         * We got what was initially requested. See if "more" asks for -- more.
         */
        if (state->more == NULL) {
                /* Nobody to ask, this is a async read_data */
                tevent_req_done(req);
                return;
        }

        more = state->more(state->buf, total, state->private_data);
        if (more == -1) {
                /* We got an invalid packet, tell the caller */
                tevent_req_error(req, EIO);
                return;
        }
        if (more == 0) {
                /* We're done, full packet received */
                tevent_req_done(req);
                return;
        }

        if (total + more < total) {
                tevent_req_error(req, EMSGSIZE);
                return;
        }

        tmp = talloc_realloc(state, state->buf, uint8_t, total+more);
        if (tevent_req_nomem(tmp, req)) {
                return;
        }
        state->buf = tmp;
}

ssize_t read_packet_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                         uint8_t **pbuf, int *perrno)
{
        struct read_packet_state *state =
                tevent_req_data(req, struct read_packet_state);

        if (tevent_req_is_unix_error(req, perrno)) {
                tevent_req_received(req);
                return -1;
        }
        *pbuf = talloc_move(mem_ctx, &state->buf);
        tevent_req_received(req);
        return talloc_get_size(*pbuf);
}

struct wait_for_read_state {
        struct tevent_fd *fde;
        int fd;
        bool check_errors;
};

static void wait_for_read_cleanup(struct tevent_req *req,
                                  enum tevent_req_state req_state);
static void wait_for_read_done(struct tevent_context *ev,
                               struct tevent_fd *fde,
                               uint16_t flags,
                               void *private_data);

struct tevent_req *wait_for_read_send(TALLOC_CTX *mem_ctx,
                                      struct tevent_context *ev, int fd,
                                      bool check_errors)
{
        struct tevent_req *req;
        struct wait_for_read_state *state;

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

        tevent_req_set_cleanup_fn(req, wait_for_read_cleanup);

        state->fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ,
                                   wait_for_read_done, req);
        if (tevent_req_nomem(state->fde, req)) {
                return tevent_req_post(req, ev);
        }

        state->fd = fd;
        state->check_errors = check_errors;
        return req;
}

static void wait_for_read_cleanup(struct tevent_req *req,
                                  enum tevent_req_state req_state)
{
        struct wait_for_read_state *state =
                tevent_req_data(req, struct wait_for_read_state);

        TALLOC_FREE(state->fde);
}

static void wait_for_read_done(struct tevent_context *ev,
                               struct tevent_fd *fde,
                               uint16_t flags,
                               void *private_data)
{
        struct tevent_req *req = talloc_get_type_abort(
                private_data, struct tevent_req);
        struct wait_for_read_state *state =
            tevent_req_data(req, struct wait_for_read_state);
        int ret, available;

        if ((flags & TEVENT_FD_READ) == 0) {
                return;
        }

        if (!state->check_errors) {
                tevent_req_done(req);
                return;
        }

        ret = ioctl(state->fd, FIONREAD, &available);

        if ((ret == -1) && (errno == EINTR)) {
                /* come back later */
                return;
        }

        if (ret == -1) {
                tevent_req_error(req, errno);
                return;
        }

        if (available == 0) {
                tevent_req_error(req, EPIPE);
                return;
        }

        tevent_req_done(req);
}

bool wait_for_read_recv(struct tevent_req *req, int *perr)
{
        int err = tevent_req_simple_recv_unix(req);

        if (err != 0) {
                *perr = err;
                return false;
        }

        return true;
}

struct accept_state {
        struct tevent_fd *fde;
        int listen_sock;
        struct samba_sockaddr addr;
        int sock;
};

static void accept_handler(struct tevent_context *ev, struct tevent_fd *fde,
                           uint16_t flags, void *private_data);

struct tevent_req *accept_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
                               int listen_sock)
{
        struct tevent_req *req;
        struct accept_state *state;

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

        state->listen_sock = listen_sock;

        state->fde = tevent_add_fd(ev, state, listen_sock, TEVENT_FD_READ,
                                   accept_handler, req);
        if (tevent_req_nomem(state->fde, req)) {
                return tevent_req_post(req, ev);
        }
        return req;
}

static void accept_handler(struct tevent_context *ev, struct tevent_fd *fde,
                           uint16_t flags, void *private_data)
{
        struct tevent_req *req = talloc_get_type_abort(
                private_data, struct tevent_req);
        struct accept_state *state = tevent_req_data(req, struct accept_state);
        int ret;

        TALLOC_FREE(state->fde);

        if ((flags & TEVENT_FD_READ) == 0) {
                tevent_req_error(req, EIO);
                return;
        }

        state->addr.sa_socklen = sizeof(state->addr.u);

        ret = accept(state->listen_sock,
                     &state->addr.u.sa,
                     &state->addr.sa_socklen);
        if ((ret == -1) && (errno == EINTR)) {
                /* retry */
                return;
        }
        if (ret == -1) {
                tevent_req_error(req, errno);
                return;
        }
        smb_set_close_on_exec(ret);
        state->sock = ret;
        tevent_req_done(req);
}

int accept_recv(struct tevent_req *req,
                int *listen_sock,
                struct samba_sockaddr *paddr,
                int *perr)
{
        struct accept_state *state = tevent_req_data(req, struct accept_state);
        int sock = state->sock;
        int err;

        if (tevent_req_is_unix_error(req, &err)) {
                if (perr != NULL) {
                        *perr = err;
                }
                tevent_req_received(req);
                return -1;
        }
        if (listen_sock != NULL) {
                *listen_sock = state->listen_sock;
        }
        if (paddr != NULL) {
                *paddr = state->addr;
        }
        tevent_req_received(req);
        return sock;
}