source: branches/samba-3.3.x/source/lib/async_sock.c

/*
   Unix SMB/CIFS implementation.
   async socket syscalls
   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"

/**
 * Discriminator for async_syscall_state
 */
enum async_syscall_type {
        ASYNC_SYSCALL_SEND,
        ASYNC_SYSCALL_SENDALL,
        ASYNC_SYSCALL_RECV,
        ASYNC_SYSCALL_RECVALL,
        ASYNC_SYSCALL_CONNECT
};

/**
 * Holder for syscall arguments and the result
 */

struct async_syscall_state {
        enum async_syscall_type syscall_type;
        struct fd_event *fde;

        union {
                struct param_send {
                        int fd;
                        const void *buffer;
                        size_t length;
                        int flags;
                } param_send;
                struct param_sendall {
                        int fd;
                        const void *buffer;
                        size_t length;
                        int flags;
                        size_t sent;
                } param_sendall;
                struct param_recv {
                        int fd;
                        void *buffer;
                        size_t length;
                        int flags;
                } param_recv;
                struct param_recvall {
                        int fd;
                        void *buffer;
                        size_t length;
                        int flags;
                        size_t received;
                } param_recvall;
                struct param_connect {
                        /**
                         * connect needs to be done on a nonblocking
                         * socket. Keep the old flags around
                         */
                        long old_sockflags;
                        int fd;
                        const struct sockaddr *address;
                        socklen_t address_len;
                } param_connect;
        } param;

        union {
                ssize_t result_ssize_t;
                size_t result_size_t;
                int result_int;
        } result;
        int sys_errno;
};

/**
 * @brief Create a new async syscall req
 * @param[in] mem_ctx   The memory context to hang the result off
 * @param[in] ev        The event context to work from
 * @param[in] type      Which syscall will this be
 * @param[in] pstate    Where to put the newly created private_data state
 * @retval The new request
 *
 * This is a helper function to prepare a new struct async_req with an
 * associated struct async_syscall_state. The async_syscall_state will be put
 * into the async_req as private_data.
 */

static struct async_req *async_syscall_new(TALLOC_CTX *mem_ctx,
                                           struct event_context *ev,
                                           enum async_syscall_type type,
                                           struct async_syscall_state **pstate)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_req_new(mem_ctx, ev);
        if (result == NULL) {
                return NULL;
        }

        state = talloc(result, struct async_syscall_state);
        if (state == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }

        state->syscall_type = type;

        result->private_data = state;

        *pstate = state;

        return result;
}

/**
 * @brief Create a new async syscall req based on a fd
 * @param[in] mem_ctx   The memory context to hang the result off
 * @param[in] ev        The event context to work from
 * @param[in] type      Which syscall will this be
 * @param[in] fd        The file descriptor we work on
 * @param[in] fde_flags EVENT_FD_READ/WRITE -- what are we interested in?
 * @param[in] fde_cb    The callback function for the file descriptor event
 * @param[in] pstate    Where to put the newly created private_data state
 * @retval The new request
 *
 * This is a helper function to prepare a new struct async_req with an
 * associated struct async_syscall_state and an associated file descriptor
 * event.
 */

static struct async_req *async_fde_syscall_new(
        TALLOC_CTX *mem_ctx,
        struct event_context *ev,
        enum async_syscall_type type,
        int fd,
        uint16_t fde_flags,
        void (*fde_cb)(struct event_context *ev,
                       struct fd_event *fde, uint16_t flags,
                       void *priv),
        struct async_syscall_state **pstate)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_syscall_new(mem_ctx, ev, type, &state);
        if (result == NULL) {
                return NULL;
        }

        state->fde = event_add_fd(ev, state, fd, fde_flags, fde_cb, result);
        if (state->fde == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }
        *pstate = state;
        return result;
}

/**
 * Retrieve a ssize_t typed result from an async syscall
 * @param[in] req       The syscall that has just finished
 * @param[out] perrno   Where to put the syscall's errno
 * @retval The return value from the asynchronously called syscall
 */

ssize_t async_syscall_result_ssize_t(struct async_req **req, int *perrno)
{
        struct async_syscall_state *state = talloc_get_type_abort(
                (*req)->private_data, struct async_syscall_state);

        int sys_errno = state->sys_errno;
        ssize_t result = state->result.result_ssize_t;

        TALLOC_FREE(*req);

        *perrno = sys_errno;
        return result;
}

/**
 * Retrieve a size_t typed result from an async syscall
 * @param[in] req       The syscall that has just finished
 * @param[out] perrno   Where to put the syscall's errno
 * @retval The return value from the asynchronously called syscall
 */

size_t async_syscall_result_size_t(struct async_req **req, int *perrno)
{
        struct async_syscall_state *state = talloc_get_type_abort(
                (*req)->private_data, struct async_syscall_state);

        int sys_errno = state->sys_errno;
        size_t result = state->result.result_ssize_t;

        TALLOC_FREE(*req);

        *perrno = sys_errno;
        return result;
}

/**
 * Retrieve a int typed result from an async syscall
 * @param[in] req       The syscall that has just finished
 * @param[out] perrno   Where to put the syscall's errno
 * @retval The return value from the asynchronously called syscall
 */

ssize_t async_syscall_result_int(struct async_req **req, int *perrno)
{
        struct async_syscall_state *state = talloc_get_type_abort(
                (*req)->private_data, struct async_syscall_state);

        int sys_errno = state->sys_errno;
        int result = state->result.result_ssize_t;

        TALLOC_FREE(*req);

        *perrno = sys_errno;
        return result;
}

/**
 * fde event handler for the "send" syscall
 * @param[in] ev        The event context that sent us here
 * @param[in] fde       The file descriptor event associated with the send
 * @param[in] flags     Can only be EVENT_FD_WRITE here
 * @param[in] priv      private data, "struct async_req *" in this case
 */

static void async_send_callback(struct event_context *ev,
                                struct fd_event *fde, uint16_t flags,
                                void *priv)
{
        struct async_req *req = talloc_get_type_abort(
                priv, struct async_req);
        struct async_syscall_state *state = talloc_get_type_abort(
                req->private_data, struct async_syscall_state);
        struct param_send *p = &state->param.param_send;

        SMB_ASSERT(state->syscall_type == ASYNC_SYSCALL_SEND);

        state->result.result_ssize_t = send(p->fd, p->buffer, p->length,
                                            p->flags);
        state->sys_errno = errno;

        TALLOC_FREE(state->fde);

        async_req_done(req);
}

/**
 * Async version of send(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 send to
 * @param[in] buffer    The buffer to send
 * @param[in] length    How many bytes to send
 * @param[in] flags     flags passed to send(2)
 *
 * This function is a direct counterpart of send(2)
 */

struct async_req *async_send(TALLOC_CTX *mem_ctx, struct event_context *ev,
                             int fd, const void *buffer, size_t length,
                             int flags)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_fde_syscall_new(
                mem_ctx, ev, ASYNC_SYSCALL_SEND,
                fd, EVENT_FD_WRITE, async_send_callback,
                &state);
        if (result == NULL) {
                return NULL;
        }

        state->param.param_send.fd = fd;
        state->param.param_send.buffer = buffer;
        state->param.param_send.length = length;
        state->param.param_send.flags = flags;

        return result;
}

/**
 * fde event handler for the "sendall" syscall group
 * @param[in] ev        The event context that sent us here
 * @param[in] fde       The file descriptor event associated with the send
 * @param[in] flags     Can only be EVENT_FD_WRITE here
 * @param[in] priv      private data, "struct async_req *" in this case
 */

static void async_sendall_callback(struct event_context *ev,
                                   struct fd_event *fde, uint16_t flags,
                                   void *priv)
{
        struct async_req *req = talloc_get_type_abort(
                priv, struct async_req);
        struct async_syscall_state *state = talloc_get_type_abort(
                req->private_data, struct async_syscall_state);
        struct param_sendall *p = &state->param.param_sendall;

        SMB_ASSERT(state->syscall_type == ASYNC_SYSCALL_SENDALL);

        state->result.result_ssize_t = send(p->fd, (char *)p->buffer + p->sent,
                                            p->length - p->sent, p->flags);
        state->sys_errno = errno;

        if (state->result.result_ssize_t == -1) {
                async_req_error(req, map_nt_error_from_unix(state->sys_errno));
                return;
        }

        if (state->result.result_ssize_t == 0) {
                async_req_error(req, NT_STATUS_END_OF_FILE);
                return;
        }

        p->sent += state->result.result_ssize_t;
        SMB_ASSERT(p->sent <= p->length);

        if (p->sent == p->length) {
                TALLOC_FREE(state->fde);
                async_req_done(req);
        }
}

/**
 * @brief Send all bytes to a socket
 * @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 send to
 * @param[in] buffer    The buffer to send
 * @param[in] length    How many bytes to send
 * @param[in] flags     flags passed to send(2)
 *
 * async_sendall calls send(2) as long as it is necessary to send all of the
 * "length" bytes
 */

struct async_req *async_sendall(TALLOC_CTX *mem_ctx, struct event_context *ev,
                                int fd, const void *buffer, size_t length,
                                int flags)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_fde_syscall_new(
                mem_ctx, ev, ASYNC_SYSCALL_SENDALL,
                fd, EVENT_FD_WRITE, async_sendall_callback,
                &state);
        if (result == NULL) {
                return NULL;
        }

        state->param.param_sendall.fd = fd;
        state->param.param_sendall.buffer = buffer;
        state->param.param_sendall.length = length;
        state->param.param_sendall.flags = flags;
        state->param.param_sendall.sent = 0;

        return result;
}

/**
 * fde event handler for the "recv" syscall
 * @param[in] ev        The event context that sent us here
 * @param[in] fde       The file descriptor event associated with the recv
 * @param[in] flags     Can only be EVENT_FD_READ here
 * @param[in] priv      private data, "struct async_req *" in this case
 */

static void async_recv_callback(struct event_context *ev,
                                struct fd_event *fde, uint16_t flags,
                                void *priv)
{
        struct async_req *req = talloc_get_type_abort(
                priv, struct async_req);
        struct async_syscall_state *state = talloc_get_type_abort(
                req->private_data, struct async_syscall_state);
        struct param_recv *p = &state->param.param_recv;

        SMB_ASSERT(state->syscall_type == ASYNC_SYSCALL_RECV);

        state->result.result_ssize_t = recv(p->fd, p->buffer, p->length,
                                            p->flags);
        state->sys_errno = errno;

        TALLOC_FREE(state->fde);

        async_req_done(req);
}

/**
 * Async version of recv(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] buffer    The buffer to recv into
 * @param[in] length    How many bytes to recv
 * @param[in] flags     flags passed to recv(2)
 *
 * This function is a direct counterpart of recv(2)
 */

struct async_req *async_recv(TALLOC_CTX *mem_ctx, struct event_context *ev,
                             int fd, void *buffer, size_t length,
                             int flags)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_fde_syscall_new(
                mem_ctx, ev, ASYNC_SYSCALL_RECV,
                fd, EVENT_FD_READ, async_recv_callback,
                &state);

        if (result == NULL) {
                return NULL;
        }

        state->param.param_recv.fd = fd;
        state->param.param_recv.buffer = buffer;
        state->param.param_recv.length = length;
        state->param.param_recv.flags = flags;

        return result;
}

/**
 * fde event handler for the "recvall" syscall group
 * @param[in] ev        The event context that sent us here
 * @param[in] fde       The file descriptor event associated with the recv
 * @param[in] flags     Can only be EVENT_FD_READ here
 * @param[in] priv      private data, "struct async_req *" in this case
 */

static void async_recvall_callback(struct event_context *ev,
                                   struct fd_event *fde, uint16_t flags,
                                   void *priv)
{
        struct async_req *req = talloc_get_type_abort(
                priv, struct async_req);
        struct async_syscall_state *state = talloc_get_type_abort(
                req->private_data, struct async_syscall_state);
        struct param_recvall *p = &state->param.param_recvall;

        SMB_ASSERT(state->syscall_type == ASYNC_SYSCALL_RECVALL);

        state->result.result_ssize_t = recv(p->fd,
                                            (char *)p->buffer + p->received,
                                            p->length - p->received, p->flags);
        state->sys_errno = errno;

        if (state->result.result_ssize_t == -1) {
                async_req_error(req, map_nt_error_from_unix(state->sys_errno));
                return;
        }

        if (state->result.result_ssize_t == 0) {
                async_req_error(req, NT_STATUS_END_OF_FILE);
                return;
        }

        p->received += state->result.result_ssize_t;
        SMB_ASSERT(p->received <= p->length);

        if (p->received == p->length) {
                TALLOC_FREE(state->fde);
                async_req_done(req);
        }
}

/**
 * Receive a specified number of bytes from a socket
 * @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] buffer    The buffer to recv into
 * @param[in] length    How many bytes to recv
 * @param[in] flags     flags passed to recv(2)
 *
 * async_recvall will call recv(2) until "length" bytes are received
 */

struct async_req *async_recvall(TALLOC_CTX *mem_ctx, struct event_context *ev,
                                int fd, void *buffer, size_t length,
                                int flags)
{
        struct async_req *result;
        struct async_syscall_state *state;

        result = async_fde_syscall_new(
                mem_ctx, ev, ASYNC_SYSCALL_RECVALL,
                fd, EVENT_FD_READ, async_recvall_callback,
                &state);
        if (result == NULL) {
                return NULL;
        }

        state->param.param_recvall.fd = fd;
        state->param.param_recvall.buffer = buffer;
        state->param.param_recvall.length = length;
        state->param.param_recvall.flags = flags;
        state->param.param_recvall.received = 0;

        return result;
}

/**
 * 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_callback(struct event_context *ev,
                                   struct fd_event *fde, uint16_t flags,
                                   void *priv)
{
        struct async_req *req = talloc_get_type_abort(
                priv, struct async_req);
        struct async_syscall_state *state = talloc_get_type_abort(
                req->private_data, struct async_syscall_state);
        struct param_connect *p = &state->param.param_connect;

        SMB_ASSERT(state->syscall_type == ASYNC_SYSCALL_CONNECT);

        TALLOC_FREE(state->fde);

        /*
         * Stevens, Network Programming says that if there's a
         * successful connect, the socket is only writable. Upon an
         * error, it's both readable and writable.
         */
        if ((flags & (EVENT_FD_READ|EVENT_FD_WRITE))
            == (EVENT_FD_READ|EVENT_FD_WRITE)) {
                int sockerr;
                socklen_t err_len = sizeof(sockerr);

                if (getsockopt(p->fd, SOL_SOCKET, SO_ERROR,
                               (void *)&sockerr, &err_len) == 0) {
                        errno = sockerr;
                }

                state->sys_errno = errno;

                DEBUG(10, ("connect returned %s\n", strerror(errno)));

                sys_fcntl_long(p->fd, F_SETFL, p->old_sockflags);

                async_req_error(req, map_nt_error_from_unix(state->sys_errno));
                return;
        }

        sys_fcntl_long(p->fd, F_SETFL, p->old_sockflags);

        state->result.result_int = 0;
        state->sys_errno = 0;

        async_req_done(req);
}

/**
 * @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 async_req *async_connect(TALLOC_CTX *mem_ctx, struct event_context *ev,
                                int fd, const struct sockaddr *address,
                                socklen_t address_len)
{
        struct async_req *result;
        struct async_syscall_state *state;
        struct param_connect *p;

        result = async_syscall_new(mem_ctx, ev, ASYNC_SYSCALL_CONNECT, &state);
        if (result == NULL) {
                return NULL;
        }
        p = &state->param.param_connect;

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

        p->old_sockflags = sys_fcntl_long(fd, F_GETFL, 0);

        if (p->old_sockflags == -1) {
                if (async_post_status(result, map_nt_error_from_unix(errno))) {
                        return result;
                }
                TALLOC_FREE(result);
                return NULL;
        }

        set_blocking(fd, true);

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

        if (state->result.result_int == 0) {
                state->sys_errno = 0;
                if (async_post_status(result, NT_STATUS_OK)) {
                        return result;
                }
                sys_fcntl_long(fd, F_SETFL, p->old_sockflags);
                TALLOC_FREE(result);
                return NULL;
        }

        /**
         * A number of error messages show that something good is progressing
         * and that we have to wait for readability.
         *
         * If none of them are present, bail out.
         */

        if (!(errno == EINPROGRESS || errno == EALREADY ||
#ifdef EISCONN
              errno == EISCONN ||
#endif
              errno == EAGAIN || errno == EINTR)) {

                state->sys_errno = errno;

                if (async_post_status(result, map_nt_error_from_unix(errno))) {
                        return result;
                }
                sys_fcntl_long(fd, F_SETFL, p->old_sockflags);
                TALLOC_FREE(result);
                return NULL;
        }

        state->fde = event_add_fd(ev, state, fd,
                                  EVENT_FD_READ | EVENT_FD_WRITE,
                                  async_connect_callback, state);
        if (state->fde == NULL) {
                sys_fcntl_long(fd, F_SETFL, p->old_sockflags);
                TALLOC_FREE(result);
                return NULL;
        }

        state->param.param_connect.fd = fd;
        state->param.param_connect.address = address;
        state->param.param_connect.address_len = address_len;

        return result;
}