source: branches/samba-3.5.x/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"

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

#ifndef TALLOC_FREE
#define TALLOC_FREE(ctx) do { talloc_free(ctx); ctx=NULL; } while(0)
#endif

struct async_send_state {
        int fd;
        const void *buf;
        size_t len;
        int flags;
        ssize_t sent;
};

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

struct tevent_req *async_send_send(TALLOC_CTX *mem_ctx,
                                   struct tevent_context *ev,
                                   int fd, const void *buf, size_t len,
                                   int flags)
{
        struct tevent_req *result;
        struct async_send_state *state;
        struct tevent_fd *fde;

        result = tevent_req_create(mem_ctx, &state, struct async_send_state);
        if (result == NULL) {
                return result;
        }
        state->fd = fd;
        state->buf = buf;
        state->len = len;
        state->flags = flags;

        fde = tevent_add_fd(ev, state, fd, TEVENT_FD_WRITE, async_send_handler,
                            result);
        if (fde == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }
        return result;
}

static void async_send_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 async_send_state *state =
                tevent_req_data(req, struct async_send_state);

        state->sent = send(state->fd, state->buf, state->len, state->flags);
        if ((state->sent == -1) && (errno == EINTR)) {
                /* retry */
                return;
        }
        if (state->sent == -1) {
                tevent_req_error(req, errno);
                return;
        }
        tevent_req_done(req);
}

ssize_t async_send_recv(struct tevent_req *req, int *perrno)
{
        struct async_send_state *state =
                tevent_req_data(req, struct async_send_state);

        if (tevent_req_is_unix_error(req, perrno)) {
                return -1;
        }
        return state->sent;
}

struct async_recv_state {
        int fd;
        void *buf;
        size_t len;
        int flags;
        ssize_t received;
};

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

struct tevent_req *async_recv_send(TALLOC_CTX *mem_ctx,
                                   struct tevent_context *ev,
                                   int fd, void *buf, size_t len, int flags)
{
        struct tevent_req *result;
        struct async_recv_state *state;
        struct tevent_fd *fde;

        result = tevent_req_create(mem_ctx, &state, struct async_recv_state);
        if (result == NULL) {
                return result;
        }
        state->fd = fd;
        state->buf = buf;
        state->len = len;
        state->flags = flags;

        fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ, async_recv_handler,
                            result);
        if (fde == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }
        return result;
}

static void async_recv_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 async_recv_state *state =
                tevent_req_data(req, struct async_recv_state);

        state->received = recv(state->fd, state->buf, state->len,
                               state->flags);
        if ((state->received == -1) && (errno == EINTR)) {
                /* retry */
                return;
        }
        if (state->received == 0) {
                tevent_req_error(req, EPIPE);
                return;
        }
        if (state->received == -1) {
                tevent_req_error(req, errno);
                return;
        }
        tevent_req_done(req);
}

ssize_t async_recv_recv(struct tevent_req *req, int *perrno)
{
        struct async_recv_state *state =
                tevent_req_data(req, struct async_recv_state);

        if (tevent_req_is_unix_error(req, perrno)) {
                return -1;
        }
        return state->received;
}

struct async_connect_state {
        int fd;
        int result;
        int sys_errno;
        long old_sockflags;
        socklen_t address_len;
        struct sockaddr_storage address;
};

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)
{
        struct tevent_req *result;
        struct async_connect_state *state;
        struct tevent_fd *fde;

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

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

        state->fd = fd;
        state->sys_errno = 0;

        state->old_sockflags = fcntl(fd, F_GETFL, 0);
        if (state->old_sockflags == -1) {
                goto post_errno;
        }

        state->address_len = address_len;
        if (address_len > sizeof(state->address)) {
                errno = EINVAL;
                goto post_errno;
        }
        memcpy(&state->address, address, address_len);

        set_blocking(fd, false);

        state->result = connect(fd, address, address_len);
        if (state->result == 0) {
                tevent_req_done(result);
                goto done;
        }

        /**
         * 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;
                goto post_errno;
        }

        fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ | TEVENT_FD_WRITE,
                           async_connect_connected, result);
        if (fde == NULL) {
                state->sys_errno = ENOMEM;
                goto post_errno;
        }
        return result;

 post_errno:
        tevent_req_error(result, state->sys_errno);
 done:
        fcntl(fd, F_SETFL, state->old_sockflags);
#ifdef __OS2__ // if the old flags have blocking set we need to set it also (fcntl bug)
        if (!(state->old_sockflags & O_NONBLOCK)) {
                set_blocking(state->fd, true);
        }
#endif
        return tevent_req_post(result, ev);
}

/**
 * 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);

        /*
         * 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 & (TEVENT_FD_READ|TEVENT_FD_WRITE))
            == (TEVENT_FD_READ|TEVENT_FD_WRITE)) {
                int ret;

                ret = connect(state->fd,
                              (struct sockaddr *)(void *)&state->address,
                              state->address_len);
                if (ret == 0) {
                        TALLOC_FREE(fde);
                        tevent_req_done(req);
                        return;
                }

                if (errno == EINPROGRESS) {
                        /* Try again later, leave the fde around */
                        return;
                }
                TALLOC_FREE(fde);
                tevent_req_error(req, errno);
                return;
        }

        state->sys_errno = 0;
        tevent_req_done(req);
}

int async_connect_recv(struct tevent_req *req, int *perrno)
{
        struct async_connect_state *state =
                tevent_req_data(req, struct async_connect_state);
        int err;

        fcntl(state->fd, F_SETFL, state->old_sockflags);
#ifdef __OS2__ // if the old flags have blocking set we need to set it also (fcntl bug)
        if (!(state->old_sockflags & O_NONBLOCK)) {
                set_blocking(state->fd, true);
        }
#endif
        if (tevent_req_is_unix_error(req, &err)) {
                *perrno = err;
                return -1;
        }

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

        *perrno = state->sys_errno;
        return -1;
}

struct writev_state {
        struct tevent_context *ev;
        int fd;
        struct iovec *iov;
        int count;
        size_t total_size;
        uint16_t flags;
};

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 (state->iov == NULL) {
                goto fail;
        }
        state->flags = TEVENT_FD_WRITE;
        if (err_on_readability) {
                state->flags |= TEVENT_FD_READ;
        }

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

        if (!tevent_queue_add(queue, ev, req, writev_trigger, NULL)) {
                goto fail;
        }
        return req;
 fail:
        TALLOC_FREE(req);
        return NULL;
}

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

        fde = tevent_add_fd(state->ev, state, state->fd, state->flags,
                            writev_handler, req);
        if (fde == NULL) {
                tevent_req_error(req, ENOMEM);
        }
}

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);
        size_t to_write, written;
        int i;

        to_write = 0;

        if ((state->flags & TEVENT_FD_READ) && (flags & TEVENT_FD_READ)) {
                tevent_req_error(req, EPIPE);
                return;
        }

        for (i=0; i<state->count; i++) {
                to_write += state->iov[i].iov_len;
        }

        written = writev(state->fd, state->iov, state->count);
        if ((written == -1) && (errno == EINTR)) {
                /* retry */
                return;
        }
        if (written == -1) {
                tevent_req_error(req, errno);
                return;
        }
        if (written == 0) {
                tevent_req_error(req, EPIPE);
                return;
        }
        state->total_size += written;

        if (written == to_write) {
                tevent_req_done(req);
                return;
        }

        /*
         * We've written less than we were asked to, drop stuff from
         * state->iov.
         */

        while (written > 0) {
                if (written < state->iov[0].iov_len) {
                        state->iov[0].iov_base =
                                (char *)state->iov[0].iov_base + written;
                        state->iov[0].iov_len -= written;
                        break;
                }
                written -= state->iov[0].iov_len;
                state->iov += 1;
                state->count -= 1;
        }
}

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

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

struct read_packet_state {
        int fd;
        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_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 *result;
        struct read_packet_state *state;
        struct tevent_fd *fde;

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

        state->buf = talloc_array(state, uint8_t, initial);
        if (state->buf == NULL) {
                goto fail;
        }

        fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ, read_packet_handler,
                            result);
        if (fde == NULL) {
                goto fail;
        }
        return result;
 fail:
        TALLOC_FREE(result);
        return NULL;
}

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 == 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;
        }

        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)) {
                return -1;
        }
        *pbuf = talloc_move(mem_ctx, &state->buf);
        return talloc_get_size(*pbuf);
}