source: vendor/current/libcli/smb/read_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 "system/network.h"
#include "lib/async_req/async_sock.h"
#include "read_smb.h"
#include "lib/util/tevent_unix.h"
#include "libcli/smb/smb_constants.h"

/*
 * Read an smb packet asynchronously, discard keepalives
 */

struct read_smb_state {
        struct tevent_context *ev;
        int fd;
        uint8_t *buf;
};

static ssize_t read_smb_more(uint8_t *buf, size_t buflen, void *private_data);
static void read_smb_done(struct tevent_req *subreq);

struct tevent_req *read_smb_send(TALLOC_CTX *mem_ctx,
                                 struct tevent_context *ev,
                                 int fd)
{
        struct tevent_req *result, *subreq;
        struct read_smb_state *state;

        result = tevent_req_create(mem_ctx, &state, struct read_smb_state);
        if (result == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->fd = fd;

        subreq = read_packet_send(state, ev, fd, 4, read_smb_more, NULL);
        if (subreq == NULL) {
                goto fail;
        }
        tevent_req_set_callback(subreq, read_smb_done, result);
        return result;
 fail:
        TALLOC_FREE(result);
        return NULL;
}

static ssize_t read_smb_more(uint8_t *buf, size_t buflen, void *private_data)
{
        if (buflen > 4) {
                return 0;       /* We've been here, we're done */
        }
        return smb_len_tcp(buf);
}

static void read_smb_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct read_smb_state *state = tevent_req_data(
                req, struct read_smb_state);
        ssize_t len;
        int err;

        len = read_packet_recv(subreq, state, &state->buf, &err);
        TALLOC_FREE(subreq);
        if (len == -1) {
                tevent_req_error(req, err);
                return;
        }

        if (CVAL(state->buf, 0) == NBSSkeepalive) {
                subreq = read_packet_send(state, state->ev, state->fd, 4,
                                          read_smb_more, NULL);
                if (tevent_req_nomem(subreq, req)) {
                        return;
                }
                tevent_req_set_callback(subreq, read_smb_done, req);
                return;
        }
        tevent_req_done(req);
}

ssize_t read_smb_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                      uint8_t **pbuf, int *perrno)
{
        struct read_smb_state *state = tevent_req_data(
                req, struct read_smb_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);
}