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packet.c
1281 lines (1112 loc) · 41.3 KB
/
packet.c
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/* Copyright (c) 2004-2006, Sara Golemon <sarag@libssh2.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms,
* with or without modification, are permitted provided
* that the following conditions are met:
*
* Redistributions of source code must retain the above
* copyright notice, this list of conditions and the
* following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* Neither the name of the copyright holder nor the names
* of any other contributors may be used to endorse or
* promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*/
#include "libssh2_priv.h"
#include <errno.h>
#include <fcntl.h>
#ifndef WIN32
#include <unistd.h>
#endif
/* Needed for struct iovec on some platforms */
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
#ifdef HAVE_POLL
# include <sys/poll.h>
#else
# ifdef HAVE_SELECT
# ifdef HAVE_SYS_SELECT_H
# include <sys/select.h>
# else
# include <sys/time.h>
# include <sys/types.h>
# endif
# endif
#endif
#include <inttypes.h>
/* RFC4253 section 6.1 Maximum Packet Length says:
*
* "All implementations MUST be able to process packets with
* uncompressed payload length of 32768 bytes or less and
* total packet size of 35000 bytes or less (including length,
* padding length, payload, padding, and MAC.)."
*/
#define MAX_SSH_PACKET_LEN 35000
inline int libssh2_packet_queue_listener(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen);
inline int libssh2_packet_x11_open(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen);
/* {{{ libssh2_packet_queue_listener
* Queue a connection request for a listener
*/
inline int libssh2_packet_queue_listener(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen)
{
/* Look for a matching listener */
unsigned char *s = data + (sizeof("forwarded-tcpip") - 1) + 5;
/* 17 = packet_type(1) + channel(4) + reason(4) + descr(4) + lang(4) */
unsigned long packet_len = 17 + (sizeof("Forward not requested") - 1);
unsigned char *p, packet[17 + (sizeof("Forward not requested") - 1)];
LIBSSH2_LISTENER *l = session->listeners;
char failure_code = 1; /* SSH_OPEN_ADMINISTRATIVELY_PROHIBITED */
uint32_t sender_channel, initial_window_size, packet_size;
unsigned char *host, *shost;
uint32_t port, sport, host_len, shost_len;
sender_channel = libssh2_ntohu32(s); s += 4;
initial_window_size = libssh2_ntohu32(s); s += 4;
packet_size = libssh2_ntohu32(s); s += 4;
host_len = libssh2_ntohu32(s); s += 4;
host = s; s += host_len;
port = libssh2_ntohu32(s); s += 4;
shost_len = libssh2_ntohu32(s); s += 4;
shost = s; s += shost_len;
sport = libssh2_ntohu32(s); s += 4;
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Remote received connection from %s:%ld to %s:%ld", shost, sport, host, port);
#endif
while (l) {
if ((l->port == port) &&
(strlen(l->host) == host_len) &&
(memcmp(l->host, host, host_len) == 0)) {
/* This is our listener */
LIBSSH2_CHANNEL *channel, *last_queued = l->queue;
if (l->queue_maxsize &&
(l->queue_maxsize <= l->queue_size)) {
/* Queue is full */
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Listener queue full, ignoring");
#endif
break;
}
channel = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_CHANNEL));
if (!channel) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
break;
}
memset(channel, 0, sizeof(LIBSSH2_CHANNEL));
channel->session = session;
channel->channel_type_len = sizeof("forwarded-tcpip") - 1;
channel->channel_type = LIBSSH2_ALLOC(session, channel->channel_type_len + 1);
if (!channel->channel_type) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
LIBSSH2_FREE(session, channel);
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
break;
}
memcpy(channel->channel_type, "forwarded-tcpip", channel->channel_type_len + 1);
channel->remote.id = sender_channel;
channel->remote.window_size_initial = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
channel->remote.window_size = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
channel->remote.packet_size = LIBSSH2_CHANNEL_PACKET_DEFAULT;
channel->local.id = libssh2_channel_nextid(session);
channel->local.window_size_initial = initial_window_size;
channel->local.window_size = initial_window_size;
channel->local.packet_size = packet_size;
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Connection queued: channel %lu/%lu win %lu/%lu packet %lu/%lu",
channel->local.id, channel->remote.id,
channel->local.window_size, channel->remote.window_size,
channel->local.packet_size, channel->remote.packet_size);
#endif
p = packet;
*(p++) = SSH_MSG_CHANNEL_OPEN_CONFIRMATION;
libssh2_htonu32(p, channel->remote.id); p += 4;
libssh2_htonu32(p, channel->local.id); p += 4;
libssh2_htonu32(p, channel->remote.window_size_initial); p += 4;
libssh2_htonu32(p, channel->remote.packet_size); p += 4;
if (libssh2_packet_write(session, packet, 17)) {
libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send channel open confirmation", 0);
return -1;
}
/* Link the channel into the end of the queue list */
if (!last_queued) {
l->queue = channel;
return 0;
}
while (last_queued->next) last_queued = last_queued->next;
last_queued->next = channel;
channel->prev = last_queued;
l->queue_size++;
return 0;
}
l = l->next;
}
/* We're not listening to you */
{
p = packet;
*(p++) = SSH_MSG_CHANNEL_OPEN_FAILURE;
libssh2_htonu32(p, sender_channel); p += 4;
libssh2_htonu32(p, failure_code); p += 4;
libssh2_htonu32(p, sizeof("Forward not requested") - 1); p += 4;
memcpy(s, "Forward not requested", sizeof("Forward not requested") - 1); p += sizeof("Forward not requested") - 1;
libssh2_htonu32(p, 0);
if (libssh2_packet_write(session, packet, packet_len)) {
libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send open failure", 0);
return -1;
}
return 0;
}
}
/* }}} */
/* {{{ libssh2_packet_x11_open
* Accept a forwarded X11 connection
*/
inline int libssh2_packet_x11_open(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen)
{
int failure_code = 2; /* SSH_OPEN_CONNECT_FAILED */
unsigned char *s = data + (sizeof("x11") - 1) + 5;
unsigned long packet_len = 17 + (sizeof("X11 Forward Unavailable") - 1);
unsigned char *p, packet[17 + (sizeof("X11 Forward Unavailable") - 1)];
/* packet_type(1) + channel(4) + reason(4) + descr(4) + lang(4) */
LIBSSH2_CHANNEL *channel;
unsigned long sender_channel, initial_window_size, packet_size;
unsigned char *shost;
unsigned long sport, shost_len;
sender_channel = libssh2_ntohu32(s); s += 4;
initial_window_size = libssh2_ntohu32(s); s += 4;
packet_size = libssh2_ntohu32(s); s += 4;
shost_len = libssh2_ntohu32(s); s += 4;
shost = s; s += shost_len;
sport = libssh2_ntohu32(s); s += 4;
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "X11 Connection Received from %s:%ld on channel %lu", shost, sport, sender_channel);
#endif
if (session->x11) {
channel = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_CHANNEL));
if (!channel) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
goto x11_exit;
}
memset(channel, 0, sizeof(LIBSSH2_CHANNEL));
channel->session = session;
channel->channel_type_len = sizeof("x11") - 1;
channel->channel_type = LIBSSH2_ALLOC(session, channel->channel_type_len + 1);
if (!channel->channel_type) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
LIBSSH2_FREE(session, channel);
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
goto x11_exit;
}
memcpy(channel->channel_type, "x11", channel->channel_type_len + 1);
channel->remote.id = sender_channel;
channel->remote.window_size_initial = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
channel->remote.window_size = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
channel->remote.packet_size = LIBSSH2_CHANNEL_PACKET_DEFAULT;
channel->local.id = libssh2_channel_nextid(session);
channel->local.window_size_initial = initial_window_size;
channel->local.window_size = initial_window_size;
channel->local.packet_size = packet_size;
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "X11 Connection established: channel %lu/%lu win %lu/%lu packet %lu/%lu",
channel->local.id, channel->remote.id,
channel->local.window_size, channel->remote.window_size,
channel->local.packet_size, channel->remote.packet_size);
#endif
p = packet;
*(p++) = SSH_MSG_CHANNEL_OPEN_CONFIRMATION;
libssh2_htonu32(p, channel->remote.id); p += 4;
libssh2_htonu32(p, channel->local.id); p += 4;
libssh2_htonu32(p, channel->remote.window_size_initial); p += 4;
libssh2_htonu32(p, channel->remote.packet_size); p += 4;
if (libssh2_packet_write(session, packet, 17)) {
libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send channel open confirmation", 0);
return -1;
}
/* Link the channel into the session */
if (session->channels.tail) {
session->channels.tail->next = channel;
channel->prev = session->channels.tail;
} else {
session->channels.head = channel;
channel->prev = NULL;
}
channel->next = NULL;
session->channels.tail = channel;
/*
* Pass control to the callback, they may turn right around and
* free the channel, or actually use it
*/
LIBSSH2_X11_OPEN(channel, (char *)shost, sport);
return 0;
} else {
failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
}
x11_exit:
p = packet;
*(p++) = SSH_MSG_CHANNEL_OPEN_FAILURE;
libssh2_htonu32(p, sender_channel); p += 4;
libssh2_htonu32(p, failure_code); p += 4;
libssh2_htonu32(p, sizeof("X11 Forward Unavailable") - 1); p += 4;
memcpy(s, "X11 Forward Unavailable", sizeof("X11 Forward Unavailable") - 1); p += sizeof("X11 Forward Unavailable") - 1;
libssh2_htonu32(p, 0);
if (libssh2_packet_write(session, packet, packet_len)) {
libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send open failure", 0);
return -1;
}
return 0;
}
/* }}} */
/* {{{ libssh2_packet_new
* Create a new packet and attach it to the brigade
*/
static int libssh2_packet_add(LIBSSH2_SESSION *session, unsigned char *data, size_t datalen, int macstate)
{
LIBSSH2_PACKET *packet;
unsigned long data_head = 0;
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Packet type %d received, length=%d", (int)data[0], (int)datalen);
#endif
if (macstate == LIBSSH2_MAC_INVALID) {
if (session->macerror) {
if (LIBSSH2_MACERROR(session, (char *)data, datalen) == 0) {
/* Calling app has given the OK, Process it anyway */
macstate = LIBSSH2_MAC_CONFIRMED;
} else {
libssh2_error(session, LIBSSH2_ERROR_INVALID_MAC, "Invalid Message Authentication Code received", 0);
if (session->ssh_msg_disconnect) {
LIBSSH2_DISCONNECT(session, SSH_DISCONNECT_MAC_ERROR, "Invalid MAC received", sizeof("Invalid MAC received") - 1, "", 0);
}
return -1;
}
} else {
libssh2_error(session, LIBSSH2_ERROR_INVALID_MAC, "Invalid Message Authentication Code received", 0);
if (session->ssh_msg_disconnect) {
LIBSSH2_DISCONNECT(session, SSH_DISCONNECT_MAC_ERROR, "Invalid MAC received", sizeof("Invalid MAC received") - 1, "", 0);
}
return -1;
}
}
/* A couple exceptions to the packet adding rule: */
switch (data[0]) {
case SSH_MSG_DISCONNECT:
{
char *message, *language;
int reason, message_len, language_len;
reason = libssh2_ntohu32(data + 1);
message_len = libssh2_ntohu32(data + 5);
message = (char *)data + 9; /* packet_type(1) + reason(4) + message_len(4) */
language_len = libssh2_ntohu32(data + 9 + message_len);
/* This is where we hack on the data a little,
* Use the MSB of language_len to to a terminating NULL (In all liklihood it is already)
* Shift the language tag back a byte (In all likelihood it's zero length anyway
* Store a NULL in the last byte of the packet to terminate the language string
* With the lengths passed this isn't *REALLY* necessary, but it's "kind"
*/
message[message_len] = '\0';
language = (char *)data + 9 + message_len + 3;
if (language_len) {
memcpy(language, language + 1, language_len);
}
language[language_len] = '\0';
if (session->ssh_msg_disconnect) {
LIBSSH2_DISCONNECT(session, reason, message, message_len, language, language_len);
}
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Disconnect(%d): %s(%s)", reason, message, language);
#endif
LIBSSH2_FREE(session, data);
session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
return -1;
}
break;
case SSH_MSG_IGNORE:
/* As with disconnect, back it up one and add a trailing NULL */
memcpy(data + 4, data + 5, datalen - 5);
data[datalen] = '\0';
if (session->ssh_msg_ignore) {
LIBSSH2_IGNORE(session, (char *)data + 4, datalen - 5);
}
LIBSSH2_FREE(session, (char *)data);
return 0;
break;
case SSH_MSG_DEBUG:
{
int always_display = data[0];
char *message, *language;
int message_len, language_len;
message_len = libssh2_ntohu32(data + 2);
message = (char *)data + 6; /* packet_type(1) + display(1) + message_len(4) */
language_len = libssh2_ntohu32(data + 6 + message_len);
/* This is where we hack on the data a little,
* Use the MSB of language_len to to a terminating NULL (In all liklihood it is already)
* Shift the language tag back a byte (In all likelihood it's zero length anyway
* Store a NULL in the last byte of the packet to terminate the language string
* With the lengths passed this isn't *REALLY* necessary, but it's "kind"
*/
message[message_len] = '\0';
language = (char *)data + 6 + message_len + 3;
if (language_len) {
memcpy(language, language + 1, language_len);
}
language[language_len] = '\0';
if (session->ssh_msg_debug) {
LIBSSH2_DEBUG(session, always_display, message, message_len, language, language_len);
}
#ifdef LIBSSH2_DEBUG_TRANSPORT
/* _libssh2_debug will actually truncate this for us so that it's not an inordinate about of data */
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Debug Packet: %s", message);
#endif
LIBSSH2_FREE(session, data);
return 0;
}
break;
case SSH_MSG_CHANNEL_EXTENDED_DATA:
data_head += 4; /* streamid(4) */
case SSH_MSG_CHANNEL_DATA:
data_head += 9; /* packet_type(1) + channelno(4) + datalen(4) */
{
LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));
if (!channel) {
libssh2_error(session, LIBSSH2_ERROR_CHANNEL_UNKNOWN, "Packet received for unknown channel, ignoring", 0);
LIBSSH2_FREE(session, data);
return 0;
}
#ifdef LIBSSH2_DEBUG_CONNECTION
{
unsigned long stream_id = 0;
if (data[0] == SSH_MSG_CHANNEL_EXTENDED_DATA) {
stream_id = libssh2_ntohu32(data + 5);
}
_libssh2_debug(session, LIBSSH2_DBG_CONN, "%d bytes received for channel %lu/%lu stream #%lu", (int)(datalen - data_head), channel->local.id, channel->remote.id, stream_id);
}
#endif
if ((channel->remote.extended_data_ignore_mode == LIBSSH2_CHANNEL_EXTENDED_DATA_IGNORE) && (data[0] == SSH_MSG_CHANNEL_EXTENDED_DATA)) {
/* Pretend we didn't receive this */
LIBSSH2_FREE(session, data);
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Ignoring extended data and refunding %d bytes", (int)(datalen - 13));
#endif
/* Adjust the window based on the block we just freed */
libssh2_channel_receive_window_adjust(channel, datalen - 13, 0);
return 0;
}
/* REMEMBER! remote means remote as source of data, NOT remote window! */
if (channel->remote.packet_size < (datalen - data_head)) {
/* Spec says we MAY ignore bytes sent beyond packet_size */
libssh2_error(session, LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, "Packet contains more data than we offered to receive, truncating", 0);
datalen = channel->remote.packet_size + data_head;
}
if (channel->remote.window_size <= 0) {
/* Spec says we MAY ignore bytes sent beyond window_size */
libssh2_error(session, LIBSSH2_ERROR_CHANNEL_WINDOW_EXCEEDED, "The current receive window is full, data ignored", 0);
LIBSSH2_FREE(session, data);
return 0;
}
/* Reset EOF status */
channel->remote.eof = 0;
if ((datalen - data_head) > channel->remote.window_size) {
libssh2_error(session, LIBSSH2_ERROR_CHANNEL_WINDOW_EXCEEDED, "Remote sent more data than current window allows, truncating", 0);
datalen = channel->remote.window_size + data_head;
} else {
/* Now that we've received it, shrink our window */
channel->remote.window_size -= datalen - data_head;
}
}
break;
case SSH_MSG_CHANNEL_EOF:
{
LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));
if (!channel) {
/* We may have freed already, just quietly ignore this... */
LIBSSH2_FREE(session, data);
return 0;
}
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "EOF received for channel %lu/%lu", channel->local.id, channel->remote.id);
#endif
channel->remote.eof = 1;
LIBSSH2_FREE(session, data);
return 0;
}
break;
case SSH_MSG_CHANNEL_REQUEST:
{
if (libssh2_ntohu32(data+5) == sizeof("exit-status") - 1
&& !memcmp("exit-status", data + 9, sizeof("exit-status") - 1)) {
/* we've got "exit-status" packet. Set the session value */
LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data+1));
if (channel) {
channel->exit_status = libssh2_ntohu32(data + 9 + sizeof("exit-status"));
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Exit status %lu received for channel %lu/%lu", channel->exit_status, channel->local.id, channel->remote.id);
#endif
}
LIBSSH2_FREE(session, data);
return 0;
}
}
break;
case SSH_MSG_CHANNEL_CLOSE:
{
LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));
if (!channel) {
/* We may have freed already, just quietly ignore this... */
LIBSSH2_FREE(session, data);
return 0;
}
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Close received for channel %lu/%lu", channel->local.id, channel->remote.id);
#endif
channel->remote.close = 1;
channel->remote.eof = 1;
/* TODO: Add a callback for this */
LIBSSH2_FREE(session, data);
return 0;
}
break;
case SSH_MSG_CHANNEL_OPEN:
if ((datalen >= (sizeof("forwarded-tcpip") + 4)) &&
((sizeof("forwarded-tcpip")-1) == libssh2_ntohu32(data + 1)) &&
(memcmp(data + 5, "forwarded-tcpip", sizeof("forwarded-tcpip") - 1) == 0)) {
int retval = libssh2_packet_queue_listener(session, data, datalen);
LIBSSH2_FREE(session, data);
return retval;
}
if ((datalen >= (sizeof("x11") + 4)) &&
((sizeof("x11")-1) == libssh2_ntohu32(data + 1)) &&
(memcmp(data + 5, "x11", sizeof("x11") - 1) == 0)) {
int retval = libssh2_packet_x11_open(session, data, datalen);
LIBSSH2_FREE(session, data);
return retval;
}
break;
case SSH_MSG_CHANNEL_WINDOW_ADJUST:
{
LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));
unsigned long bytestoadd = libssh2_ntohu32(data + 5);
if (channel && bytestoadd) {
channel->local.window_size += bytestoadd;
}
#ifdef LIBSSH2_DEBUG_CONNECTION
_libssh2_debug(session, LIBSSH2_DBG_CONN, "Window adjust received for channel %lu/%lu, adding %lu bytes, new window_size=%lu", channel->local.id, channel->remote.id, bytestoadd, channel->local.window_size);
#endif
LIBSSH2_FREE(session, data);
return 0;
}
break;
}
packet = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_PACKET));
memset(packet, 0, sizeof(LIBSSH2_PACKET));
packet->data = data;
packet->data_len = datalen;
packet->data_head = data_head;
packet->mac = macstate;
packet->brigade = &session->packets;
packet->next = NULL;
if (session->packets.tail) {
packet->prev = session->packets.tail;
packet->prev->next = packet;
session->packets.tail = packet;
} else {
session->packets.head = packet;
session->packets.tail = packet;
packet->prev = NULL;
}
if (data[0] == SSH_MSG_KEXINIT && !(session->state & LIBSSH2_STATE_EXCHANGING_KEYS)) {
/* Remote wants new keys
* Well, it's already in the brigade,
* let's just call back into ourselves
*/
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Renegotiating Keys");
#endif
libssh2_kex_exchange(session, 1);
/* If there was a key reexchange failure, let's just hope we didn't send NEWKEYS yet, otherwise remote will drop us like a rock */
}
return 0;
}
/* }}} */
/* {{{ libssh2_blocking_read
* Force a blocking read, regardless of socket settings
*/
static ssize_t libssh2_blocking_read(LIBSSH2_SESSION *session, unsigned char *buf, size_t count)
{
size_t bytes_read = 0;
#if !defined(HAVE_POLL) && !defined(HAVE_SELECT)
int polls = 0;
#endif
#ifndef WIN32
fcntl(session->socket_fd, F_SETFL, 0);
#else
{
u_long block = FALSE;
ioctlsocket(session->socket_fd, FIONBIO, &block);
}
#endif
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Blocking read: %d bytes", (int)count);
#endif
while (bytes_read < count) {
int ret;
ret = LIBSSH2_READ(session, buf + bytes_read, count - bytes_read);
if (ret < 0) {
#ifdef WIN32
switch (WSAGetLastError()) {
case WSAEWOULDBLOCK: errno = EAGAIN; break;
case WSAENOTSOCK: errno = EBADF; break;
case WSAENOTCONN:
case WSAECONNABORTED: errno = ENOTCONN; break;
case WSAEINTR: errno = EINTR; break;
}
#endif
if (errno == EAGAIN) {
#ifdef HAVE_POLL
struct pollfd read_socket;
read_socket.fd = session->socket_fd;
read_socket.events = POLLIN;
if (poll(&read_socket, 1, 30000) <= 0) {
return -1;
}
#elif defined(HAVE_SELECT)
fd_set read_socket;
struct timeval timeout;
FD_ZERO(&read_socket);
FD_SET(session->socket_fd, &read_socket);
timeout.tv_sec = 30;
timeout.tv_usec = 0;
if (select(session->socket_fd + 1, &read_socket, NULL, NULL, &timeout) <= 0) {
return -1;
}
#else
if (polls++ > LIBSSH2_SOCKET_POLL_MAXLOOPS) {
return -1;
}
usleep(LIBSSH2_SOCKET_POLL_UDELAY);
#endif /* POLL/SELECT/SLEEP */
continue;
}
if (errno == EINTR) {
continue;
}
if ((errno == EBADF) || (errno == EIO) || (errno == ENOTCONN)) {
session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
}
return -1;
}
if (ret == 0) continue;
bytes_read += ret;
}
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Blocking read: %d bytes actually read", (int)bytes_read);
#endif
return bytes_read;
}
/* }}} */
/* {{{ libssh2_packet_read
* Collect a packet into the input brigade
* block only controls whether or not to wait for a packet to start,
* Once a packet starts, libssh2 will block until it is complete
* Returns packet type added to input brigade (0 if nothing added), or -1 on failure
*/
int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
{
int packet_type = -1;
if (session->socket_state == LIBSSH2_SOCKET_DISCONNECTED) {
return 0;
}
#ifndef WIN32
fcntl(session->socket_fd, F_SETFL, O_NONBLOCK);
#else
{
u_long non_block = TRUE;
ioctlsocket(session->socket_fd, FIONBIO, &non_block);
}
#endif
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Checking for packet: will%s block", should_block ? "" : " not");
#endif
if (session->state & LIBSSH2_STATE_NEWKEYS) {
/* Temporary Buffer
* The largest blocksize (currently) is 32, the largest MAC (currently) is 20
*/
unsigned char block[2 * 32], *payload, *s, *p, tmp[6];
ssize_t read_len;
unsigned long blocksize = session->remote.crypt->blocksize;
unsigned long packet_len, payload_len;
int padding_len;
int macstate;
int free_payload = 1;
/* Note: If we add any cipher with a blocksize less than 6 we'll need to get more creative with this
* For now, all blocksize sizes are 8+
*/
if (should_block) {
read_len = libssh2_blocking_read(session, block, blocksize);
if(read_len <= 0)
return read_len;
} else {
ssize_t nread;
read_len = LIBSSH2_READ(session, block, 1);
if (read_len <= 0) {
return 0;
}
nread = libssh2_blocking_read(session, block + read_len, blocksize - read_len);
if(nread <= 0)
return nread;
read_len += nread;
}
if (read_len < blocksize) {
return (session->socket_state == LIBSSH2_SOCKET_DISCONNECTED) ? 0 : -1;
}
if (session->remote.crypt->crypt(session, block, &session->remote.crypt_abstract)) {
libssh2_error(session, LIBSSH2_ERROR_DECRYPT, "Error decrypting packet preamble", 0);
return -1;
}
packet_len = libssh2_ntohu32(block);
/* RFC4253 section 6.1 Maximum Packet Length says:
*
* "All implementations MUST be able to process packets with
* uncompressed payload length of 32768 bytes or less and
* total packet size of 35000 bytes or less (including length,
* padding length, payload, padding, and MAC.)."
*/
if(packet_len > MAX_SSH_PACKET_LEN) {
return -1;
}
padding_len = block[4];
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Processing packet %lu bytes long (with %lu bytes padding)", packet_len, padding_len);
#endif
memcpy(tmp, block, 5); /* Use this for MAC later */
payload_len = packet_len - 1; /* padding_len(1) */
/* Sanity Check */
if ((payload_len > LIBSSH2_PACKET_MAXPAYLOAD) ||
((packet_len + 4) % blocksize)) {
/* If something goes horribly wrong during the decryption phase, just bailout and die gracefully */
session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
libssh2_error(session, LIBSSH2_ERROR_PROTO, "Fatal protocol error, invalid payload size", 0);
return -1;
}
s = payload = LIBSSH2_ALLOC(session, payload_len);
memcpy(s, block + 5, blocksize - 5);
s += blocksize - 5;
p = s;
while (p - payload < payload_len) {
read_len = payload_len - (p - payload);
if (read_len > 4096) read_len = 4096;
if (libssh2_blocking_read(session, p, read_len) < read_len) {
LIBSSH2_FREE(session, payload);
return -1;
}
p += read_len;
while (s < p) {
memcpy(block, s, blocksize);
if (session->remote.crypt->crypt(session, block, &session->remote.crypt_abstract)) {
libssh2_error(session, LIBSSH2_ERROR_DECRYPT, "Error decrypting packet preamble", 0);
LIBSSH2_FREE(session, payload);
return -1;
}
memcpy(s, block, blocksize);
s += blocksize;
}
}
read_len = libssh2_blocking_read(session, block, session->remote.mac->mac_len);
if (read_len < session->remote.mac->mac_len) {
LIBSSH2_FREE(session, payload);
return -1;
}
/* Calculate MAC hash */
session->remote.mac->hash(session, block + session->remote.mac->mac_len, session->remote.seqno, tmp, 5, payload, payload_len, &session->remote.mac_abstract);
macstate = (strncmp((char *)block, (char *)block + session->remote.mac->mac_len, session->remote.mac->mac_len) == 0) ? LIBSSH2_MAC_CONFIRMED : LIBSSH2_MAC_INVALID;
session->remote.seqno++;
/* Ignore padding */
payload_len -= padding_len;
if (session->remote.comp &&
strcmp(session->remote.comp->name, "none")) {
/* Decompress */
unsigned char *data;
unsigned long data_len;
if (session->remote.comp->comp(session, 0, &data, &data_len, LIBSSH2_PACKET_MAXDECOMP, &free_payload, payload, payload_len, &session->remote.comp_abstract)) {
LIBSSH2_FREE(session, payload);
return -1;
}
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Payload decompressed: %lu bytes(compressed) to %lu bytes(uncompressed)", data_len, payload_len);
#endif
if (free_payload) {
LIBSSH2_FREE(session, payload);
payload = data;
payload_len = data_len;
} else {
if (data == payload) {
/* It's not to be freed, because the compression layer reused payload,
* So let's do the same!
*/
payload_len = data_len;
} else {
/* No comp_method actually lets this happen, but let's prepare for the future */
LIBSSH2_FREE(session, payload);
/* We need a freeable struct otherwise the brigade won't know what to do with it */
payload = LIBSSH2_ALLOC(session, data_len);
if (!payload) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for copy of uncompressed data", 0);
return -1;
}
memcpy(payload, data, data_len);
payload_len = data_len;
}
}
}
packet_type = payload[0];
libssh2_packet_add(session, payload, payload_len, macstate);
} else { /* No cipher active */
unsigned char *payload;
unsigned char buf[24];
ssize_t buf_len;
unsigned long payload_len;
uint32_t packet_length;
unsigned long padding_length;
if (should_block) {
buf_len = libssh2_blocking_read(session, buf, 5);
} else {
ssize_t nread;
buf_len = LIBSSH2_READ(session, buf, 1);
if (buf_len <= 0) {
return buf_len;
}
nread = libssh2_blocking_read(session, buf, 5 - buf_len);
if(nread <= 0)
return -1;
buf_len += nread;
}
if (buf_len < 5) {
/* Something bad happened */
return -1;
}
packet_length = libssh2_ntohu32(buf);
/* RFC4253 section 6.1 Maximum Packet Length says:
*
* "All implementations MUST be able to process packets with
* uncompressed payload length of 32768 bytes or less and
* total packet size of 35000 bytes or less (including length,
* padding length, payload, padding, and MAC.)."
*/
if(packet_length > MAX_SSH_PACKET_LEN) {
return -1;
}
padding_length = buf[4];
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Processing plaintext packet %lu bytes long (with %lu bytes padding)", packet_length, padding_length);
#endif
payload_len = packet_length - padding_length - 1; /* padding_length(1) */
payload = LIBSSH2_ALLOC(session, payload_len);
if (!payload) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for copy of plaintext data", 0);
return -1;
}
if (libssh2_blocking_read(session, payload, payload_len) < payload_len) {
return (session->socket_state == LIBSSH2_SOCKET_DISCONNECTED) ? 0 : -1;
}
while (padding_length) {
int l;
/* Flush padding */
l = libssh2_blocking_read(session, buf, padding_length);
if (l > 0)
padding_length -= l;
else
break;
}
packet_type = payload[0];
/* MACs don't exist in non-encrypted mode */
libssh2_packet_add(session, payload, payload_len, LIBSSH2_MAC_CONFIRMED);
session->remote.seqno++;
}
return packet_type;
}
/* }}} */
/* {{{ libssh2_packet_ask
* Scan the brigade for a matching packet type, optionally poll the socket for a packet first
*/
int libssh2_packet_ask_ex(LIBSSH2_SESSION *session, unsigned char packet_type, unsigned char **data, unsigned long *data_len,
unsigned long match_ofs, const unsigned char *match_buf, unsigned long match_len, int poll_socket)
{
LIBSSH2_PACKET *packet = session->packets.head;
if (poll_socket) {
if (libssh2_packet_read(session, 0) < 0) {
return -1;
}
}
#ifdef LIBSSH2_DEBUG_TRANSPORT
_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Looking for packet of type: %d", (int)packet_type);
#endif
while (packet) {
if (packet->data[0] == packet_type &&
(packet->data_len >= (match_ofs + match_len)) &&
(!match_buf || (memcmp(packet->data + match_ofs, match_buf, match_len) == 0))) {
*data = packet->data;
*data_len = packet->data_len;
if (packet->prev) {
packet->prev->next = packet->next;
} else {