path: root/libssh/src/client.c

/*
 * client.c - SSH client functions
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2003-2008 by Aris Adamantiadis
 *
 * The SSH 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 2.1 of the License, or (at your
 * option) any later version.
 *
 * The SSH 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the SSH Library; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifndef _WIN32
#include <netinet/in.h>
#include <arpa/inet.h>
#endif

#include "libssh/priv.h"
#include "libssh/ssh2.h"
#include "libssh/buffer.h"
#include "libssh/packet.h"
#include "libssh/options.h"
#include "libssh/socket.h"
#include "libssh/session.h"
#include "libssh/dh.h"
#include "libssh/ecdh.h"
#include "libssh/threads.h"
#include "libssh/misc.h"
#include "libssh/pki.h"
#include "libssh/kex.h"

#define set_status(session, status) do {\
        if (session->common.callbacks && session->common.callbacks->connect_status_function) \
            session->common.callbacks->connect_status_function(session->common.callbacks->userdata, status); \
    } while (0)

/**
 * @internal
 * @brief Callback to be called when the socket is connected or had a
 * connection error. Changes the state of the session and updates the error
 * message.
 * @param code one of SSH_SOCKET_CONNECTED_OK or SSH_SOCKET_CONNECTED_ERROR
 * @param user is a pointer to session
 */
static void socket_callback_connected(int code, int errno_code, void *user){
	ssh_session session=(ssh_session)user;

	if(session->session_state != SSH_SESSION_STATE_CONNECTING){
		ssh_set_error(session,SSH_FATAL, "Wrong state in socket_callback_connected : %d",
				session->session_state);

		return;
	}
	SSH_LOG(SSH_LOG_RARE,"Socket connection callback: %d (%d)",code, errno_code);
	if(code == SSH_SOCKET_CONNECTED_OK)
		session->session_state=SSH_SESSION_STATE_SOCKET_CONNECTED;
	else {
		session->session_state=SSH_SESSION_STATE_ERROR;
		ssh_set_error(session,SSH_FATAL,"%s",strerror(errno_code));
	}
	session->ssh_connection_callback(session);
}

/**
 * @internal
 *
 * @brief Gets the banner from socket and saves it in session.
 * Updates the session state
 *
 * @param  data pointer to the beginning of header
 * @param  len size of the banner
 * @param  user is a pointer to session
 * @returns Number of bytes processed, or zero if the banner is not complete.
 */
static int callback_receive_banner(const void *data, size_t len, void *user) {
  char *buffer = (char *)data;
  ssh_session session=(ssh_session) user;
  char *str = NULL;
  size_t i;
  int ret=0;

  if(session->session_state != SSH_SESSION_STATE_SOCKET_CONNECTED){
  	ssh_set_error(session,SSH_FATAL,"Wrong state in callback_receive_banner : %d",session->session_state);

  	return SSH_ERROR;
  }
  for(i=0;i<len;++i){
#ifdef WITH_PCAP
  	if(session->pcap_ctx && buffer[i] == '\n'){
  		ssh_pcap_context_write(session->pcap_ctx,SSH_PCAP_DIR_IN,buffer,i+1,i+1);
  	}
#endif
  	if(buffer[i]=='\r')
  		buffer[i]='\0';
  	if(buffer[i]=='\n'){
  		buffer[i]='\0';
  		str=strdup(buffer);
  		/* number of bytes read */
  		ret=i+1;
  		session->serverbanner=str;
  		session->session_state=SSH_SESSION_STATE_BANNER_RECEIVED;
  		SSH_LOG(SSH_LOG_PACKET,"Received banner: %s",str);
		session->ssh_connection_callback(session);

  		return ret;
  	}
  	if(i>127){
  		/* Too big banner */
  		session->session_state=SSH_SESSION_STATE_ERROR;
  		ssh_set_error(session,SSH_FATAL,"Receiving banner: too large banner");

  		return 0;
  	}
  }

  return ret;
}

/** @internal
 * @brief Sends a SSH banner to the server.
 *
 * @param session      The SSH session to use.
 *
 * @param server       Send client or server banner.
 *
 * @return 0 on success, < 0 on error.
 */
int ssh_send_banner(ssh_session session, int server) {
  const char *banner = NULL;
  char buffer[128] = {0};
  int err=SSH_ERROR;

  banner = session->version == 1 ? CLIENTBANNER1 : CLIENTBANNER2;

  if (server) {
    session->serverbanner = strdup(banner);
    if (session->serverbanner == NULL) {
      goto end;
    }
  } else {
    session->clientbanner = strdup(banner);
    if (session->clientbanner == NULL) {
      goto end;
    }
  }

  snprintf(buffer, 128, "%s\n", banner);

  if (ssh_socket_write(session->socket, buffer, strlen(buffer)) == SSH_ERROR) {
    goto end;
  }
#ifdef WITH_PCAP
  if(session->pcap_ctx)
  	ssh_pcap_context_write(session->pcap_ctx,SSH_PCAP_DIR_OUT,buffer,strlen(buffer),strlen(buffer));
#endif
  err=SSH_OK;
end:

  return err;
}

/** @internal
 * @brief launches the DH handshake state machine
 * @param session session handle
 * @returns SSH_OK or SSH_ERROR
 * @warning this function returning is no proof that DH handshake is
 * completed
 */
static int dh_handshake(ssh_session session) {

  int rc = SSH_AGAIN;

  switch (session->dh_handshake_state) {
    case DH_STATE_INIT:
      switch(session->next_crypto->kex_type){
        case SSH_KEX_DH_GROUP1_SHA1:
        case SSH_KEX_DH_GROUP14_SHA1:
          rc = ssh_client_dh_init(session);
          break;
#ifdef HAVE_ECDH
        case SSH_KEX_ECDH_SHA2_NISTP256:
          rc = ssh_client_ecdh_init(session);
          break;
#endif
#ifdef HAVE_CURVE25519
        case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
          rc = ssh_client_curve25519_init(session);
          break;
#endif
        default:
          rc = SSH_ERROR;
      }

      if (rc == SSH_ERROR) {
          return SSH_ERROR;
      }

      session->dh_handshake_state = DH_STATE_INIT_SENT;
    case DH_STATE_INIT_SENT:
    	/* wait until ssh_packet_dh_reply is called */
    	break;
    case DH_STATE_NEWKEYS_SENT:
    	/* wait until ssh_packet_newkeys is called */
    	break;
    case DH_STATE_FINISHED:
      return SSH_OK;
    default:
      ssh_set_error(session, SSH_FATAL, "Invalid state in dh_handshake(): %d",
          session->dh_handshake_state);

      return SSH_ERROR;
  }

  return rc;
}

static int ssh_service_request_termination(void *s){
  ssh_session session = (ssh_session)s;
  if(session->session_state == SSH_SESSION_STATE_ERROR ||
      session->auth_service_state != SSH_AUTH_SERVICE_SENT)
    return 1;
  else
    return 0;
}

/**
 * @internal
 *
 * @brief Request a service from the SSH server.
 *
 * Service requests are for example: ssh-userauth, ssh-connection, etc.
 *
 * @param  session      The session to use to ask for a service request.
 * @param  service      The service request.
 *
 * @return SSH_OK on success
 * @return SSH_ERROR on error
 * @return SSH_AGAIN No response received yet
 * @bug actually only works with ssh-userauth
 */
int ssh_service_request(ssh_session session, const char *service) {
  ssh_string service_s = NULL;
  int rc=SSH_ERROR;

  if(session->auth_service_state != SSH_AUTH_SERVICE_NONE)
    goto pending;
  if (buffer_add_u8