/*
* packet.c - packet building functions
*
* This file is part of the SSH Library
*
* Copyright (c) 2011 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 "config.h"
#include <stdlib.h>
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include "libssh/priv.h"
#include "libssh/buffer.h"
#include "libssh/crypto.h"
#include "libssh/dh.h"
#include "libssh/misc.h"
#include "libssh/packet.h"
#include "libssh/pki.h"
#include "libssh/session.h"
#include "libssh/socket.h"
#include "libssh/ssh2.h"
#include "libssh/curve25519.h"
/**
* @internal
*
* @brief Handle a SSH_DISCONNECT packet.
*/
SSH_PACKET_CALLBACK(ssh_packet_disconnect_callback){
int rc;
uint32_t code = 0;
char *error = NULL;
ssh_string error_s;
(void)user;
(void)type;
rc = ssh_buffer_get_u32(packet, &code);
if (rc != 0) {
code = ntohl(code);
}
error_s = ssh_buffer_get_ssh_string(packet);
if (error_s != NULL) {
error = ssh_string_to_char(error_s);
SSH_STRING_FREE(error_s);
}
SSH_LOG(SSH_LOG_PACKET, "Received SSH_MSG_DISCONNECT %d:%s",
code, error != NULL ? error : "no error");
ssh_set_error(session, SSH_FATAL,
"Received SSH_MSG_DISCONNECT: %d:%s",
code, error != NULL ? error : "no error");
SAFE_FREE(error);
ssh_socket_close(session->socket);
session->alive = 0;
session->session_state = SSH_SESSION_STATE_ERROR;
/* TODO: handle a graceful disconnect */
return SSH_PACKET_USED;
}
/**
* @internal
*
* @brief Handle a SSH_IGNORE and SSH_DEBUG packet.
*/
SSH_PACKET_CALLBACK(ssh_packet_ignore_callback){
(void)session; /* unused */
(void)user;
(void)type;
(void)packet;
SSH_LOG(SSH_LOG_PROTOCOL,"Received %s packet",type==SSH2_MSG_IGNORE ? "SSH_MSG_IGNORE" : "SSH_MSG_DEBUG");
/* TODO: handle a graceful disconnect */
return SSH_PACKET_USED;
}
SSH_PACKET_CALLBACK(ssh_packet_newkeys){
ssh_string sig_blob = NULL;
ssh_signature sig = NULL;
int rc;
(void)packet;
(void)user;
(void)type;
SSH_LOG(SSH_LOG_PROTOCOL, "Received SSH_MSG_NEWKEYS");
if (session->session_state != SSH_SESSION_STATE_DH ||
session->dh_handshake_state != DH_STATE_NEWKEYS_SENT) {
ssh_set_error(session,
SSH_FATAL,
"ssh_packet_newkeys called in wrong state : %d:%d",
session->session_state,session->dh_handshake_state);
goto error;
}
if(session->server){
/* server things are done in server.c */
session->dh_handshake_state=DH_STATE_FINISHED;
} else {
ssh_key server_key;
/* client */
/* Verify the host's signature. FIXME do it sooner */
sig_blob = session->next_crypto->dh_server_signature;
session->next_crypto->dh_server_signature = NULL;
/* get the server public key */
server_key = ssh_dh_get_next_server_publickey(session);
if (server_key == NULL) {
goto error;
}
rc = ssh_pki_import_signature_blob(sig_blob, server_key, &sig);
if (rc != SSH_OK) {
goto error;
}
/* Check if signature from server matches user preferences */
if (session->opts.wanted_methods[SSH_HOSTKEYS]) {
if (!ssh_match_group(session->opts.wanted_methods[SSH_HOSTKEYS],
sig->type_c)) {
ssh_set_error(session,
SSH_FATAL,
"Public key from server (%s) doesn't match user "
"preference (%s)",
sig->type_c,
session->opts.wanted_methods[SSH_HOSTKEYS]);
goto error;
}
}
rc = ssh_pki_signature_verify(session,
sig,
server_key,
session->next_crypto->secret_hash,
session->next_crypto->digest_len);
ssh_string_burn(sig_blob);
SSH_STRING_FREE(sig_blob);
ssh_signature_free(sig);
if (rc == SSH_ERROR) {
goto error;
}
SSH_LOG(SSH_LOG_PROTOCOL,"Signature verified and valid");
/* When receiving this packet, we switch on the incomming crypto. */
rc = ssh_packet_set_newkeys(session, SSH_DIRECTION_IN);
if (rc != SSH_OK) {
goto error;
}
}
session->dh_handshake_state = DH_STATE_FINISHED;
session->ssh_connection_callback(session);
return SSH_PACKET_USED;
error:
session->session_state = SSH_SESSION_STATE_ERROR;
return SSH_PACKET_USED;
}
/**
* @internal
* @brief handles a SSH_SERVICE_ACCEPT packet
*
*/
SSH_PACKET_CALLBACK(ssh_packet_service_accept){
(void)packet;
(void)type;
(void)user;
session->auth.service_state = SSH_AUTH_SERVICE_ACCEPTED;
SSH_LOG(SSH_LOG_PACKET,
"Received SSH_MSG_SERVICE_ACCEPT");
return SSH_PACKET_USED;
}
/**
* @internal
* @brief handles a SSH2_MSG_EXT_INFO packet defined in RFC 8308
*
*/
SSH_PACKET_CALLBACK(ssh_packet_ext_info)
{
int rc;
uint32_t nr_extensions = 0;
uint32_t i;
(void)type;
(void)user;
SSH_LOG(SSH_LOG_PACKET, "Received SSH_MSG_EXT_INFO");
rc = ssh_buffer_get_u32(packet, &nr_extensions);
if (rc == 0) {
SSH_LOG(SSH_LOG_PACKET, "Failed to read number of extensions");
return SSH_PACKET_USED;
}
nr_extensions = ntohl(nr_extensions);
if (nr_extensions > 128) {
SSH_LOG(SSH_LOG_PACKET, "Invalid number of extensions");
return SSH_PACKET_USED;
}
SSH_LOG(SSH_LOG_PACKET, "Follows %u extensions", nr_extensions);
for (i = 0; i < nr_extensions; i++) {
char *name = NULL;
char *value = NULL;
int cmp;
rc = ssh_buffer_unpack(packet, "ss", &name, &value);
if (rc != SSH_OK) {
SSH_LOG(SSH_LOG_PACKET, "Error reading extension name-value pair");
return SSH_PACKET_USED;
}
cmp = strcmp(name, "server-sig-algs");
if (cmp == 0) {
/* TODO check for NULL bytes */
SSH_LOG(SSH_LOG_PACKET, "Extension: %s=<%s>", name, value);
if (ssh_match_group(value, "rsa-sha2-512")) {
session->extensions |= SSH_EXT_SIG_RSA_SHA512;
}
if (ssh_match_group(value, "rsa-sha2-256")) {
session->extensions |= SSH_EXT_SIG_RSA_SHA256;
}
}
free(name);
free(value);
}
return SSH_PACKET_USED;
}