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/*
* 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>
#include <arpa/inet.h>
#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 = buffer_get_u32(packet, &code);
if (rc != 0) {
code = ntohl(code);
}
error_s = 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_dh_reply){
int rc;
(void)type;
(void)user;
SSH_LOG(SSH_LOG_PROTOCOL,"Received SSH_KEXDH_REPLY");
if(session->session_state!= SSH_SESSION_STATE_DH &&
session->dh_handshake_state != DH_STATE_INIT_SENT){
ssh_set_error(session,SSH_FATAL,"ssh_packet_dh_reply called in wrong state : %d:%d",
session->session_state,session->dh_handshake_state);
goto error;
}
switch(session->next_crypto->kex_type){
case SSH_KEX_DH_GROUP1_SHA1:
case SSH_KEX_DH_GROUP14_SHA1:
rc=ssh_client_dh_reply(session, packet);
break;
#ifdef HAVE_ECDH
case SSH_KEX_ECDH_SHA2_NISTP256:
rc = ssh_client_ecdh_reply(session, packet);
break;
#endif
#ifdef HAVE_CURVE25519
case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
rc = ssh_client_curve25519_reply(session, packet);
break;
#endif
default:
ssh_set_error(session,SSH_FATAL,"Wrong kex type in ssh_packet_dh_reply");
goto error;
}
if(rc==SSH_OK) {
session->dh_handshake_state = DH_STATE_NEWKEYS_SENT;
return SSH_PACKET_USED;
}
error:
session->session_state=SSH_SESSION_STATE_ERROR;
return SSH_PACKET_USED;
}
SSH_PACKET_CALLBACK(ssh_packet_newkeys){
ssh_string sig_blob = 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 key;
/* client */
rc = make_sessionid(session);
if (rc != SSH_OK) {
goto error;
}
/*
* Set the cryptographic functions for the next crypto
* (it is needed for generate_session_keys for key lengths)
*/
if (crypt_set_algorithms(session, SSH_3DES) /* knows nothing about DES*/ ) {
goto error;
}
if (generate_session_keys(session) < 0) {
goto error;
}
/* 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 */
rc = ssh_pki_import_pubkey_blob(session->next_crypto->server_pubkey, &key);
if (rc < 0) {
return SSH_ERROR;
}
/* check if public key from server matches user preferences */
if (session->opts.wanted_methods[SSH_HOSTKEYS]) {
if(!ssh_match_group(session->opts.wanted_methods[SSH_HOSTKEYS],
key->type_c)) {
ssh_set_error(session,
SSH_FATAL,
"Public key from server (%s) doesn't match user "
"preference (%s)",
key->type_c,
session->opts.wanted_methods[SSH_HOSTKEYS]);
ssh_key_free(key);
return -1;
}
}
rc = ssh_pki_signature_verify_blob(session,
sig_blob,
key,
session->next_crypto->secret_hash,
session->next_crypto->digest_len);
/* Set the server public key type for known host checking */
session->next_crypto->server_pubkey_type = key->type_c;
ssh_key_free(key);
ssh_string_burn(sig_blob);
ssh_string_free(sig_blob);
sig_blob = NULL;
if (rc == SSH_ERROR) {
goto error;
}
SSH_LOG(SSH_LOG_PROTOCOL,"Signature verified and valid");
/*
* Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
* current_crypto
*/
if (session->current_crypto) {
crypto_free(session->current_crypto);
session->current_crypto=NULL;
}
/* FIXME later, include a function to change keys */
session->current_crypto = session->next_crypto;
session->next_crypto = crypto_new();
if (session->next_crypto == NULL) {
ssh_set_error_oom(session);
goto error;
}
session->next_crypto->session_id = malloc(session->current_crypto->digest_len);
if (session->next_crypto->session_id == NULL) {
ssh_set_error_oom(session);
goto error;
}
memcpy(session->next_crypto->session_id, session->current_crypto->session_id,
session->current_crypto->digest_len);
}
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;
}
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