/*
* Key re-exchange (rekey) is triggered by this function.
* It can not be called again after the rekey is initialized!
*/
int ssh_send_rekex(ssh_session session)
{
int rc;
if (session->dh_handshake_state != DH_STATE_FINISHED) {
/* Rekey/Key exchange is already in progress */
SSH_LOG(SSH_LOG_PACKET, "Attempting rekey in bad state");
return SSH_ERROR;
}
if (session->current_crypto == NULL) {
/* No current crypto used -- can not exchange it */
SSH_LOG(SSH_LOG_PACKET, "No crypto to rekey");
return SSH_ERROR;
}
if (session->client) {
rc = ssh_set_client_kex(session);
if (rc != SSH_OK) {
SSH_LOG(SSH_LOG_PACKET, "Failed to set client kex");
return rc;
}
} else {
#ifdef WITH_SERVER
rc = server_set_kex(session);
if (rc == SSH_ERROR) {
SSH_LOG(SSH_LOG_PACKET, "Failed to set server kex");
return rc;
}
#else
SSH_LOG(SSH_LOG_PACKET, "Invalid session state.");
return SSH_ERROR;
#endif /* WITH_SERVER */
}
session->dh_handshake_state = DH_STATE_INIT;
rc = ssh_send_kex(session, session->server);
if (rc < 0) {
SSH_LOG(SSH_LOG_PACKET, "Failed to send kex");
return rc;
}
/* Reset the handshake state */
session->dh_handshake_state = DH_STATE_INIT_SENT;
return SSH_OK;
}
/**
* @internal
*
* @brief A function to be called each time a step has been done in the
* connection.
*/
static void ssh_client_connection_callback(ssh_session session){
int ssh1,ssh2;
switch(session->session_state){
case SSH_SESSION_STATE_NONE:
case SSH_SESSION_STATE_CONNECTING:
break;
case SSH_SESSION_STATE_SOCKET_CONNECTED:
/* If SSHv1 is disabled, we can send the banner immedietly */
if (session->opts.ssh1 == 0) {
ssh_set_fd_towrite(session);
ssh_send_banner(session, 0);
}
break;
case SSH_SESSION_STATE_BANNER_RECEIVED:
if (session->serverbanner == NULL) {
goto error;
}
set_status(session, 0.4f);
SSH_LOG(SSH_LOG_RARE,
"SSH server banner: %s", session->serverbanner);
/* Here we analyze the different protocols the server allows. */
if (ssh_analyze_banner(session, 0, &ssh1, &ssh2) < 0) {
goto error;
}
/* Here we decide which version of the protocol to use. */
if (ssh2 && session->opts.ssh2) {
session->version = 2;
#ifdef WITH_SSH1
} else if(ssh1 && session->opts.ssh1) {
session->version = 1;
#endif
} else if(ssh1 && !session->opts.ssh1){
#ifdef WITH_SSH1
ssh_set_error(session, SSH_FATAL,
"SSH-1 protocol not available (configure session to allow SSH-1)");
goto error;
#else
ssh_set_error(session, SSH_FATAL,
"SSH-1 protocol not available (libssh compiled without SSH-1 support)");
goto error;
#endif
} else {
ssh_set_error(session, SSH_FATAL,
"No version of SSH protocol usable (banner: %s)",
session->serverbanner);
goto error;
}
/* from now, the packet layer is handling incoming packets */
if (session->version == 2) {
ssh_packet_register_socket_callback(session, session->socket);
}
#ifdef WITH_SSH1
else
session->socket_callbacks.data=ssh_packet_socket_callback1;
#endif
ssh_packet_set_default_callbacks(session);
session->session_state=SSH_SESSION_STATE_INITIAL_KEX;
if (session->opts.ssh1 == 1) {
ssh_send_banner(session, 0);
}
set_status(session, 0.5f);
break;
case SSH_SESSION_STATE_INITIAL_KEX:
/* TODO: This state should disappear in favor of get_key handle */
#ifdef WITH_SSH1
if(session->version==1){
if (ssh_get_kex1(session) < 0)
goto error;
set_status(session,0.6f);
session->connected = 1;
break;
}
#endif
break;
case SSH_SESSION_STATE_KEXINIT_RECEIVED:
set_status(session,0.6f);
ssh_list_kex(&session->next_crypto->server_kex);
if (ssh_set_client_kex(session) < 0) {
goto error;
}
if (ssh_kex_select_methods(session) == SSH_ERROR)
goto error;
if (ssh_send_kex(session, 0) < 0) {
goto error;
}
set_status(session,0.8f);
session->session_state=SSH_SESSION_STATE_DH;
if (dh_handshake(session) == SSH_ERROR) {
goto error;
}
/* FALL THROUGH */
case SSH_SESSION_STATE_DH:
if(session->dh_handshake_state==DH_STATE_FINISHED){
set_status(session,1.0f);
session->connected = 1;
if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED)
session->session_state = SSH_SESSION_STATE_AUTHENTICATED;
else
session->session_state=SSH_SESSION_STATE_AUTHENTICATING;
}
break;
case SSH_SESSION_STATE_AUTHENTICATING:
break;
case SSH_SESSION_STATE_ERROR:
goto error;
default:
ssh_set_error(session,SSH_FATAL,"Invalid state %d",session->session_state);
}
return;
error:
ssh_socket_close(session->socket);
session->alive = 0;
session->session_state=SSH_SESSION_STATE_ERROR;
}
/**
* @internal
*
* @brief A function to be called each time a step has been done in the
* connection.
*/
static void ssh_client_connection_callback(ssh_session session)
{
int rc;
switch(session->session_state) {
case SSH_SESSION_STATE_NONE:
case SSH_SESSION_STATE_CONNECTING:
break;
case SSH_SESSION_STATE_SOCKET_CONNECTED:
ssh_set_fd_towrite(session);
ssh_send_banner(session, 0);
break;
case SSH_SESSION_STATE_BANNER_RECEIVED:
if (session->serverbanner == NULL) {
goto error;
}
set_status(session, 0.4f);
SSH_LOG(SSH_LOG_RARE,
"SSH server banner: %s", session->serverbanner);
/* Here we analyze the different protocols the server allows. */
rc = ssh_analyze_banner(session, 0);
if (rc < 0) {
ssh_set_error(session, SSH_FATAL,
"No version of SSH protocol usable (banner: %s)",
session->serverbanner);
goto error;
}
ssh_packet_register_socket_callback(session, session->socket);
ssh_packet_set_default_callbacks(session);
session->session_state = SSH_SESSION_STATE_INITIAL_KEX;
rc = ssh_set_client_kex(session);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_send_kex(session, 0);
if (rc < 0) {
goto error;
}
set_status(session, 0.5f);
break;
case SSH_SESSION_STATE_INITIAL_KEX:
/* TODO: This state should disappear in favor of get_key handle */
break;
case SSH_SESSION_STATE_KEXINIT_RECEIVED:
set_status(session,0.6f);
ssh_list_kex(&session->next_crypto->server_kex);
if (session->next_crypto->client_kex.methods[0] == NULL) {
/* in rekeying state if next_crypto client_kex is empty */
rc = ssh_set_client_kex(session);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_send_kex(session, 0);
if (rc < 0) {
goto error;
}
}
if (ssh_kex_select_methods(session) == SSH_ERROR)
goto error;
set_status(session,0.8f);
session->session_state=SSH_SESSION_STATE_DH;
if (dh_handshake(session) == SSH_ERROR) {
goto error;
}
/* FALL THROUGH */
case SSH_SESSION_STATE_DH:
if(session->dh_handshake_state==DH_STATE_FINISHED){
set_status(session,1.0f);
session->connected = 1;
if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED)
session->session_state = SSH_SESSION_STATE_AUTHENTICATED;
else
session->session_state=SSH_SESSION_STATE_AUTHENTICATING;
}
break;
case SSH_SESSION_STATE_AUTHENTICATING:
break;
case SSH_SESSION_STATE_ERROR:
goto error;
default:
ssh_set_error(session,SSH_FATAL,"Invalid state %d",session->session_state);
}
return;
error:
ssh_socket_close(session->socket);
session->alive = 0;
session->session_state=SSH_SESSION_STATE_ERROR;
}
