server: Fixed the server implementation.
Signed-off-by: Andreas Schneider <asn@cynapses.org>
Этот коммит содержится в:
milo
Andreas Schneider
родитель
51a21823f9
Коммит
8ef0fbc294
327
libssh/server.c
327
libssh/server.c
@ -49,6 +49,9 @@
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session->callbacks->connect_status_function(session->callbacks->userdata, status); \
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} while (0)
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static int dh_handshake_server(ssh_session session);
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/**
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* @addtogroup libssh_server
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*
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@ -379,6 +382,7 @@ SSH_PACKET_CALLBACK(ssh_packet_kexdh_init){
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session->session_state=SSH_SESSION_STATE_ERROR;
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} else {
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session->dh_handshake_state=DH_STATE_INIT_SENT;
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dh_handshake_server(session);
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}
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ssh_string_free(e);
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@ -393,11 +397,6 @@ static int dh_handshake_server(ssh_session session) {
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ssh_string sign;
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ssh_public_key pub;
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ssh_private_key prv;
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/* waiting for SSH_MSG_KEXDH_INIT */
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while(session->dh_handshake_state != DH_STATE_INIT_SENT){
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ssh_handle_packets(session,-1);
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}
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/* received SSH_MSG_KEXDH_INIT */
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if (dh_generate_y(session) < 0) {
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ssh_set_error(session, SSH_FATAL, "Could not create y number");
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@ -497,74 +496,304 @@ static int dh_handshake_server(ssh_session session) {
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ssh_log(session, SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
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session->dh_handshake_state=DH_STATE_NEWKEYS_SENT;
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while(session->dh_handshake_state != DH_STATE_FINISHED)
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ssh_handle_packets(session,-1);
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return 0;
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}
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if (generate_session_keys(session) < 0) {
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/**
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* @internal
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*
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* @brief Analyze the SSH banner to find out if we have a SSHv1 or SSHv2
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* server.
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*
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* @param session The session to analyze the banner from.
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* @param ssh1 The variable which is set if it is a SSHv1 server.
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* @param ssh2 The variable which is set if it is a SSHv2 server.
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*
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* @return 0 on success, < 0 on error.
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*
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* @see ssh_get_banner()
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*/
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static int ssh_analyze_banner(ssh_session session, int *ssh1, int *ssh2) {
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const char *banner = session->clientbanner;
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const char *openssh;
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ssh_log(session, SSH_LOG_RARE, "Analyzing banner: %s", banner);
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if (strncmp(banner, "SSH-", 4) != 0) {
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ssh_set_error(session, SSH_FATAL, "Protocol mismatch: %s", banner);
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return -1;
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}
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/*
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* Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
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* current_crypto
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* Typical banners e.g. are:
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* SSH-1.5-blah
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* SSH-1.99-blah
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* SSH-2.0-blah
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*/
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if (session->current_crypto) {
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crypto_free(session->current_crypto);
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switch(banner[4]) {
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case '1':
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*ssh1 = 1;
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if (banner[6] == '9') {
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*ssh2 = 1;
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} else {
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*ssh2 = 0;
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}
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break;
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case '2':
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*ssh1 = 0;
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*ssh2 = 1;
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break;
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default:
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ssh_set_error(session, SSH_FATAL, "Protocol mismatch: %s", banner);
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return -1;
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}
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/* FIXME TODO later, include a function to change keys */
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session->current_crypto = session->next_crypto;
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session->next_crypto = crypto_new();
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if (session->next_crypto == NULL) {
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return -1;
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openssh = strstr(banner, "OpenSSH");
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if (openssh != NULL) {
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int major, minor;
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major = strtol(openssh + 8, (char **) NULL, 10);
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minor = strtol(openssh + 10, (char **) NULL, 10);
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session->openssh = SSH_VERSION_INT(major, minor, 0);
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ssh_log(session, SSH_LOG_RARE,
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"We are talking to an OpenSSH client version: %d.%d (%x)",
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major, minor, session->openssh);
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}
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return 0;
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}
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/* FIXME TODO BUG
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* Makes linker happy until I work on server code
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/**
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* @internal
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*
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* @brief A function to be called each time a step has been done in the
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* connection.
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*/
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static char *ssh_get_banner(ssh_session session){
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(void)session;
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return strdup("BUG");
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static void ssh_server_connection_callback(ssh_session session){
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int ssh1,ssh2;
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enter_function();
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switch(session->session_state){
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case SSH_SESSION_STATE_NONE:
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case SSH_SESSION_STATE_CONNECTING:
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case SSH_SESSION_STATE_SOCKET_CONNECTED:
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break;
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case SSH_SESSION_STATE_BANNER_RECEIVED:
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if (session->clientbanner == NULL) {
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goto error;
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}
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set_status(session, 0.4f);
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ssh_log(session, SSH_LOG_RARE,
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"SSH client banner: %s", session->clientbanner);
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/* Here we analyze the different protocols the server allows. */
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if (ssh_analyze_banner(session, &ssh1, &ssh2) < 0) {
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goto error;
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}
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/* Here we decide which version of the protocol to use. */
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if (ssh2 && session->ssh2) {
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session->version = 2;
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} else if(ssh1 && session->ssh1) {
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session->version = 1;
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} else if(ssh1 && !session->ssh1){
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#ifdef WITH_SSH1
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ssh_set_error(session, SSH_FATAL,
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"SSH-1 protocol not available (configure session to allow SSH-1)");
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goto error;
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#else
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ssh_set_error(session, SSH_FATAL,
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"SSH-1 protocol not available (libssh compiled without SSH-1 support)");
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goto error;
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#endif
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} else {
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ssh_set_error(session, SSH_FATAL,
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"No version of SSH protocol usable (banner: %s)",
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session->clientbanner);
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goto error;
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}
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/* from now, the packet layer is handling incoming packets */
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if(session->version==2)
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session->socket_callbacks.data=ssh_packet_socket_callback;
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#ifdef WITH_SSH1
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else
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session->socket_callbacks.data=ssh_packet_socket_callback1;
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#endif
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ssh_packet_set_default_callbacks(session);
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set_status(session, 0.5f);
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session->session_state=SSH_SESSION_STATE_INITIAL_KEX;
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if (ssh_send_kex(session, 1) < 0) {
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goto error;
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}
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break;
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case SSH_SESSION_STATE_INITIAL_KEX:
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/* TODO: This state should disappear in favor of get_key handle */
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#ifdef WITH_SSH1
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if(session->version==1){
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if (ssh_get_kex1(session) < 0)
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goto error;
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set_status(session,0.6f);
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session->connected = 1;
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break;
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}
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#endif
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break;
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case SSH_SESSION_STATE_KEXINIT_RECEIVED:
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set_status(session,0.6f);
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ssh_list_kex(session, &session->client_kex); // log client kex
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crypt_set_algorithms_server(session);
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if (set_kex(session) < 0) {
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goto error;
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}
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set_status(session,0.8f);
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session->session_state=SSH_SESSION_STATE_DH;
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break;
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case SSH_SESSION_STATE_DH:
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if(session->dh_handshake_state==DH_STATE_FINISHED){
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if (generate_session_keys(session) < 0) {
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goto error;
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}
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/*
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* Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
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* current_crypto
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*/
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if (session->current_crypto) {
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crypto_free(session->current_crypto);
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}
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/* FIXME TODO later, include a function to change keys */
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session->current_crypto = session->next_crypto;
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session->next_crypto = crypto_new();
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if (session->next_crypto == NULL) {
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goto error;
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}
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set_status(session,1.0f);
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session->connected = 1;
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session->session_state=SSH_SESSION_STATE_AUTHENTICATING;
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}
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break;
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case SSH_SESSION_STATE_AUTHENTICATING:
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break;
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case SSH_SESSION_STATE_ERROR:
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goto error;
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default:
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ssh_set_error(session,SSH_FATAL,"Invalid state %d",session->session_state);
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}
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leave_function();
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return;
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error:
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ssh_socket_close(session->socket);
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session->alive = 0;
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session->session_state=SSH_SESSION_STATE_ERROR;
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leave_function();
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}
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/**
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* @internal
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*
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* @brief Gets the banner from socket and saves it in session.
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* Updates the session state
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*
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* @param data pointer to the beginning of header
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* @param len size of the banner
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* @param user is a pointer to session
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* @returns Number of bytes processed, or zero if the banner is not complete.
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*/
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static int callback_receive_banner(const void *data, size_t len, void *user) {
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char *buffer = (char *) data;
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ssh_session session = (ssh_session) user;
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char *str = NULL;
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size_t i;
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int ret=0;
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enter_function();
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for (i = 0; i < len; i++) {
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#ifdef WITH_PCAP
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if(session->pcap_ctx && buffer[i] == '\n') {
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ssh_pcap_context_write(session->pcap_ctx,
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SSH_PCAP_DIR_IN,
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buffer,
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i + 1,
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i + 1);
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}
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#endif
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if (buffer[i] == '\r') {
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buffer[i]='\0';
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}
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if (buffer[i] == '\n') {
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buffer[i]='\0';
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str = strdup(buffer);
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/* number of bytes read */
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ret = i + 1;
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session->clientbanner = str;
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session->session_state = SSH_SESSION_STATE_BANNER_RECEIVED;
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ssh_log(session, SSH_LOG_PACKET, "Received banner: %s", str);
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session->ssh_connection_callback(session);
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leave_function();
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return ret;
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}
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if(i > 127) {
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/* Too big banner */
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session->session_state = SSH_SESSION_STATE_ERROR;
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ssh_set_error(session, SSH_FATAL, "Receiving banner: too large banner");
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leave_function();
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return 0;
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}
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}
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leave_function();
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return ret;
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}
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/* Do the banner and key exchange */
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int ssh_accept(ssh_session session) {
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if (ssh_send_banner(session, 1) < 0) {
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return -1;
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}
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int rc;
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session->alive = 1;
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rc = ssh_send_banner(session, 1);
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if (rc < 0) {
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return -1;
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}
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session->clientbanner = ssh_get_banner(session);
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if (session->clientbanner == NULL) {
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return -1;
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}
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session->alive = 1;
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if (server_set_kex(session) < 0) {
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return -1;
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}
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session->ssh_connection_callback = ssh_server_connection_callback;
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session->session_state = SSH_SESSION_STATE_SOCKET_CONNECTED;
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ssh_socket_set_callbacks(session->socket,&session->socket_callbacks);
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session->socket_callbacks.data=callback_receive_banner;
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#if 0
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session->socket_callbacks.exception=socket_callback_exception;
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#endif
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session->socket_callbacks.userdata=session;
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if (ssh_send_kex(session, 1) < 0) {
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return -1;
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}
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rc = server_set_kex(session);
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if (rc < 0) {
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return -1;
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}
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/* TODO here things won't work anymore */
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// if (ssh_get_kex(session,1) < 0) {
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// return -1;
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// }
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while (session->session_state != SSH_SESSION_STATE_ERROR &&
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session->session_state != SSH_SESSION_STATE_AUTHENTICATING &&
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session->session_state != SSH_SESSION_STATE_DISCONNECTED) {
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/*
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* loop until SSH_SESSION_STATE_BANNER_RECEIVED or
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* SSH_SESSION_STATE_ERROR
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*/
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ssh_handle_packets(session,-1);
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ssh_log(session,SSH_LOG_PACKET, "ssh_accept: Actual state : %d",
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session->session_state);
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}
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ssh_list_kex(session, &session->client_kex);
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crypt_set_algorithms_server(session);
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leave_function();
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if (session->session_state == SSH_SESSION_STATE_ERROR ||
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session->session_state == SSH_SESSION_STATE_DISCONNECTED) {
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return SSH_ERROR;
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}
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if (dh_handshake_server(session) < 0) {
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return -1;
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}
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session->connected = 1;
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return 0;
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return SSH_OK;
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}
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/**
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