kex: use runtime callbacks (client)

Signed-off-by: Aris Adamantiadis <aris@0xbadc0de.be>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/curve25519.h

@@ -48,7 +48,6 @@ typedef unsigned char ssh_curve25519_privkey[CURVE25519_PRIVKEY_SIZE];
 
 
 int ssh_client_curve25519_init(ssh_session session);
-int ssh_client_curve25519_reply(ssh_session session, ssh_buffer packet);
 
 #ifdef WITH_SERVER
 int ssh_server_curve25519_init(ssh_session session, ssh_buffer packet);

include/libssh/dh.h

@@ -43,7 +43,6 @@ int ssh_dh_import_next_pubkey_blob(ssh_session session, ssh_string pubkey_blob);
 
 int ssh_dh_build_k(ssh_session session);
 int ssh_client_dh_init(ssh_session session);
-int ssh_client_dh_reply(ssh_session session, ssh_buffer packet);
 
 ssh_key ssh_dh_get_current_server_publickey(ssh_session session);
 int ssh_dh_get_current_server_publickey_blob(ssh_session session,

include/libssh/ecdh.h

@@ -41,8 +41,7 @@
 #define HAVE_ECDH 1
 #endif
 
-/* Common functions.  */
+extern struct ssh_packet_callbacks_struct ssh_ecdh_client_callbacks;
-int ssh_client_ecdh_reply(ssh_session session, ssh_buffer packet);
 
 /* Backend-specific functions.  */
 int ssh_client_ecdh_init(ssh_session session);

src/curve25519.c

@@ -39,6 +39,19 @@
 #include "libssh/pki.h"
 #include "libssh/bignum.h"
 
+static SSH_PACKET_CALLBACK(ssh_packet_client_curve25519_reply);
+
+static ssh_packet_callback dh_client_callbacks[] = {
+    ssh_packet_client_curve25519_reply
+};
+
+static struct ssh_packet_callbacks_struct ssh_curve25519_client_callbacks = {
+    .start = SSH2_MSG_KEX_ECDH_REPLY,
+    .n_callbacks = 1,
+    .callbacks = dh_client_callbacks,
+    .user = NULL
+};
+
 /** @internal
  * @brief Starts curve25519-sha256@libssh.org / curve25519-sha256 key exchange
  */
@@ -64,7 +77,8 @@ int ssh_client_curve25519_init(ssh_session session){
       ssh_set_error_oom(session);
       return SSH_ERROR;
   }
-
+  /* register the packet callbacks */
+  ssh_packet_set_callbacks(session, &ssh_curve25519_client_callbacks);
   rc = ssh_packet_send(session);
 
   return rc;
@@ -117,11 +131,15 @@ static int ssh_curve25519_build_k(ssh_session session) {
  * @brief parses a SSH_MSG_KEX_ECDH_REPLY packet and sends back
  * a SSH_MSG_NEWKEYS
  */
-int ssh_client_curve25519_reply(ssh_session session, ssh_buffer packet){
+static SSH_PACKET_CALLBACK(ssh_packet_client_curve25519_reply){
   ssh_string q_s_string = NULL;
   ssh_string pubkey_blob = NULL;
   ssh_string signature = NULL;
   int rc;
+  (void)type;
+  (void)user;
+
+  ssh_packet_remove_callbacks(session, &ssh_curve25519_client_callbacks);
 
   pubkey_blob = ssh_buffer_get_ssh_string(packet);
   if (pubkey_blob == NULL) {
@@ -171,10 +189,18 @@ int ssh_client_curve25519_reply(ssh_session session, ssh_buffer packet){
   }
 
   rc=ssh_packet_send(session);
+  if (rc == SSH_ERROR) {
+    goto error;
+  }
+
   SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent");
-  return rc;
+  session->dh_handshake_state = DH_STATE_NEWKEYS_SENT;
+
+  return SSH_PACKET_USED;
+
 error:
-  return SSH_ERROR;
+  session->session_state=SSH_SESSION_STATE_ERROR;
+  return SSH_PACKET_USED;
 }
 
 #ifdef WITH_SERVER

src/dh.c

@@ -652,6 +652,19 @@ int ssh_dh_build_k(ssh_session session) {
   return 0;
 }
 
+static SSH_PACKET_CALLBACK(ssh_packet_client_dh_reply);
+
+static ssh_packet_callback dh_client_callbacks[]= {
+    ssh_packet_client_dh_reply
+};
+
+static struct ssh_packet_callbacks_struct ssh_dh_client_callbacks = {
+    .start = SSH2_MSG_KEXDH_REPLY,
+    .n_callbacks = 1,
+    .callbacks = dh_client_callbacks,
+    .user = NULL
+};
+
 /** @internal
  * @brief Starts diffie-hellman-group1 key exchange
  */
@@ -680,6 +693,9 @@ int ssh_client_dh_init(ssh_session session){
   ssh_string_free(e);
   e=NULL;
 
+  /* register the packet callbacks */
+  ssh_packet_set_callbacks(session, &ssh_dh_client_callbacks);
+
   rc = ssh_packet_send(session);
   return rc;
   error:
@@ -691,11 +707,15 @@ int ssh_client_dh_init(ssh_session session){
   return SSH_ERROR;
 }
 
-int ssh_client_dh_reply(ssh_session session, ssh_buffer packet){
+SSH_PACKET_CALLBACK(ssh_packet_client_dh_reply){
   ssh_string f;
   ssh_string pubkey_blob = NULL;
   ssh_string signature = NULL;
   int rc;
+  (void)type;
+  (void)user;
+
+  ssh_packet_remove_callbacks(session, &ssh_dh_client_callbacks);
 
   pubkey_blob = ssh_buffer_get_ssh_string(packet);
   if (pubkey_blob == NULL){
@@ -740,10 +760,16 @@ int ssh_client_dh_reply(ssh_session session, ssh_buffer packet){
   }
 
   rc=ssh_packet_send(session);
+  if (rc == SSH_ERROR) {
+    goto error;
+  }
+
   SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent");
-  return rc;
+  session->dh_handshake_state = DH_STATE_NEWKEYS_SENT;
+  return SSH_PACKET_USED;
 error:
-  return SSH_ERROR;
+  session->session_state=SSH_SESSION_STATE_ERROR;
+  return SSH_PACKET_USED;
 }
 
 int ssh_make_sessionid(ssh_session session) {

src/ecdh.c

@@ -30,16 +30,32 @@
 
 #ifdef HAVE_ECDH
 
+static SSH_PACKET_CALLBACK(ssh_packet_client_ecdh_reply);
+
+static ssh_packet_callback ecdh_client_callbacks[]= {
+    ssh_packet_client_ecdh_reply
+};
+
+struct ssh_packet_callbacks_struct ssh_ecdh_client_callbacks = {
+    .start = SSH2_MSG_KEX_ECDH_REPLY,
+    .n_callbacks = 1,
+    .callbacks = ecdh_client_callbacks,
+    .user = NULL
+};
+
 /** @internal
  * @brief parses a SSH_MSG_KEX_ECDH_REPLY packet and sends back
  * a SSH_MSG_NEWKEYS
  */
-int ssh_client_ecdh_reply(ssh_session session, ssh_buffer packet){
+SSH_PACKET_CALLBACK(ssh_packet_client_ecdh_reply){
   ssh_string q_s_string = NULL;
   ssh_string pubkey_blob = NULL;
   ssh_string signature = NULL;
   int rc;
+  (void)type;
+  (void)user;
 
+  ssh_packet_remove_callbacks(session, &ssh_ecdh_client_callbacks);
   pubkey_blob = ssh_buffer_get_ssh_string(packet);
   if (pubkey_blob == NULL) {
     ssh_set_error(session,SSH_FATAL, "No public key in packet");
@@ -77,10 +93,18 @@ int ssh_client_ecdh_reply(ssh_session session, ssh_buffer packet){
   }
 
   rc=ssh_packet_send(session);
+  if (rc == SSH_ERROR) {
+    goto error;
+  }
+
   SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent");
-  return rc;
+  session->dh_handshake_state = DH_STATE_NEWKEYS_SENT;
+
+  return SSH_PACKET_USED;
+
 error:
-  return SSH_ERROR;
+  session->session_state=SSH_SESSION_STATE_ERROR;
+  return SSH_PACKET_USED;
 }
 
 #endif /* HAVE_ECDH */

src/ecdh_crypto.c

@@ -108,6 +108,10 @@ int ssh_client_ecdh_init(ssh_session session){
   session->next_crypto->ecdh_privkey = key;
   session->next_crypto->ecdh_client_pubkey = client_pubkey;
 
+  /* register the packet callbacks */
+  ssh_packet_set_callbacks(session, &ssh_ecdh_client_callbacks);
+  session->dh_handshake_state = DH_STATE_INIT_SENT;
+
   rc = ssh_packet_send(session);
 
   return rc;

src/ecdh_gcrypt.c

@@ -106,6 +106,10 @@ int ssh_client_ecdh_init(ssh_session session)
     session->next_crypto->ecdh_client_pubkey = client_pubkey;
     client_pubkey = NULL;
 
+    /* register the packet callbacks */
+    ssh_packet_set_callbacks(session, &ssh_ecdh_client_callbacks);
+    session->dh_handshake_state = DH_STATE_INIT_SENT;
+
     rc = ssh_packet_send(session);
 
  out:

src/ecdh_mbedcrypto.c

@@ -106,6 +106,9 @@ int ssh_client_ecdh_init(ssh_session session)
     session->next_crypto->ecdh_client_pubkey = client_pubkey;
     client_pubkey = NULL;
 
+    /* register the packet callbacks */
+    ssh_packet_set_callbacks(session, &ssh_ecdh_client_callbacks);
+    session->dh_handshake_state = DH_STATE_INIT_SENT;
     rc = ssh_packet_send(session);
 
 out:

src/packet.c

@@ -74,7 +74,7 @@ static ssh_packet_callback default_packet_handlers[]= {
 #else
   NULL,
 #endif
-  ssh_packet_dh_reply,                     // SSH2_MSG_KEXDH_REPLY                31
+  NULL,                                    // SSH2_MSG_KEXDH_REPLY                31
                                            // SSH2_MSG_KEX_DH_GEX_GROUP           31
   NULL,                                    // SSH2_MSG_KEX_DH_GEX_INIT            32
   NULL,                                    // SSH2_MSG_KEX_DH_GEX_REPLY           33

src/packet_cb.c

@@ -92,50 +92,6 @@ SSH_PACKET_CALLBACK(ssh_packet_ignore_callback){
 	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:
-    case SSH_KEX_DH_GROUP16_SHA512:
-    case SSH_KEX_DH_GROUP18_SHA512:
-      rc=ssh_client_dh_reply(session, packet);
-      break;
-#ifdef HAVE_ECDH
-    case SSH_KEX_ECDH_SHA2_NISTP256:
-    case SSH_KEX_ECDH_SHA2_NISTP384:
-    case SSH_KEX_ECDH_SHA2_NISTP521:
-      rc = ssh_client_ecdh_reply(session, packet);
-      break;
-#endif
-#ifdef HAVE_CURVE25519
-    case SSH_KEX_CURVE25519_SHA256:
-    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;
   ssh_signature sig = NULL;