Improve dh_handshake_server().

git-svn-id: svn+ssh://svn.berlios.de/svnroot/repos/libssh/trunk@655 7dcaeef0-15fb-0310-b436-a5af3365683c

libssh/server.c

@@ -323,22 +323,29 @@ static int server_set_kex(SSH_SESSION * session) {
 }
 
 static int dh_handshake_server(SSH_SESSION *session) {
-    STRING *e,*f,*pubkey,*sign;
+  STRING *e;
+  STRING *f;
+  STRING *pubkey;
+  STRING *sign;
   PUBLIC_KEY *pub;
   PRIVATE_KEY *prv;
-    BUFFER *buf=buffer_new();
+
-    if (packet_wait(session, SSH2_MSG_KEXDH_INIT, 1) != SSH_OK)
+  if (packet_wait(session, SSH2_MSG_KEXDH_INIT, 1) != SSH_OK) {
     return -1;
+  }
+
   e = buffer_get_ssh_string(session->in_buffer);
-    if(!e){
+  if (e == NULL) {
     ssh_set_error(session, SSH_FATAL, "No e number in client request");
     return -1;
   }
   if (dh_import_e(session, e) < 0) {
     ssh_set_error(session, SSH_FATAL, "Cannot import e number");
+    string_free(e);
     return -1;
   }
-    free(e);
+  string_free(e);
+
   if (dh_generate_y(session) < 0) {
     ssh_set_error(session, SSH_FATAL, "Could not create y number");
     return -1;
@@ -347,7 +354,13 @@ static int dh_handshake_server(SSH_SESSION *session){
     ssh_set_error(session, SSH_FATAL, "Could not create f number");
     return -1;
   }
+
   f = dh_get_f(session);
+  if (f == NULL) {
+    ssh_set_error(session, SSH_FATAL, "Could not get the f number");
+    return -1;
+  }
+
   switch(session->hostkeys){
     case TYPE_DSS:
       prv = session->dsa_key;
@@ -358,19 +371,43 @@ static int dh_handshake_server(SSH_SESSION *session){
     default:
       prv = NULL;
   }
+
   pub = publickey_from_privatekey(prv);
+  if (pub == NULL) {
+    ssh_set_error(session, SSH_FATAL,
+        "Could not get the public key from the private key");
+    string_free(f);
+    return -1;
+  }
   pubkey = publickey_to_string(pub);
   publickey_free(pub);
+  if (pubkey == NULL) {
+    ssh_set_error(session, SSH_FATAL, "Not enough space");
+    string_free(f);
+    return -1;
+  }
+
   dh_import_pubkey(session, pubkey);
   if (dh_build_k(session) < 0) {
+    ssh_set_error(session, SSH_FATAL, "Could not import the public key");
+    string_free(f);
     return -1;
   }
+
   if (make_sessionid(session) != SSH_OK) {
+    ssh_set_error(session, SSH_FATAL, "Could not create a session id");
+    string_free(f);
     return -1;
   }
+
   sign = ssh_sign_session_id(session, prv);
-    buffer_free(buf);
+  if (sign == NULL) {
-    /* free private keys as they should not be readable past this point */
+    ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
+    string_free(f);
+    return -1;
+  }
+
+  /* Free private keys as they should not be readable after this point */
   if (session->rsa_key) {
     privatekey_free(session->rsa_key);
     session->rsa_key = NULL;
@@ -379,33 +416,61 @@ static int dh_handshake_server(SSH_SESSION *session){
     privatekey_free(session->dsa_key);
     session->dsa_key = NULL;
   }
-    buffer_add_u8(session->out_buffer,SSH2_MSG_KEXDH_REPLY);
+
-    buffer_add_ssh_string(session->out_buffer,pubkey);
+  if (buffer_add_u8(session->out_buffer, SSH2_MSG_KEXDH_REPLY) < 0 ||
-    buffer_add_ssh_string(session->out_buffer,f);
+      buffer_add_ssh_string(session->out_buffer, pubkey) < 0 ||
-    buffer_add_ssh_string(session->out_buffer,sign);
+      buffer_add_ssh_string(session->out_buffer, f) < 0 ||
-    free(sign);
+      buffer_add_ssh_string(session->out_buffer, sign) < 0) {
-    packet_send(session);
+    ssh_set_error(session, SSH_FATAL, "Not enough space");
-    free(f);
+    buffer_free(session->out_buffer);
-    buffer_add_u8(session->out_buffer,SSH2_MSG_NEWKEYS);
+    string_free(f);
-    packet_send(session);
+    string_free(sign);
+    return -1;
+  }
+  string_free(f);
+  string_free(sign);
+
+  if (packet_send(session) != SSH_OK) {
+    return -1;
+  }
+
+  if (buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
+    buffer_free(session->out_buffer);
+    return -1;
+  }
+
+  if (packet_send(session) != SSH_OK) {
+    return -1;
+  }
   ssh_log(session, SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
 
-    packet_wait(session,SSH2_MSG_NEWKEYS,1);
+  if (packet_wait(session, SSH2_MSG_NEWKEYS, 1) != SSH_OK) {
+    return -1;
+  }
   ssh_log(session, SSH_LOG_PACKET, "Got SSH_MSG_NEWKEYS");
+
   if (generate_session_keys(session) < 0) {
     return -1;
   }
-    /* once we got SSH2_MSG_NEWKEYS we can switch next_crypto and current_crypto */
+
-    if(session->current_crypto)
+  /*
+   * Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
+   * current_crypto
+   */
+  if (session->current_crypto) {
     crypto_free(session->current_crypto);
-    /* XXX later, include a function to change keys */
+  }
+
+  /* FIXME TODO later, include a function to change keys */
   session->current_crypto = session->next_crypto;
   session->next_crypto = crypto_new();
   if (session->next_crypto == NULL) {
     return -1;
   }
+
   return 0;
 }
+
 /* do the banner and key exchange */
 int ssh_accept(SSH_SESSION *session){
     ssh_send_banner(session,1);