src/omemo/omemo.c

@@ -1145,6 +1145,11 @@ omemo_on_message_recv(const char* const from_jid, uint32_t sid,
         return NULL;
     }
 
+    if (payload == NULL) {
+        signal_buffer_free(plaintext_key);
+        return NULL;
+    }
+
     size_t plaintext_len = payload_len;
     plaintext = malloc(plaintext_len + 1);
     res = aes128gcm_decrypt(plaintext, &plaintext_len, payload, payload_len, iv,

src/xmpp/message.c

@@ -1102,6 +1102,8 @@ _handle_groupchat(xmpp_stanza_t* const stanza)
             case OMEMO_ERR_DECRYPT_FAILED:
                 message->plain = g_strdup("OMEMO message received but decryption failed.");
                 break;
+            case OMEMO_ERR_KEY_TRANSPORT:
+                break;
             default:
                 message->plain = g_strdup("OMEMO message received but could not be decrypted.");
                 break;
@@ -1283,6 +1285,8 @@ _handle_muc_private_message(xmpp_stanza_t* const stanza)
             case OMEMO_ERR_DECRYPT_FAILED:
                 message->plain = g_strdup("OMEMO message received but decryption failed.");
                 break;
+            case OMEMO_ERR_KEY_TRANSPORT:
+                break;
             default:
                 message->plain = g_strdup("OMEMO message received but could not be decrypted.");
                 break;
@@ -1471,6 +1475,8 @@ _handle_chat(xmpp_stanza_t* const stanza, gboolean is_mam, gboolean is_carbon, c
             case OMEMO_ERR_DECRYPT_FAILED:
                 message->plain = g_strdup("OMEMO message received but decryption failed.");
                 break;
+            case OMEMO_ERR_KEY_TRANSPORT:
+                break;
             default:
                 message->plain = g_strdup("OMEMO message received but could not be decrypted.");
                 break;

src/xmpp/omemo.c

@@ -333,6 +333,7 @@ omemo_receive_message(xmpp_stanza_t* const stanza, gboolean* trusted, omemo_erro
     unsigned char* payload_raw = NULL;
     char* iv_text = NULL;
     char* payload_text = NULL;
+    size_t payload_len = 0;
 
     *error = OMEMO_ERR_NONE;
 
@@ -372,20 +373,15 @@ omemo_receive_message(xmpp_stanza_t* const stanza, gboolean* trusted, omemo_erro
     }
 
     xmpp_stanza_t* payload = xmpp_stanza_get_child_by_name(encrypted, "payload");
-    if (!payload) {
-        *error = OMEMO_ERR_OTHER;
-        goto quit;
-    }
-    payload_text = xmpp_stanza_get_text(payload);
-    if (!payload_text) {
-        *error = OMEMO_ERR_OTHER;
-        goto quit;
-    }
-    size_t payload_len;
-    payload_raw = g_base64_decode(payload_text, &payload_len);
-    if (!payload_raw) {
-        *error = OMEMO_ERR_OTHER;
-        goto quit;
+    if (payload) {
+        payload_text = xmpp_stanza_get_text(payload);
+        if (payload_text) {
+            payload_raw = g_base64_decode(payload_text, &payload_len);
+            if (!payload_raw) {
+                *error = OMEMO_ERR_OTHER;
+                goto quit;
+            }
+        }
     }
 
     xmpp_stanza_t* key_stanza;
@@ -425,6 +421,10 @@ omemo_receive_message(xmpp_stanza_t* const stanza, gboolean* trusted, omemo_erro
                                       keys, payload_raw, payload_len,
                                       g_strcmp0(type, STANZA_TYPE_GROUPCHAT) == 0, trusted, error);
 
+    if (plaintext == NULL && *error == OMEMO_ERR_NONE && payload == NULL) {
+        *error = OMEMO_ERR_KEY_TRANSPORT;
+    }
+
     if (keys) {
         g_list_free_full(keys, (GDestroyNotify)omemo_key_free);
     }

src/xmpp/xmpp.h

@@ -132,6 +132,7 @@ typedef enum {
     OMEMO_ERR_DECRYPT_FAILED,
     OMEMO_ERR_INVALID_JID,
     OMEMO_ERR_MUC_SENDER_NOT_FOUND,
+    OMEMO_ERR_KEY_TRANSPORT,
     OMEMO_ERR_OTHER
 } omemo_error_t;