Merge pull request #1515 from mwuttke97/fix_omemo_empty_devlist

[OMEMO] Fix sending messages

src/command/cmd_funcs.c

@@ -2151,30 +2151,21 @@ cmd_msg(ProfWin* window, const char* const command, gchar** args)
 
         ProfChatWin* chatwin = wins_get_chat(barejid);
         if (!chatwin) {
+            // NOTE: This will also start the new OMEMO session and send a MAM request.
             chatwin = chatwin_new(barejid);
         }
         ui_focus_win((ProfWin*)chatwin);
 
-#ifdef HAVE_OMEMO
-        gboolean is_otr_secure = FALSE;
-
-#ifdef HAVE_LIBOTR
-        is_otr_secure = otr_is_secure(barejid);
-#endif // HAVE_LIBOTR
-
-        if (omemo_automatic_start(barejid) && is_otr_secure) {
-            win_println(window, THEME_DEFAULT, "!", "Chat could be either OMEMO or OTR encrypted. Use '/omemo start %s' or '/otr start %s' to start a session.", usr, usr);
-            return TRUE;
-        } else if (omemo_automatic_start(barejid)) {
-            omemo_start_session(barejid);
-            chatwin->is_omemo = TRUE;
-        }
-#endif // HAVE_OMEMO
-
         if (msg) {
+            // NOTE: In case the message is OMEMO encrypted, we can't be sure
+            // whether the key bundles of the recipient have already been
+            // received. In the case that *no* bundles have been received yet,
+            // the message won't be sent, and an error is shown to the user.
+            // Other cases are not handled here.
             cl_ev_send_msg(chatwin, msg, NULL);
         } else {
 #ifdef HAVE_LIBOTR
+            // Start the OTR session after this (i.e. the first) message was sent
             if (otr_is_secure(barejid)) {
                 chatwin_otr_secured(chatwin, otr_is_trusted(barejid));
             }

src/event/client_events.c

@@ -134,27 +134,33 @@ cl_ev_send_msg_correct(ProfChatWin* chatwin, const char* const msg, const char*
     if (chatwin->is_omemo) {
 #ifdef HAVE_OMEMO
         char* id = omemo_on_message_send((ProfWin*)chatwin, plugin_msg, request_receipt, FALSE, replace_id);
+        if (id != NULL) {
             chat_log_omemo_msg_out(chatwin->barejid, plugin_msg, NULL);
             log_database_add_outgoing_chat(id, chatwin->barejid, plugin_msg, replace_id, PROF_MSG_ENC_OMEMO);
             chatwin_outgoing_msg(chatwin, plugin_msg, id, PROF_MSG_ENC_OMEMO, request_receipt, replace_id);
             free(id);
+        }
 #endif
     } else if (chatwin->is_ox) {
 #ifdef HAVE_LIBGPGME
         // XEP-0373: OpenPGP for XMPP
         char* id = message_send_chat_ox(chatwin->barejid, plugin_msg, request_receipt, replace_id);
+        if (id != NULL) {
             chat_log_pgp_msg_out(chatwin->barejid, plugin_msg, NULL);
             log_database_add_outgoing_chat(id, chatwin->barejid, plugin_msg, replace_id, PROF_MSG_ENC_OX);
             chatwin_outgoing_msg(chatwin, plugin_msg, id, PROF_MSG_ENC_OX, request_receipt, replace_id);
             free(id);
+        }
 #endif
     } else if (chatwin->pgp_send) {
 #ifdef HAVE_LIBGPGME
         char* id = message_send_chat_pgp(chatwin->barejid, plugin_msg, request_receipt, replace_id);
+        if (id != NULL) {
             chat_log_pgp_msg_out(chatwin->barejid, plugin_msg, NULL);
             log_database_add_outgoing_chat(id, chatwin->barejid, plugin_msg, replace_id, PROF_MSG_ENC_PGP);
             chatwin_outgoing_msg(chatwin, plugin_msg, id, PROF_MSG_ENC_PGP, request_receipt, replace_id);
             free(id);
+        }
 #endif
     } else {
         gboolean handled = FALSE;

src/omemo/omemo.c

@@ -705,6 +705,7 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
     memcpy(key_tag, key, AES128_GCM_KEY_LENGTH);
     memcpy(key_tag + AES128_GCM_KEY_LENGTH, tag, AES128_GCM_TAG_LENGTH);
 
+    // List of barejids of the recipients of this message
     GList* recipients = NULL;
     if (muc) {
         ProfMucWin* mucwin = (ProfMucWin*)win;
@@ -727,6 +728,7 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
 
     omemo_ctx.identity_key_store.recv = false;
 
+    // Encrypt keys for the recipients
     GList* recipients_iter;
     for (recipients_iter = recipients; recipients_iter != NULL; recipients_iter = recipients_iter->next) {
         GList* recipient_device_id = NULL;
@@ -772,6 +774,17 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
 
     g_list_free_full(recipients, free);
 
+    // Don't send the message if no key could be encrypted.
+    // (Since none of the recipients would be able to read the message.)
+    if (keys == NULL) {
+        win_println(win, THEME_ERROR, "!", "This message cannot be decrypted for any recipient.\n"
+                "You should trust your recipients' device fingerprint(s) using \"/omemo fingerprint trust FINGERPRINT\".\n"
+                "It could also be that the key bundle of the recipient(s) have not been received. "
+                "In this case, you could try \"omemo end\", \"omemo start\", and send the message again.");
+        goto out;
+    }
+
+    // Encrypt keys for the sender
     if (!muc) {
         GList* sender_device_id = g_hash_table_lookup(omemo_ctx.device_list, jid->barejid);
         for (device_ids_iter = sender_device_id; device_ids_iter != NULL; device_ids_iter = device_ids_iter->next) {
@@ -784,6 +797,12 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
                 .device_id = GPOINTER_TO_INT(device_ids_iter->data)
             };
 
+            // Don't encrypt for this device (according to
+            // <https://xmpp.org/extensions/xep-0384.html#encrypt>).
+            if (address.device_id == omemo_ctx.device_id) {
+                continue;
+            }
+
             res = session_cipher_create(&cipher, omemo_ctx.store, &address, omemo_ctx.signal);
             if (res != 0) {
                 log_error("[OMEMO] cannot create cipher for %s device id %d", address.name, address.device_id);
@@ -808,6 +827,7 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
         }
     }
 
+    // Send the message
     if (muc) {
         ProfMucWin* mucwin = (ProfMucWin*)win;
         assert(mucwin->memcheck == PROFMUCWIN_MEMCHECK);

src/ui/chatwin.c

@@ -80,12 +80,22 @@ chatwin_new(const char* const barejid)
         }
     }
 
+    // We start a new OMEMO session if this contact has been configured accordingly.
+    // However, if OTR is *also* configured, ask the user to choose between OMEMO and OTR.
 #ifdef HAVE_OMEMO
-    if (omemo_automatic_start(barejid)) {
+    gboolean is_otr_secure = FALSE;
+#ifdef HAVE_LIBOTR
+    is_otr_secure = otr_is_secure(barejid);
+#endif // HAVE_LIBOTR
+    if (omemo_automatic_start(barejid) && is_otr_secure) {
+        win_println(window, THEME_DEFAULT, "!", "This chat could be either OMEMO or OTR encrypted, but not both. "
+                "Use '/omemo start' or '/otr start' to select the encryption method.");
+    } else if (omemo_automatic_start(barejid)) {
+        // Start the OMEMO session
         omemo_start_session(barejid);
         chatwin->is_omemo = TRUE;
     }
-#endif
+#endif // HAVE_OMEMO
 
     if (prefs_get_boolean(PREF_MAM)) {
         iq_mam_request(chatwin);