mcabber-ignore-duplicate-subscriptions.patch

--- a/mcabber/xmpp.c
+++ b/mcabber/xmpp.c
@@ -1538,7 +1538,9 @@
 {
   char *r;
   char *buf;
+  GSList* roster_node;
   int newbuddy;
+  guint subscription;
   guint hook_result;
   LmMessageSubType mstype = lm_message_get_sub_type(m);
   const char *from = lm_message_get_from(m);
@@ -1556,14 +1558,21 @@
   }
   r = jidtodisp(from);
 
-  newbuddy = !roster_find(r, jidsearch, 0);
+  roster_node = roster_find(r, jidsearch, 0);
+  if (roster_node) {
+      newbuddy = 0;
+      subscription = buddy_getsubscription(roster_node->data);
+  } else {
+      newbuddy = 1;
+      subscription = 0;
+  }
 
   hook_result = hk_subscription(mstype, r, msg);
 
   if (mstype == LM_MESSAGE_SUB_TYPE_SUBSCRIBE) {
     /* The sender wishes to subscribe to our presence */
 
-    if (hook_result) {
+    if (hook_result || (subscription & sub_from)) {
       g_free(r);
       return LM_HANDLER_RESULT_REMOVE_MESSAGE;
     }
@@ -1600,6 +1609,11 @@
     scr_LogPrint(LPRINT_LOGNORM, "%s", buf);
     g_free(buf);
   } else if (mstype == LM_MESSAGE_SUB_TYPE_UNSUBSCRIBE) {
+    if (!(subscription & sub_from)) {
+      g_free(r);
+      return LM_HANDLER_RESULT_REMOVE_MESSAGE;
+    }
+
     /* The sender is unsubscribing from our presence */
     xmpp_send_s10n(from, LM_MESSAGE_SUB_TYPE_UNSUBSCRIBED);
     buf = g_strdup_printf("<%s> is unsubscribing from your "
@@ -1608,6 +1622,11 @@
     scr_LogPrint(LPRINT_LOGNORM, "%s", buf);
     g_free(buf);
   } else if (mstype == LM_MESSAGE_SUB_TYPE_SUBSCRIBED) {
+    if (subscription & sub_to) {
+      g_free(r);
+      return LM_HANDLER_RESULT_REMOVE_MESSAGE;
+    }
+
     /* The sender has allowed us to receive their presence */
     buf = g_strdup_printf("<%s> has allowed you to receive their "
                           "presence updates", from);
@@ -1615,6 +1634,11 @@
     scr_LogPrint(LPRINT_LOGNORM, "%s", buf);
     g_free(buf);
   } else if (mstype == LM_MESSAGE_SUB_TYPE_UNSUBSCRIBED) {
+    if (!(subscription & sub_to)) {
+      g_free(r);
+      return LM_HANDLER_RESULT_REMOVE_MESSAGE;
+    }
+
     /* The subscription request has been denied or a previously-granted
        subscription has been cancelled */
     roster_unsubscribed(from);

The patch looks good; what's annoying is that it is just a workaround for a server bug :/
Still, if we want a client-side solution, what about this slightly updated version?

diff --git a/mcabber/mcabber/xmpp.c b/mcabber/mcabber/xmpp.c
--- a/mcabber/mcabber/xmpp.c
+++ b/mcabber/mcabber/xmpp.c
@@ -1591,6 +1591,7 @@ static LmHandlerResult handle_s10n(LmMes
   char *r;
   char *buf;
   int newbuddy;
+  guint subscription;
   guint hook_result;
   LmMessageSubType mstype = lm_message_get_sub_type(m);
   const char *from = lm_message_get_from(m);
@@ -1609,16 +1610,15 @@ static LmHandlerResult handle_s10n(LmMes
   r = jidtodisp(from);

   newbuddy = !roster_find(r, jidsearch, 0);
+  subscription = roster_getsubscription(r);

   hook_result = hk_subscription(mstype, r, msg);

   if (mstype == LM_MESSAGE_SUB_TYPE_SUBSCRIBE) {
     /* The sender wishes to subscribe to our presence */

-    if (hook_result) {
-      g_free(r);
-      return LM_HANDLER_RESULT_REMOVE_MESSAGE;
-    }
+    if (hook_result || (subscription & sub_from))
+      goto handle_s10n_return;

     buf = g_strdup_printf("<%s> wants to subscribe to your presence updates",
                           from);
@@ -1654,6 +1654,8 @@ static LmHandlerResult handle_s10n(LmMes
   } else if (mstype == LM_MESSAGE_SUB_TYPE_UNSUBSCRIBE) {
     /* The sender is unsubscribing from our presence */
     xmpp_send_s10n(from, LM_MESSAGE_SUB_TYPE_UNSUBSCRIBED);
+    if (!(subscription & sub_from))
+      goto handle_s10n_return;
     buf = g_strdup_printf("<%s> is unsubscribing from your "
                           "presence updates", from);
     scr_WriteIncomingMessage(r, buf, 0, HBB_PREFIX_INFO, 0);
@@ -1661,6 +1663,8 @@ static LmHandlerResult handle_s10n(LmMes
     g_free(buf);
   } else if (mstype == LM_MESSAGE_SUB_TYPE_SUBSCRIBED) {
     /* The sender has allowed us to receive their presence */
+    if (subscription & sub_to)
+      goto handle_s10n_return;
     buf = g_strdup_printf("<%s> has allowed you to receive their "
                           "presence updates", from);
     scr_WriteIncomingMessage(r, buf, 0, HBB_PREFIX_INFO, 0);
@@ -1671,6 +1675,8 @@ static LmHandlerResult handle_s10n(LmMes
        subscription has been cancelled */
     roster_unsubscribed(from);
     update_roster = TRUE;
+    if (!(subscription & sub_to))
+      goto handle_s10n_return;
     buf = g_strdup_printf("<%s> has cancelled your subscription to "
                           "their presence updates", from);
     scr_WriteIncomingMessage(r, buf, 0, HBB_PREFIX_INFO, 0);
@@ -1683,6 +1689,8 @@ static LmHandlerResult handle_s10n(LmMes

   if (newbuddy)
     update_roster = TRUE;
+
+handle_s10n_return:
   g_free(r);
   return LM_HANDLER_RESULT_REMOVE_MESSAGE;
 }