From 5ecb0c5d0c702c77778d7f1ea9846081c40561b4 Mon Sep 17 00:00:00 2001
From: Dmitry Podgorny <pasis.ua@gmail.com>
Date: Sat, 24 Jun 2017 02:10:03 +0300
Subject: [PATCH] conn: clear system handlers on reconnect

xmpp_conn_t object can be reused with saving user's handlers.
However, saving system handlers can lead to a fail during connection
process. This is because old object may contain timed handlers for
missed features or other handlers that would handle incoming stanzas
incorrectly.
---
 ChangeLog     |  2 ++
 src/common.h  |  1 +
 src/conn.c    |  2 ++
 src/handler.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 3022d40..047232b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,8 @@
 	- OpenSSL tls module disables insecure SSLv2 SSLv3 and TLSv1
 	- Support of handlers with the same callback function, but different
 	  userdata
+	- System handlers are deleted on xmpp_conn_t reconnection. Old system
+	  handlers could cause problems
 	- New public function xmpp_sha1_digest()
 
 0.9.1
diff --git a/src/common.h b/src/common.h
index ab06e6b..1290d72 100644
--- a/src/common.h
+++ b/src/common.h
@@ -266,6 +266,7 @@ void handler_add(xmpp_conn_t * const conn,
                  const char * const name,
                  const char * const type,
                  void * const userdata);
+void handler_system_delete_all(xmpp_conn_t *conn);
 
 /* utility functions */
 void disconnect_mem_error(xmpp_conn_t * const conn);
diff --git a/src/conn.c b/src/conn.c
index d8e34d2..f4e19a7 100644
--- a/src/conn.c
+++ b/src/conn.c
@@ -1215,6 +1215,8 @@ static void _conn_reset(xmpp_conn_t * const conn)
     conn->secured = 0;
     conn->tls_failed = 0;
     conn->error = 0;
+
+    handler_system_delete_all(conn);
 }
 
 static int _conn_connect(xmpp_conn_t * const conn,
diff --git a/src/handler.c b/src/handler.c
index d71646f..dc53534 100644
--- a/src/handler.c
+++ b/src/handler.c
@@ -87,6 +87,7 @@ void handler_fire_stanza(xmpp_conn_t * const conn,
                 head_old = head;
                 _handler_item_remove(&head, item);
                 if (head != head_old) {
+                    /* TODO implement hash_replace() */
                     hash_drop(conn->id_handlers, id);
                     hash_add(conn->id_handlers, id, head);
                 }
@@ -614,3 +615,73 @@ void handler_add(xmpp_conn_t * const conn,
 {
     _handler_add(conn, handler, ns, name, type, userdata, 0);
 }
+
+/** Delete all system handlers.
+ *  This function is used to reset conn object before re-connecting.
+ *
+ *  @param conn a Strophe connection object
+ */
+void handler_system_delete_all(xmpp_conn_t *conn)
+{
+    xmpp_handlist_t *item, *next, *head, *head_old;
+    hash_iterator_t *iter;
+    const char *key;
+    char *key2;
+
+    /* TODO unify all kinds of handlers and avoid copy-paste below */
+
+    item = conn->handlers;
+    while (item) {
+        if (!item->user_handler) {
+            next = item->next;
+            _handler_item_remove(&conn->handlers, item);
+            if (item->ns) xmpp_free(conn->ctx, item->ns);
+            if (item->name) xmpp_free(conn->ctx, item->name);
+            if (item->type) xmpp_free(conn->ctx, item->type);
+            xmpp_free(conn->ctx, item);
+            item = next;
+        } else
+            item = item->next;
+    }
+
+    item = conn->timed_handlers;
+    while (item) {
+        if (!item->user_handler) {
+            next = item->next;
+            _handler_item_remove(&conn->timed_handlers, item);
+            xmpp_free(conn->ctx, item);
+            item = next;
+        } else
+            item = item->next;
+    }
+
+    iter = hash_iter_new(conn->id_handlers);
+    key = iter == NULL ? NULL : hash_iter_next(iter);
+    while (key != NULL) {
+        head = head_old = (xmpp_handlist_t *)hash_get(conn->id_handlers, key);
+        item = head;
+        while (item) {
+            if (!item->user_handler) {
+                next = item->next;
+                _handler_item_remove(&head, item);
+                xmpp_free(conn->ctx, item->id);
+                xmpp_free(conn->ctx, item);
+                item = next;
+            } else
+                item = item->next;
+        }
+        if (head != head_old)
+            key2 = xmpp_strdup(conn->ctx, key);
+        /* Hash table implementation is not perfect, so we need to find next
+           key before dropping current one. Otherwise, we will get access to
+           freed memory. */
+        key = hash_iter_next(iter);
+        if (head != head_old) {
+            /* TODO implement hash_replace() to reduce number of allocations */
+            hash_drop(conn->id_handlers, key2);
+            if (head != NULL)
+                hash_add(conn->id_handlers, key2, head);
+            xmpp_free(conn->ctx, key2);
+        }
+    }
+}