# HG changeset patch
# User Mark Doliner <mark@kingant.net>
# Date 1391153359 28800
# Node ID b8e2a5fbffd3052ccba7160b56eac70f8e19c49a
# Parent  e733020a9d3840275ffa931a9aeefe4d8befc08e
Fix problems logging into some servers including jabber.org and
chat.facebook.com.

See my length comment in iq.c for details.

diff --git a/libpurple/protocols/jabber/iq.c b/libpurple/protocols/jabber/iq.c
--- a/libpurple/protocols/jabber/iq.c
+++ b/libpurple/protocols/jabber/iq.c
@@ -283,6 +283,52 @@
 	g_hash_table_remove(js->iq_callbacks, id);
 }
 
+/**
+ * Verify that the 'from' attribute of an IQ reply is a valid match for
+ * a given IQ request. The expected behavior is outlined in section
+ * 8.1.2.1 of the XMPP CORE spec (RFC 6120). We consider the reply to
+ * be a valid match if any of the following is true:
+ * - Request 'to' matches reply 'from' (including the case where
+ *   neither are set).
+ * - Request 'to' was empty and reply 'from' is server JID.
+ * - Request 'to' was empty and reply 'from' is my JID. The spec says
+ *   we should only allow bare JID, but we also allow full JID for
+ *   compatibility with some servers.
+ *
+ * These rules should allow valid IQ replies while preventing spoofed
+ * ones.
+ *
+ * For more discussion see the "Spoofing of iq ids and misbehaving
+ * servers" email thread from January 2014 on the jdev and security
+ * mailing lists.
+ *
+ * @return TRUE if this reply is valid for the given request.
+ */
+static gboolean does_reply_from_match_request_to(JabberStream *js, JabberID *to, JabberID *from)
+{
+	if (jabber_id_equal(to, from)) {
+		/* Request 'to' matches reply 'from' */
+		return TRUE;
+	}
+
+	if (!to && purple_strequal(from->domain, js->user->domain)) {
+		/* Request 'to' is empty and reply 'from' domain matches our domain */
+
+		if (!from->node && !from->resource) {
+			/* Reply 'from' is server bare JID */
+			return TRUE;
+		}
+
+		if (purple_strequal(from->node, js->user->node)
+				&& (!from->resource || purple_strequal(from->resource, js->user->resource))) {
+			/* Reply 'from' is my full or bare JID */
+			return TRUE;
+		}
+	}
+
+	return FALSE;
+}
+
 void jabber_iq_parse(JabberStream *js, xmlnode *packet)
 {
 	JabberIqCallbackData *jcd;
@@ -377,8 +423,9 @@
 
 	/* First, lets see if a special callback got registered */
 	if(type == JABBER_IQ_RESULT || type == JABBER_IQ_ERROR) {
-		if((jcd = g_hash_table_lookup(js->iq_callbacks, id))) {
-			if(jabber_id_equal(js, jcd->to, from_id)) {
+		jcd = g_hash_table_lookup(js->iq_callbacks, id);
+		if (jcd) {
+			if (does_reply_from_match_request_to(js, jcd->to, from_id)) {
 				jcd->callback(js, from, type, id, packet, jcd->data);
 				jabber_iq_remove_callback_by_id(js, id);
 				jabber_id_free(from_id);
diff --git a/libpurple/protocols/jabber/jutil.c b/libpurple/protocols/jabber/jutil.c
--- a/libpurple/protocols/jabber/jutil.c
+++ b/libpurple/protocols/jabber/jutil.c
@@ -510,30 +510,21 @@
 
 
 gboolean
-jabber_id_equal(JabberStream *js, const JabberID *jid1, const JabberID *jid2)
+jabber_id_equal(const JabberID *jid1, const JabberID *jid2)
 {
-	const JabberID *j1, *j2;
-	JabberID *bare_user_jid;
-	gboolean equal;
+	if (!jid1 && !jid2) {
+		/* Both are null therefore equal */
+		return TRUE;
+	}
 
-	/* If an outgoing stanza has no 'to', or an incoming has no 'from',
-	 * then those are "the server acting as my account". This function will
-	 * handle that correctly.
-	 */
-	if (!jid1 && !jid2)
-		return TRUE;
+	if (!jid1 || !jid2) {
+		/* One is null, other is non-null, therefore not equal */
+		return FALSE;
+	}
 
-	bare_user_jid = jabber_id_to_bare_jid(js->user);
-	j1 = jid1 ? jid1 : bare_user_jid;
-	j2 = jid2 ? jid2 : bare_user_jid;
-
-	equal = purple_strequal(j1->node, j2->node) &&
-			purple_strequal(j1->domain, j2->domain) &&
-			purple_strequal(j1->resource, j2->resource);
-
-	jabber_id_free(bare_user_jid);
-
-	return equal;
+	return purple_strequal(jid1->node, jid2->node) &&
+			purple_strequal(jid1->domain, jid2->domain) &&
+			purple_strequal(jid1->resource, jid2->resource);
 }
 
 char *jabber_get_domain(const char *in)
diff --git a/libpurple/protocols/jabber/jutil.h b/libpurple/protocols/jabber/jutil.h
--- a/libpurple/protocols/jabber/jutil.h
+++ b/libpurple/protocols/jabber/jutil.h
@@ -46,12 +46,10 @@
 JabberID* jabber_id_new(const char *str);
 
 /**
- * Compare two JIDs for equality.
- *
- * Warning: If either JID is NULL then this function uses the user's
- * bare JID, instead!
+ * Compare two JIDs for equality. In addition to the node and domain,
+ * the resources of the two JIDs must also be equal (or both absent).
  */
-gboolean jabber_id_equal(JabberStream *js, const JabberID *jid1, const JabberID *jid2);
+gboolean jabber_id_equal(const JabberID *jid1, const JabberID *jid2);
 
 void jabber_id_free(JabberID *jid);