b2b_logic: provide custom max_duration at bridge time

Many thanks to Erhan Onur Sendag(@ErhanOnur) for reporting and
providing a patch for the first version and also to Norm Brandinger
(@NormB) for providing the final patch!

Close #3800

Author: razvancrainea

modules/b2b_logic/b2b_logic.h

@@ -83,6 +83,12 @@ enum b2b_tuple_state {
 #define B2BL_BR_FLAG_PENDING_SDP                   (1<<8)
 #define B2BL_BR_FLAG_BR_MSG_LATE_BYE               (1<<9)
 
+/* Internal flag: set when a per-bridge lifetime was explicitly provided
+ * via the max_duration flag on b2b_bridge(). Prevents b2b_add_dlginfo()
+ * from overwriting the per-bridge lifetime with the global max_duration
+ * modparam value when the bridged call is confirmed (200 OK). */
+#define B2BL_BR_FLAG_EXPLICIT_LIFETIME             (1<<10)
+
 /* reply flags */
 #define B2BL_RPL_FLAG_PASS_CONTACT                 (1<<0)
 

modules/b2b_logic/bridging.c

@@ -1679,8 +1679,11 @@ int b2bl_bridge(struct sip_msg* msg, b2bl_tuple_t* tuple,
 
 	if (lifetime)
 	{
-		tuple->lifetime = lifetime + get_ticks();
-		LM_DBG("Lifetime defined = [%d]\n", tuple->lifetime);
+		unsigned int ticks = get_ticks();
+		tuple->lifetime = lifetime + ticks;
+		tuple->bridge_flags |= B2BL_BR_FLAG_EXPLICIT_LIFETIME;
+		LM_DBG("Per-bridge lifetime set = [%u] (duration=%d, ticks=%u)\n",
+			tuple->lifetime, lifetime, ticks);
 	}
 	else
 		tuple->lifetime = -1;
@@ -2025,6 +2028,9 @@ int b2bl_bridge_2calls(str* key1, str* key2)
 	}
 	e1->sdp_type = B2BL_SDP_LATE;
 	e1->state = 0;
+	/* Clear any per-bridge lifetime from a previous b2b_bridge() call;
+	 * this bridge path always uses the global max_duration */
+	tuple->bridge_flags &= ~B2BL_BR_FLAG_EXPLICIT_LIFETIME;
 	tuple->state = B2B_BRIDGING_STATE;
 	if(max_duration)
 		tuple->lifetime = get_ticks() + max_duration;
@@ -2413,6 +2419,9 @@ int b2bl_bridge_msg(struct sip_msg* msg, str* key, int entity_no,
 	}
 	bridging_entity->sdp_type = B2BL_SDP_NORMAL;
 	bridging_entity->state = 0;
+	/* Clear any per-bridge lifetime from a previous b2b_bridge() call;
+	 * this bridge path always uses the global max_duration */
+	tuple->bridge_flags &= ~B2BL_BR_FLAG_EXPLICIT_LIFETIME;
 	if(max_duration)
 		tuple->lifetime = get_ticks() + max_duration;
 	else

modules/b2b_logic/doc/b2b_logic_admin.xml

@@ -333,7 +333,10 @@ modparam("b2b_logic", "update_period", 60)
 	<section id="param_max_duration" xreflabel="max_duration">
 		<title><varname>max_duration</varname> (int)</title>
 		<para>
-			The maximum duration of a call.
+			The maximum duration of a call. This value is applied as the default
+			lifetime for all B2B sessions. It can be overridden on a per-bridge
+			basis by using the <emphasis>max_duration</emphasis> flag of the
+			<xref linkend="func_b2b_bridge"/> function.
 		</para>
 		<para>
 		<emphasis>Default value is <quote>12 * 3600 (12 hours)</quote>.</emphasis>
@@ -782,7 +785,9 @@ b2b_client_new("client1", "sip:alice@opensips.org");
 					<listitem><para>
 					<emphasis>max_duration=[nn]</emphasis> - Maximum duration of the B2B
 					session. If the lifetime expires, the B2BUA will send BYE messages to both
-					ends and delete the record. Example: "max_duration=300".
+					ends and delete the record. This per-bridge value takes precedence over the
+					global <xref linkend="param_max_duration"/> module parameter.
+					Example: "max_duration=300".
 					</para></listitem>
 					<listitem><para>
 					<emphasis>notify</emphasis> - Enable rfc3515 NOTIFY to inform the agent

modules/b2b_logic/logic.c

@@ -161,10 +161,19 @@ int b2b_add_dlginfo(str* key, str* entity_key, int src, b2b_dlginfo_t* dlginfo,
 		return -1;
 	}
 	/* a connected call */
-	if(max_duration)
-		tuple->lifetime = get_ticks() + max_duration;
-	else
-		tuple->lifetime = 0;
+	if (tuple->bridge_flags & B2BL_BR_FLAG_EXPLICIT_LIFETIME) {
+		/* A per-bridge lifetime was set via the max_duration flag on
+		 * b2b_bridge(); preserve it instead of overwriting with the
+		 * global max_duration modparam */
+		LM_DBG("Preserving per-bridge lifetime [%u] for tuple [%.*s]\n",
+			tuple->lifetime, tuple->key ? tuple->key->len : 0,
+			tuple->key ? tuple->key->s : "");
+	} else {
+		if(max_duration)
+			tuple->lifetime = get_ticks() + max_duration;
+		else
+			tuple->lifetime = 0;
+	}
 	entity = b2bl_search_entity(tuple, entity_key, src, &ent_head);
 	if(entity == NULL)
 	{