Added support for Content-Disposition: no-cancel

As per RFC3841, section 9.1, the TM module may be instructed not to cancel all ongoing branches when a 2xx reply is received. It will keep the pending branches ongoing until (1) all branches will receive a final reply or (2) the transactionhits the timeout.

This is work sponsored by Harris Corporation (https://www.harris.com)

modules/tm/h_table.h

@@ -199,6 +199,8 @@ struct totag_elem {
 #define T_NO_NEW_BRANCHES_FLAG  (1<<8)
 /* transaction must forward the REASON header (for CANCEL)  */
 #define T_CANCEL_REASON_FLAG    (1<<9)
+/* transaction must accept multiple 200 OK (different branches)  */
+#define T_MULTI_200OK_FLAG      (1<<10)
 
 /* transaction UAC's flags */
 /* is the UAC pending for CANCEL ?  */

modules/tm/t_cancel.c

@@ -66,8 +66,16 @@ void cancel_uacs( struct cell *t, branch_bm_t cancel_bm )
 
 	/* cancel pending client transactions, if any */
 	for( i=0 ; i<t->nr_of_outgoings ; i++ )
-		if (cancel_bm & (1<<i))
-			cancel_branch(t, i);
+		if (cancel_bm & (1<<i)) {
+			/* any reply actually received on this branch */
+			if (t->uac[i].last_received!=0) {
+				/* send a cancel out */
+				cancel_branch(t, i);
+			} else {
+				/* set flag to catch the delaied replies */
+				t->uac[i].flags |= T_UAC_TO_CANCEL_FLAG;
+			}
+		}
 }
 
 

modules/tm/t_cancel.h

@@ -55,20 +55,14 @@ char *build_cancel(struct cell *Trans,unsigned int branch,
 
 inline static short should_cancel_branch( struct cell *t, int b )
 {
-	int last_received;
-
-	last_received = t->uac[b].last_received;
 	/* cancel only if provisional received and no one else
 	   attempted to cancel yet */
 	if ( t->uac[b].local_cancel.buffer.s==NULL ) {
-		if ( last_received>=100 && last_received<200 ) {
+		if ( t->uac[b].last_received<200 ) {
 			/* we'll cancel -- label it so that no one else
 			(e.g. another 200 branch) will try to do the same */
 			t->uac[b].local_cancel.buffer.s=BUSY_BUFFER;
 			return 1;
-		} else if (last_received==0) {
-			/* set flag to catch the delaied replies */
-			t->uac[b].flags |= T_UAC_TO_CANCEL_FLAG;
 		}
 	}
 	return 0;

modules/tm/t_funcs.c

@@ -47,6 +47,7 @@
 #include "../../hash_func.h"
 #include "../../dset.h"
 #include "../../mem/mem.h"
+#include "../../parser/parse_list_hdr.h"
 #include "t_funcs.h"
 #include "t_fwd.h"
 #include "t_msgbuilder.h"
@@ -176,6 +177,26 @@ static int kill_transaction( struct cell *trans )
 }
 
 
+int tm_has_request_disponsition_no_cancel(struct sip_msg *msg)
+{
+	str RD_hdr_name = {"Request-Disposition",19};
+	str opt = {"no-cancel",9};
+	struct hdr_field *hdr;
+
+	/* be sure all SIP headers are parsed */
+	if (parse_headers(msg, HDR_EOH_F, 0) < 0) {
+		LM_ERR("failed to parse SIP headers while looking for "
+			"Request-Disposition\n");
+		return -1;
+	}
+
+	hdr = get_header_by_name( msg, RD_hdr_name.s, RD_hdr_name.len);
+	if (hdr==NULL)
+		return -1;
+
+	return list_hdr_has_option( hdr, &opt);
+}
+
 
 int t_relay_to( struct sip_msg  *p_msg , struct proxy_l *proxy, int flags)
 {
@@ -229,6 +250,9 @@ int t_relay_to( struct sip_msg  *p_msg , struct proxy_l *proxy, int flags)
 	if (flags&TM_T_REPLY_repl_FLAG) t->flags|=T_IS_LOCAL_FLAG;
 	if (flags&TM_T_REPLY_nodnsfo_FLAG) t->flags|=T_NO_DNS_FAILOVER_FLAG;
 	if (flags&TM_T_REPLY_reason_FLAG) t->flags|=T_CANCEL_REASON_FLAG;
+	if ((flags&TM_T_REPLY_do_cancel_dis_FLAG) &&
+	tm_has_request_disponsition_no_cancel(p_msg)==0 )
+		t->flags|=T_MULTI_200OK_FLAG;
 
 	/* now go ahead and forward ... */
 	ret=t_forward_nonack( t, p_msg, proxy, 0/*no reset*/, 0/*unlocked*/);

modules/tm/t_funcs.h

@@ -66,11 +66,12 @@ extern int noisy_ctimer;
 
 
 /* t_reply_to flags */
-#define TM_T_REPLY_repl_FLAG     (1<<0)
-#define TM_T_REPLY_not_used      (1<<1)
-#define TM_T_REPLY_noerr_FLAG    (1<<2)
-#define TM_T_REPLY_nodnsfo_FLAG  (1<<3)
-#define TM_T_REPLY_reason_FLAG   (1<<4)
+#define TM_T_REPLY_repl_FLAG          (1<<0)
+#define TM_T_REPLY_not_used           (1<<1)
+#define TM_T_REPLY_noerr_FLAG         (1<<2)
+#define TM_T_REPLY_nodnsfo_FLAG       (1<<3)
+#define TM_T_REPLY_reason_FLAG        (1<<4)
+#define TM_T_REPLY_do_cancel_dis_FLAG (1<<5)
 
 
 /* send a private buffer: utilize a retransmission structure
@@ -183,5 +184,7 @@ void cleanup_localcancel_timers( struct cell *t );
 int t_relay_to( struct sip_msg  *p_msg, struct proxy_l *proxy, int replicate);
 
 
+int tm_has_request_disponsition_no_cancel(struct sip_msg *msg);
+
 #endif
 

modules/tm/t_reply.c

@@ -793,6 +793,20 @@ static inline int t_pick_branch( struct cell *t, int *res_code, int *do_cancel)
 }
 
 
+/* Quick and harmless test to see if the transaction still has 
+   pending branches */
+static inline int tran_is_completed( struct cell *t )
+{
+	int i;
+
+	for( i=t->first_branch ; i<t->nr_of_outgoings ; i++ )
+		if ( t->uac[i].last_received<200 )
+			return 0;
+
+	return 1;
+}
+
+
 /* This is the neurological point of reply processing -- called
  * from within a REPLY_LOCK, t_should_relay_response decides
  * how a reply shall be processed and how transaction state is
@@ -820,6 +834,31 @@ static enum rps t_should_relay_response( struct cell *Trans , int new_code,
 	   out
 	*/
 	LM_DBG("T_code=%d, new_code=%d\n", Trans->uas.status,new_code);
+
+	/* a final reply after 200 OK on a transaction with multi branch 200 OK */
+	if ( is_invite(Trans) && new_code>=200
+	&& Trans->flags&T_MULTI_200OK_FLAG
+	&& Trans->uas.status>=200 && Trans->uas.status<300) {
+		*should_store=0;
+		picked_branch=-1;
+		Trans->uac[branch].last_received=new_code;
+		if (new_code>=300) {
+			/* negative reply, we simply discard (no relay, no save) */
+			*should_relay = -1;
+			return RPS_DISCARDED;
+		}
+		/* 2xx reply - is this the last branch to complete?? */
+		if (tran_is_completed(Trans)) {
+			/* last branch gets also a 200OK, no more pending branches */
+			*should_relay = branch;
+			return RPS_COMPLETED;
+		} else {
+			/* 200 OK, but still having ongoing branches */
+			*should_relay = branch;
+			return RPS_RELAY;
+		}
+	}
+
 	inv_through=new_code>=200 && new_code<300 && is_invite(Trans);
 	/* if final response sent out, allow only INVITE 2xx  */
 	if ( Trans->uas.status >= 200 ) {
@@ -847,7 +886,7 @@ static enum rps t_should_relay_response( struct cell *Trans , int new_code,
 #ifdef EXTRA_DEBUG
 		/* don't report on retransmissions */
 		if (Trans->uac[branch].last_received==new_code) {
-			LM_DBG("final reply retransmission\n");
+			LM_DBG("final rely retransmission\n");
 		} else
 		/* if you FR-timed-out, faked a local 408 and 487 came, don't
 		 * report on it either */
@@ -972,6 +1011,14 @@ static enum rps t_should_relay_response( struct cell *Trans , int new_code,
 		*should_store=0;
 		*should_relay= new_code==100? -1 : branch;
 		if (new_code>=200 ) {
+			/* if a a multi-200OK transaction, prevent the transaction
+			   completion if we still have pending branches */
+			if (Trans->flags&T_MULTI_200OK_FLAG) {
+				if (tran_is_completed(Trans))
+					return RPS_COMPLETED;
+				else
+					return RPS_RELAY;
+			}
 			which_cancel( Trans, cancel_bitmap );
 			return RPS_COMPLETED;
 		} else return RPS_PROVISIONAL;

modules/tm/t_reply.h

@@ -44,7 +44,9 @@ enum rps {
 	/* transaction completed */
 	RPS_COMPLETED,
 	/* provisional reply not affecting transaction state */
-	RPS_PROVISIONAL
+	RPS_PROVISIONAL,
+	/* just relay the reply*/
+	RPS_RELAY
 };
 
 extern char tm_tags[TOTAG_VALUE_LEN];

modules/tm/tm.c

@@ -1330,6 +1330,9 @@ static int w_t_relay( struct sip_msg  *p_msg , char *proxy, char *flags)
 			t->flags|=T_NO_DNS_FAILOVER_FLAG;
 		if (((int)(long)flags)&TM_T_REPLY_reason_FLAG)
 			t->flags|=T_CANCEL_REASON_FLAG;
+		if ( (((int)(long)flags)&TM_T_REPLY_do_cancel_dis_FLAG) &&
+		tm_has_request_disponsition_no_cancel(p_msg)==0 )
+			t->flags|=T_MULTI_200OK_FLAG;
 
 		/* update the transaction only if in REQUEST route; for other types
 		   of routes we do not want to inherit the local changes */