Merged revisions 318919 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

........
  r318919 | bbryant | 2011-05-13 14:04:50 -0400 (Fri, 13 May 2011) | 10 lines
  
  This patch fixes an issue with SRTP which makes HOLD/UNHOLD impossible when too
  much time has passed between sending audio.
  
  (closes issue #18206)
  Reported by: bernhardsi
  Patches: 
        res_srtp_unhold.patch uploaded by bernhards (license 1138)
  Tested by: bernhards, notthematrix
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@318920 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_srtp.c

@@ -314,8 +314,11 @@ static int ast_srtp_unprotect(struct ast_srtp *srtp, void *buf, int *len, int rt
 {
 	int res = 0;
 	int i;
+	int retry = 0;
 	struct ast_rtp_instance_stats stats = {0,};
 
+	tryagain:
+
 	for (i = 0; i < 2; i++) {
 		res = rtcp ? srtp_unprotect_rtcp(srtp->session, buf, len) : srtp_unprotect(srtp->session, buf, len);
 		if (res != err_status_no_ctx) {
@@ -334,6 +337,49 @@ static int ast_srtp_unprotect(struct ast_srtp *srtp, void *buf, int *len, int rt
 		}
 	}
 
+	if (retry == 0  && res == err_status_replay_old) {
+		ast_log(LOG_WARNING, "SRTP unprotect: %s\n", srtp_errstr(res));
+
+		if (srtp->session) {
+			struct ast_srtp_policy *policy;
+			struct ao2_iterator it;
+			int policies_count = 0;
+			
+			// dealloc first
+			ast_log(LOG_WARNING, "SRTP destroy before re-create\n");
+			srtp_dealloc(srtp->session);
+			
+			// get the count
+			policies_count = ao2_container_count(srtp->policies);
+			
+			// get the first to build up
+			it = ao2_iterator_init(srtp->policies, 0);
+			policy = ao2_iterator_next(&it);
+
+			ast_log(LOG_WARNING, "SRTP try to re-create\n");
+        		if (srtp_create(&srtp->session, &policy->sp) == err_status_ok) {
+				ast_log(LOG_WARNING, "SRTP re-created with first policy\n");
+				
+				// unref first element
+				ao2_t_ref(policy, -1, "Unreffing first policy for re-creating srtp session");
+				
+				// if we have more than one policy, add them afterwards	
+				if (policies_count > 1) {
+					ast_log(LOG_WARNING, "Add all the other %d policies\n", policies_count-1);
+					while ((policy = ao2_iterator_next(&it))) {
+						srtp_add_stream(srtp->session, &policy->sp);
+						ao2_t_ref(policy, -1, "Unreffing n-th policy for re-creating srtp session");
+					}
+				}
+				
+				retry++;
+				ao2_iterator_destroy(&it);
+				goto tryagain;
+			}
+			ao2_iterator_destroy(&it);
+		}
+	}
+
 	if (res != err_status_ok && res != err_status_replay_fail ) {
 		ast_log(LOG_WARNING, "SRTP unprotect: %s\n", srtp_errstr(res));
 		errno = EAGAIN;