res_rtp_asterisk: Add ability to propose local address in ICE

You can now add the "include_local_address" flag to an entry in
rtp.conf "[ice_host_candidates]" to include both the advertized
address and the local address in ICE negotiation:

[ice_host_candidates]
192.168.1.1 = 1.2.3.4,include_local_address

This causes both 192.168.1.1 and 1.2.3.4 to be advertized.

Change-Id: Ide492cd45ce84546175ca7d557de80d9770513db

configs/samples/rtp.conf.sample

@@ -118,13 +118,19 @@ rtpend=20000
 ;
 ; The format for these overrides is:
 ;
-;    <local address> => <advertised address>
+;    <local address> => <advertised address>,[include_local_address]
 ;
 ; The following will replace 192.168.1.10 with 1.2.3.4 during ICE
 ; negotiation:
 ;
 ;192.168.1.10 => 1.2.3.4
 ;
+; The following will include BOTH 192.168.1.10 and 1.2.3.4 during ICE
+; negotiation instead of replacing 192.168.1.10.  This can make it easier
+; to serve both local and remote clients.
+;
+;192.168.1.10 => 1.2.3.4,include_local_address
+;
 ; You can define an override for more than 1 interface if you have a multihomed
 ; server. Any local interface that is not matched will be passed through
 ; unaltered. Both IPv4 and IPv6 addresses are supported.

doc/CHANGES-staging/rtp_ice_include_local_address.txt

+Subject: RTP/ICE
+
+You can now indicate that you'd like an ice_host_candidate's local address
+to be published as well as the mapped address.  See the sample rtp.conf
+for more information.

res/res_rtp_asterisk.c

@@ -252,6 +252,7 @@ static AST_LIST_HEAD_STATIC(ioqueues, ast_rtp_ioqueue_thread);
 struct ast_ice_host_candidate {
 	pj_sockaddr local;
 	pj_sockaddr advertised;
+	unsigned int include_local;
 	AST_RWLIST_ENTRY(ast_ice_host_candidate) next;
 };
 
@@ -615,21 +616,26 @@ static void host_candidate_overrides_clear(void)
 }
 
 /*! \brief Applies the ICE host candidate mapping */
-static void host_candidate_overrides_apply(unsigned int count, pj_sockaddr addrs[])
+static unsigned int host_candidate_overrides_apply(unsigned int count, unsigned int max_count, pj_sockaddr addrs[])
 {
 	int pos;
 	struct ast_ice_host_candidate *candidate;
+	unsigned int added = 0;
 
 	AST_RWLIST_RDLOCK(&host_candidates);
 	for (pos = 0; pos < count; pos++) {
 		AST_LIST_TRAVERSE(&host_candidates, candidate, next) {
 			if (!pj_sockaddr_cmp(&candidate->local, &addrs[pos])) {
 				pj_sockaddr_copy_addr(&addrs[pos], &candidate->advertised);
+				if (candidate->include_local && (count + (++added)) <= max_count) {
+					pj_sockaddr_cp(&addrs[count + (added - 1)], &candidate->local);
+				}
 				break;
 			}
 		}
 	}
 	AST_RWLIST_UNLOCK(&host_candidates);
+	return added;
 }
 
 /*! \brief Helper function which updates an ast_sockaddr with the candidate used for the component */
@@ -3303,6 +3309,7 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
 {
 	pj_sockaddr address[PJ_ICE_MAX_CAND];
 	unsigned int count = PJ_ARRAY_SIZE(address), pos = 0;
+	unsigned int max_count = PJ_ARRAY_SIZE(address);
 	int basepos = -1;
 
 	/* Add all the local interface IP addresses */
@@ -3314,7 +3321,7 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
 		pj_enum_ip_interface(pj_AF_INET6(), &count, address);
 	}
 
-	host_candidate_overrides_apply(count, address);
+	count += host_candidate_overrides_apply(count, max_count, address);
 
 	for (pos = 0; pos < count; pos++) {
 		if (!rtp_address_is_ice_blacklisted(&address[pos])) {
@@ -8640,6 +8647,8 @@ static int rtp_reload(int reload)
 	for (var = ast_variable_browse(cfg, "ice_host_candidates"); var; var = var->next) {
 		struct ast_sockaddr local_addr, advertised_addr;
 		pj_str_t address;
+		unsigned int include_local_address = 0;
+		char *sep;
 
 		ast_sockaddr_setnull(&local_addr);
 		ast_sockaddr_setnull(&advertised_addr);
@@ -8649,6 +8658,14 @@ static int rtp_reload(int reload)
 			continue;
 		}
 
+		sep = strchr(var->value,',');
+		if (sep) {
+			*sep = '\0';
+			sep++;
+			sep = ast_skip_blanks(sep);
+			include_local_address = strcmp(sep, "include_local_address") == 0;
+		}
+
 		if (ast_parse_arg(var->value, PARSE_ADDR | PARSE_PORT_IGNORE, &advertised_addr)) {
 			ast_log(LOG_WARNING, "Invalid advertised ICE host address: %s\n", var->value);
 			continue;
@@ -8659,6 +8676,8 @@ static int rtp_reload(int reload)
 			break;
 		}
 
+		candidate->include_local = include_local_address;
+
 		pj_sockaddr_parse(pj_AF_UNSPEC(), 0, pj_cstr(&address, ast_sockaddr_stringify(&local_addr)), &candidate->local);
 		pj_sockaddr_parse(pj_AF_UNSPEC(), 0, pj_cstr(&address, ast_sockaddr_stringify(&advertised_addr)), &candidate->advertised);