implement and document ng "media address"

README.md

@@ -520,6 +520,7 @@ Optionally included keys are:
 
 		If given, the media addresses from the SDP body are trusted as correct endpoints. Otherwise, the
 		address is taken from the `received from` key. Corresponds to the *rtpproxy* `r` flag.
+		Can be overridden through the `media address` key.
 
 	- `symmetric`
 
@@ -560,7 +561,7 @@ Optionally included keys are:
 
 	Contains a list of exactly two elements. The first element denotes the address family and the second
 	element is the SIP message's source address itself. The address family can be one of `IP4` or `IP6`.
-	Used if the `trust address` flag isn't present.
+	Used if neither the `trust address` flag nor the `media address` key is present.
 
 * `ICE`
 
@@ -582,13 +583,20 @@ Optionally included keys are:
 
 	Valid values are: `RTP/AVP`, `RTP/AVPF`, `RTP/SAVP`, `RTP/SAVPF`.
 
+* `media address`
+
+	This can be used to override both the addresses present in the SDP body
+	and the `received from` address. Contains either an IPv4 or an IPv6 address, expressed as a simple
+	string. The format must be dotted-quad notation for IPv4 or RFC 5952 notation for IPv6.
+	It's up to the RTP proxy to determine the address family type.
+
 An example of a complete `offer` request dictionary could be (SDP body abbreviated):
 
 	{ "command": "offer", "call-id": "cfBXzDSZqhYNcXM", "from-tag": "mS9rSAn0Cr",
 	"sdp": "v=0\r\no=...", "via-branch": "5KiTRPZHH1nL6",
 	"flags": [ "trust address" ], "replace": [ "origin", "session connection" ],
 	"direction": [ "external", "external" ], "received-from": [ "IP4", "10.65.31.43" ],
-	"ICE": "force", "transport protocol": "RTP/SAVPF" }
+	"ICE": "force", "transport protocol": "RTP/SAVPF", "media address": "2001:d8::6f24:65b" }
 
 The response message only contains the key `sdp` in addition to `result`, which contains the re-written
 SDP body that the SIP proxy should insert into the SIP message.

daemon/call.c

@@ -2616,6 +2616,7 @@ static void call_ng_process_flags(struct sdp_ng_flags *out, bencode_item_t *inpu
 	if (!out->transport_protocol_str.s)
 		bencode_dictionary_get_str(input, "transport-protocol", &out->transport_protocol_str);
 	out->transport_protocol = transport_protocol(&out->transport_protocol_str);
+	bencode_dictionary_get_str(input, "media address", &out->media_address);
 }
 
 static unsigned int stream_hash(struct stream_input *s) {

daemon/sdp.c

@@ -172,7 +172,7 @@ static inline int inet_pton_str(int af, str *src, void *dst) {
 	int ret;
 	p = s[src->len];
 	s[src->len] = '\0';
-	ret = inet_pton(af, src->s, dst);
+	ret = smart_pton(af, src->s, dst);
 	s[src->len] = p;
 	return ret;
 }
@@ -187,12 +187,22 @@ static int __parse_address(struct in6_addr *out, str *network_type, str *address
 				&& memcmp(network_type->s, "in", 2))
 			return -1;
 	}
+
+	if (!address_type) {
+		if (inet_pton_str(AF_INET, address, &in4) == 1)
+			goto ip4;
+		if (inet_pton_str(AF_INET6, address, out) == 1)
+			return 0;
+		return -1;
+	}
+
 	if (address_type->len != 3)
 		return -1;
 	if (!memcmp(address_type->s, "IP4", 3)
 			|| !memcmp(address_type->s, "ip4", 3)) {
 		if (inet_pton_str(AF_INET, address, &in4) != 1)
 			return -1;
+ip4:
 		in4_to_6(out, in4.s_addr);
 	}
 	else if (!memcmp(address_type->s, "IP6", 3)
@@ -748,13 +758,21 @@ void sdp_free(GQueue *sessions) {
 static int fill_stream_address(struct stream_input *si, struct sdp_media *media, struct sdp_ng_flags *flags) {
 	struct sdp_session *session = media->session;
 
-	if (!flags->trust_address) {
+	if (flags->media_address.s) {
-		if (is_addr_unspecified(&flags->parsed_address)) {
+		if (is_addr_unspecified(&flags->parsed_media_address)) {
-			if (__parse_address(&flags->parsed_address, NULL, &flags->received_from_family,
+			if (__parse_address(&flags->parsed_media_address, NULL, NULL,
+						&flags->media_address))
+				return -1;
+		}
+		si->stream.ip46 = flags->parsed_media_address;
+	}
+	else if (!flags->trust_address) {
+		if (is_addr_unspecified(&flags->parsed_received_from)) {
+			if (__parse_address(&flags->parsed_received_from, NULL, &flags->received_from_family,
 						&flags->received_from_address))
 				return -1;
 		}
-		si->stream.ip46 = flags->parsed_address;
+		si->stream.ip46 = flags->parsed_received_from;
 	}
 	else if (media->connection.parsed)
 		si->stream.ip46 = media->connection.address.parsed;

daemon/sdp.h

@@ -10,9 +10,11 @@ struct sdp_ng_flags {
 	int desired_family[2];
 	str received_from_family;
 	str received_from_address;
+	str media_address;
 	str transport_protocol_str;
 	enum transport_protocol transport_protocol;
-	struct in6_addr parsed_address;
+	struct in6_addr parsed_received_from;
+	struct in6_addr parsed_media_address;
 	enum stream_direction directions[2];
 	int asymmetric:1,
 	    symmetric:1,