23 Oct
2008
23 Oct
'08
4:46 a.m.
We have the following scenario:
Nated UAC receives INVITE
Call is established, we proxy audio
Far end sends Re-INVITE (to inform UAC to use UDPTL)
We don't proxy audio so call fails
So I need to understand how the appropriate way to force us to proxy the
audio when the far end of a reinvite is NATed.
Relevant parts of openser.cfg (OpenSER 1.3.2): We're using mediaproxy.
modparam("usrloc", "nat_bflag", 6)
route {
# -----------------------------------------------------------------
# Record Route Section
# -----------------------------------------------------------------
#If it's an INVITE & client is NATed,
if (method=="INVITE" && client_nat_test("3")) {
#Record-route and specify the record-route header explicitly
record_route_preset("64.38.1.1:5060;nat=yes"); # insert IP
address
#xlog("invite and nated so record_route_preset");
#If not Nated and not REGISTER then normal record-route
} else if (method!="REGISTER") {
record_route();
xlog("not register and not nated so record_route");
};
#if (method!="REGISTER") {
# record_route();
#};
# -----------------------------------------------------------------
# Loose Route Section
# -----------------------------------------------------------------
if (loose_route()) {
#Ensure we are dealing with a re-INVITE. Only connected
calls have tag=
#entry in the To header. So if it's loose routed and doesn't
have totag
#and it's an invite or reply then something's wrong
xlog("loose_route");
if ((method=="INVITE" || method=="REFER") &&
!has_totag())
{
sl_send_reply("403", "Forbidden");
xlog("403 in lr");
return;
};
if (method=="INVITE") {
if (!allow_trusted()) {
xlog("!allow_ trusted for r-uri <$ru>");
if (!proxy_authorize("","subscriber"))
{
proxy_challenge("domain.com","1");
return;
} else if (!check_from()) {
sl_send_reply("403", "Use
From=ID");
return;
};
consume_credentials();
};
#check client is nated or that we've already
identified it's nated
if (client_nat_test("3") ||
search("^Route:.*;nat=yes")) {
setbflag(6);
xlog("Recipient is nated so setbflag 6 and
use mediaproxy: r-uri <$ru>");
use_media_proxy();
};
};
route(1);
return;
};
}
route[1] {
# -----------------------------------------------------------------
# Default Message Handler
# -----------------------------------------------------------------
#Call reply_route(1) to intercept response messages heading to the
client
t_on_reply("1");
#Try to relay the message to its destination
if (!t_relay()) {
#If it can't and it's an INVITE or ACK end the media
proxying
log(1,"route[1] !t_relay");
if (method=="INVITE" || method=="ACK") {
end_media_session();
};
sl_reply_error();
} else {
log(1,"route[1] t_relay");
};
}
onreply_route[1]
#Handles message that are returned to the sender i.e. response to caller's
original request
{
xlog("hit onreply_route(1). rs $rs si $si rm $rm ru $ru tu $tu fu
$fu rr $rr");
if (isbflagset(6)) {
xlog("flag(6) is set for $fu . We're currently in
onreply_route(1)");
};
if (isbflagset(7)) {
xlog("flag(7) is set for $fu . We're currently in
onreply_route(1)");
};
if (status=~"(180)|(183)|2[0-9][0-9]") {
xlog("status matches for $fu . We're currently in
onreply_route(1)");
};
if ((isbflagset(6) || isbflagset(7)) &&
(status=~"(180)|(183)|2[0-9][0-9]")) {
#Check the SDP payload length. Assume if we have something
we can call mediaproxy
if (!search("^Content-Length:[ ]*0")) {
log(1,"using media proxy in onreply_route(1)");
use_media_proxy();
};
};
if (client_nat_test("1")) {
fix_nated_contact();
};
}
The re-invite looks like this:
INVITE sip:6422334455@58.28.1.1:5061 SIP/2.0
Via: SIP/2.0/UDP 202.180.1.1:5060;branch=z9hG4bK251fed3b;rport
Route: <sip:147.202.1.1;lr=on;ftag=as45a8ade4>
From: "user" <sip:022998877@202.180.1.1>;tag=as45a8ade4
To: <sip:022334455@147.202.1.1>;tag=4c813866c894f124i1
Contact: <sip:022998877@202.180.1.1>
Call-ID: 0818dfa10f1da0f25daa4759332d3c55(a)202.180.1.1
CSeq: 103 INVITE
User-Agent: UAS
Max-Forwards: 70
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY
Supported: replaces
Content-Type: application/sdp
Content-Length: 349
v=0
o=root 5466 5467 IN IP4 202.180.1.1
s=session
c=IN IP4 202.180.1.1
t=0 0
m=image 4724 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:9600
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:72
a=T38FaxUdpEC:t38UDPRedundancy
Our OK looks like this:
SIP/2.0 200 OK
To: <sip:022334455@147.202.1.1>;tag=4c813866c894f124i1
From: "user" <sip:022998877@202.180.1.1>;tag=as45a8ade4
Call-ID: 0818dfa10f1da0f25daa4759332d3c55(a)202.180.1.1
CSeq: 103 INVITE
Via: SIP/2.0/UDP 202.180.1.1:5060;branch=z9hG4bK251fed3b;rport=5060
Record-Route: <sip:147.202.1.1;lr=on;ftag=as45a8ade4>
Contact: 6422334455 <sip:6422334455@58.28.1.1:5061>
Server: Linksys/SPA2102-5.1.9
Content-Length: 265
Content-Type: application/sdp
v=0
o=- 69685 69685 IN IP4 192.168.1.113
s=-
c=IN IP4 192.168.1.113
t=0 0
m=image 16386 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:200
a=T38FaxMaxDatagram:200
a=T38FaxUdpEC:t38UDPRedundancy
Unfortunately this code doesn't result in the c record of the OK being
updated to the server IP (it is still the private IP of the UAC). In the
loose route section, the re-invite doesn't pass (client_nat_test("3") ||
search("^Route:.*;nat=yes")) so we don't use mediaproxy. In the on-reply
route bflag(6) is not set. I don't understand why bflag(6) is not set since
the r-uri is to a registered user that has bflag(6) set (at least that's how
I understand it).
Could anyone point me in the right direction?
Thanks
Cameron