[Serusers] ACK for non-2XX not record-routed
Emmanuel Hislen
hislen at alcatel-lucent.com
Thu Mar 22 00:50:25 CET 2007
Hi,
Agreed on the definition of Route Set, and I have no intention to modify
it in-dialog. I'm just worried by the fact that SER doesn't remove the
Route header from a request that was record-routed to it before sending
it to the next hop.
Here are the SIP messages to illustrate what I mean...
Setup:
UA A ------> SER ------> UA B
A is 192.168.1.236
SER is 192.168.1.77
B is 192.168.1.239
Here is the body of my simple ser.cfg for completeness:
**********
# ------------------------- request routing logic -------------------
# main routing logic
route{
# initial sanity checks -- messages with
# max_forwards==0, or excessively long requests
if (!mf_process_maxfwd_header("10")) {
sl_send_reply("483","Too Many Hops");
break;
};
if (msg:len >= 2048 ) {
sl_send_reply("513", "Message too big");
break;
};
xlog("L_DBG","===> Main Route logic...\n");
# we record-route all messages -- to make sure that
# subsequent messages will go through our proxy; that's
# particularly good if upstream and downstream entities
# use different transport protocol
if (!method=="REGISTER") {
xlog("L_DBG","===> Doing Record Route...\n");
record_route();
}
# subsequent messages withing a dialog should take the
# path determined by record-routing
if (loose_route()) {
xlog("L_DBG","===> Loose Routing logic...\n");
if ((method=="INVITE" || method=="REFER") &&
!has_totag()) {
sl_send_reply("403", "Forbidden");
break;
};
# mark routing logic in request
append_hf("P-hint: rr-enforced\r\n");
route(1);
break;
};
xlog("L_DBG","===> No Loose Routing involved...\n");
if (uri!=myself) {
xlog("L_DBG","===> NOT for ME...\n");
# mark routing logic in request
append_hf("P-hint: outbound\r\n");
route(1);
break;
};
if (uri==myself) {
xlog("L_DBG","===> for ME...[method <%rm> r-uri <%ru>]\n");
if (method=="ACK") {
route(1);
break;
} else if (method=="CANCEL") {
route(1);
break;
} else if (method=="INVITE" || method=="OPTIONS") {
route(3);
break;
} else if (method=="REGISTER") {
route(2);
break;
};
};
route(1);
}
route[1]
{
# send it out now; use stateful forwarding as it works reliably
# even for UDP2TCP
if (!t_relay()) {
sl_reply_error();
};
}
route[2]
{
# -----------------------------------------------------------------
# REGISTER Message Handler
# -----------------------------------------------------------------
# we don't expect ANY Register in this setup...
sl_send_reply("401", "Unauthorized");
break;
}
route[3]
{
# -----------------------------------------------------------------
# INVITE Message Handler
# -----------------------------------------------------------------
if (uri=~"^sip:[0-9]*@") { # PSTN
xlog("L_DBG","===> for PSTN...\n");
rewritehost("192.168.1.239"); # PSTN GW
avp_write("i:45", "inv_timeout");
route(1);
break;
} else {
xlog("L_DBG","===> NOT for PSTN...\n");
sl_send_reply("404", "User Not Found");
break;
}
}
**********
Now A calls B, call successful. This shows handling of an ACK to a 2XX
response.
(I'm removing SDP bodies to keep it short)
INVITE captured on A:
**********
181742.720: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
INVITE sip:85307 at 192.168.1.77:5060;user=phone SIP/2.0
To: <sip:85307 at 192.168.1.77:5060;user=phone>
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 INVITE
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115514019052115
Max-Forwards: 70
Allow: REFER,OPTIONS,BYE,CANCEL,ACK,INVITE
Supported: replaces
Contact: sip:192.168.1.236:5060
Content-Type: application/sdp
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
User-Agent: Foo-Bar
Content-Length: 205
**********
INVITE captured on B, has Record-Route from SER:
**********
181747.640: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
INVITE sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
Record-Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
To: <sip:85307 at 192.168.1.77:5060;user=phone>
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 INVITE
Via: SIP/2.0/UDP 192.168.1.77;branch=z9hG4bK4014.1299ece.0
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115514019052115
Max-Forwards: 16
Allow: REFER,OPTIONS,BYE,CANCEL,ACK,INVITE
Supported: replaces
Contact: sip:192.168.1.236:5060
Content-Type: application/sdp
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
User-Agent: Foo-Bar
Content-Length: 205
**********
--------------------
200 OK captured on B, has Record-Route:
**********
181749.780: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.1.77;branch=z9hG4bK4014.1299ece.0
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115514019052115
To: <sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 INVITE
Allow: REFER,OPTIONS,BYE,CANCEL,ACK,INVITE
Supported: replaces
Record-Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
Contact: <sip:85307 at 192.168.1.239:5060;user=phone>
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
Content-Type: application/sdp
Server: Foo-Bar
User-Agent: Foo-Bar
Content-Length: 204
**********
200 OK captured on A, has Record-Route:
**********
181744.870: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115514019052115
To: <sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 INVITE
Allow: REFER,OPTIONS,BYE,CANCEL,ACK,INVITE
Supported: replaces
Record-Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
Contact: <sip:85307 at 192.168.1.239:5060;user=phone>
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
Content-Type: application/sdp
Server: Foo-Bar
User-Agent: Foo-Bar
Content-Length: 204
**********
--------------------
ACK captured on A, has Route header:
**********
181744.880: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
ACK sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
To:
<sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 ACK
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115521825db60f5
Max-Forwards: 70
Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
User-Agent: Foo-Bar
Content-Length: 0
**********
ACK captured on B, has NO Route header, has Record-Route header:
**********
181749.800: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
ACK sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
Record-Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
To:
<sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817361 ACK
Via: SIP/2.0/UDP 192.168.1.77;branch=0
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK0115521825db60f5
Max-Forwards: 16
User-Agent: Foo-Bar
Content-Length: 0
P-hint: rr-enforced
**********
--------------------
--------------------
Now A re-INVITEs B, B rejects with 415, this shows handling of an ACK to
a non-2XX response.
re-INVITE captured on A, has Route header
**********
181775.580: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
INVITE sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
To:
<sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817362 INVITE
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK01155e16dc5473f3
Max-Forwards: 70
Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
Contact: sip:192.168.1.236:5060
Content-Type: application/sdp
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
User-Agent: Foo-Bar
Content-Length: 200
**********
re-INVITE captured on B, has NO Route header, has Record-Route header:
**********
181780.500: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
INVITE sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
Record-Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
To:
<sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817362 INVITE
Via: SIP/2.0/UDP 192.168.1.77;branch=z9hG4bK1014.fff3b3e5.0
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK01155e16dc5473f3
Max-Forwards: 16
Contact: sip:192.168.1.236:5060
Content-Type: application/sdp
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
User-Agent: Foo-Bar
Content-Length: 200
P-hint: rr-enforced
**********
--------------------
415 captured on B:
**********
181780.510: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
SIP/2.0 415 Unsupported Media Type
Via: SIP/2.0/UDP 192.168.1.77;branch=z9hG4bK1014.fff3b3e5.0
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK01155e16dc5473f3
To: <sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817362 INVITE
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
Server: Foo-Bar
User-Agent: Foo-Bar
Content-Length: 0
**********
415 captured on A:
**********
181775.600: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
SIP/2.0 415 Unsupported Media Type
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK01155e16dc5473f3
To: <sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817362 INVITE
Accept: application/sdp
Accept-Encoding:
Accept-Language: en
Server: Foo-Bar
User-Agent: Foo-Bar
Content-Length: 0
**********
--------------------
ACK captured on A, has same Route header as re-INVITE as per RFC3261
section 17.1.1.3:
**********
181775.600: SENDING to 192.168.1.77:5060
-----------------------------------------------------------------------------
ACK sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
To:
<sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
CSeq: 1817362 ACK
Via: SIP/2.0/UDP 192.168.1.236:5060;branch=z9hG4bK01155e16dc5473f3
Max-Forwards: 70
Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
User-Agent: Foo-Bar
Content-Length: 0
**********
ACK captured on B, still has Route Header !?!?!?!:
**********
181780.510: RECEIVED from 192.168.1.77:5060
-----------------------------------------------------------------------------
ACK sip:85307 at 192.168.1.239:5060;user=phone SIP/2.0
Via: SIP/2.0/UDP 192.168.1.77;branch=z9hG4bK1014.fff3b3e5.0
From: <sip:192.168.1.236:5060>;tag=b2ce30d4-2062aaaa-ec187086
Call-ID: f40a387b-3-2062aaaa at 192.168.1.236
To: <sip:85307 at 192.168.1.77:5060;user=phone>;tag=d85b805d-2062aaaa-ef187086
CSeq: 1817362 ACK
Route: <sip:192.168.1.77;ftag=b2ce30d4-2062aaaa-ec187086;lr>
User-Agent: Sip EXpress router(0.9.6 (i386/linux))
Content-Length: 0
**********
--------------------
I'm under the impression that SER handles the second ACK as if it was
the ACK for a non-2XX response to an initial INVITE (reasonably assuming
initial INVITES have usually no Route header). In other words SER
assumes that this ACK is not supposed to be Record Routed and therefore
does not remove the Route header. Something like that...
Let me know what you think.
Thanks,
Emmanuel.
Miklos Tirpak wrote:
> Hello,
>
> comments inline
>
> On 03/20/2007 09:52 AM, Greger V. Teigre wrote:
>> I'm not sure that I understand what you mean is wrong. It would be
>> easier to follow if you include the ACKs. And non-2xxs, what is
>> exactly the exchange? A full SIP trace would help...
>> g-)
>>
>> Emmanuel Hislen wrote:
>>> Hi,
>>>
>>>
>>> I've been using SER (0.9.6) as a Proxy doing Loose Routing between 2
>>> endpoints.
>>>
>>>
>>> If I place a call I can see how the ACK for the 2XX response to the
>>> INVITE is properly handled (Route header removed, Record-Route
>>> inserted).
>>>
>>> Now with the call still up, I do a re-INVITE which is rejected with a
>>> 415. The re-INVITE request sent by UAC contained a Route header, as
>>> it was an in-dialog request in a record-routed dialog. Now as per
>>> RFC3261 section 17.1.1.3:
>>>
>>> If the INVITE request whose response is being acknowledged had Route
>>> header fields, those header fields MUST appear in the ACK. This is
>>> to ensure that the ACK can be routed properly through any downstream
>>> stateless proxies.
>>>
>>>
>>> My UAC complied with the above, but SER seemed to choke on this:
>>>
>>> whereas the ACK for 2XX was successfully routed by SER in the
>>> original INVITE, the ACK for non-2XX (looking exactly the same: same
>>> Request URI, same IP destination, same Route header, ... different
>>> Via branch of course) is not handled properly: yes the ACK reaches
>>> UAS but it still has the Route header in it, and no Record-Route was
>>> added. And I'm guessing that if there had been another proxy in the
>>> Route Set on the way to the UAS it would have been bypassed.
>
> just to make some definition clear: Route set is the collection of Route
> headers, the Record-route headers are used only to learn the route-set.
> So the missing Record-route header does not have any impact of the ACK
> routing, however could have an impact of routing the BYE for example in
> your case. But the RFC says that the in-dialog requests do not modify
> the previously learned route-set:
>
> "12.2 Requests within a Dialog
> ...
> Requests within a dialog MAY contain Record-Route and Contact header
> fields. However, these requests do not cause the dialog's route set
> to be modified, although they may modify the remote target URI.
> Specifically, requests that are not target refresh requests do not
> modify the dialog's remote target URI, and requests that are target
> refresh requests do. For dialogs that have been established with an
> INVITE, the only target refresh request defined is re-INVITE (see
> Section 14). Other extensions may define different target refresh
> requests for dialogs established in other ways.
>
> Note that an ACK is NOT a target refresh request."
>
> But be careful with modifying the route-set in SER (not with
> record-routeing but with modifying the route headers directly)!
> More info: http://tracker.iptel.org/browse/SER-212?page=all
>
> Regards,
> Miklos
>
>>>
>>>
>>> SER traces for ACK-2XX:
>>>
>>>> 0(13574) ===> Loose Routing logic...
>>>> 0(13574) parse_headers: flags=-1
>>>> 0(13574) DEBUG: t_newtran: msg id=89 , global msg id=88 , T on
>>>> entrance=0xffffffff
>>>> 0(13574) parse_headers: flags=-1
>>>> 0(13574) parse_headers: flags=60
>>>> 0(13574) t_lookup_request: start searching: hash=41794, isACK=1
>>>> 0(13574) parse_headers: flags=28
>>>> 0(13574) DEBUG: t_lookup_request: e2e proxy ACK found
>>>> 0(13574) parse_headers: flags=4
>>>> 0(13574) DEBUG: totag for e2e ACK found: 0
>>>> 0(13574) SER: forwarding ACK statelessly
>>>
>>>
>>> SER traces for ACK-non-2XX:
>>>
>>>> 0(13574) ===> Loose Routing logic...
>>>> 0(13574) parse_headers: flags=-1
>>>> 0(13574) DEBUG: t_newtran: msg id=92 , global msg id=91 , T on
>>>> entrance=0xffffffff
>>>> 0(13574) parse_headers: flags=-1
>>>> 0(13574) parse_headers: flags=60
>>>> 0(13574) t_lookup_request: start searching: hash=41807, isACK=1
>>>> 0(13574) DEBUG: RFC3261 transaction matched, tid=007d7195499e33a1
>>>> 0(13574) DEBUG: t_lookup_request: transaction found (T=0xb616ae48)
>>>> 0(13574) DEBUG: cleanup_uac_timers: RETR/FR timers reset
>>>> 0(13574) DEBUG: add_to_tail_of_timer[2]: 0xb616ae90
>>>> 0(13574) DEBUG:destroy_avp_list: destroying list (nil)
>>>> 0(13574) receive_msg: cleaning up
>>>
>>>
>>> This doesn't seem right, am I missing something here?
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Emmanuel.
>>> _______________________________________________
>>> Serusers mailing list
>>> Serusers at lists.iptel.org
>>> http://lists.iptel.org/mailman/listinfo/serusers
>>>
>>>
>> _______________________________________________
>> Serusers mailing list
>> Serusers at lists.iptel.org
>> http://lists.iptel.org/mailman/listinfo/serusers
>
>
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