[kamailio/kamailio] Topos does not unmask Refer-To header in in-dialog Refer request (Issue #4301)
xadhoom created an issue (kamailio/kamailio#4301)
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### Description
When topos receives an in-dialog REFER, it correctly unmask everywhing as expected, but not the Refer-To header, which breaks transfers.
### Troubleshooting
#### SIP Traffic
<!-- If the issue is exposed by processing specific SIP messages, grab them with ngrep or save in a pcap file, then add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->
For example, this is the refer from a client:
``` REFER sip:atpsh-685d3cd2-69-2@172.23.42.1;transport=tcp SIP/2.0 Via: SIP/2.0/TCP 172.23.42.1:23045;rport;branch=z9hG4bKlaklhcax Max-Forwards: 70 To: sip:3338063766@example.voismart.com;tag=Brcm20gBS5eZe From: "Joe" sip:1001@example.voismart.com;tag=xbdlk Call-ID: kpjiixyvombnlkw@fedora.fritz.box CSeq: 340 REFER Contact: sip:1001@172.23.42.1:23045;transport=tcp Refer-To: sip:atpsh-685d3cd2-69-4@172.23.42.1;transport=tcp?Replaces=lmhzfrkbucirwbc%40fedora.fritz.box%3bto-tag%3dXDQD403r30jeS%3bfrom-tag%3dtwbnd Referred-By: "Joe" sip:1001@example.voismart.com User-Agent: Twinkle/1.10.3 Content-Length: 0
```
And this is what exits from topos proxy: ``` REFER sip:3338063766@172.23.42.211:5060;transport=udp SIP/2.0 Via: SIP/2.0/TCP 172.23.42.250;branch=z9hG4bK89f.32493a6f0ee894aad0bf66f581e5053a.0;i=3 Max-Forwards: 69 To: sip:3338063766@example.voismart.com;tag=Brcm20gBS5eZe From: "Joe" sip:1001@example.voismart.com;tag=xbdlk Call-ID: kpjiixyvombnlkw@fedora.fritz.box CSeq: 340 REFER Refer-To: sip:atpsh-685d3cd2-69-4@172.23.42.1;transport=tcp?Replaces=lmhzfrkbucirwbc%40fedora.fritz.box%3bto-tag%3dXDQD403r30jeS%3bfrom-tag%3dtwbnd Referred-By: "Joe" sip:1001@example.voismart.com User-Agent: Twinkle/1.10.3 Content-Length: 0 Route: sip:172.23.42.3;transport=tcp;r2=on;lr=on;ftag=xbdlk;did=c84.2b02 Route: sip:172.23.42.3;r2=on;lr=on;ftag=xbdlk;did=c84.2b02 Contact: sip:btpsh-685d3cd2-69-2@172.23.42.250 ```
### Possible Solutions
Will try to find a solution, I see that in `tps_msg.c` `parse_refer_to.h` is included so perhaps there was some idea about it, but since I'm not an expert in kamailio internals may need some time.
### Additional Information v6.0.x and master
xadhoom left a comment (kamailio/kamailio#4301)
I see that topoh actually does that, so maybe is just needed to port that part. Will try.
miconda left a comment (kamailio/kamailio#4301)
Can you provide a pcap file for such case, from the beginning of first call involved, till the end of all calls?
xadhoom left a comment (kamailio/kamailio#4301)
Attached.
The network scheme is the following:
client -> edge proxy (with topos) -> "worker" proxy -> freeswitch
Even the b2bua says "202 Accepted", it fails since the refer-to header points to nowhere (another call is placed by FS which then fails).
[topos_refer_to.pcap.gz](https://github.com/user-attachments/files/21032411/topos_refer_to.pcap.gz)
xadhoom left a comment (kamailio/kamailio#4301)
In the end, since to properly un-topos it needs some step and my C knowledge is not that good, I was able to do it from the script.
For example: ``` route[MANGLE_REFER] { if (!has_totag()) return;
if (!is_method("REFER")) return;
if ($rt ne "") { $var(hdrs) = $(rt{uri.headers}); $var(hdrs) = $(var(hdrs){s.urldecode.param}); $var(uri-user) = $(rt{uri.user});
if ($(var(hdrs){param.in,Replaces,&}) == 0) { xlog("L_DBG", "Detected blind transfer to $rt skipping mangling \n"); return; }
$var(replaces) = $(var(hdrs){param.value,Replaces,&}); $var(from-tag) = $(var(replaces){param.value,from-tag}); $var(to-tag) = $(var(replaces){param.value,to-tag}); $var(call-id) = $(var(replaces){s.select,0,;});
xlog("L_DBG", "Got Refer-To: $rt \n"); xlog("L_DBG", "Got Refer-To headers $var(hdrs) \n"); xlog("L_DBG", "Got Refer-To replaces $var(replaces) \n"); xlog("L_DBG", "Got Refer-To uri user $var(uri-user) \n"); xlog("L_DBG", "Got Refer-To call-id $var(call-id) \n"); xlog("L_DBG", "Got Refer-To from tag $var(from-tag) \n"); xlog("L_DBG", "Got Refer-To to tag $var(to-tag) \n");
$var(query) = $_s(SELECT b_contact FROM topos_d WHERE a_callid = '$var(call-id)' AND a_uuid = '$var(uri-user)'); sql_xquery("conn1", "$var(query)", "topos_rset"); switch ($rc) { case 1: xlog("L_DBG", "B-Contact for refer is $xavp(topos_rset=>b_contact)\n"); break; case -1: xlog("L_ERR", "Error in topos lookup of refer target contact \n"); return; break; default: xlog("L_ERR", "Unhandled result $rc in lookup of refer target contact \n"); return; }
remove_hf("Refer-To");
$var(params) = $_s($var(call-id);to-tag=$var(to-tag);from-tag=$var(from-tag)); $var(params_enc) = $(var(params){s.urlencode.param}); $var(new_replaces) = $_s(Replaces=$var(params_enc));
xlog("L_DBG", "Replacing refer target contact with $var(new_replaces) \n");
append_hf("Refer-To: <$xavp(topos_rset=>b_contact)?$var(new_replaces)>\r\n"); } else { xlog("L_ERR", "Uh? Refer without Refer-To \n");
return; } } ```
and then (for example) in call it from the route WITHIN_DIALOG just before the loose_route relay.
This won't work if call-id is masked, but in my setup I'm not using call-id masking.
-
Daniel-Constantin Mierla -
Matteo