[OpenSER-Users] Snom number-guessing and OpenSER

Klaus Darilion klaus.mailinglists at pernau.at
Tue Oct 9 09:26:19 CEST 2007



Edoardo Serra schrieb:
> Tnx, comments inline
> 
> Klaus Darilion ha scritto:
>> Yes - the perl module sees the original received message. I dirty 
>> workaround would be to t_relay the message to openser again, and in 
>> the second iteration forward the request to perl and then drop it 
>> (without generating a second transaction).
> 
> Uhm...  it sounds dirty... I was thinking at implementing the SIP Server 
> which will handle PUBLISH messages completely in perl anf forwarding 
> from OpenSER to that server (without using perl module in openser)

That would work in any case.

But you could also extend openser to allow adding a body to the reply.

> Otherwise, is there a way to make openser relay stateless the 200 OK ?
> It could lookup("location") and forward to the user..

relaying of reply is done like relaying of the request. If you relay a 
request statefull, a transaction is created inside tm module. Every 
received reply is checked against transactions in tm module. If it 
matches a transaction the reply is forwarded stateful, if it does not 
match it is relayed stateless.

klaus

> 
> Tnx again
> 
> Edoardo
> 
> 
>>
>> regards
>> klaus
>>
>>>
>>> About the to-tag I'll have a look at Net::SIP if it has a way to 
>>> generate one.
>>>
>>> regards
>>>
>>> Edoardo
>>>
>>>
>>> Klaus Darilion ha scritto:
>>>> Some hints:
>>>>
>>>> A reply should have a to-tag.
>>>> Openser adds a Via header during forwarding (with a generated 
>>>> branch.id). This branch.id is also used for transaction matching.
>>>>
>>>> regards
>>>> klaus
>>>>
>>>>
>>>> Edoardo Serra schrieb:
>>>>> Hi all,
>>>>>     I'm trying to develop an extension to support SNOM's number 
>>>>> guessing feature (I don't know if it's somehow a standard but 
>>>>> description on how it works is here: 
>>>>> http://kb.snom.com/kb/index.php?View=entry&CategoryID=14&EntryID=14)
>>>>>
>>>>> As I have to do some 'complicated' db queries I was thinking to use 
>>>>> PERL module to handle number guessing request from the phone.
>>>>>
>>>>> I see there's no way (please correct me if I'm wrong) from OpenSER, 
>>>>> neither from OpenSER::Message, to send a stateless reply with a 
>>>>> customized body (SNOM says that possible number completion shoud be 
>>>>> included in the body of a 200 OK reply).
>>>>>
>>>>> For this reason I have to use Net::SIP to generate the reply packet 
>>>>> but I'm doing something wrong as OpenSER is not forwarding it back 
>>>>> to the client.
>>>>>
>>>>> Test client is a Snom 360 and is behind a NAT, OpenSER has a public IP
>>>>>
>>>>> Here is my routing logic in openser.cfg
>>>>>
>>>>> ------------------- BEGIN openser.cfg
>>>>> route{
>>>>>
>>>>>         if (!mf_process_maxfwd_header("10")) {
>>>>>                 sl_send_reply("483","Too Many Hops");
>>>>>                 exit;
>>>>>         };
>>>>>         if (msg:len >=  2048 ) {
>>>>>                 sl_send_reply("513", "Message too big");
>>>>>                 exit;
>>>>>         };
>>>>>
>>>>>         if (nat_uac_test("19")) {
>>>>>                 fix_nated_contact();
>>>>>                 force_rport();
>>>>>                 setbflag(6);
>>>>>         }
>>>>>
>>>>>
>>>>>         if (method=="PUBLISH") {
>>>>>                 if ($hdr(Event)=="number-guessing") {
>>>>>                         log("- Initial PUBLISH\n");
>>>>>                         t_newtran();
>>>>>                         t_on_reply("1");
>>>>>                         perl_exec("numberguessing");
>>>>>                         exit;
>>>>>                 }
>>>>>                 sl_send_reply("501", "Not implemented");
>>>>>                 exit;
>>>>>         }
>>>>>
>>>>>         if (method=="REGISTER") {
>>>>>                 if (nat_uac_test("19")) {
>>>>>                         fix_nated_contact();
>>>>>                         force_rport();
>>>>>                         setbflag(6);
>>>>>                 }
>>>>>                 save("location");
>>>>>                 exit;
>>>>>         };
>>>>>
>>>>>         exit;
>>>>> }
>>>>>
>>>>> route[1] {
>>>>>         log("--------------------- Stateful Reply\n");
>>>>>         if (!t_relay()) {
>>>>>                 sl_reply_error();
>>>>>         };
>>>>>         exit;
>>>>> }
>>>>> ------------------- END openser.cfg
>>>>>
>>>>> Here is my Simple Perl
>>>>>
>>>>>
>>>>> ------------------- BEGIN net-sip.pl
>>>>> use OpenSER qw ( log );
>>>>> use OpenSER::Constants;
>>>>> use Net::SIP;
>>>>>
>>>>> # Predefined body, not querying db yet
>>>>> my $body = '"Franky Chang" sip:101 at 192.168.0.1;user=phone
>>>>> "Steven Jones" sip:102 at 192.168.0.1;user=phone
>>>>> "Marie Sun" sip:103 at 192.168.0.1;user=phone
>>>>> ';
>>>>>
>>>>>
>>>>> sub numberguessing {
>>>>>         my $m = shift;
>>>>>         my $pkt = Net::SIP::Request->new( $m->getMessage() );
>>>>>         my $resp = $pkt->create_response(200, "OK");
>>>>>         $resp->set_body($body);
>>>>>         
>>>>> $resp->add_header('Content-Type','application/number-guessing');
>>>>>
>>>>>         my $leg = Net::SIP::Leg->new(
>>>>>             addr => '111.222.333.444', port => '5061');
>>>>>
>>>>>         $leg->deliver( $resp, '111.222.333.444:5060' );
>>>>>
>>>>>         # 111.222.333.444 is the IP of OpenSER
>>>>>         # I'm sending from port 5061 to port 5060
>>>>>
>>>>>         return 1;
>>>>> }
>>>>> ------------------- END net-sip.pl
>>>>>
>>>>> OpenSER in verbose debugging module says that it cannot find a 
>>>>> matching transaction for the 200 OK reply (probably because is 
>>>>> originated from port 5061 and it has never forwarded it to that 
>>>>> port ? )
>>>>>
>>>>> Here is OpenSER DEBUG log:
>>>>>
>>>>>  0(24828) SIP Reply  (status):
>>>>>  0(24828)  version: <SIP/2.0>
>>>>>  0(24828)  status:  <200>
>>>>>  0(24828)  reason:  <OK>
>>>>>  0(24828) parse_headers: flags=2
>>>>>  0(24828) get_hdr_field: cseq <cseq>: <1> <PUBLISH>
>>>>>  0(24828) DEBUG:parse_to:end of header reached, state=10
>>>>>  0(24828) DBUG:parse_to: display={"Edoardo"}, 
>>>>> ruri={sip:eserra at 111.222.333.444}
>>>>>  0(24828) DEBUG: get_hdr_field: <to> [43]; 
>>>>> uri=[sip:eserra at 111.222.333.444]
>>>>>  0(24828) DEBUG: to body ["Edoardo" <sip:eserra at 111.222.333.444>
>>>>> ]
>>>>>  0(24828) Found param type 232, <branch> = <z9hG4bK-m3j054b6d8q6>; 
>>>>> state=6
>>>>>  0(24828) Found param type 235, <rport> = <n/a>; state=17
>>>>>  0(24828) end of header reached, state=5
>>>>>  0(24828) parse_headers: Via found, flags=2
>>>>>  0(24828) parse_headers: this is the first via
>>>>>  0(24828) After parse_msg...
>>>>>  0(24828) DEBUG:forward_reply: found module tm, passing reply to it
>>>>>  0(24828) DEBUG: t_check: start=0xffffffff
>>>>>  0(24828) parse_headers: flags=22
>>>>>  0(24828) DEBUG: t_reply_matching: failure to match a transaction
>>>>>  0(24828) DEBUG: t_check: end=(nil)
>>>>>  0(24828) parse_headers: flags=4
>>>>>  0(24828) DEBUG: get_hdr_body : content_length=135
>>>>>  0(24828) found end of header
>>>>>  0(24828) ERROR:forward_reply: no 2nd via found in reply
>>>>>  0(24828) DEBUG:destroy_avp_list: destroying list (nil)
>>>>>  0(24828) receive_msg: cleaning up
>>>>>
>>>>> Here is also the tshark dump of the 2 packets (PUBLISH and its reply)
>>>>>
>>>>> Request-Line: PUBLISH sip:eserra at 213.92.23.108 SIP/2.0
>>>>> Message Header
>>>>>     Via: SIP/2.0/UDP 
>>>>> 192.168.254.151:2051;branch=z9hG4bK-ma9r5n0t4jfq;rport
>>>>>     From: "Edoardo" <sip:eserra at 111.222.333.444>;tag=39wlni6ex1
>>>>>     To: "Edoardo" <sip:eserra at 111.222.333.444>
>>>>>     Call-ID: 3c27c039249b-jml9w7t9sywx
>>>>>     CSeq: 1 PUBLISH
>>>>>     Max-Forwards: 70
>>>>>     Event: number-guessing
>>>>>     Content-Type: application/text
>>>>>     Content-Length: 25
>>>>> Message body
>>>>>     Number: 10\r\n
>>>>>     Max-Hits: 3\r\n
>>>>>
>>>>>
>>>>> Status-Line: SIP/2.0 200 OK
>>>>> Message Header
>>>>>     call-id: 3c27c0daa600-emnlo1xcejtn
>>>>>     cseq: 1 PUBLISH
>>>>>     from: "Edoardo" <sip:eserra at 111.222.333.444>;tag=6c1y8pp3fb
>>>>>     to: "Edoardo" <sip:eserra at 111.222.333.444>
>>>>>     via: SIP/2.0/UDP 
>>>>> 192.168.254.151:2051;branch=z9hG4bK-623oddiyzg56;rport
>>>>>     content-type: application/number-guessing
>>>>>     Content-Length: 135
>>>>> Message body
>>>>>     "Franky Chang" sip:101 at 192.168.0.1;user=phone\n
>>>>>     "Steven Jones" sip:102 at 192.168.0.1;user=phone\n
>>>>>     "Marie Sun" sip:103 at 192.168.0.1;user=phone\n
>>>>>
>>>>> Hope this info is enough for a debug :)
>>>>>
>>>>> Tnx in advance
>>>>>
>>>>> Regards
>>>>>
>>>>> Edoardo Serra
>>>>> EXSORSA LLC
>>>>>
>>>>>
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>>>>
>>>
>>>
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>>
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