Thank you Mark for the tips.

Is the code below close to what you were thinking?

I ran some initial tests and it seems to be working.  I can override the 
default Referred-By value by setting the SIPREFERREDBYHDR variable.

static void transfer_refer(struct ast_sip_session *session, const char *target)
{
        pjsip_evsub *sub;
        enum ast_control_transfer message = AST_TRANSFER_SUCCESS;
        pj_str_t tmp;
        pjsip_tx_data *packet;

        if (pjsip_xfer_create_uac(session->inv_session->dlg, NULL, &sub) != 
PJ_SUCCESS) {
                message = AST_TRANSFER_FAILED;
                ast_queue_control_data(session->channel, AST_CONTROL_TRANSFER, 
&message, sizeof(message));

                return;
        }

        if (pjsip_xfer_initiate(sub, pj_cstr(&tmp, target), &packet) != 
PJ_SUCCESS) {
                message = AST_TRANSFER_FAILED;
                ast_queue_control_data(session->channel, AST_CONTROL_TRANSFER, 
&message, sizeof(message));
                pjsip_evsub_terminate(sub, PJ_FALSE);

                return;
        }

        /**** Start of changes ****/
        pjsip_hdr *hdr;
        const pj_str_t str_ref_by = { "Referred-By", 11 };

        const char *ref_by_val = pbx_builtin_getvar_helper(session->channel, 
"SIPREFERREDBYHDR");
        pj_str_t tmp2;
        if (ref_by_val && !ast_strlen_zero(ref_by_val))
          {
            hdr = (pjsip_hdr*)pjsip_generic_string_hdr_create(packet->pool, 
&str_ref_by, pj_cstr(&tmp2, ref_by_val));
          }
        else
          {
            /* Add Referred-By header */
            hdr = (pjsip_hdr*)pjsip_generic_string_hdr_create(packet->pool, 
&str_ref_by, &session->inv_session->dlg->local.info_str);
          }
        pjsip_msg_add_hdr(packet->msg, hdr);
        /**** End of changes ****/

        pjsip_xfer_send_request(sub, packet);
        ast_queue_control_data(session->channel, AST_CONTROL_TRANSFER, 
&message, sizeof(message));
}

From: asterisk-dev-boun...@lists.digium.com 
[mailto:asterisk-dev-boun...@lists.digium.com] On Behalf Of Mark Michelson
Sent: Tuesday, August 25, 2015 1:17 PM
To: Asterisk Developers Mailing List
Subject: Re: [asterisk-dev] Transfer cmd (PJSIP not sending Referred-By but 
chan_sip does)

That code gets you about 95% of the way there.

The biggest difference would be that the pjsip_msg_add_hdr() call may need to 
be broken up based on whether the SIPREFERREDBYHDR channel variable is set or 
not. To determine that, you can use the pbx_builtin_getvar_helper() function 
call declared in include/asterisk/pbx.h to retrieve the variable value, and the 
ast_strlen_zero() function to determine if the channel variable value is 
zero-length or not.

Other than that, you should be able to omit the call to 
pjsua_process_msg_data() since Asterisk doesn't use pjsua.

On 08/25/2015 12:35 PM, Dan Cropp wrote:

In doing a little research, it seems the Referred-By header could be added 
after the pjsip_xfer_initiate.

This is the approach PJSIP did for some code as far back as PJSIP 1.6.



    /*

     * Create REFER request.

     */

    status = pjsip_xfer_initiate(sub, dest, &tdata);

    if (status != PJ_SUCCESS) {

                pjsua_perror(THIS_FILE, "Unable to create REFER request", 
status);

                pjsip_dlg_dec_lock(dlg);

                return status;

    }



    /* Add Referred-By header */

    gs_hdr = pjsip_generic_string_hdr_create(tdata->pool, &str_ref_by,

                                                                                
     &dlg->local.info_str);

    pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr*)gs_hdr);





    /* Add additional headers etc */

    pjsua_process_msg_data( tdata, msg_data);



    /* Send. */

    status = pjsip_xfer_send_request(sub, tdata);

    if (status != PJ_SUCCESS) {

                pjsua_perror(THIS_FILE, "Unable to send REFER request", status);

                pjsip_dlg_dec_lock(dlg);

                return status;

    }



Could anyone provider some insight into how difficult this might be for me to 
add and submit for approval?  Depending on the answer, my manager may be 
willing to let me work on this.

I've developed in C/C++ for over 25 years so I'm plenty familiar with the 
language.

I'm less familiar with the syntax and coding standards of Asterisk.  I know the 
group is very good at letting people know about their mistakes and how to fix 
them.



Have a great day!
Dan

From: 
asterisk-dev-boun...@lists.digium.com<mailto:asterisk-dev-boun...@lists.digium.com>
 [mailto:asterisk-dev-boun...@lists.digium.com] On Behalf Of Dan Cropp
Sent: Tuesday, August 25, 2015 10:50 AM
To: Asterisk Developers Mailing List
Subject: Re: [asterisk-dev] Transfer cmd (PJSIP not sending Referred-By but 
chan_sip does)

Thank you Mark

From: 
asterisk-dev-boun...@lists.digium.com<mailto:asterisk-dev-boun...@lists.digium.com>
 [mailto:asterisk-dev-boun...@lists.digium.com] On Behalf Of Mark Michelson
Sent: Tuesday, August 25, 2015 10:30 AM
To: Asterisk Developers Mailing List
Subject: Re: [asterisk-dev] Transfer cmd (PJSIP not sending Referred-By but 
chan_sip does)

The answer to this is actually pretty simple: adding Referred-By in outgoing 
SIP REFERs is simply not implemented in chan_pjsip's chan_pjsip_transfer() 
function.

As far as the syntax required for the Transfer() application, that's probably a 
case where that needs to be clarified in documentation. There are lots of 
places in PJSIP configuration where we require full SIP URIs rather than just 
IP addresses or bare URIs (user@domain).

On 08/25/2015 10:00 AM, Dan Cropp wrote:
I asked the question on asterisk-users but did not receive a response, so I am 
sending the question here.

I am running Asterisk 13.5.0.

A call comes in, Asterisk answers it.  After some actions, the call needs to be 
Transferred (SIP REFER) to another number.  The other switch is responsible for 
accepting the Transfer and tromboning the lines internally.  It will also send 
a BYE so Asterisk no longer has the call.

The behavior works when I have the endpoint configured at chan_sip.  It does 
not work when the endpoint is configured as PJSIP.  I worked with the other 
switch vendor and he determined chan_sip includes the Referred-By header.  
PJSIP does not include the Referred-By header.  The other switch requires the 
Referred-By header to be present.

I tried setting the channel's SIPREFERREDBYHDR variable before the Transfer 
command and that still did not force the Referred-By header to be part of the 
REFER packet.
I tried the PJSIP_HEADER add and it still did not add the Referred-By header to 
the REFER packet.

Is there a PJSIP setting to force the Referred-By to be part of the REFER 
packet?

chan_sip (succeeds)
19:27:32.512123 IP (tos 0x0, ttl 64, id 11492, offset 0, flags [none], proto 
UDP (17), length 630)
    192.168.xxx.xxx.sip > 192.168.yyy.yyy.sip: SIP, length: 602
        REFER sip:3...@192.168.yyy.yyy:5060 SIP/2.0
        Via: SIP/2.0/UDP 192.168.xxx.xxx:5060;branch=z9hG4bK58f4bd1d
        Max-Forwards: 70
        From: <sip:3...@192.168.xxx.xxx>;tag=as44000cf4
        To: <sip:3...@192.168.yyy.yyy>;tag=7Iy0JkwDC
        Contact: <sip:3...@192.168.xxx.xxx:5060>
        Call-ID: 
jdeuqpak-00...@192.168.yyy.yyy<mailto:jdeuqpak-00...@192.168.yyy.yyy>
        CSeq: 102 REFER
        User-Agent: Asterisk PBX 13.5.0
        Date: Thu, 20 Aug 2015 19:27:32 GMT
        Refer-To: <sip:3...@192.168.yyy.yyy>
        Referred-By: <sip:3...@192.168.xxx.xxx:5060>
        Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, 
INFO, PUBLISH, MESSAGE
        Supported: replaces, timer
        Content-Length: 0

Pjsip
18:46:58.386372 IP (tos 0x0, ttl 64, id 38690, offset 0, flags [DF], proto UDP 
(17), length 654)
    192.168.xxx.xxx.sip > 192.168.yyy.yyy.sip: SIP, length: 626
        REFER sip:3...@192.168.yyy.yyy:5060 SIP/2.0
        Via: SIP/2.0/UDP 
192.168.xxx.xxx:5060;rport;branch=z9hG4bKPjec41c3b9-d734-482d-82c1-2a6f8d9452a3
        From: 
<sip:3...@192.168.xxx.xxx>;tag=3c10f423-e468-42ea-87a1-658ae106581c
        To: <sip:3...@192.168.yyy.yyy>;tag=WITKDakt
        Contact: <sip:192.168.xxx.xxx:5060>
        Call-ID: 
s6wk6l6q-00...@192.168.yyy.yyy<mailto:s6wk6l6q-00...@192.168.yyy.yyy>
        CSeq: 981 REFER
        Event: refer
        Expires: 600
        Supported: 100rel, timer, replaces, norefersub
        Accept: message/sipfrag;version=2.0
        Allow-Events: message-summary, presence, dialog, refer
        Refer-To: <sip:3...@192.168.yyy.yyy>
        Max-Forwards: 70
        User-Agent: Asterisk PBX 13.5.0
        Content-Length:  0



One other slight oddity.
To get chan_sip to Transfer
3...@192.168.yyy.yyy<mailto:3...@192.168.yyy.yyy>

To get PJSIP to Transfer with the correct Refer-To header, I had to include the 
<> and sip:
<sip:3...@192.168.yyy.yyy>


Have a great day!
Dan





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