[asterisk-bugs] [JIRA] (ASTERISK-25469) chan_sip enabled unnegotiated session-timers after reinvite if minse is non-default.

[Walter Doekes (JIRA)]

Walter Doekes created ASTERISK-25469:
----------------------------------------

             Summary: chan_sip enabled unnegotiated session-timers after reinvite if minse is non-default.
                 Key: ASTERISK-25469
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-25469
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_sip/Interoperability
    Affects Versions: 11.20.0
            Reporter: Walter Doekes


If I give Alice these two sip.conf settings:
{noformat}
session-minse=91
session-expires=92
{noformat}

If Alice then gets called, and Alice initiates one or more reINVITEs, Asterisk enables session timers. In the 200 to the reINVITEs, Asterisk will add this:
{noformat}
Session-Expires: 92;refresher=uac
{noformat}
and then it expects reinvites from Alice.

It seems plausible that the cause should be found here:
{code}
        /* Add Session-Timers related headers */
        if (st_get_mode(p, 0) == SESSION_TIMER_MODE_ORIGINATE
                || (st_get_mode(p, 0) == SESSION_TIMER_MODE_ACCEPT
                        && st_get_se(p, FALSE) != DEFAULT_MIN_SE)) {
                char i2astr[10];

                if (!p->stimer->st_interval) {
                        p->stimer->st_interval = st_get_se(p, TRUE);
                }

                p->stimer->st_active = TRUE;
                if (st_get_mode(p, 0) == SESSION_TIMER_MODE_ORIGINATE) {
                        snprintf(i2astr, sizeof(i2astr), "%d", p->stimer->st_interval);
                        add_header(&req, "Session-Expires", i2astr);
                }

                snprintf(i2astr, sizeof(i2astr), "%d", st_get_se(p, FALSE));
                add_header(&req, "Min-SE", i2astr);
        }
{code}

Default mode is SESSION_TIMER_MODE_ACCEPT and the get_mins_se is non-standard, so Asterisk enables session timers.

When the reINVITE is seen, we get here:
{noformat}
        /* If this is an invite, add Session-Timers related headers if the feature is active for this session */
        if (p->method == SIP_INVITE && p->stimer && p->stimer->st_active == TRUE) {
                char se_hdr[256];
                snprintf(se_hdr, sizeof(se_hdr), "%d;refresher=%s", p->stimer->st_interval,
                        p->stimer->st_ref == SESSION_TIMER_REFRESHER_US ? "uas" : "uac");
                add_header(resp, "Session-Expires", se_hdr);
...
{noformat}

The headers get added, and somewhere along the road, the timers get activated too.

See attached SIPp scenario that trips on the bug.



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