5 Oct
2011
5 Oct
'11
5:45 p.m.
On Wednesday 05 October 2011, Hugh Waite wrote:
We have discovered the cause of the problem I
described, but we still do
not understand why.
Hello Hugh,
After a SIP request arrives we make some changes to
the
P-Preferred/Asserted-Identity headers after our own validation. To allow
these changes to be visible later (e.g. in $hdr() variables) we call
msg_apply_changes(). It seems that calling this function causes the
transaction matching to fail for subsequent messages (e.g. ACK and
CANCEL).
Non-Working Example:
append_hf("My-Header: yes\r\n");
msg_apply_changes();
if (is_present_hf("My-Header"))
{
# log("Found my header") - this gets run
}
t_relay();
If the destination responds with a 4XX then the ACK does not match and the
4XX is retransmitted. If a CANCEL is sent, then it does not match and is
not relayed.
Working Example:
append_hf("My-Header: yes\r\n");
if (is_present_hf("My-Header"))
{
# log("Found my header") - this does not get run
}
t_relay();
In this example, the header is not found, but the transaction matching
works properly
Is this something to do with re-parsing the request? And is it a bug to be
investigated?
It is documentated that msg_apply_changes() is a bit risky function.. But i'm
not aware of this side effects so far. It could be a design limitation (then
it needs to be properly documented) or just a bug. Can you please open a bug
report on the tracker about this?
Best regards,
Henning