Support overlapping SIP&HTTP headers in WS HTTP initial requests

[vladpaiu]

Summary
Support overlapping SIP&HTTP headers in WS HTTP initial requests

Details
HTTP proxies can sometimes add VIA header to the HTTP request switching from WS to SIP. Since we are using the SIP parser to go over a HTTP request, that will fail with :

Oct 30 13:08:01 vlad-x1carbon ./opensips[31764]: ERROR:core:parse_via: bad char on state 100
Oct 30 13:08:01 vlad-x1carbon ./opensips[31764]: ERROR:core:parse_via: <HTTP/1.1 test@localhost#015#012#015#012>
Oct 30 13:08:01 vlad-x1carbon ./opensips[31764]: ERROR:core:parse_via: via parse failed
Oct 30 13:08:01 vlad-x1carbon ./opensips[31764]: ERROR:core:get_hdr_field: bad via
Oct 30 13:08:01 vlad-x1carbon ./opensips[31764]: INFO:core:parse_headers: bad header field

Steps to reproduce :

• have OpenSIPS running with a ws listener
• run curl http://127.0.0.1:5060 -H "Host: 127.0.0.1" -H "Origin: 127.0.0.1" -H "Upgrade: websocket" -H "Connection: Upgrade" -H "Sec-Websocket-Protocol: sip" -H "Sec-Websocket-Key: ONdMbIDTYRA5rFwlmqhK5Q==" -H "Sec-Websocket-Version: 13" -H "Via: HTTP/1.1 test@localhost"

Solution
Introduce a flag in parser to decide if we want to internally implicit parse well-known SIP headers ( current list is VIA / TO / Content-Length / CSEQ ) & add a define to always parse ( aka. assume SIP context ). From WS HTTP contexts, do not parse those.

Compatibility
Should not affect anything

Closing issues
Opening PR to make sure we are all in agreement with the solution here.

[razvancrainea]

Looks good to me :)