The http_client module - todo
======================
- clean up			
  Clean up curl connections, pconn and conn objects at exit time. Just to be nice.

- connection parameters
	read=line/all		- Implemented in API, but not in parameter
	tlsverify=on/off
	failover=httpcon	Other httpcon that can be used for failover in case of 5xx response or timeout
				not implemented


- Add XAVP parameter setting before running curl_connect

- save fingerprint of cert for trust-on-first-use procedure

- connection and last status for httpcon-object, needs to be object in process memory
	- done.
	- test what happens if we allocate curlcon objects in shared memory and use locks
		Code implemeneted in git master branch for testing
	- if 5xx response or timeout set flag
	- function in dialplan - httpcon_exists(object)
	- pv $curlstatus(object) ??
	- this is per process !!!

- Figure out a way to communicate back the content-type of the response. Another pvar arg?
	- This is per process!

- Reload of configuration file from RPC interface
	- Need to close connections (if we have open ones according to idea above)
	- Need to rebuild core httpcon objects and "mirrors" in pkg memory
		- Should we just abandon old pkg objects and let them rot away
		  in space and time?
	- Can we add a lock to the connection list while switching if we load a new
          list, then switch active list and then free the old ones

- rpc
	curl.listcon	list all connection objects with properties
			-- Done, but not documented
	curl.modcon     modify connection object
			url
			username
			password
			scheme
			timeout
			read
			tlsverify
			failover
	curl.addcon	add connection object
	curl.rmcon	remove connection object

	Maybe RPC commands to change default settings for proxys

- Async - event_route when done
	(with and without suspending transaction)
	Need background task process to run curl request
	event_route[curl:connectioncomplete]
	$curlcon == connection
	$curl == URL
	$curlres == result


- Option to try connections at module load with CURLOPT_CONNECT_ONLY
  just to make sure URLs resolve correctly in DNS and ports are open

- Make it possible to define modparams in any order. For now, httpcon definitions only use default
  values from modparam's defined on lines above in the config file. (issue #541)

- Option to configure DNS resolvers for CURL to use


Development API
---------------
- xcap_client needs to add headers:
  char* hdr_name= NULL;

                memset(buf, 0, 128* sizeof(char));
                match_header= buf;

                hdr_name= (match_type==IF_MATCH)?"If-Match":"If-None-Match";

                len=sprintf(match_header, "%s: %s\n", hdr_name, match_etag);

                match_header[len]= '\0';
  https://curl.haxx.se/libcurl/c/CURLOPT_HEADERFUNCTION.html

- It also does get a headers from the reply, which needs a callback
- auth_identify sets the CURLOPT_CAINFO option
  https://curl.haxx.se/libcurl/c/CURLOPT_CAINFO.html
  This can be set in the httpconf object

- Document that some options like useragent doesn't work in the
  old http_query function


Issues in the bug tracker
-------------------------

- none


Solved issues
--------------
- https://github.com/kamailio/kamailio/issues/541 - closed
  Support setting proxy 
  Comitted another patch, which included default and per-connection proxy
  settings. 
- https://github.com/kamailio/kamailio/issues/515 - closed
  Support various auth methods - digest, basic etc
  Comitted another patch, which included default and per-connection settings
- https://github.com/kamailio/kamailio/pull/481 - closed
  Support TLS client certificates
- https://github.com/kamailio/kamailio/pull/435 - closed
  Pull request that fixed a lot of issues.
- https://github.com/kamailio/kamailio/issues/542  - closed
  Support connection reuse. Needs private memory structures to track connections