Avoid chunking in the post redirect case

[duke8253]

After fixing #8265 we started seeing some crashes happening, this fixes the crash.

[shinrich]

The problem is we were marking that the post body should be chunked. But in the post redirect case, the data is being replayed from a static buffer. There is no real VC to be doing the chunked calculation against. So p->do_chunking is not set. So chunked_buffer_start is not set. So the call to clone that nullptr causes the crash.

[ 00 ] traffic_server      HttpTunnel::producer_run(HttpTunnelProducer*)                ( P_IOBuffer.h:753 )
[ 01 ] traffic_server      HttpTunnel::tunnel_run(HttpTunnelProducer*)                  ( HttpTunnel.cc:720 )
[ 02 ] traffic_server      HttpSM::do_setup_post_tunnel(HttpVC_t)                       ( HttpSM.cc:5923 )
[ 03 ] traffic_server      HttpSM::state_send_server_request_header(int, void*)         ( HttpSM.cc:2197 )
[ 04 ] traffic_server      HttpSM::state_read_server_response_header(int, void*)        ( HttpSM.cc:2004 )
[ 05 ] traffic_server      HttpSM::main_handler(int, void*)                             ( HttpSM.cc:2701 )
[ 06 ] traffic_server      write_signal_and_update(int, UnixNetVConnection*)            ( UnixNetVConnection.cc:117 )
[ 07 ] traffic_server      write_to_net_io(NetHandler*, UnixNetVConnection*, EThread*)  ( UnixNetVConnection.cc:162 )
[ 08 ] traffic_server      NetHandler::process_ready_list()                             ( UnixNet.cc:432 )
[ 09 ] traffic_server      NetHandler::waitForActivity(long)                            ( UnixNet.cc:552 )
[ 10 ] traffic_server      EThread::execute_regular()                                   ( UnixEThread.cc:303 )
[ 11 ] traffic_server      execute                                                      ( UnixEThread.cc:364 )
[ 12 ] traffic_server      EThread::execute()                                           ( UnixEThread.cc:342 )
[ 13 ] traffic_server      spawn_thread_internal                                        ( Thread.cc:92 )
[ 14 ] libpthread-2.17.so  start_thread                                                 ( pthread_create.c:307 )

I think in the past (9.0), we were placing transfer-encoding headers on the H2 client requests. And chunkifying the H2 request data before it came to the HttpSM. With 9.1, we cleaned up that logic.

[masaori335]

Any idea of why this AuTest doesn't cover this case? Can we make it to cover?

trafficserver/tests/gold_tests/h2/http2.test.py

Lines 184 to 192 in edef25c

	# Test Case 6: Post with chunked body
	# While HTTP/2 does not support Transfer-encoding we pass that into curl to encourage it to not set the content length
	# on the post body
	tr = Test.AddTestRun()
	tr.Processes.Default.Command = 'curl -s -k -H "Transfer-Encoding: chunked" -d "{0}" https://127.0.0.1:{1}/postchunked'.format(
	post_body, ts.Variables.ssl_port)
	tr.Processes.Default.ReturnCode = 0
	tr.Processes.Default.Streams.All = "gold/post_chunked.gold"
	tr.StillRunningAfter = server

[shinrich]

We can add a test for redirects with a chunked post. Perhaps in a separate PR. I don't think the existing tests have follow redirect enabled.

[masaori335]

Right, we haven't covered the combination of POST + Chunk + Redirect + H2. Separate PR is good. Thanks!

[zwoop]

Cherry-picked to v9.2.x