Now we can make use of TRACE_PRINTF() to iterate over headers as they
are received or dumped. It's worth noting that the dumps may occasionally
be interrupted due to a buffer full or a realign, but in this case it
will be visible because the trace will restart from the first one. All
these headers (and trailers) may be interleaved with other connections'
so they're all preceeded by the pointer to the connection and optionally
the stream (or alternately the stream ID) to help discriminating them.
Since it's not easy to read the header directions, sent headers are
prefixed with "sndh" and received headers are prefixed with "rcvh", both
of which are rare enough in the traces to conveniently support a quick
grep.
In order to avoid code duplication, h2_encode_headers() was implemented
as a wrapper on top of hpack_encode_header(), which optionally emits the
header to the trace if the trace is active. In addition, for headers that
are encoded using a different method, h2_trace_header() was added as well.
Header names are truncated to 256 bytes and values to 1024 bytes. If
the lengths are larger, they will be truncated and suffixed with
"(... +xxx)" where "xxx" is the number of extra bytes.
Example of what an end-to-end H2 request gives:
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh :method: GET
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh :path: /
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh :scheme: http
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh :authority: localhost:14446
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh user-agent: curl/7.54.1
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh accept: */*
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c13120(F,FRP) dsi=1 rcvh cookie: blah
[00|h2|5|mux_h2.c:5491] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh :method: GET
[00|h2|5|mux_h2.c:5572] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh :authority: localhost:14446
[00|h2|5|mux_h2.c:5596] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh :path: /
[00|h2|5|mux_h2.c:5647] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh user-agent: curl/7.54.1
[00|h2|5|mux_h2.c:5647] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh accept: */*
[00|h2|5|mux_h2.c:5647] h2s_bck_make_req_headers(): h2c=0x1c1cd90(B,FRH) h2s=0x1c1e3d0(1,IDL) sndh cookie: blah
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c1cd90(B,FRP) dsi=1 rcvh :status: 200
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c1cd90(B,FRP) dsi=1 rcvh content-length: 0
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c1cd90(B,FRP) dsi=1 rcvh x-req: size=102, time=0 ms
[00|h2|5|mux_h2.c:4818] h2c_decode_headers(): h2c=0x1c1cd90(B,FRP) dsi=1 rcvh x-rsp: id=dummy, code=200, cache=1, size=0, time=0 ms (0 real)
[00|h2|5|mux_h2.c:5210] h2s_frt_make_resp_headers(): h2c=0x1c13120(F,FRH) h2s=0x1c1c780(1,HCR) sndh :status: 200
[00|h2|5|mux_h2.c:5231] h2s_frt_make_resp_headers(): h2c=0x1c13120(F,FRH) h2s=0x1c1c780(1,HCR) sndh content-length: 0
[00|h2|5|mux_h2.c:5231] h2s_frt_make_resp_headers(): h2c=0x1c13120(F,FRH) h2s=0x1c1c780(1,HCR) sndh x-req: size=102, time=0 ms
[00|h2|5|mux_h2.c:5231] h2s_frt_make_resp_headers(): h2c=0x1c13120(F,FRH) h2s=0x1c1c780(1,HCR) sndh x-rsp: id=dummy, code=200, cache=1, size=0, time=0 ms (0 real)
At some point the frontend/backend names would be useful but that's a more
general comment than just the H2 traces.
The HAProxy documentation has been split into a number of different files for
ease of use.
Please refer to the following files depending on what you're looking for :
- INSTALL for instructions on how to build and install HAProxy
- BRANCHES to understand the project's life cycle and what version to use
- LICENSE for the project's license
- CONTRIBUTING for the process to follow to submit contributions
The more detailed documentation is located into the doc/ directory :
- doc/intro.txt for a quick introduction on HAProxy
- doc/configuration.txt for the configuration's reference manual
- doc/lua.txt for the Lua's reference manual
- doc/SPOE.txt for how to use the SPOE engine
- doc/network-namespaces.txt for how to use network namespaces under Linux
- doc/management.txt for the management guide
- doc/regression-testing.txt for how to use the regression testing suite
- doc/peers.txt for the peers protocol reference
- doc/coding-style.txt for how to adopt HAProxy's coding style
- doc/internals for developer-specific documentation (not all up to date)
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