Better diff with the --ignore-all-space option.

It became explicit in rfc9113:

> The same pseudo-header field name MUST NOT appear more than once in a
> field block.

While at it, the duplicate pseudo-header error can be consolidated in a
single location instead of adding one more branch.

Instead of passing both a decoder and individual decoder fields, the
signature for h2h_addhdr() changed to only take the decoder. The order
of parameters is destination first, then the source following the
calling conventon of functions like memcpy().

Internally the function is reorganized with a bunch of txt variables to
keep track of the header being added, its name and value. In addition to
clarity, this also helps improve safety and correctness.

For example the :authority pseudo-header name is erased in place to turn
it into a regular host header, but having a dedicated txt for the header
name allows its preservation.

Control characters will be caught by vct_ishdrval() anyways, but this
condition would also reject allowed obs-text non-ASCII characters.
Signed-off-by: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

Signed-off-by: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

Signed-off-by: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

Signed-off-by: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

Fixes #3952

This requirement was dropped in the updated rfc 9113.

Fixes: #3911

Conflicts:
	bin/varnishd/http2/cache_http2_proto.c

I accidentally committed an earlier, wrong version. o/ Dridi

Ref #3407

https://github.com/varnishcache/varnish-cache/pull/3407#issuecomment-696146625

Conflicts:
	include/vct.h

The previous commit introduces more than just this macro and was skipped
on purpose.

Conflicts:
	include/vdef.h

The extra space before the colon looked uncanny. The rest is just code
indentation improvements.

Better diff with the --ignore-all-space --word-diff options.

There is room for further improvement in the dynamic between HPACK and
the HTTP/2 session, but this will serve as the first step.

Conflicts:
	include/tbl/h2_error.h

There are other components than the cache process that could benefit
from it, in particular libvcc. The relationship with vas.h is somewhat
unfortunate but that also centralize the Tcheck() logic in pdiff() and
doesn't actually require vas.h unless the macros are used, in which
case it's almost guaranteed that the calling code already included
vas.h in the first place.

The benefits should outweigh the drawbacks.

Conflicts:
	bin/varnishd/cache/cache.h
	bin/varnishtest/vtc_http.c

This way it can be used almost anywhere in the code base and out of tree,
not just in the cache process. The function was slightly polished after
prior discussions with phk and slink.

Conflicts:
	include/vas.h

Its first action ${string,repeat,<uint>,<string>} helps simplify many
unwieldy test cases that will hopefully be easier to edit from now on.

Conflicts:
	bin/varnishtest/tests/c00071.vtc
	bin/varnishtest/tests/r02219.vtc
	bin/varnishtest/vtc_main.c

Conflicts:
	bin/varnishtest/vtc.c

Instead of having a mere value, these would be able to compute a macro
expansion. We parse the contents inside the ${...} delimiters as a VAV,
but there can't be (yet?) nested curly {braces}, even quoted.

The first argument inside the delimiters is the macro name, and other
VAV arguments are treated as arguments to the macro's function.

For example ${foo,bar,baz} would call the a macro "foo"'s function with
arguments "bar" and "baz". Simple macros don't take arguments and work
as usual.

Conflicts:
	bin/varnishtest/vtc.c
	bin/varnishtest/vtc_main.c

The latter operates on a VSB, which is always what call sites are doing
anyway. It also takes the responsibility of ignoring unknown macros, in
preparation for more responsibilities that will also require the ability
to fail a test case.

Conflicts:
	bin/varnishtest/vtc_http.c

I kept a variable called "s" to cut noise from the diff.

Before the h2 frame dispatch we only need to check that coming from a
HEADERS frame the very next frame is a CONTINUATION, when the HPACK
block didn't fit in the former.

The CONTINUATION dispatch will then make the stream consistency check.

Conflicts:
	bin/varnishtest/tests/t02005.vtc

When a stream times out waiting for window credits, and all the other
streams are broke, declare the whole connection bankrupt.

Conflicts:
	bin/varnishd/http2/cache_http2.h

It replaces idle_send_timeout when the stream is waiting for window
credits before sending more DATA frames. The idle_send_timeout will
still apply to individual writes to the socket, but triggering it is
considered a failure condition (this was already the case).

The two loops are merged into a single one to better deal with the
lack of ordering guarantees of request vs connection stream control
flow window crediting.

Refs #2980

Conflicts:
	bin/varnishd/http2/cache_http2_proto.c
	bin/varnishd/http2/cache_http2_send.c

This parameter needs to be somewhat high because web browsers may for
example only credit streams for image resources just enough to parse
metadata like width and height of a picture in order to perform layout
computations and fetch resources more sensitive to latency before the
effective image payloads.

Conflicts:
	include/tbl/params.h

Conflicts:
	bin/varnishd/http2/cache_http2_send.c
	include/tbl/h2_error.h

The new meaning for h2->sess->t_idle is now the time since the last
complete frame, except before the first frame where it corresponds to
the creation of the session.

Conflicts:
	bin/varnishd/http2/cache_http2_proto.c