- Do not switch to HTTP/2 for an HTTP proxy that is not tunnelling to
  the destination host.

We already do something similar for HTTPS proxies by not sending h2. [1]

Prior to this change setting CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE would
incorrectly use HTTP/2 to talk to the proxy, which is not something we
support (yet?). Also it's debatable whether or not that setting should
apply to HTTP/2 proxies.

[1]: https://github.com/curl/curl/commit/17c5d05

Bug: https://github.com/curl/curl/issues/3570
Bug: https://github.com/curl/curl/issues/3832

Closes https://github.com/curl/curl/pull/3853

Closes https://github.com/curl/curl/pull/3842

Older versions of OpenSSL report FIPS availabilty via an OPENSSL_FIPS
define. It uses this define to determine whether to publish -fips at
the end of the version displayed. Applications that utilize the version
reported by OpenSSL will see a mismatch if they compare it to what curl
reports, as curl is not modifying the version in the same way. This
change simply adds a check to see if OPENSSL_FIPS is defined, and will
alter the reported version to match what OpenSSL itself provides. This
only appears to be applicable in versions of OpenSSL <1.1.1

Closes #3771

Currently you can do things like --cert <(cat ./cert.crt) with (at least) the
openssl backend, but that doesn't work for nss because is_file rejects fifos.

I don't actually know if this is sufficient, nss might do things internally
(like seeking back) that make this not work, so actual testing is needed.

Closes #3807

Closes #3846

Closes #3838

The zoneid can be used with IPv6 numerical addresses.

Updated test 1560 to verify.

Closes #3834

Closes #3837

Reported-by: Ricardo Gomes

Bug: #3537
Closes #3836

The time field in the curl_fileinfo struct will always be zero. No code
was ever implemented to actually convert the date string to a time_t.

Fixes #3829
Closes #3835

(and make the code style comply)

Fixes #3833

... to make the host name "usable". Store the scope id and put it back
when extracting a URL out of it.

Also makes curl_url_set() syntax check CURLUPART_HOST.

Fixes #3817
Closes #3822

... for functions related to pipelining. Those functions were removed in
2f44e94e.

Closes #3828

... due to SHA-1 signatures in test certs

Closes #3823
Closes #3776

- better log output

- make sure multiplex is enabled for it to be used

As soon as a TLS backend gets ALPN conformation about the specific HTTP
version it can now set the multiplex situation for the "bundle" and
trigger moving potentially queued up transfers to the CONNECT state.

With transfers being queued up, we only move one at a a time back to the
CONNECT state but now we mark moved transfers so that when a moved
transfer is confirmed "successful" (it connected) it will trigger the
move of another pending transfer. Previously, it would otherwise wait
until the transfer was done before doing this. This makes queued up
pending transfers get processed (much) faster.

Fixes #3813
Closes #3815

In case the name pointer isn't set (due to memory pressure most likely)
we need to skip the prefix matching and reject with a badcookie to avoid
a possible NULL pointer dereference.

Closes #3820 #3821
Reported-by: Jonathan Moerman
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

Closes #3808

Closes #3811

This limits all accepted input strings passed to libcurl to be less than
CURL_MAX_INPUT_LENGTH (8000000) bytes, for these API calls:
curl_easy_setopt() and curl_url_set().

The 8000000 number is arbitrary picked and is meant to detect mistakes
or abuse, not to limit actual practical use cases. By limiting the
acceptable string lengths we also reduce the risk of integer overflows
all over.

NOTE: This does not apply to `CURLOPT_POSTFIELDS`.

Test 1559 verifies.

Closes #3805

Closes #3809

Closes https://github.com/curl/curl/pull/3769

Just like we do for mbed TLS, use our local implementation of MD4 when
OpenSSL doesn't support it. This allows a type-3 message to include the
NT response.

Kerberos was incorrectly indented as a subsection under FTP, which is
incorrect as they are both top level sections. A fix for this was first
attempted in commit fef38a08 but that
was a few paddles short of being complete.

Add the subsections under "Structs in libcurl" to the table of contents.

Reviewed-by: Daniel Stenberg <daniel@haxx.se>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>

Make all struct members under the Curl_handler section
print in monospace font.

Closes #3801
Reviewed-by: Daniel Stenberg <daniel@haxx.se>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>

Introducing the curl bug bounty program on hackerone. We now recommend
filing security issues directly in the hackerone ticket system which
only is readable to curl security team members.

Assisted-by: Daniel Gustafsson

Closes #3488

RFC 4616 specifies the authzid is optional in the client authentication
message and that the server will derive the authorisation identity
(authzid) from the authentication identity (authcid) when not specified
by the client.

Follow-up to 76b63489 which renamed logfile as curl_dbg_logfile.

Ref: https://github.com/curl/curl/commit/76b6348#r33259088

Follow up to 762a292f.