As Windows SSPI authentication calls fail when a particular mechanism
isn't available, introduced these functions for DIGEST, NTLM, Kerberos 5
and Negotiate to allow both HTTP and SASL authentication the opportunity
to query support for a supported mechanism before selecting it.

For now each function returns TRUE to maintain compatability with the
existing code when called.

...and removed some old ones

RFC7512 provides a standard method to reference certificates in PKCS#11
tokens, by means of a URI starting 'pkcs11:'.

We're working on fixing various applications so that whenever they would
have been able to use certificates from a file, users can simply insert
a PKCS#11 URI instead and expect it to work. This expectation is now a
part of the Fedora packaging guidelines, for example.

This doesn't work with cURL because of the way that the colon is used
to separate the certificate argument from the passphrase. So instead of

   curl -E 'pkcs11:manufacturer=piv_II;id=%01' …

I instead need to invoke cURL with the colon escaped, like this:

   curl -E 'pkcs11\:manufacturer=piv_II;id=%01' …

This is suboptimal because we want *consistency* — the URI should be
usable in place of a filename anywhere, without having strange
differences for different applications.

This patch therefore disables the processing in parse_cert_parameter()
when the string starts with 'pkcs11:'. It means you can't pass a
passphrase with an unescaped PKCS#11 URI, but there's no need to do so
because RFC7512 allows a PIN to be given as a 'pin-value' attribute in
the URI itself.

Also, if users are already using RFC7512 URIs with the colon escaped as
in the above example — even providing a passphrase for cURL to handling
instead of using a pin-value attribute, that will continue to work
because their string will start 'pkcs11\:' and won't match the check.

What *does* break with this patch is the extremely unlikely case that a
user has a file which is in the local directory and literally named
just "pkcs11", and they have a passphrase on it. If that ever happened,
the user would need to refer to it as './pkcs11:<passphrase>' instead.

This allows for better memmory debugging and torture tests.

This fixes tests that were added after 113f04e6 as the tests would
fail otherwise.

We bring back "Proxy-Connection: Keep-Alive" now unconditionally to fix
regressions with old and stupid proxies, but we could possibly switch to
using it only for CONNECT or only for NTLM in a future if we want to
gradually reduce it.

Fixes #954

Reported-by: János Fekete

This reverts commit 113f04e6.

Follow-up to a96319eb (document the new behavior)

Follow up to a96319eb

I discovered some people have been using "https://example.com" style
strings as proxy and it "works" (curl doesn't complain) because curl
ignores unknown schemes and then assumes plain HTTP instead.

I think this misleads users into believing curl uses HTTPS to proxies
when it doesn't. Now curl rejects proxy strings using unsupported
schemes instead of just ignoring and defaulting to HTTP.

Third commit to fix issue #944 regarding SOCKS5 error handling.

Reported-by: David Kalnischkies

Second commit to fix issue #944 regarding SOCKS5 error handling.

Reported-by: David Kalnischkies

First commit to fix issue #944 regarding SOCKS5 error handling.

Reported-by: David Kalnischkies

The server developer.netscape.com does not resolve into any
ip address and can be removed.

Undo change introduced in d4643d6e which caused iPAddress match to be
ignored if dNSName was present but did not match.

Also, if iPAddress is present but does not match, and dNSName is not
present, fail as no-match. Prior to this change in such a case the CN
would be checked for a match.

Bug: https://github.com/curl/curl/issues/959


Reported-by:  <wmsch@users.noreply.github.com>

Closes #956

Follow-up to e577c43b to fix test case 569 brekage: stop the parser at
whitespace as well.

Help-by: Erik Janssen

Mark's new document about HTTP Retries
(https://mnot.github.io/I-D/httpbis-retry/) made me check our code and I
spotted that we don't retry failed HEAD requests which seems totally
inconsistent and I can't see any reason for that separate treatment.

So, no separate treatment for HEAD starting now. A HTTP request sent
over a reused connection that gets cut off before a single byte is
received will be retried on a fresh connection.

Made-aware-by: Mark Nottingham

Makes libcurl work in communication with gstreamer-based RTSP
servers. The original code validates the session id to be in accordance
with the RFC. I think it is better not to do that:

- For curl the actual content is a don't care.

- The clarity of the RFC is debatable, is $ allowed or only as \$, that
  is imho not clear

- Gstreamer seems to url-encode the session id but % is not allowed by
the RFC

- less code

With this patch curl will correctly handle real-life lines like:
Session: biTN4Kc.8%2B1w-AF.; timeout=60

Bug: https://curl.haxx.se/mail/lib-2016-08/0076.html

Added in 5fce88aa

This makes it possible to use specific compilers or a cache.

Sample use for clcache:
set CC=clcache.bat
nmake /f Makefile.vc DEBUG=no MODE=static VC=14 GEN_PDB=no