At the moment, cURL's SSL backend needs to be configured at build time.
As such, it is totally okay for them to hard-code their backend-specific
data in the ssl_connect_data struct.

In preparation for making the SSL backend a runtime option, let's make
the access of said private data a bit more abstract so that it can be
adjusted later in an easy manner.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

In 86b88948 (sasl_gssapi: Added GSS-API based Kerberos V5 variables,
2014-12-03), an SSPI-specific field was added to the kerberos5data
struct without moving the #include "curl_sspi.h" later in the same file.

This broke the build when SSPI was enabled, unless Secure Channel was
used as SSL backend, because it just so happens that Secure Channel also
requires "curl_sspi.h" to be #included.

In f4739f63

 (urldata: include curl_sspi.h when Windows SSPI is enabled,
2017-02-21), this bug was fixed incorrectly: Instead of moving the
appropriate conditional #include, the Secure Channel-conditional part
was now also SSPI-conditional.

Fix this problem by moving the correct #include instead.

This is also required for an upcoming patch that moves all the Secure
Channel-specific stuff out of urldata.h and encapsulates it properly in
vtls/schannel.c instead.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Since 5017d5ad

 (polarssl: now require 1.3.0+, 2014-03-17), we require
a newer PolarSSL version. No need to keep code trying to support any
older version.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

In the ongoing endeavor to abstract out all SSL backend-specific
functionality, this is the next step: Instead of hard-coding how the
different SSL backends access their internal data in getinfo.c, let's
implement backend-specific functions to do that task.

This will also allow for switching SSL backends as a runtime option.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

There are convenient no-op versions of the init/cleanup functions now,
no need to define private ones for axTLS.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

These functions are all available via the Curl_ssl struct now, no need
to declare them separately anymore.

As the global declarations are removed, the corresponding function
definitions are marked as file-local. The only two exceptions here are
Curl_mbedtls_shutdown() and Curl_polarssl_shutdown(): only the
declarations were removed, there are no function definitions to mark
file-local.

Please note that Curl_nss_force_init() is *still* declared globally, as
the only SSL backend-specific function, because it was introduced
specifically for the use case where cURL was compiled with
`--without-ssl --with-nss`. For details, see f3b77e56

 (http_ntlm: add
support for NSS, 2010-06-27).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The _shutdown() function calls the _session_free() function; While this
is not a problem now (because schannel.h declares both functions), a
patch looming in the immediate future with make all of these functions
file-local.

So let's just move the _session_free() function's definition before it
is called.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The connect_finish() function (like many other functions after it) calls
the Curl_axtls_close() function; While this is not a problem now
(because axtls.h declares the latter function), a patch looming in the
immediate future with make all of these functions file-local.

So let's just move the Curl_axtls_close() function's definition before
it is called.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

That will allow us to choose the SSL backend at runtime.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The entire idea of introducing the Curl_ssl struct to describe SSL
backends is to prepare for choosing the SSL backend at runtime.

To that end, convert all the #ifdef have_curlssl_* style conditionals
to use bit flags instead.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The SHA-256 checksumming is also an SSL backend-specific function.
Let's include it in the struct declaring the functionality of SSL
backends.

In contrast to MD5, there is no fall-back code. To indicate this, the
respective entries are NULL for those backends that offer no support for
SHA-256 checksumming.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The MD5 summing is also an SSL backend-specific function. So let's
include it, offering the previous fall-back code as a separate function
now: Curl_none_md5sum(). To allow for that, the signature had to be
changed so that an error could be returned from the implementation
(Curl_none_md5sum() can run out of memory).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This is the first step to unify the SSL backend handling. Now all the
SSL backend-specific functionality is accessed via a global instance of
the Curl_ssl struct.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

The idea of introducing the Curl_ssl struct was to unify how the SSL
backends are declared and called. To this end, we now provide an
instance of the Curl_ssl struct for each and every SSL backend.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This new struct is similar in nature to Curl_handler: it will define the
functions and capabilities of all the SSL backends (where Curl_handler
defines the functions and capabilities of protocol handlers).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This patch makes the signature of the _sha256sum() functions consistent
among the SSL backends, in preparation for unifying the way all SSL
backends are accessed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This patch makes the signature of the _data_pending() functions
consistent among the SSL backends, in preparation for unifying the way
all SSL backends are accessed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This patch makes the signature of the _cleanup() functions consistent
among the SSL backends, in preparation for unifying the way all SSL
backends are accessed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

This will make the upcoming multissl backend much easier to implement.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Closes #1829

Reported-by: Dan Fandrich
Bug: https://github.com/curl/curl/pull/1758#issuecomment-324861615

... as the previous fixed length 128 bytes buffer was sometimes too
small.

Fixes #1823
Closes #1831

Reported-by: Benjamin Sergeant
Assisted-by: Bill Pyne, Ray Satiro, Nick Zitzmann

... to get the event/revent defines that might be used for the poll
struct.

Reported-by: Michael Smith
Fixes #1828
Closes #1833

These were missed in commit c468c27b.

Embedded manifest option didn't work due to incorrect path.

Fixes https://github.com/curl/curl/issues/1832

When working on this code I found the previous setup a bit weird while
using proper defines increases readability.

Closes #1824

It is a defined possible greeting at server startup that means the
connection is already authenticated. See
https://tools.ietf.org/html/rfc3501#section-7.1.4

Test 846 added to verify.

Fixes #1818
Closes #1820

Recent changes that replaced CURL_SIZEOF_LONG in the source with
SIZEOF_LONG broke builds that use the premade configuration files and
don't have SIZEOF_LONG defined.

Bug: https://github.com/curl/curl/issues/1816

Bug: #1816

The previous message was just too long for ordinary people and it was
encouraging users to use `--insecure` a little too easy.

Based-on-work-by: Frank Denis

Closes #1810
Closes #1817

By default, the MinGW CRT globs command-line arguments. This prevents
getting a single asterisk into an argument as test 1299 does. Turn off
globbing by setting the global variable _CRT_glob to 0 for MinGW.

Fixes https://github.com/curl/curl/issues/1751
Closes https://github.com/curl/curl/pull/1813

libidn was replaced with libidn2 last year in configure.
Caveat: libidn2 may depend on a list of further libs.
These can be manually specified via CURL_LDFLAG_EXTRAS.

Closes https://github.com/curl/curl/pull/1815

Recent changes that replaced CURL_SIZEOF_LONG in the source with
SIZEOF_LONG broke builds that use the premade configuration files and
don't have SIZEOF_LONG defined.

Closes https://github.com/curl/curl/pull/1814

closes #1799

Reported-by: John David Anglin
Bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=872502#10