The CURLSSLBACKEND_WOLFSSL is supposed to be an alias for
CURLSSLBACKEND_CYASSL, but used an erronous value. To reduce the risk
for a similar mistake, define the backend aliases to use the enum values
instead.

Reported-by: Gisle Vanem
Bug: https://curl.haxx.se/mail/lib-2017-08/0120.html

Regression since 1328f69d

Fixes #1841
Reported-by: Andrei Karas

This new feature flag reports When cURL was built with multiple SSL
backends.

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

Let's add a compile time safe API to select an SSL backend. This
function needs to be called *before* curl_global_init(), and can be
called only once.

Side note: we do not explicitly test that it is called before
curl_global_init(), but we do verify that it is not called multiple times
(even implicitly).

If SSL is used before the function was called, it will use whatever the
CURL_SSL_BACKEND environment variable says (or default to the first
available SSL backend), and if a subsequent call to
curl_global_sslset() disagrees with the previous choice, it will fail
with CURLSSLSET_TOO_LATE.

The function also accepts an "avail" parameter to point to a (read-only)
NULL-terminated list of available backends. This comes in real handy if
an application wants to let the user choose between whatever SSL backends
the currently available libcurl has to offer: simply call

	curl_global_sslset(-1, NULL, &avail);

which will return CURLSSLSET_UNKNOWN_BACKEND and populate the avail
variable to point to the relevant information to present to the user.

Just like with the HTTP/2 push functions, we have to add the function
declaration of curl_global_sslset() function to the header file
*multi.h* because VMS and OS/400 require a stable order of functions
declared in include/curl/*.h (where the header files are sorted
alphabetically). This looks a bit funny, but it cannot be helped.

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

There is information about the compiled-in SSL backends that is really
no concern of any code other than the SSL backend itself, such as which
function (if any) implements SHA-256 summing.

And there is information that is really interesting to the user, such as
the name, or the curl_sslbackend value.

Let's factor out the latter into a publicly visible struct. This
information will be used in the upcoming API to set the SSL backend
globally.

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

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

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

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

... regression since issue #1774 (commit 10b3df10) since obviously
some older gcc doesn't know __powerpc__ while some newer doesn't know
__ppc__ ...

Fixes #1797
Closes #1798
Reported-by: Ryan Schmidt

... as they're not used externally and internally we check for the sizes
already in configure etc.

Closes #1767

The required low-level logic was already available as part of
`libssh2` (via `LIBSSH2_FLAG_COMPRESS` `libssh2_session_flag()`[1]
option.)

This patch adds the new `libcurl` option `CURLOPT_SSH_COMPRESSION`
(boolean) and the new `curl` command-line option `--compressed-ssh`
to request this `libssh2` feature. To have compression enabled, it
is required that the SSH server supports a (zlib) compatible
compression method and that `libssh2` was built with `zlib` support
enabled.

[1] https://www.libssh2.org/libssh2_session_flag.html

Ref: https://github.com/curl/curl/issues/1732
Closes https://github.com/curl/curl/pull/1735

Closes #1774

Fixes #1752

The long list of architectures in include/curl/system.h is annoying to
maintain, and needs to be extended for each and every architecture to
support.

Instead, let's rely on the __SIZEOF_LONG__ define of the gcc compiler
(we are in the GNUC condition anyway), which tells us if long is 4
bytes or 8 bytes.

This fixes the build of libcurl 7.55.0 on architectures such as
OpenRISC or ARC.

Closes #1766

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

... to avoid compiler warnings if the user doesn't want
WIN32_LEAN_AND_MEAN.

Make sure to always define WIN32_LEAN_AND_MEAN before including any
Windows headers to avoid pulling in unnecessary headers. This avoids
unnecessary macro clashes and compiler warnings.

Ref: https://github.com/curl/curl/issues/1562
Closes https://github.com/curl/curl/pull/1672

If libcurl was built with GSS-API support, it unconditionally advertised
GSS-API authentication while connecting to a SOCKS5 proxy.  This caused
problems in environments with improperly configured Kerberos: a stock
libcurl failed to connect, despite libcurl built without GSS-API
connected fine using username and password.

This commit introduces the CURLOPT_SOCKS5_AUTH option to control the
allowed methods for SOCKS5 authentication at run time.

Note that a new option was preferred over reusing CURLOPT_PROXYAUTH
for compatibility reasons because the set of authentication methods
allowed by default was different for HTTP and SOCKS5 proxies.

Bug: https://curl.haxx.se/mail/lib-2017-01/0005.html
Closes https://github.com/curl/curl/pull/1454

Reported-by: Neil Kolban
Fixes: 1598

... and CURLOPT_REQUEST_TARGET instead of CURLOPT_STRIP_PATH_SLASH.

This option instead provides the full "alternative" target to use in the
request, instead of extracting the path from the URL.

Test 1298 and 1299 updated accordingly.

Idea-by: Evert Pot
Suggestion: https://daniel.haxx.se/blog/2017/06/19/options-with-curl/comment-page-1/#comment-18373

Closes #1593

typecheck-gcc expected curl_socket_t instead of curl_off_t arguments
for CURLINFO_OFF_T. Detected by test1521, unfortunately only when run
locally.

Closes https://github.com/curl/curl/pull/1592

... to enable sending "OPTIONS *" which wasn't possible previously.

This option currently only works for HTTP.

Added test cases 1298 + 1299 to verify

Fixes #1280
Closes #1462

This change introduces new alternatives for the existing six
curl_easy_getinfo() options that return sizes or speeds as doubles. The
new versions are named like the old ones but with an appended '_T':

CURLINFO_CONTENT_LENGTH_DOWNLOAD_T
CURLINFO_CONTENT_LENGTH_UPLOAD_T
CURLINFO_SIZE_DOWNLOAD_T
CURLINFO_SIZE_UPLOAD_T
CURLINFO_SPEED_DOWNLOAD_T
CURLINFO_SPEED_UPLOAD_T

Closes #1511

CURLSYS_PULL_WS2TCPIP_H got renamed to CURL_PULL_WS2TCPIP_H in commit
73a2fcea.

Rely entirely on curl/system.h now.

Introduced in Aug 2008 with commit 14240e9e. Now gone.

Fixes #1456

... and update the certinfo.c example accordingly.

Fixes https://github.com/curl/curl/issues/846

... so that they get the required "struct curl_tlssessioninfo **"
arguments.

Fixes #1524

... and support and additional "security patched" date for those who
enhance older versions that way. Pass on the define CURL_PATCHSTAMP with
a date for that.

Building with non-release headers shows the date as [unreleased].

Also: this changes the date format generated in the curlver.h file to be
"YYYY-MM-DD" (no name of the day or month, no time, no time zone) to
make it easier on the eye and easier to parse. Example (new) date
string: 2017-05-09

Suggested-by: Brian Childs

Closes #1474

Closes https://github.com/curl/curl/pull/1452

Closes https://github.com/curl/curl/pull/1452

Info values starting with CURLINFO_SOCKET expect a curl_socket_t, not a
curl_slist argument.

This fixes the following GCC warning when building the examples with
--enable-optimize:

../../include/curl/typecheck-gcc.h:126:42: warning: call to
‘_curl_easy_getinfo_err_curl_slist’ declared with attribute warning:
curl_easy_getinfo expects a pointer to 'struct curl_slist *' for this
info [enabled by default]
sendrecv.c:90:11: note: in expansion of macro ‘curl_easy_getinfo’
res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);

Closes https://github.com/curl/curl/pull/1447

All the callbacks passed to curl_easy_setopt are defined as function
pointers. The possibility to pass both functions and function pointers
was handled for the callbacks that typecheck-gcc.h defined as
compatible, but not for the public callback types themselves.

This makes all compatible callback types defined in typecheck-gcc.h
function pointers too and checks all functions uniformly with
_curl_callback_compatible, which handles both functions and function
pointers.

A symptom of the problem was a warning in tool_operate.c with
--disable-libcurl-option and without --enable-debug as that file
passes the callback functions to curl_easy_setopt directly.

Fixes https://github.com/curl/curl/issues/1403
Closes https://github.com/curl/curl/pull/1404

Reported-by: Marcel Raad
Fixes #1408
Closes #1409

Closes #1397

Triggered a test failure on test 1541 for the build known as
"Linux 4.4 i686 tcc 0.9.26 glibc 2.20"