Previously, options set explicitly through command line options could be
overridden by the configuration files parsed automatically when
ssh_connect() was called.

By calling ssh_options_parse_config() explicitly, the configuration
files are parsed before setting the options, avoiding the options
override.  Once the configuration files are parsed, the automatic
configuration parsing is not executed.

Fixes #4972
Closes #5283
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>

From libssh 0.9.0, ssh_key_type() returns different key types for ECDSA
keys depending on the curve.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Fixes #5252
Closes #5253

Prior to this change a match would never be successful because it
was mistakenly coded to compare binary data from libssh to a
user-specified hex string (ie CURLOPT_SSH_HOST_PUBLIC_KEY_MD5).

Reported-by: fds242@users.noreply.github.com

Fixes https://github.com/curl/curl/issues/4971
Closes https://github.com/curl/curl/pull/4974

Previously, it was not possible to get a known hosts file entry due to
the lack of an API.  ssh_session_get_known_hosts_entry(), introduced in
libssh-0.9.0, allows libcurl to obtain such information and behave the
same as when compiled with libssh2.

This also tries to avoid the usage of deprecated functions when the
replacements are available.  The behaviour will not change if versions
older than libssh-0.8.0 are used.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>

Fixes #4953
Closes #4962

Spotted by 'codespell'

Closes #4957

... even for macros

Reviewed-by: Daniel Gustafsson
Reviewed-by: Jay Satiro
Reported-by: Jay Satiro
Fixes #4683
Closes #4722

This reverts commit ba82673dac3e8d00a76aa5e3779a0cb80e7442af.

Bug: #4683

- Disable warning C4127 "conditional expression is constant" globally
  in curl_setup.h for when building with Microsoft's compiler.

This mainly affects building with the Visual Studio project files found
in the projects dir.

Prior to this change the cmake and winbuild build systems already
disabled 4127 globally for when building with Microsoft's compiler.
Also, 4127 was already disabled for all build systems in the limited
circumstance of the WHILE_FALSE macro which disabled the warning
specifically for while(0). This commit removes the WHILE_FALSE macro and
all other cruft in favor of disabling globally in curl_setup.

Background:

We have various macros that cause 0 or 1 to be evaluated, which would
cause warning C4127 in Visual Studio. For example this causes it:

    #define Curl_resolver_asynch() 1

Full behavior is not clearly defined and inconsistent across versions.
However it is documented that since VS 2015 Update 3 Microsoft has
addressed this somewhat but not entirely, not warning on while(true) for
example.

Prior to this change some C4127 warnings occurred when I built with
Visual Studio using the generated projects in the projects dir.

Closes https://github.com/curl/curl/pull/4658

The WHILE_FALSE construction is used to avoid compiler warnings in
macro constructions. This fixes a few instances where it was not
used in order to keep the code consistent.

Closes #4649
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

The regexp looking for assignments within conditions was too greedy
and matched a too long string in the case of multiple conditionals
on the same line. This is basically only a problem in single line
macros, and the code which exemplified this was essentially:

  do { if((x) != NULL) { x = NULL; } } while(0)

..where the final parenthesis of while(0) matched the regexp, and
the legal assignment in the block triggered the warning. Fix by
making the regexp less greedy by matching for the tell-tale signs
of the if statement ending.

Also remove the one occurrence where the warning was disabled due
to a construction like the above, where the warning didn't apply
when fixed.

Closes #4647
Reviewed-by: Daniel Stenberg <daniel@haxx.se>