- Treat CURL_SSLVERSION_MAX_NONE the same as
  CURL_SSLVERSION_MAX_DEFAULT. Prior to this change NONE would mean use
  the minimum version also as the maximum.

This is a follow-up to 6015cefb which changed the behavior of setting
the SSL version so that the requested version would only be the minimum
and not the maximum. It appears it was (mostly) implemented in OpenSSL
but not other backends. In other words CURL_SSLVERSION_TLSv1_0 used to
mean use just TLS v1.0 and now it means use TLS v1.0 *or later*.

- Fix CURL_SSLVERSION_MAX_DEFAULT for OpenSSL.

Prior to this change CURL_SSLVERSION_MAX_DEFAULT with OpenSSL was
erroneously treated as always TLS 1.3, and would cause an error if
OpenSSL was built without TLS 1.3 support.

Co-authored-by: Daniel Gustafsson

Fixes https://github.com/curl/curl/issues/2969
Closes https://github.com/curl/curl/pull/3012

As OpenSSL 1.1.1 starts to complain and fail on sha1 CAs:

"SSL certificate problem: CA signature digest algorithm too weak"

Closes #3014

Assisted-by: Daniel Gustafsson
Closes #3019

In order for this API to fully work for libcurl itself, it now offers a
CURLU_GUESS_SCHEME flag that makes it "guess" scheme based on the host
name prefix just like libcurl always did. If there's no known prefix, it
will guess "http://".

Separately, it relaxes the check of the host name so that IDN host names
can be passed in as well.

Both these changes are necessary for libcurl itself to use this API.

Assisted-by: Daniel Gustafsson
Closes #3018

One can still use CA certificates stored in NSS database.

Reported-by: Maxime Legros
Bug: https://curl.haxx.se/mail/lib-2018-09/0077.html

Closes #3016

In the CURLUPART_URL case, there is no codepath which invokes url
decoding so remove the assignment of the urldecode variable. This
fixes the deadstore bug-report from clang static analysis.

Closes #3015
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

TODO item 1.1 was implemented in commit 946ce5b6

, update reference
to it with instead referencing the implemented option.

Closes #3013
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

User must have OpenSSL installed even if not used by libcurl at all
since 7.61.1 release.  Broken at
7867aaa9

Reviewed-by: Sergei Nikulov
Closes #3001

.... since getsock may update the expiry timer.

Fixes #2996
Closes #3000

Closes #3004

The reallocation was using the input pointer for the return value, which
leads to a memory leak on reallication failure. Fix by instead use the
safe internal API call Curl_saferealloc().

Closes #3005
Reviewed-by: Daniel Stenberg <daniel@haxx.se>
Reviewed-by: Nick Zitzmann <nickzman@gmail.com>

Make sure to not overwrite the reallocated pointer in realloc() calls
to avoid a memleak on memory errors.

ftp_send_command() was using vsnprintf() without including the libcurl
*rintf() replacement header. Fix by including curl_printf.h and also
add curl_memory.h while at it since memdebug.h depends on it.

Closes #2999
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

Closes #2994

... so that they can clear the original pointer on failure, which makes
the error-paths and their cleanups easier.

Closes #2992

Closes #2998

Closes #2989

Fixes #2983
Closes #2988

The failf() macro is the name used for invoking Curl_failf(). While
there isn't a way to turn off failf like there is for infof, but it's
still a good idea to use the macro.

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

Strings broken on multiple rows in the .c file need to have appropriate
whitespace padding on either side of the concatenation point to render
a correct amalgamated string. Fix by adding a space at the occurrences
found.

Closes #2986
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

The FTP command allocated by aprintf() must be freed after usage.

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

Commit 8238ba9c

 inadvertently removed
the actual command to be sent from the send buffer in a refactoring.
Add back copying the command into the buffer. Also add more guards
against malformed input while at it.

Closes #2985
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

When erroring out on a request being too large, the existing buffer was
leaked. Fix by explicitly freeing on the way out.

Closes #2966
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

Closes #2984

This yields

  "the scheme is %s\n"

instead of

  "the scheme is %s0

Closes #2970

to help user understand what the problem is

Reported-by: Daniel Shahaf

Fixes #2763
Closes #2977

The previous test certificates contained RSA keys of only 1024 bits.
However, RSA claims that 1024-bit RSA keys are likely to become
crackable some time before 2010. The NIST recommends at least 2048-bit
keys for RSA for now.

Better use full 2048 also for testing.

Closes #2973

Closes #2968
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

On Windows, the read function from <io.h> is used, which has its byte
count parameter as unsigned int instead of size_t.

Closes https://github.com/curl/curl/pull/2972

Closes https://github.com/curl/curl/pull/2979

- Use memcpy instead of strncpy to copy a string without termination,
  since gcc8 warns about using strncpy to copy as many bytes from a
  string as its length.

Suggested-by: Viktor Szakats

Closes https://github.com/curl/curl/issues/2980

Closes #2967

This example is simply not working correctly but there's nobody around
with the skills and energy to fix it.

Closes #2407