The new API added in Linux 4.11 only requires setting a socket option
before connecting, without the whole sento() machinery.

Notably, this makes it possible to use TFO with SSL connections on Linux
as well, without the need to mess around with OpenSSL (or whatever other
SSL library) internals.

Closes #2056

Fixes #2097
Closes #2108

eg consider a non-existent interface eth8, curl --interface eth8

Before: curl: (45) Could not resolve host: eth8
After: curl: (45) Couldn't bind to 'eth8'

Bug: https://github.com/curl/curl/issues/2104
Reported-by: Alfonso Martone

Fixes #2106
Reported-by: youngchopin on github

Host names like "127.0.0.1 moo" would otherwise be accepted by some
getaddrinfo() implementations.

Updated test 1034 and 1035 accordingly.

Fixes #2073
Closes #2092

Closes #2098

Fixes a scan-build warning.

- Add braces around multi-line if statement.

Closes https://github.com/curl/curl/pull/2096

... so that IPv6 addresses can be passed like they can for connect-to
and how they're used in URLs.

Added test 1324 to verify
Reported-by: Alex Malinovich

Fixes #2087
Closes #2091

The previous fix https://github.com/curl/curl/pull/1788 worked just for
Xcode 9. This commit extends the fix to older Xcode versions effectively
by not using connectx function.

Fixes https://github.com/curl/curl/issues/1330
Fixes https://github.com/curl/curl/issues/2080
Closes https://github.com/curl/curl/pull/1336
Closes #2082

Fixes #2079
Closes #2081

Closes #1455

Follow-up to aadb7c7b. Verified by new test 1263.

Closes #2072

There is a conflict on symbol 'free_func' between openssl/crypto.h and
zlib.h on AIX. This is an attempt to resolve it.

Bug: https://curl.haxx.se/mail/lib-2017-11/0032.html
Reported-By: Michael Felt

Reported-by: Brian Carpenter

Closes #2071

Closes #2069

... to make url.c smaller.

Closes #1944

Ensure HAVE_SETMODE is set to 1 on OSes that have setmode. Without this,
curl will corrupt binary files when writing them to stdout on Windows.

Closes https://github.com/curl/curl/pull/2067

CID 984459, detected by Coverity

Update CMakeLists.txt to add curl.rc to the correct list.

The --interface command (CURLOPT_INTERFACE option) already uses
SO_BINDTODEVICE on Linux, but it tries to parse it as an interface or IP
address first, which fails in case the user passes a VRF.

Try to use the socket option immediately and parse it as a fallback
instead.  Update the documentation to mention this feature, and that it
requires the binary to be ran by root or with CAP_NET_RAW capabilities
for this to work.

Closes #2024

Closes #2043

As documented in RFC 3501 section 9:
https://tools.ietf.org/html/rfc3501#section-9

Closes #2061

... previously it would store it already in the happy eyeballs stage
which could lead to the IPv6 bit being set for an IPv4 connection,
leading to curl not wanting to do EPSV=>PASV for FTP transfers.

Closes #2053

... even when there's no socket to wait for, the timeout can still be
very short.