When CURL_SOCKET_BAD is returned in the callback, it should be treated
as an error (CURLE_COULDNT_CONNECT) if no other socket is subsequently
created when trying to connect to a server.

Bug: http://curl.haxx.se/mail/lib-2015-06/0047.html

... by using plain structs instead of pointers for the connection cache,
we can avoid several dynamic allocations that weren't necessary.

This header file must be included after all header files except
memdebug.h, as it does similar memory function redefinitions and can be
similarly affected by conflicting definitions in system or dependent
library headers.

By making sure Curl_getconnectinfo() uses the correct connection cache
to find the last connection.

Bug: https://github.com/bagder/curl/pull/168

(trynextip)
- Don't try the "other" protocol family unless IPv6 is available. In an
IPv4-only build the other family can only be IPv6 which is unavailable.

This change essentially stops IPv4-only builds from attempting the
"happy eyeballs" secondary parallel connection that is supposed to be
used by the "other" address family.

Prior to this change in IPv4-only builds that secondary parallel
connection attempt could be erroneously used by the same family (IPv4)
which caused a bug where every address after the first for a host could
be tried twice, often in parallel. This change fixes that bug. An
example of the bug is shown below.

Assume MTEST resolves to 3 addresses 127.0.0.2, 127.0.0.3 and 127.0.0.4:

* STATE: INIT => CONNECT handle 0x64f4b0; line 1046 (connection #-5000)
* Rebuilt URL to: http://MTEST/
* Added connection 0. The cache now contains 1 members
* STATE: CONNECT => WAITRESOLVE handle 0x64f4b0; line 1083
(connection #0)
*   Trying 127.0.0.2...
* STATE: WAITRESOLVE => WAITCONNECT handle 0x64f4b0; line 1163
(connection #0)
*   Trying 127.0.0.3...
* connect to 127.0.0.2 port 80 failed: Connection refused
*   Trying 127.0.0.3...
* connect to 127.0.0.3 port 80 failed: Connection refused
*   Trying 127.0.0.4...
* connect to 127.0.0.3 port 80 failed: Connection refused
*   Trying 127.0.0.4...
* connect to 127.0.0.4 port 80 failed: Connection refused
* connect to 127.0.0.4 port 80 failed: Connection refused
* Failed to connect to MTEST port 80: Connection refused
* Closing connection 0
* The cache now contains 0 members
* Expire cleared
curl: (7) Failed to connect to MTEST port 80: Connection refused

The bug was born in commit bagder/curl@2d435c7.

In function Curl_closesocket() in connect.c the call to
Curl_multi_closed() was wrongly omitted if a socket close function
(CURLOPT_CLOSESOCKETFUNCTION) is registered.

That would lead to not removing the socket from the internal hash table
and not calling the multi socket callback appropriately.

Bug: http://curl.haxx.se/bug/view.cgi?id=1493

... and as a consequence, introduce curl_printf.h with that re-define
magic instead and make all libcurl code use that instead.

... even if the last IPv6 connection attempt has failed.

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1187531#c4

... in case the protocol versions are mixed in a DNS response
(IPv6 -> IPv4 -> IPv6).

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1187531#c3

Reported-by: Chris Young

For consistency, as we seem to have a bit of a mixed bag, changed all
instances of ipv4 and ipv6 in comments and documentations to use the
correct case.

There was a confusion between these: this commit tries to disambiguate them.
- Scope can be computed from the address itself.
- Scope id is scope dependent: it is currently defined as 1-based local
  interface index for link-local scoped addresses, and as a site index(?) for
  (obsolete) site-local addresses. Linux only supports it for link-local
  addresses.
The URL parser properly parses a scope id as an interface index, but stores it
in a field named "scope": confusion. The field has been renamed into "scope_id".
Curl_if2ip() used the scope id as it was a scope. This caused failures
to bind to an interface.
Scope is now computed from the addresses and Curl_if2ip() matches them.
If redundantly specified in the URL, scope id is check for mismatch with
the interface index.

This commit should fix SF bug #1451.

Otherwise we may read uninitialized bytes later in the unix-domain
sockets case.

This patch prepares for adding UNIX domain sockets support.

TCP_NODELAY and TCP_KEEPALIVE are specific to TCP/IP sockets, so do not
apply these to other socket types. bindlocal only works for IP sockets
(independent of TCP/UDP), so filter that out too for other types.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>

When the connection code decides to close a socket it informs the multi
system via the Curl_multi_closed function. The multi system may, in
turn, invoke the CURLMOPT_SOCKETFUNCTION function with
CURL_POLL_REMOVE. This happens after the socket has already been
closed. Reorder the code so that CURL_POLL_REMOVE is called before the
socket is closed.

Debug output 'typo' fix.

Don't print an extra "0x" in
  * Pipe broke: handle 0x0x2546d88, url = /

Add debug output.
Print the number of connections in the connection cache when
  adding one, and not only when one is removed.

Fix typos in comments.

warning: unused parameter 'reason'

... for the local variable name in functions holding the return
code. Using the same name universally makes code easier to read and
follow.

Also, unify code for checking for CURLcode errors with:

 if(result) or if(!result)

instead of

 if(result == CURLE_OK), if(CURLE_OK == result) or if(result != CURLE_OK)

cppcheck pointed these out.

cppcheck pointed this out.

Coverity pointed out several of these.

Introducing Curl_expire_latest(). To be used when we the code flow only
wants to get called at a later time that is "no later than X" so that
something can be checked (and another timeout be added).

The low-speed logic for example could easily be made to set very many
expire timeouts if it would be called faster or sooner than what it had
set its own timer and this goes for a few other timers too that aren't
explictiy checked for timer expiration in the code.

If there's no condition the code that says if(time-passed >= TIME), then
Curl_expire_latest() is preferred to Curl_expire().

If there exists such a condition, it is on the other hand important that
Curl_expire() is used and not the other.

Bug: http://curl.haxx.se/mail/lib-2014-06/0235.html
Reported-by: Florian Weimer

A conditionally compiled block in connect.c references WinSock 2
symbols, but used `#ifdef HAVE_WINSOCK_H` instead of `#ifdef
HAVE_WINSOCK2_H`.

Bug: http://curl.haxx.se/mail/lib-2014-08/0155.html

... pointed out by MSVC2013

Bug: http://curl.haxx.se/bug/view.cgi?id=1391

Make all code use connclose() and connkeep() when changing the "close
state" for a connection. These two macros take a string argument with an
explanation, and debug builds of curl will include that in the debug
output. Helps tracking connection re-use/close issues.

In commit 0b3750b5 (released in 7.36.0) we fixed a timeout issue
but instead broke the timings.

To fix this, I introduce a new timestamp to use for the timeouts and
restored the previous timestamp and timestamp position so that the old
timer functionality is restored.

In addition to that, that change also broke connection timeouts for when
more than one connect was used (as it would then count the total time
from the first connect and not for the most recent one). Now
Curl_timeleft() has been modified so that it checks against different
start times depending on which timeout it checks.

Test 1303 is updated accordingly.

Bug: http://curl.haxx.se/mail/lib-2014-05/0147.html
Reported-by: Ryan Braud

In case the first address in the tempaddr array is NULL,
the code would previously dereference an unchecked null pointer.

It leads to the "next family" tries starting from the wrong point and thus
fails!

Bug: http://curl.haxx.se/bug/view.cgi?id=1337
Reported-by: ricker

A follow up patch to commit d2671340 as _WIN32_WINNT_WIN2K and
_WIN32_WINNT_WIN2K may not be defined on all systems.

Following some auto build failures after commit c7a76bb0 changed
the preprocessor check to use _WIN32_WINNT.

Starting with Visual Studio 2013 (VC12) and Windows 8.1 the
GetVersionInfoEx() function has been marked as deprecated and it's
return value atered. Updated connect.c and curl_sspi.c to use
VerifyVersionInfo() where possible, which has been available since
Windows 2000.

With the recently added timeout "reminder" functionality, there's no
reason left for us to execute timeout code before the time is
ripe. Simplifies the handling too.

This will make the *TIMEOUT and *CONNECTTIMEOUT options more accurate
again, which probably is most important when the *_MS versions are used.

In multi_socket, make sure to update 'now' after having handled activity
on a socket.

getpeername() doesn't work for UDP sockets since they're not connected

Reported-by: Priyanka Shah
Bug: http://curl.haxx.se/mail/archive-2014-01/0016.html