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

AF_INET6 may not exist then

Patched-by: Iida Yosiaki
Bug: http://curl.haxx.se/bug/view.cgi?id=1322

warning: 'res' may be used uninitialized in this function

Fixes a bug when all addresses in the first family fail immediately, due
to "Network unreachable" for example, curl would hang and never try the
next address family.

Iterate through all address families when to trying establish the first
connection attempt.

Bug: http://curl.haxx.se/bug/view.cgi?id=1315
Reported-by: Michal Górny and Anthony G. Basile

(bug introduced in 255826c4, never present in a release)

Reported-by: Dima Tisnek
Bug: http://curl.haxx.se/mail/lib-2013-12/0006.html

This fixes a rare Happy Eyeballs bug where if the first IP family runs
out of addresses before the second-family-timer fires, and the second
IP family's first connect fails immediately, no further IPs of the
second family are attempted.

singleipconnect() could return the file descriptor of an open socket
even though the function returned a CURLE_COULDNT_CONNECT error code
from commit ed1662c3 and 02fbc26d.

This could cause tests 19, 704 and 1233 to fail on FreeBSD, AIX and
Solaris.

singleipconnect() did not return the open socket descriptor on some
errors, thereby sometimes causing a socket leak. This patch ensures
the socket is always returned.

The temporary sockets used for Happy Eyeballs were not closed properly,
if curl exited prematurely, which this patch fixes.

This patch adds a 200ms delay between the first and second address
family socket connection attempts.

It also iterates over IP addresses in the order returned by the
system, meaning most dual-stack systems will try IPv6 first.

Additionally, it refactors the connect code, removing most code that
handled synchronous connects. Since all sockets are now non-blocking,
the logic can be made simpler.

No need for a rhs condition on a bitwise compare.

Introduced in commit 7d7df831 curl would loop displaying "Whut?"
if it was trying to connect to an address and port that didn't have
anything listening on it.

This patch fixes a bug in Happy Eyeballs where curl would wait for a
connect response from socket1 before checking socket2.

Also, it updates error messages for failed connections, showing the ip
addresses that failed rather than just the host name repeatedly.

Bug: http://curl.haxx.se/mail/lib-2013-10/0236.html
Reported-by: Paul Marks

This patch invokes two socket connect()s nearly simultaneously, and
the socket that is first connected "wins" and is subsequently used for
the connection. The other is terminated.

There is a very slight IPv4 preference, in that if both sockets connect
simultaneously IPv4 is checked first and thus will win.

This is a regression since the switch to always-multi internally
c4312741.

Test 1316 was modified since we now clearly call the Curl_client_write()
function when doing the LIST transfer part and then the
handler->protocol says FTP and ftpc.transfertype is 'A' which implies
text converting even though that the response is initially a HTTP
CONNECT response in this case.

As a remedy to the problem when a socket gets closed and a new one is
opened with the same file descriptor number and as a result
multi.c:singlesocket() doesn't detect the difference, the new function
Curl_multi_closed() gets told when a socket is closed so that it can be
removed from the socket hash. When the old one has been removed, a new
socket should be detected fine by the singlesocket() on next invoke.

Bug: http://curl.haxx.se/bug/view.cgi?id=1248
Reported-by: Erik Johansson

The code within #ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID wrongly had two
closing braces when it should only have one, so builds without that
define would fail.

Bug: http://curl.haxx.se/mail/lib-2013-05/0000.html

MacOS X doesn't have TCP_KEEPIDLE/TCP_KEEPINTVL but only a single
TCP_KEEPALIVE (see
http://developer.apple.com/library/mac/#DOCUMENTATION/Darwin/Reference/ManPages/man4/tcp.4.html).
Here is a patch for CURLOPT_TCP_KEEPIDLE on OSX platforms.

I am using curl_easy_setopt(CURLOPT_INTERFACE, "if!something") to force
transfers to use a particular interface but the transfer fails with
CURLE_INTERFACE_FAILED, "Failed binding local connection end" if the
interface I specify has no IPv6 address. The cause is as follows:

The remote hostname resolves successfully and has an IPv6 address and an
IPv4 address.

cURL attempts to connect to the IPv6 address first.

bindlocal (in lib/connect.c) fails because Curl_if2ip cannot find an
IPv6 address on the interface.

This is a fatal error in singleipconnect()

This change will make cURL try the next IP address in the list.

Also included are two changes related to IPv6 address scope:

- Filter the choice of address in Curl_if2ip to only consider addresses
with the same scope ID as the connection address (mismatched scope for
local and remote address does not result in a working connection).

- bindlocal was ignoring the scope ID of addresses returned by
Curl_if2ip . Now it uses them.

Bug: http://curl.haxx.se/bug/view.cgi?id=1189

The Microsoft knowledge-base article
http://support.microsoft.com/kb/823764 describes how to use SNDBUF to
overcome a performance shortcoming in winsock, but it doesn't apply to
Windows Vista and later versions. If the described SNDBUF magic is
applied when running on those more recent Windows versions, it seems to
instead have the reversed effect in many cases and thus make libcurl
perform less good on those systems.

This fix thus adds a run-time version-check that does the SNDBUF magic
conditionally depending if it is deemed necessary or not.

Bug: http://curl.haxx.se/bug/view.cgi?id=1188
Reported by: Andrew Kurushin
Tested by: Christian Hägele