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

... instead of just #if

This workaround fixes an issue on MinGW/Msys regarding the Perl
testsuite scripts not being able to signal or control the server
processes. The MinGW Perl runtime only sees the Msys processes and
their corresponding PIDs, but sockfilt (and other servers) wrote the
Windows PID into their PID-files. Since this PID is useless to the
testsuite, the write_pidfile function was changed to search for the
Msys PID and write that into the PID-file.

3 more bug fixes, 6 more contributors

Reported by: Tomas Mlcoch

... so that it adheres to the API documentation.

Reported by: Tomas Mlcoch

At some point recently we lost the default value for the easy handle's
connection cache, and this change puts it back to 5 - which is the
former default value and it is documented in the curl_easy_setopt.3 man
page.

The new read and write wrapper functions support reading from stdin
and writing to stdout/stderr on Windows by using the appropriate
Windows API functions and data types.

Reported by: Fredrik Thulin

Copy the CURLOPT_MAXCONNECTS option to CURLMOPT_MAXCONNECTS in
curl_easy_perform().

Bug: http://curl.haxx.se/bug/view.cgi?id=1212
Reported-by: Steven Gu

Based on a patch posted to the list by Richard Michael.

Count up numcookies in Curl_cookie_add() only when cookie is new one

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

(This doesn't need to appear in the release notes.)

Patch by: Robert Wruck
Bug: http://curl.haxx.se/bug/view.cgi?id=1209

The last remaining code piece that still used FTPSENDF now uses PPSENDF.
In the problematic case, a PREQUOTE series was done on a re-used
connection when Curl_pp_init() hadn't been called so it had messed up
pointers. The init call is done properly from Curl_pp_sendf() so this
change fixes this particular crash.

Bug: http://curl.haxx.se/mail/lib-2013-03/0319.html
Reported by: Sam Deane