Proposed patch to getaddrinfo.c to support IPv6 on Windows

I'm proposing this change to /src/port/getaddrinfo.c to support IPv6
under windows.

10a11,14

> * Windows may or may not have these routines, so we handle Windows
special

> * by dynamically checking for their existence. If they already
exist, we

> * use the Windows native routines, but if not, we use our own.

> *

31a36,121

>

> #ifdef WIN32

>

> #define WIN32_LEAN_AND_MEAN

> /* Bring in windows.h for LoadLibrary, FreeLibrary, and GetProcAddress
routines */

> #include <windows.h>

>

> /*

> * The native routines may or may not exist on the Windows platform we
are on,

> * so we dynamically look up the routines, and call them via function
pointers.

> * Here we need to declare what the function pointers look like

> */

> typedef

> int

> (__stdcall * getaddrinfo_ptr_t)(const char * nodename, const char *
servname,

> const struct addrinfo * hints, struct addrinfo ** res);

>

> typedef

> void

> (__stdcall * freeaddrinfo_ptr_t)(struct addrinfo * ai);

>

> typedef

> int

> (__stdcall * getnameinfo_ptr_t)(const struct sockaddr * sa, int salen,

> char * host, int hostlen, char * serv, int servlen, int flags);

>

> /* static pointers to the native Windows IPv6 routines, so we only do
the lookup once. */

> static getaddrinfo_ptr_t getaddrinfo_ptr = NULL;

> static freeaddrinfo_ptr_t freeaddrinfo_ptr = NULL;

> static getnameinfo_ptr_t getnameinfo_ptr = NULL;

>

> static

> bool haveNativeWindowsIPv6routines(void)

> {

> void * hLibrary = NULL;

> static bool alreadyLookedForIpv6routines = FALSE;

>

> if (alreadyLookedForIpv6routines)

> return (getaddrinfo_ptr != NULL);

>

> /*

> * For Windows XP and Windows 2003 (and longhorn/vista), the IPv6

> * routines are present the WinSock 2 library (ws2_32.dll). Try
that first

> */

>

> hLibrary = LoadLibraryA("ws2_32");

>

> if (hLibrary == NULL || GetProcAddress(hLibrary, "getaddrinfo") ==
NULL)

> {

> /* Well, ws2_32 doesn't exist, or more likely doesn't have
getaddrinfo. */

> if (hLibrary != NULL)

> FreeLibrary(hLibrary);

>

> /* In Windows 2000, there was only the IPv6 Technology
Preview

> * look in the IPv6 WinSock library (wship6.dll).

> */

>

> hLibrary = LoadLibraryA("wship6");

> }

>

> /* If hLibrary is null, we couldn't find a dll that supports the
functions */

> if (hLibrary != NULL)

> {

> /* We found a dll, so now get the addresses of the routines
*/

>

> getaddrinfo_ptr = GetProcAddress(hLibrary, "getaddrinfo");

> freeaddrinfo_ptr = GetProcAddress(hLibrary, "freeaddrinfo");

> getnameinfo_ptr = GetProcAddress(hLibrary, "getnameinfo");

>

> /* If any one of the routines is missing, let's play it safe
and ignore them all */

> if (getaddrinfo_ptr == NULL || freeaddrinfo_ptr == NULL ||
getnameinfo_ptr == NULL)

> {

> FreeLibrary(hLibrary);

> hLibrary = NULL;

> getaddrinfo_ptr = NULL;

> freeaddrinfo_ptr = NULL;

> getnameinfo_ptr = NULL;

> }

> }

>

> alreadyLookedForIpv6routines = TRUE;

> return (getaddrinfo_ptr != NULL);

> }

> #endif

>

>

49a140,148

> #ifdef WIN32

> /*

> * If Windows has native IPv6 support, use the native Windows
routine.

> * Otherwise, fall through and use our own code.

> */

> if (haveNativeWindowsIPv6routines())

> return (*getaddrinfo_ptr)(node,service,hintp,res);

> #endif

>

162a262,272

> #ifdef WIN32

> /*

> * If Windows has native IPv6 support, use the native
Windows routine.

> * Otherwise, fall through and use our own code.

> */

> if (haveNativeWindowsIPv6routines())

> {

> (*freeaddrinfo_ptr)(node,service,hintp,res);

> return;

> }

> #endif

218a329,338

>

> #ifdef WIN32

> /*

> * If Windows has native IPv6 support, use the native Windows
routine.

> * Otherwise, fall through and use our own code.

> */

> if (haveNativeWindowsIPv6routines())

> return
(*getnameinfo_ptr)(sa,salen,node,nodelen,service,servicelen,flags);

> #endif

>