Add code to use Windows getaddrinfo and friends if they exist. This

has to be tested dynamically if we want to make portable executables.
Chuck McDevitt and Andrew Dunstan.

src/port/getaddrinfo.c

@@ -8,11 +8,15 @@
  * platform, we'll need to split this file and provide a separate configure
  * test for getnameinfo().
  *
+ * 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.
+ *
  *
  * Copyright (c) 2003-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/port/getaddrinfo.c,v 1.17 2005/07/28 04:03:14 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/port/getaddrinfo.c,v 1.18 2005/08/24 22:13:23 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,6 +33,103 @@
 
 #include "getaddrinfo.h"
 
+
+#ifdef WIN32
+
+#define WIN32_LEAN_AND_MEAN
+
+#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 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 in 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 with 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
+
+
 /*
  * get address info for ipv4 sockets.
  *
@@ -47,6 +148,15 @@ getaddrinfo(const char *node, const char *service,
 			   *psin;
 	struct addrinfo hints;
 
+#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
+
 	if (hintp == NULL)
 	{
 		memset(&hints, 0, sizeof(hints));
@@ -160,6 +270,18 @@ freeaddrinfo(struct addrinfo * res)
 {
 	if (res)
 	{
+#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
+
 		if (res->ai_addr)
 			free(res->ai_addr);
 		free(res);
@@ -188,7 +310,6 @@ gai_strerror(int errcode)
 	}
 
 	return hstrerror(hcode);
-
 #else							/* !HAVE_HSTRERROR */
 
 	switch (errcode)
@@ -216,6 +337,16 @@ getnameinfo(const struct sockaddr * sa, int salen,
 			char *node, int nodelen,
 			char *service, int servicelen, int flags)
 {
+#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
+
 	/* Invalid arguments. */
 	if (sa == NULL || (node == NULL && service == NULL))
 		return EAI_FAIL;