configure: detect IPv6 support on Windows

This patch was "nicked" from the MINGW-packages project by Daniel.

Alexpux/MINGW-packages@9253d0b
Signed-off-by: Johannes Schindelin <[email protected]>

configure.ac

@@ -1083,7 +1083,11 @@ AC_HELP_STRING([--disable-ipv6],[Disable IPv6 support]),
 
   AC_TRY_RUN([ /* is AF_INET6 available? */
 #include <sys/types.h>
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#else
 #include <sys/socket.h>
+#endif
 #include <stdlib.h> /* for exit() */
 main()
 {
@@ -1110,7 +1114,12 @@ if test "$ipv6" = yes; then
   AC_MSG_CHECKING([if struct sockaddr_in6 has sin6_scope_id member])
   AC_TRY_COMPILE([
 #include <sys/types.h>
-#include <netinet/in.h>] ,
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <netinet/in.h>
+#endif] ,
   struct sockaddr_in6 s; s.sin6_scope_id = 0; , have_sin6_scope_id=yes)
   if test "$have_sin6_scope_id" = yes; then
     AC_MSG_RESULT([yes])

m4/curl-functions.m4

@@ -44,6 +44,10 @@ curl_includes_arpa_inet="\
 #ifdef HAVE_ARPA_INET_H
 #  include <arpa/inet.h>
 #endif
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#endif
 /* includes end */"
   AC_CHECK_HEADERS(
     sys/types.h sys/socket.h netinet/in.h arpa/inet.h,
@@ -2098,6 +2102,12 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
         struct addrinfo *ai = 0;
         int error;
 
+        #ifdef HAVE_WINSOCK2_H
+        WSADATA wsa;
+        if (WSAStartup(MAKEWORD(2,2), &wsa))
+                exit(2);
+        #endif
+
         memset(&hints, 0, sizeof(hints));
         hints.ai_flags = AI_NUMERICHOST;
         hints.ai_family = AF_UNSPEC;