Index: configure
===================================================================
--- configure	(revision 30480)
+++ configure	(working copy)
@@ -3212,6 +3216,51 @@
 fi


+echocheck "struct ipv6_mreq"
+_struct_ipv6_mreq=no
+def_ipv6_mreq="#define HAVE_STRUCT_IPV6_MREQ 0"
+for header in "netinet/in.h" "ws2tcpip.h" ; do
+  cat > $TMPC << EOF
+#include <$header>
+int main(void) { struct ipv6_mreq mreq6; return 0; }
+EOF
+  cc_check && _struct_ipv6_mreq=yes && \
+    def_ipv6_mreq="#define HAVE_STRUCT_IPV6_MREQ 1" && break
+done
+echores "$_struct_ipv6_mreq"
+
+
+echocheck "struct sockaddr_in6"
+_struct_sockaddr_in6=no
+def_sockaddr_in6="#define HAVE_STRUCT_SOCKADDR_IN6 0"
+for header in "netinet/in.h" "ws2tcpip.h" ; do
+  cat > $TMPC << EOF
+#include <$header>
+int main(void) { struct sockaddr_in6 addr; return 0; }
+EOF
+  cc_check && _struct_sockaddr_in6=yes && \
+    def_sockaddr_in6="#define HAVE_STRUCT_SOCKADDR_IN6 1" && break
+done
+echores "$_struct_sockaddr_in6"
+
+
+echocheck "struct sockaddr sa_len"
+_struct_sockaddr_sa_len=no
+def_sockaddr_sa_len="#define HAVE_STRUCT_SOCKADDR_SA_LEN 0"
+cat > $TMPC << EOF
+#if HAVE_WINSOCK2_H
+#include <winsock2.h>
+#else
+#include <sys/types.h>
+#include <sys/socket.h>
+#endif
+int main(void) { const void *p = &((struct sockaddr *)0)->sa_len; return 0; }
+EOF
+cc_check $cc_check_winsock2_h && _struct_sockaddr_sa_len=yes && \
+  def_sockaddr_sa_len="#define HAVE_STRUCT_SOCKADDR_SA_LEN 1"
+echores "$_struct_sockaddr_sa_len"
+
+
 echocheck "arpa/inet.h"
 arpa_inet_h=no
 def_arpa_inet_h='#define HAVE_ARPA_INET_H 0'
@@ -9025,10 +9096,13 @@
 $def_inet6
 $def_inet_aton
 $def_inet_pton
+$def_ipv6_mreq
 $def_live
 $def_nemesi
 $def_network
 $def_smb
+$def_sockaddr_in6
+$def_sockaddr_sa_len
 $def_socklen_t
 $def_vstream
 $def_addrinfo
@@ -9179,8 +9253,6 @@
 #define HAVE_POLL_H 1
 #define HAVE_PPC4XX 0
 #define HAVE_SETMODE 0
-#define HAVE_STRUCT_IPV6_MREQ 1
-#define HAVE_STRUCT_SOCKADDR_IN6 1
 #define HAVE_SYS_SELECT_H 0
 #define HAVE_VFP_ARGS 1
 #define HAVE_VIRTUALALLOC 0