Move checking for V4-mapped addresses to util.c.

filter.c

@@ -24,15 +24,12 @@ THE SOFTWARE.
 #include "util.h"
 #include "filter.h"
 
-static unsigned char v4prefix[16] =
-    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0, 0, 0, 0 };
-
 int
 import_filter(const unsigned char *id,
               const unsigned char *prefix, unsigned short plen,
               const unsigned char *nexthop)
 {
-    if(plen >= 96 && in_prefix(prefix, v4prefix, 96))
+    if(plen >= 96 && v4mapped(prefix))
         return 1;
 
     return 0;

util.c

@@ -275,3 +275,12 @@ martian_prefix(const unsigned char *prefix, int plen)
         (plen >= 10 && prefix[0] == 0xFE && (prefix[1] & 0xC0) == 0x80) ||
         (plen >= 128 && memcmp(prefix, zeroes, 16) == 0);
 }
+
+static unsigned char v4prefix[16] =
+    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0, 0, 0, 0 };
+
+int
+v4mapped(const unsigned char *address)
+{
+    return in_prefix(address, v4prefix, 96);
+}

util.h

@@ -49,6 +49,7 @@ int parse_address(const char *address, unsigned char *addr_r);
 int parse_net(const char *net, unsigned char *prefix_r, unsigned char *plen_r);
 int wait_for_fd(int direction, int fd, int msecs);
 int martian_prefix(const unsigned char *prefix, int plen);
+int v4mapped(const unsigned char *address);
 
 /* If debugging is disabled, we want to avoid calling format_address
    for every omitted debugging message.  So debug is a macro.  But