radix: fix ipv6 address parsing warning

The check meant to see if the ip address part of the ip/cidr combo
was more specific than needed wasn't fully implemented, leading to
warnings being issued on completely valid and correct input.

This patch implements the same logic as in IPv4. If the ip address
as specified is different from the ip after the mask has been applied,
a warning is displayed.

Bug: #5747.

src/util-radix-tree.c

@@ -1058,14 +1058,19 @@ SCRadixNode *SCRadixAddKeyIPV6String(const char *str, SCRadixTree *tree, void *u
     }
 
     if (netmask != 128) {
-        struct in6_addr mask6;
+        struct in6_addr mask6, check;
         CIDRGetIPv6(netmask, &mask6);
+        memcpy(&check, &addr, sizeof(check));
+        bool diff = false;
         for (int i = 0; i < 16; i++) {
             addr.s6_addr[i] &= mask6.s6_addr[i];
+            diff |= (addr.s6_addr[i] != check.s6_addr[i]);
         }
+        if (diff) {
             char nstr[64];
             PrintInet(AF_INET6, (void *)&addr.s6_addr, nstr, sizeof(nstr));
             SCLogWarning(SC_ERR_INVALID_IP_NETBLOCK, "adding '%s' as '%s/%u'", str, nstr, netmask);
+        }
 #if defined(DEBUG_VALIDATION) || defined(UNITTESTS)
         SCRadixValidateIPv6Key((uint8_t *)&addr.s6_addr, netmask);
 #endif