[rbldnsd] PATCH: 6to4 and v4-in-v6 - Plea for a new release

[Michael Tokarev]

How about this:

diff --git a/rbldnsd_packet.c b/rbldnsd_packet.c
index 7ee6cb7..b6cc92c 100644
--- a/rbldnsd_packet.c
+++ b/rbldnsd_packet.c
@@ -223,22 +223,20 @@ static void dntoip(struct dnsqinfo *qi, int flags) {
   unsigned qlab = qi->qi_dnlab;

   qi->qi_ip4valid = qlab == 4 && dntoip4addr(q, &qi->qi_ip4);
-  if (qi->qi_ip4valid) {
-    if (flags & DSTF_IP6REV) {
-      /* construct IP4MAPPED address */
-      memcpy(qi->qi_ip6, ip6mapped_pfx, sizeof(ip6mapped_pfx));
-      PACK32(qi->qi_ip6 + sizeof(ip6mapped_pfx), qi->qi_ip4);
-      qi->qi_ip6valid = 1;
-    }
-  }
-  else {
+  if (!qi->qi_ip4valid) {
     qi->qi_ip6valid =
       qlab == 32 && qi->qi_dnlen0 == 64 && dntoip6addr(q, qi->qi_ip6);
-    if (flags & DSTF_IP4REV &&
-       memcmp(qi->qi_ip6, ip6mapped_pfx, sizeof(ip6mapped_pfx)) == 0) {
-      /* construct IP4 from IP4MAPPED */
-      qi->qi_ip4 = unpack32(qi->qi_ip6 + sizeof(ip6mapped_pfx));
+    if (qi->qi_ip6valid && (flags & DSTF_IP4REV)) {
+      if (qi->qi_ip6[0] == 0x20 && qi->qi_ip6[1] == 0x02) {
+        /* construct IP4 from 2002:V4ADDR::/48 6to4 address, RFC3056 */
+        qi->qi_ip4 = unpack32(qi->qi_ip6 + 2);
+        qi->qi_ip4valid = 1;
+    }
+    else if (memcmp(qi->qi_ip6, ip6mapped_pfx, sizeof(ip6mapped_pfx)) == 0)) {
+      /* construct IP4 from IP4MAPPED, ::ffff:V4ADDR */
+      qi->qi_ip4 = unpack32(qi->qi_ip6 + (is6to4 ? 2 : sizeof(ip6mapped_pfx)));
       qi->qi_ip4valid = 1;
+      qi->qi_ip6valid = 0; /* don't bother looking v6 */
     }
   }
 }

(I'm not sure what to do with 2002: prefix wrt ip6valid flag).

Thanks,

/mjt