Index: dnsrbl.c
diff -u -p dnsrbl.c.orig dnsrbl.c
--- dnsrbl.c.orig	2013-01-20 01:01:15.000000000 +0900
+++ dnsrbl.c	2015-12-24 03:29:26.479821000 +0900
@@ -138,9 +138,15 @@ dnsrbl_check_source(ad, stage, ap, priv)
 	if (dnsrbl_matched(priv, source))
 		return 1;
 
-	/* No IPv6 DNSRBL exists right now */
-	if (sa->sa_family != AF_INET)
+	switch (sa->sa_family) {
+	case AF_INET:
+#ifdef AF_INET6
+	case AF_INET6:
+#endif
+		break;
+	default:
 		return 0;
+	}
 
 	blacklisted = SA(&source->d_blacklisted);
 
@@ -174,8 +180,8 @@ dnsrbl_check_source(ad, stage, ap, priv)
 
 	reverse_endian(SA(&ss), sa);
 
-	if ((iptostring(SA(&ss), salen, req, NS_MAXDNAME)) == NULL){
-		mg_log(LOG_ERR, "iptostring failed: %s", strerror(errno));
+	if ((iptorevstr(SA(&ss), salen, req, NS_MAXDNAME)) == NULL){
+		mg_log(LOG_ERR, "iptorevstr failed: %s", strerror(errno));
 		goto end;
 	}
 
@@ -277,7 +283,6 @@ end:
 }
 
 
-/* XXX this code is probably broken with IPv6 */
 void
 reverse_endian(dst, src)
 	struct sockaddr *src;
@@ -317,6 +322,41 @@ reverse_endian(dst, src)
 	return;
 }
 
+char *
+iptorevstr(sa, salen, buf, buflen)
+	struct sockaddr *sa;
+	socklen_t salen;
+	char *buf;
+	size_t buflen;
+{
+	void *addr;
+	char *addr6;
+	int i;
+
+	switch (sa->sa_family) {
+	case AF_INET:
+		addr = (void *)SADDR4(sa);
+		if (inet_ntop(sa->sa_family, addr, buf, buflen) != NULL)
+			return buf;
+		break;
+#ifdef AF_INET6
+	case AF_INET6:
+		if (buflen < sizeof(struct in6_addr) * 4)
+			break;
+		addr6 = (char *)SADDR6(sa);
+		sprintf(buf, "%x.%x", addr6[i] & 0x0f, (addr6[i] & 0xf0) >> 4);
+		for (i = 1; i < sizeof(struct in6_addr); ++i) {
+			sprintf(buf + i * 4 - 1, ".%x.%x",
+			    addr6[i] & 0x0f, (addr6[i] & 0xf0) >> 4);
+		}
+		return buf;
+#endif
+	default:
+		return NULL;
+	}
+	return NULL;
+}
+
 void	/* acllist must be write locked */
 dnsrbl_source_add(name, domain, blacklisted, cidr) 
 	char *name;
Index: dnsrbl.h
diff -u dnsrbl.h.orig dnsrbl.h
--- dnsrbl.h.orig	2007-11-07 09:02:27.000000000 +0900
+++ dnsrbl.h	2015-12-24 03:26:03.856861429 +0900
@@ -55,6 +55,7 @@
 int dnsrbl_check_source(acl_data_t *, acl_stage_t,
 			struct acl_param *, struct mlfi_priv *);
 void reverse_endian(struct sockaddr *, struct sockaddr *);
+char *iptorevstr((struct sockaddr *, socklen_t, char *, size_t);
 void dnsrbl_source_add(char *, char *, struct sockaddr *, int);
 struct dnsrbl_entry *dnsrbl_byname(char *);
 void dnsrbl_clear(void);