diff -Naur dhcpcd-3.0.17.orig/configure.c dhcpcd-3.0.17/configure.c
--- dhcpcd-3.0.17.orig/configure.c	2007-05-14 14:27:21 +0400
+++ dhcpcd-3.0.17/configure.c	2007-05-21 14:54:55 +0400
@@ -620,24 +620,48 @@
 
 	/* Now we have made a resolv.conf we can obtain a hostname if we need one */
 	if (options->dohostname && ! dhcp->hostname) {
-		he = gethostbyaddr (inet_ntoa (dhcp->address),
-							sizeof (struct in_addr), AF_INET);
-		if (he) {
-			dname = he->h_name;
-			while (*dname > 32)
-				dname++;
-			dnamel = dname - he->h_name;
-			memcpy (newhostname, he->h_name, dnamel);
-			newhostname[dnamel] = 0;
+		union {
+			struct sockaddr sa;
+			struct sockaddr_in sin;
+		} su;
+		socklen_t salen;
+		char addr[NI_MAXHOST];
+		struct addrinfo hints, *res;
+		int result;
+
+		salen = sizeof (struct sockaddr);
+		memset (&su.sa, 0, salen);
+		su.sin.sin_family = AF_INET;
+		memcpy (&su.sin.sin_addr, &dhcp->address, sizeof (struct in_addr));
+
+		logger (LOG_DEBUG, "Looking up hostname via DNS");
+		if ((result = getnameinfo (&su.sa, salen, addr, sizeof (addr),
+						 NULL, 0, NI_NAMEREQD)) != 0)
+			logger (LOG_ERR, "Failed to lookup hostname via DNS: %s", gai_strerror (result));
+		else {
+			/* Check for a malicious PTR record */
+			memset (&hints, 0, sizeof (hints));
+			hints.ai_socktype = SOCK_DGRAM;
+			hints.ai_flags = AI_NUMERICHOST;
+			if (getaddrinfo (addr, "0", &hints, &res) == 0) {
+				freeaddrinfo (res);
+				addr[0] = '\0';
+				logger (LOG_ERR, "malicious PTR record detected");
+			} else if (*addr) {
+			    strlcpy(newhostname,addr, sizeof (newhostname));
+			    /* strange logic from upstream was here ... */
+			}
 		}
 	}
 
+
 	gethostname (curhostname, sizeof (curhostname));
 
 	if (options->dohostname
 		|| strlen (curhostname) == 0
 		|| strcmp (curhostname, "(none)") == 0
-		|| strcmp (curhostname, "localhost") == 0)
+		|| strcmp (curhostname, "localhost") == 0
+		|| strcmp (curhostname, "localhost.localdomain") == 0)
 	{
 		if (dhcp->hostname)
 			strlcpy (newhostname, dhcp->hostname, sizeof (newhostname));