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));