Add a utility function extract_classless_route() and

use it to simplify logic at both places that process
RFC 3442 data.

3 files changed, 55 insertions, 51 deletions

diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index 1bfa93ac545..8543adae8c3 100644
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcpd.h,v 1.224 2017/08/28 17:33:42 krw Exp $	*/
+/*	$OpenBSD: dhcpd.h,v 1.225 2017/08/29 13:21:30 krw Exp $	*/
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -233,6 +233,8 @@ void		 read_client_conf(char *);
 void		 read_client_leases(char *, struct client_lease_tq *);
 
 /* kroute.c */
+int		 extract_classless_route(uint8_t *, unsigned int,
+	in_addr_t *, in_addr_t *, in_addr_t *);
 void		 delete_address(struct in_addr);
 void		 set_resolv_conf(char *, uint8_t *, unsigned int,
     uint8_t *, unsigned int);
diff --git a/sbin/dhclient/kroute.c b/sbin/dhclient/kroute.c
index 4af542eedcf..0f90ff5a14e 100644
--- a/sbin/dhclient/kroute.c
+++ b/sbin/dhclient/kroute.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kroute.c,v 1.142 2017/08/26 18:52:56 krw Exp $	*/
+/*	$OpenBSD: kroute.c,v 1.143 2017/08/29 13:21:30 krw Exp $	*/
 
 /*
  * Copyright 2012 Kenneth R Westerback <krw@openbsd.org>
@@ -163,40 +163,51 @@ priv_flush_routes(int index, int routefd, int rdomain)
 	free(buf);
 }
 
+int
+extract_classless_route(uint8_t *rtstatic, unsigned int rtstatic_len,
+    in_addr_t *dest, in_addr_t *netmask, in_addr_t *gateway)
+{
+	unsigned int	 bits, bytes, len;
+
+	if (rtstatic[0] > 32)
+		return -1;
+
+	bits = rtstatic[0];
+	bytes = (bits + 7) / 8;
+	len = 1 + bytes + sizeof(*gateway);
+	if (len > rtstatic_len)
+		return -1;
+
+	memcpy(dest, &rtstatic[1], bytes);
+	if (bits == 0)
+		*netmask = INADDR_ANY;
+	else
+		*netmask = htonl(0xffffffff << (32 - bits));
+	*dest &= *netmask;
+	memcpy(gateway, &rtstatic[1 +  bytes], sizeof(*gateway));
+
+	return len;
+}
+
 void
 set_routes(struct in_addr addr, struct in_addr addrmask, uint8_t *rtstatic,
     unsigned int rtstatic_len)
 {
 	const struct in_addr	 any = { INADDR_ANY };
 	struct in_addr		 dest, gateway, netmask;
-	unsigned int		 i, bits, bytes;
+	unsigned int		 i;
+	int			 len;
 
 	flush_routes();
 
 	/* Add classless static routes. */
 	i = 0;
 	while (i < rtstatic_len) {
-		bits = rtstatic[i++];
-		bytes = (bits + 7) / 8;
-
-		if (bytes > sizeof(netmask.s_addr))
-			return;
-		else if (i + bytes > rtstatic_len)
-			return;
-
-		if (bits != 0)
-			netmask.s_addr = htonl(0xffffffff << (32 - bits));
-		else
-			netmask.s_addr = INADDR_ANY;
-
-		memcpy(&dest, &rtstatic[i], bytes);
-		dest.s_addr = dest.s_addr & netmask.s_addr;
-		i += bytes;
-
-		if (i + sizeof(gateway) > rtstatic_len)
+		len = extract_classless_route(&rtstatic[i], rtstatic_len - i,
+		    &dest.s_addr, &netmask.s_addr, &gateway.s_addr);
+		if (len <= 0)
 			return;
-		memcpy(&gateway.s_addr, &rtstatic[i], sizeof(gateway.s_addr));
-		i += sizeof(gateway.s_addr);
+		i += len;
 
 		if (gateway.s_addr == INADDR_ANY) {
 			/*
diff --git a/sbin/dhclient/options.c b/sbin/dhclient/options.c
index 9f84615b3e0..24ac6d64ce0 100644
--- a/sbin/dhclient/options.c
+++ b/sbin/dhclient/options.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: options.c,v 1.102 2017/08/28 17:33:42 krw Exp $	*/
+/*	$OpenBSD: options.c,v 1.103 2017/08/29 13:21:30 krw Exp $	*/
 
 /* DHCP options parsing and reassembly. */
 
@@ -588,43 +588,34 @@ pretty_print_classless_routes(unsigned char *src, size_t srclen,
     unsigned char *buf, size_t buflen)
 {
 	char		 bitsbuf[5];	/* to hold "/nn " */
-	struct in_addr	 net, gateway;
-	unsigned int	 bytes;
-	int		 bits, rslt;
-
-	while (srclen) {
-		bits = *src;
-		src++;
-		srclen--;
-
-		bytes = (bits + 7) / 8;
-		if (srclen < (bytes + sizeof(gateway.s_addr)) ||
-		    bytes > sizeof(net.s_addr))
-			goto toobig;
-		rslt = snprintf(bitsbuf, sizeof(bitsbuf), "/%d ", bits);
+	struct in_addr	 dest, netmask, gateway;
+	unsigned int	 i;
+	int		 len, rslt;
+
+	i = 0;
+	while (i < srclen) {
+		len = extract_classless_route(&src[i], srclen - i,
+		    &dest.s_addr, &netmask.s_addr, &gateway.s_addr);
+		if (len <= 0)
+			goto bad;
+		i += len;
+
+		rslt = snprintf(bitsbuf, sizeof(bitsbuf), "/%d ",
+		    33 - ffs(netmask.s_addr));
 		if (rslt == -1 || (unsigned int)rslt >= sizeof(bitsbuf))
-			goto toobig;
-
-		memset(&net, 0, sizeof(net));
-		memcpy(&net.s_addr, src, bytes);
-		src += bytes;
-		srclen -= bytes;
-
-		memcpy(&gateway.s_addr, src, sizeof(gateway.s_addr));
-		src += sizeof(gateway.s_addr);
-		srclen -= sizeof(gateway.s_addr);
+			goto bad;
 
 		if (strlen(buf) > 0)
 			strlcat(buf, ", ", buflen);
-		strlcat(buf, inet_ntoa(net), buflen);
+		strlcat(buf, inet_ntoa(dest), buflen);
 		strlcat(buf, bitsbuf, buflen);
 		if (strlcat(buf, inet_ntoa(gateway), buflen) >= buflen)
-			goto toobig;
+			goto bad;
 	}
 
 	return;
 
-toobig:
+bad:
 	memset(buf, 0, buflen);
 }