Import the OpenBSD dhclient as shipped with OpenBSD-3.7 (the tag

OPENBSD_3_7).

1 files changed, 253 insertions, 0 deletions

diff --git a/sbin/dhclient/packet.c b/sbin/dhclient/packet.c
new file mode 100644
index 0000000..1a22044
--- /dev/null
+++ b/sbin/dhclient/packet.c
@@ -0,0 +1,253 @@
+/*	$OpenBSD: packet.c,v 1.9 2004/05/04 18:58:50 deraadt Exp $	*/
+
+/* Packet assembly code, originally contributed by Archie Cobbs. */
+
+/*
+ * Copyright (c) 1995, 1996, 1999 The Internet Software Consortium.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of The Internet Software Consortium nor the names
+ *    of its contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
+ * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * This software has been written for the Internet Software Consortium
+ * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
+ * Enterprises.  To learn more about the Internet Software Consortium,
+ * see ``http://www.vix.com/isc''.  To learn more about Vixie
+ * Enterprises, see ``http://www.vix.com''.
+ */
+
+#include "dhcpd.h"
+
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <netinet/if_ether.h>
+
+#define ETHER_HEADER_SIZE (ETHER_ADDR_LEN * 2 + sizeof(u_int16_t))
+
+u_int32_t	checksum(unsigned char *, unsigned, u_int32_t);
+u_int32_t	wrapsum(u_int32_t);
+
+void	assemble_ethernet_header(struct interface_info *, unsigned char *,
+	    int *, struct hardware *);
+ssize_t	decode_ethernet_header(struct interface_info *, unsigned char *,
+	    int bufix, struct hardware *);
+
+u_int32_t
+checksum(unsigned char *buf, unsigned nbytes, u_int32_t sum)
+{
+	int i;
+
+	/* Checksum all the pairs of bytes first... */
+	for (i = 0; i < (nbytes & ~1U); i += 2) {
+		sum += (u_int16_t)ntohs(*((u_int16_t *)(buf + i)));
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
+	}
+
+	/*
+	 * If there's a single byte left over, checksum it, too.
+	 * Network byte order is big-endian, so the remaining byte is
+	 * the high byte.
+	 */
+	if (i < nbytes) {
+		sum += buf[i] << 8;
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
+	}
+
+	return (sum);
+}
+
+u_int32_t
+wrapsum(u_int32_t sum)
+{
+	sum = ~sum & 0xFFFF;
+	return (htons(sum));
+}
+
+void
+assemble_hw_header(struct interface_info *interface, unsigned char *buf,
+    int *bufix, struct hardware *to)
+{
+	struct ether_header eh;
+
+	if (to != NULL && to->hlen == 6) /* XXX */
+		memcpy(eh.ether_dhost, to->haddr, sizeof(eh.ether_dhost));
+	else
+		memset(eh.ether_dhost, 0xff, sizeof(eh.ether_dhost));
+	if (interface->hw_address.hlen == sizeof(eh.ether_shost))
+		memcpy(eh.ether_shost, interface->hw_address.haddr,
+		    sizeof(eh.ether_shost));
+	else
+		memset(eh.ether_shost, 0x00, sizeof(eh.ether_shost));
+
+	eh.ether_type = htons(ETHERTYPE_IP);
+
+	memcpy(&buf[*bufix], &eh, ETHER_HEADER_SIZE);
+	*bufix += ETHER_HEADER_SIZE;
+}
+
+void
+assemble_udp_ip_header(unsigned char *buf, int *bufix, u_int32_t from,
+    u_int32_t to, unsigned int port, unsigned char *data, int len)
+{
+	struct ip ip;
+	struct udphdr udp;
+
+	ip.ip_v = 4;
+	ip.ip_hl = 5;
+	ip.ip_tos = IPTOS_LOWDELAY;
+	ip.ip_len = htons(sizeof(ip) + sizeof(udp) + len);
+	ip.ip_id = 0;
+	ip.ip_off = 0;
+	ip.ip_ttl = 16;
+	ip.ip_p = IPPROTO_UDP;
+	ip.ip_sum = 0;
+	ip.ip_src.s_addr = from;
+	ip.ip_dst.s_addr = to;
+
+	ip.ip_sum = wrapsum(checksum((unsigned char *)&ip, sizeof(ip), 0));
+	memcpy(&buf[*bufix], &ip, sizeof(ip));
+	*bufix += sizeof(ip);
+
+	udp.uh_sport = htons(LOCAL_PORT);	/* XXX */
+	udp.uh_dport = port;			/* XXX */
+	udp.uh_ulen = htons(sizeof(udp) + len);
+	memset(&udp.uh_sum, 0, sizeof(udp.uh_sum));
+
+	udp.uh_sum = wrapsum(checksum((unsigned char *)&udp, sizeof(udp),
+	    checksum(data, len, checksum((unsigned char *)&ip.ip_src,
+	    2 * sizeof(ip.ip_src),
+	    IPPROTO_UDP + (u_int32_t)ntohs(udp.uh_ulen)))));
+
+	memcpy(&buf[*bufix], &udp, sizeof(udp));
+	*bufix += sizeof(udp);
+}
+
+ssize_t
+decode_hw_header(unsigned char *buf, int bufix, struct hardware *from)
+{
+	struct ether_header eh;
+
+	memcpy(&eh, buf + bufix, ETHER_HEADER_SIZE);
+
+	memcpy(from->haddr, eh.ether_shost, sizeof(eh.ether_shost));
+	from->htype = ARPHRD_ETHER;
+	from->hlen = sizeof(eh.ether_shost);
+
+	return (sizeof(eh));
+}
+
+ssize_t
+decode_udp_ip_header(unsigned char *buf, int bufix, struct sockaddr_in *from,
+    unsigned char *data, int buflen)
+{
+	struct ip *ip;
+	struct udphdr *udp;
+	u_int32_t ip_len = (buf[bufix] & 0xf) << 2;
+	u_int32_t sum, usum;
+	static int ip_packets_seen;
+	static int ip_packets_bad_checksum;
+	static int udp_packets_seen;
+	static int udp_packets_bad_checksum;
+	static int udp_packets_length_checked;
+	static int udp_packets_length_overflow;
+	int len = 0;
+
+	ip = (struct ip *)(buf + bufix);
+	udp = (struct udphdr *)(buf + bufix + ip_len);
+
+	/* Check the IP header checksum - it should be zero. */
+	ip_packets_seen++;
+	if (wrapsum(checksum(buf + bufix, ip_len, 0)) != 0) {
+		ip_packets_bad_checksum++;
+		if (ip_packets_seen > 4 &&
+		    (ip_packets_seen / ip_packets_bad_checksum) < 2) {
+			note("%d bad IP checksums seen in %d packets",
+			    ip_packets_bad_checksum, ip_packets_seen);
+			ip_packets_seen = ip_packets_bad_checksum = 0;
+		}
+		return (-1);
+	}
+
+	if (ntohs(ip->ip_len) != buflen)
+		debug("ip length %d disagrees with bytes received %d.",
+		    ntohs(ip->ip_len), buflen);
+
+	memcpy(&from->sin_addr, &ip->ip_src, 4);
+
+	/*
+	 * Compute UDP checksums, including the ``pseudo-header'', the
+	 * UDP header and the data.   If the UDP checksum field is zero,
+	 * we're not supposed to do a checksum.
+	 */
+	if (!data) {
+		data = buf + bufix + ip_len + sizeof(*udp);
+		len = ntohs(udp->uh_ulen) - sizeof(*udp);
+		udp_packets_length_checked++;
+		if (len + data > buf + bufix + buflen) {
+			udp_packets_length_overflow++;
+			if (udp_packets_length_checked > 4 &&
+			    (udp_packets_length_checked /
+			    udp_packets_length_overflow) < 2) {
+				note("%d udp packets in %d too long - dropped",
+				    udp_packets_length_overflow,
+				    udp_packets_length_checked);
+				udp_packets_length_overflow =
+				    udp_packets_length_checked = 0;
+			}
+			return (-1);
+		}
+		if (len + data != buf + bufix + buflen)
+			debug("accepting packet with data after udp payload.");
+	}
+
+	usum = udp->uh_sum;
+	udp->uh_sum = 0;
+
+	sum = wrapsum(checksum((unsigned char *)udp, sizeof(*udp),
+	    checksum(data, len, checksum((unsigned char *)&ip->ip_src,
+	    2 * sizeof(ip->ip_src),
+	    IPPROTO_UDP + (u_int32_t)ntohs(udp->uh_ulen)))));
+
+	udp_packets_seen++;
+	if (usum && usum != sum) {
+		udp_packets_bad_checksum++;
+		if (udp_packets_seen > 4 &&
+		    (udp_packets_seen / udp_packets_bad_checksum) < 2) {
+			note("%d bad udp checksums in %d packets",
+			    udp_packets_bad_checksum, udp_packets_seen);
+			udp_packets_seen = udp_packets_bad_checksum = 0;
+		}
+		return (-1);
+	}
+
+	memcpy(&from->sin_port, &udp->uh_sport, sizeof(udp->uh_sport));
+
+	return (ip_len + sizeof(*udp));
+}