Use a udp socket to communicate with the dhcp servers. The bpf interface

can't be used to forward the packets. Bpf would relay the packets to wrong
interface. Reports and tests by Hans Kremers and Colin Harford
OK henning@

1 files changed, 73 insertions, 5 deletions

diff --git a/usr.sbin/dhcrelay/dhcrelay.c b/usr.sbin/dhcrelay/dhcrelay.c
index 7cf9c1a9a6b..54c2f130f6a 100644
--- a/usr.sbin/dhcrelay/dhcrelay.c
+++ b/usr.sbin/dhcrelay/dhcrelay.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcrelay.c,v 1.21 2004/08/15 23:24:14 jaredy Exp $ */
+/*	$OpenBSD: dhcrelay.c,v 1.22 2004/10/12 16:39:35 claudio Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@cvs.openbsd.org>
@@ -45,6 +45,7 @@ void	 usage(void);
 void	 relay(struct interface_info *, struct dhcp_packet *, int,
 	    unsigned int, struct iaddr, struct hardware *);
 char	*print_hw_addr(int, int, unsigned char *);
+void	 got_response(struct protocol *);
 
 time_t cur_time;
 
@@ -58,15 +59,17 @@ struct interface_info *interfaces = NULL;
 struct server_list {
 	struct server_list *next;
 	struct sockaddr_in to;
+	int fd;
 } *servers;
 
 int
 main(int argc, char *argv[])
 {
-	int			 ch, no_daemon = 0;
+	int			 ch, no_daemon = 0, opt;
 	extern char		*__progname;
 	struct server_list	*sp = NULL;
 	struct passwd		*pw;
+	struct sockaddr_in	 laddr;
 
 	/* Initially, log errors to stderr as well as to syslogd. */
 	openlog(__progname, LOG_NDELAY, DHCPD_LOG_FACILITY);
@@ -135,17 +138,36 @@ main(int argc, char *argv[])
 	if (!sp)
 		usage();
 
+	discover_interfaces(interfaces);
+
+	bzero(&laddr, sizeof laddr);
+	laddr.sin_len = sizeof laddr;
+	laddr.sin_family = AF_INET;
+	laddr.sin_port = server_port;
+	laddr.sin_addr.s_addr = interfaces->primary_address.s_addr;
 	/* Set up the server sockaddrs. */
 	for (sp = servers; sp; sp = sp->next) {
 		sp->to.sin_port = server_port;
 		sp->to.sin_family = AF_INET;
 		sp->to.sin_len = sizeof sp->to;
+		sp->fd = socket(AF_INET, SOCK_DGRAM, 0);
+		if (sp->fd == -1)
+			error("socket: %m");
+		opt = 1;
+		if (setsockopt(sp->fd, SOL_SOCKET, SO_REUSEPORT,
+		    &opt, sizeof(opt)) == -1)
+			error("setsockopt: %m");
+		if (bind(sp->fd, (struct sockaddr *)&laddr, sizeof laddr) == -1)
+			error("bind: %m");
+		if (connect(sp->fd, (struct sockaddr *)&sp->to,
+		    sizeof sp->to) == -1)
+			error("connect: %m");
+		add_protocol("server", sp->fd, got_response, sp);
 	}
 
 	tzset();
 
 	time(&cur_time);
-	discover_interfaces(interfaces);
 	bootp_packet_handler = relay;
 	if (!no_daemon)
 		daemon(0, 0);
@@ -209,6 +231,11 @@ relay(struct interface_info *ip, struct dhcp_packet *packet, int length,
 		return;
 	}
 
+	if (ip == NULL) {
+		note("ignoring non BOOTREPLY form server");
+		return;
+	}
+
 	/* If giaddr is set on a BOOTREQUEST, ignore it - it's already
 	   been gatewayed. */
 	if (packet->giaddr.s_addr) {
@@ -225,8 +252,7 @@ relay(struct interface_info *ip, struct dhcp_packet *packet, int length,
 	/* Otherwise, it's a BOOTREQUEST, so forward it to all the
 	   servers. */
 	for (sp = servers; sp; sp = sp->next) {
-		if (send_packet(interfaces, packet, length,
-		    ip->primary_address, &sp->to, NULL) != -1) {
+		if (send(sp->fd, packet, length, 0) != -1) {
 			debug("forwarded BOOTREQUEST for %s to %s",
 			    print_hw_addr(packet->htype, packet->hlen,
 			    packet->chaddr), inet_ntoa(sp->to.sin_addr));
@@ -275,3 +301,45 @@ bad:
 	return habuf;
 
 }
+
+void
+got_response(struct protocol *l)
+{
+	ssize_t result;
+	struct iaddr ifrom;
+	union {
+		/*
+		 * Packet input buffer.  Must be as large as largest
+		 * possible MTU.
+		 */
+		unsigned char packbuf[4095];
+		struct dhcp_packet packet;
+	} u;
+	struct server_list *sp = l->local;
+
+	if ((result = recv(l->fd, u.packbuf, sizeof(u), 0)) == -1 &&
+	    errno != ECONNREFUSED) {
+		/*
+		 * Ignore ECONNREFUSED as to many dhcp server send a bogus
+		 * icmp unreach for every request.
+		 */
+		warn("recv failed for %s: %m",
+		    inet_ntoa(sp->to.sin_addr));
+		return;
+	}
+	if (result == 0)
+		return;
+
+	if (result < BOOTP_MIN_LEN) {
+		note("Discarding packet with invalid size.");
+		return;
+	}
+
+	if (bootp_packet_handler) {
+		ifrom.len = 4;
+		memcpy(ifrom.iabuf, &sp->to.sin_addr, ifrom.len);
+
+		(*bootp_packet_handler)(NULL, &u.packet, result,
+		    sp->to.sin_port, ifrom, NULL);
+	}
+}