From fa97acc108b8cd7a00b9b692991d5f6fb608630e Mon Sep 17 00:00:00 2001
From: Ted Lemon <source@isc.org>
Date: Sun, 8 Jun 1997 03:55:58 +0000
Subject: [PATCH] If the lease we want to give the client is different than the
 one it's asking for, and we recognize the one it's asking for as ours, NAK
 it.

---
 CHANGES          |  3 +++
 includes/dhcpd.h |  3 ++-
 server/dhcp.c    | 50 +++++++++++++++++++++++++++++++++++-------------
 3 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/CHANGES b/CHANGES
index cff17ea91..95e48214f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,9 @@
 
 - Always write out two digits for single-byte quantities in arrays.
 
+- When parsing a lease database, correctly transfer the client
+  hostname and hostname to the memory-resident lease structure.
+
 970605
 
 - Add client-hostname token to lexer so that the parser can use it.
diff --git a/includes/dhcpd.h b/includes/dhcpd.h
index ad84130c2..3b708800a 100644
--- a/includes/dhcpd.h
+++ b/includes/dhcpd.h
@@ -547,7 +547,8 @@ void dhcpinform PROTO ((struct packet *));
 void nak_lease PROTO ((struct packet *, struct iaddr *cip));
 void ack_lease PROTO ((struct packet *, struct lease *, unsigned char, TIME));
 void dhcp_reply PROTO ((struct lease *));
-struct lease *find_lease PROTO ((struct packet *, struct shared_network *));
+struct lease *find_lease PROTO ((struct packet *,
+				 struct shared_network *, int *));
 struct lease *mockup_lease PROTO ((struct packet *,
 				   struct shared_network *,
 				   struct host_decl *));
diff --git a/server/dhcp.c b/server/dhcp.c
index 7823637b7..78c28469f 100644
--- a/server/dhcp.c
+++ b/server/dhcp.c
@@ -42,7 +42,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: dhcp.c,v 1.47 1997/05/09 08:27:14 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: dhcp.c,v 1.48 1997/06/08 03:55:58 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -86,7 +86,7 @@ void dhcp (packet)
 void dhcpdiscover (packet)
 	struct packet *packet;
 {
-	struct lease *lease = find_lease (packet, packet -> shared_network);
+	struct lease *lease = find_lease (packet, packet -> shared_network, 0);
 	struct host_decl *hp;
 
 	note ("DHCPDISCOVER from %s via %s",
@@ -164,6 +164,7 @@ void dhcprequest (packet)
 	struct lease *lease;
 	struct iaddr cip;
 	struct subnet *subnet;
+	int ours = 0;
 
 	if (packet -> options [DHO_DHCP_REQUESTED_ADDRESS].len) {
 		cip.len = 4;
@@ -180,7 +181,7 @@ void dhcprequest (packet)
 	   client. */
 
 	if (subnet)
-		lease = find_lease (packet, subnet -> shared_network);
+		lease = find_lease (packet, subnet -> shared_network, &ours);
 	else
 		lease = (struct lease *)0;
 
@@ -265,6 +266,11 @@ void dhcprequest (packet)
 	   client asked for, don't send it - some other server probably
 	   made the cut. */
 	if (lease && !addr_eq (lease -> ip_addr, cip)) {
+		/* If we found the address the client asked for, but
+                   it wasn't what got picked, the lease belongs to us,
+                   so we can tenuously justify NAKing it. */
+		if (ours)
+			nak_lease (packet, &cip);
 		return;
 	}
 
@@ -289,7 +295,17 @@ void dhcprequest (packet)
 void dhcprelease (packet)
 	struct packet *packet;
 {
-	struct lease *lease = find_lease (packet, packet -> shared_network);
+	struct lease *lease;
+
+	/* DHCPRELEASEmust specify address. */
+	if (!packet -> options [DHO_DHCP_REQUESTED_ADDRESS].len) {
+		return;
+	}
+
+	cip.len = 4;
+	memcpy (cip.iabuf,
+		packet -> options [DHO_DHCP_REQUESTED_ADDRESS].data, 4);
+	lease = find_lease_by_ip_addr (cip);
 
 	note ("DHCPRELEASE of %s from %s via %s",
 	      inet_ntoa (packet -> raw -> ciaddr),
@@ -310,18 +326,19 @@ void dhcprelease (packet)
 void dhcpdecline (packet)
 	struct packet *packet;
 {
-	struct lease *lease = find_lease (packet, packet -> shared_network);
+	struct lease *lease;
 	struct iaddr cip;
 
-	if (packet -> options [DHO_DHCP_REQUESTED_ADDRESS].len) {
-		cip.len = 4;
-		memcpy (cip.iabuf,
-			packet -> options [DHO_DHCP_REQUESTED_ADDRESS].data,
-			4);
-	} else {
-		cip.len = 0;
+	/* DHCPDECLINE must specify address. */
+	if (!packet -> options [DHO_DHCP_REQUESTED_ADDRESS].len) {
+		return;
 	}
 
+	cip.len = 4;
+	memcpy (cip.iabuf,
+		packet -> options [DHO_DHCP_REQUESTED_ADDRESS].data, 4);
+	lease = find_lease_by_ip_addr (cip);
+
 	note ("DHCPDECLINE on %s from %s via %s",
 	      piaddr (cip),
 	      print_hw_addr (packet -> raw -> htype,
@@ -1056,9 +1073,10 @@ void dhcp_reply (lease)
 	lease -> state = (struct lease_state *)0;
 }
 
-struct lease *find_lease (packet, share)
+struct lease *find_lease (packet, share, ours)
 	struct packet *packet;
 	struct shared_network *share;
+	int *ours;
 {
 	struct lease *uid_lease, *ip_lease, *hw_lease;
 	struct lease *lease = (struct lease *)0;
@@ -1140,6 +1158,12 @@ struct lease *find_lease (packet, share)
 	} else
 		ip_lease = (struct lease *)0;
 
+	/* If ip_lease is valid at this point, set ours to one, so that
+	   even if we choose a different lease, we know that the address
+	   the client was requesting was ours, and thus we can NAK it. */
+	if (ip_lease)
+		*ours = 1;
+
 	/* If the requested IP address isn't on the network the packet
 	   came from, or if it's been abandoned, don't use it. */
 	if (ip_lease && (ip_lease -> shared_network != share ||
-- 
2.47.3