Always record the client identifier used to obtain a lease. Servers

obeying RFC 2131 will never echo the identifier in OFFER/ACK packets.
Servers obeying RFC 6842 will always echo the identifier. Confused
servers may or may not do the echoing.

This permits more reliable association of recorded leases with the MAC
address in use at the time the lease was obtained.

Requested by & ok tb@

1 files changed, 16 insertions, 1 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index 8a8fab3959e..3c0fb4caf58 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.569 2018/05/11 15:44:15 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.570 2018/05/16 19:51:10 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -1270,6 +1270,21 @@ packet_to_lease(struct interface_info *ifi, struct option_data *options)
 		lease->filename[DHCP_FILE_LEN] = '\0';
 	}
 
+	/*
+	 * Record the client identifier used to obtain the lease.  We already
+	 * checked that the packet client identifier is absent (RFC 2131) or
+	 * matches what we sent (RFC 6842),
+	 */
+	i = DHO_DHCP_CLIENT_IDENTIFIER;
+	if (lease->options[i].len == 0 && config->send_options[i].len != 0) {
+		lease->options[i].len = config->send_options[i].len;
+		lease->options[i].data = malloc(lease->options[i].len);
+		if (lease->options[i].data == NULL)
+			fatal("lease client-identifier");
+		memcpy(lease->options[i].data, config->send_options[i].data,
+		    lease->options[i].len);
+	}
+
 	time(&lease->epoch);
 	return lease;