dhclient: add ability to ignore options in offers

A machine might exist on multiple networks, all of which offer, say, default
routes or name servers. There's no easy way to indicate in the config
that those options are only valid for a single interface.

Now, we can write:

    interface "lan0" {
      request routers;
      require routers;
    }
    interface "lan1" {
      ignore routers;
    }

And only take action on default routes offered on lan0.

Tested by:	Jose Luis Duran <jlduran at gmail dot com>
MFC after:	2 months
Reviewed by:	allanjude, imp
Sponsored by:	Zenith Electronics LLC
Sponsored by:	Klara, Inc.
Pull Request:	#693

1 files changed, 11 insertions, 2 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index da9a567fad04..4261251b6b78 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1039,7 +1039,6 @@ dhcpoffer(struct packet *packet)
 
 	note("%s from %s", name, piaddr(packet->client_addr));
 
-
 	/* If this lease doesn't supply the minimum required parameters,
 	   blow it off. */
 	for (i = 0; ip->client->config->required_options[i]; i++) {
@@ -1141,8 +1140,9 @@ dhcpoffer(struct packet *packet)
 struct client_lease *
 packet_to_lease(struct packet *packet)
 {
+	struct interface_info *ip = packet->interface;
 	struct client_lease *lease;
-	int i;
+	int i, j;
 
 	lease = malloc(sizeof(struct client_lease));
 
@@ -1156,6 +1156,15 @@ packet_to_lease(struct packet *packet)
 	/* Copy the lease options. */
 	for (i = 0; i < 256; i++) {
 		if (packet->options[i].len) {
+			int ignored = 0;
+			for (j = 0; ip->client->config->ignored_options[j]; j++)
+				if (i ==
+				    ip->client->config->ignored_options[j]) {
+					ignored = 1;
+					break;
+				}
+			if (ignored)
+			    continue;
 			lease->options[i].data =
 			    malloc(packet->options[i].len + 1);
 			if (!lease->options[i].data) {