From f091d59e0f9abec9304d9d230fafc2dec001baba Mon Sep 17 00:00:00 2001
From: Holger Weiss <holger@zedat.fu-berlin.de>
Date: Wed, 13 Jun 2012 12:36:42 +0200
Subject: check_dhcp: Fix handling of "pad" options

Don't let "pad" options[*] terminate the parsing of DHCP options.  This
bug was triggered by using check_dhcp against Windows 2003 DHCP servers
(see #3503921).

[*] Cf. RFC 2132, 3.1.
---
 plugins-root/check_dhcp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'plugins-root')

diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 2a1875c4..ac892747 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -839,8 +839,7 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
 	/* process all DHCP options present in the packet */
 	for(x=4;x<MAX_DHCP_OPTIONS_LENGTH;){
 
-		/* end of options (0 is really just a pad, but bail out anyway) */
-		if((int)offer_packet->options[x]==-1 || (int)offer_packet->options[x]==0)
+		if((int)offer_packet->options[x]==-1)
 			break;
 
 		/* get option type */
@@ -872,7 +871,9 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
 			}
 
 		/* skip option data we're ignoring */
-		if(option_type!=DHCP_OPTION_REBINDING_TIME)
+		if(option_type==0) /* "pad" option, see RFC 2132 (3.1) */
+			x+=1;
+		else
 			x+=option_length;
 		}
 
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