Invalid Domain Search option isn't considered as a fatal error

In the original Domain Search option patch, an invalid option value
would cause the whole lease to be rejected. However, DHCP servers who
emit such an invalid value are more common than I thought. With this new
patch, just the option is rejected, not the entire lease.

PR:		bin/163431
Submitted by:	Fabian Keil <fk@fabiankeil.de> (earlier version)
Reviewed by:	Fabian Keil <fk@fabiankeil.de>
Sponsored by:	Yakaz (http://www.yakaz.com)

1 files changed, 17 insertions, 9 deletions

diff --git a/sbin/dhclient/options.c b/sbin/dhclient/options.c
index 3f87028..17643e7 100644
--- a/sbin/dhclient/options.c
+++ b/sbin/dhclient/options.c
@@ -211,7 +211,7 @@ parse_option_buffer(struct packet *packet,
 void
 expand_domain_search(struct packet *packet)
 {
-	int offset, expanded_len;
+	int offset, expanded_len, next_domain_len;
 	struct option_data *option;
 	unsigned char *domain_search, *cursor;
 
@@ -224,9 +224,13 @@ expand_domain_search(struct packet *packet)
 	expanded_len = 0;
 	offset = 0;
 	while (offset < option->len) {
+		next_domain_len = find_search_domain_name_len(option, &offset);
+		if (next_domain_len < 0)
+			/* The Domain Search option value is invalid. */
+			return;
+
 		/* We add 1 for the space between domain names. */
-		expanded_len +=
-		    find_search_domain_name_len(option, &offset) + 1;
+		expanded_len += next_domain_len + 1;
 	}
 	if (expanded_len > 0)
 		/* Remove 1 for the superfluous trailing space. */
@@ -271,8 +275,9 @@ find_search_domain_name_len(struct option_data *option, int *offset)
 			/* This is a pointer to another list of labels. */
 			if (i + 1 >= option->len) {
 				/* The pointer is truncated. */
-				error("Truncated pointer in DHCP Domain "
+				warning("Truncated pointer in DHCP Domain "
 				    "Search option.");
+				return (-1);
 			}
 
 			pointer = ((label_len & ~(0xC0)) << 8) +
@@ -282,8 +287,9 @@ find_search_domain_name_len(struct option_data *option, int *offset)
 				 * The pointer must indicates a prior
 				 * occurance.
 				 */
-				error("Invalid forward pointer in DHCP Domain "
-				    "Search option compression.");
+				warning("Invalid forward pointer in DHCP "
+				    "Domain Search option compression.");
+				return (-1);
 			}
 
 			pointed_len = find_search_domain_name_len(option,
@@ -295,7 +301,9 @@ find_search_domain_name_len(struct option_data *option, int *offset)
 		}
 
 		if (i + label_len >= option->len) {
-			error("Truncated label in DHCP Domain Search option.");
+			warning("Truncated label in DHCP Domain Search "
+			    "option.");
+			return (-1);
 		}
 
 		/*
@@ -308,9 +316,9 @@ find_search_domain_name_len(struct option_data *option, int *offset)
 		i += label_len + 1;
 	}
 
-	error("Truncated DHCP Domain Search option.");
+	warning("Truncated DHCP Domain Search option.");
 
-	return (0);
+	return (-1);
 }
 
 void