From: Roy Marples <roy@marples.name>
Date: Wed, 14 May 2008 09:07:54 +0000 (+0000)
Subject: If we have space, ensure our packet options are correctly terminated.
X-Git-Tag: v4.0.2~414
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=52eedd1bc7e1f0cb7eeabd43118d22c86a63401d;p=thirdparty%2Fdhcpcd.git

If we have space, ensure our packet options are correctly terminated.
---

diff --git a/client.c b/client.c
index af0d8169..1227c6b8 100644
--- a/client.c
+++ b/client.c
@@ -1185,6 +1185,8 @@ handle_packet(struct if_state *state, const struct options *options)
 {
 	struct interface *iface = state->interface;
 	struct dhcp_message *dhcp;
+	uint8_t *p;
+	ssize_t bytes;
 
 	/* Allocate our buffer space for BPF.
 	 * We cannot do this until we have opened our socket as we don't
@@ -1199,13 +1201,11 @@ handle_packet(struct if_state *state, const struct options *options)
 	 * the first one fails for any reason, we can use the next. */
 
 	dhcp = xmalloc(sizeof(*dhcp));
-
 	do {
-		if (get_packet(iface, (uint8_t *)dhcp,
-			       state->buffer,
-			       &state->buffer_len, &state->buffer_pos) == -1)
+		bytes = get_packet(iface, (uint8_t *)dhcp, state->buffer,
+				   &state->buffer_len, &state->buffer_pos);
+		if (bytes == -1)
 			break;
-
 		if (dhcp->cookie != htonl(MAGIC_COOKIE)) {
 			logger(LOG_DEBUG, "bogus cookie, ignoring");
 			continue;
@@ -1217,6 +1217,15 @@ handle_packet(struct if_state *state, const struct options *options)
 			       dhcp->xid, state->xid);
 			continue;
 		}
+		/* We should ensure that the packet is terminated correctly
+		 * if we have space for the terminator */
+		if ((size_t)bytes < sizeof(struct dhcp_message)) {
+			p = (uint8_t *)dhcp + bytes - 1;
+			while (p > dhcp->options && *p == DHCP_PAD)
+				p--;
+			if (*p != DHCP_END)
+				*++p = DHCP_END;
+		}
 		if (handle_dhcp(state, &dhcp, options) == 0)
 			return 0;
 	} while (state->buffer_pos != 0);