sd-dhcp-client: move magic cookie into DHCPMessage struct

Also move the checking of it to the main message handler, rather than the
options parser.

Fix a bug, so we now drop the packet if any of the magic bytes don't match.
Before we used to only drop the packet if they were all wrong.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 06b2d1c60d..5824e6ee91 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -22,6 +22,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <net/ethernet.h>
+#include <net/if_arp.h>
 #include <sys/param.h>
 #include <sys/ioctl.h>
 
@@ -936,6 +937,11 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                 return 0;
         }
 
+        if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) {
+                log_dhcp_client(client, "not a DHCP message: ignoring");
+                return 0;
+        }
+
         if (message->op != BOOTREPLY) {
                 log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
                 return 0;
@@ -948,6 +954,11 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                 return 0;
         }
 
+        if (message->htype != ARPHRD_ETHER || message->hlen != ETHER_ADDR_LEN) {
+                log_dhcp_client(client, "not an ethernet packet");
+                return 0;
+        }
+
         if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
                    ETH_ALEN)) {
                 log_dhcp_client(client, "received chaddr does not match "