Some clients end option 53 buried inside of the packet.

Pointed out on the list by Martin Lorentz

diff --git a/src/lib/dhcp.c b/src/lib/dhcp.c
index cc78947..1ed7491 100644 (file)
--- a/src/lib/dhcp.c
+++ b/src/lib/dhcp.c
@@ -109,6 +109,45 @@ static int dhcp_header_sizes[] = {
 #define DEFAULT_PACKET_SIZE (300)
 #define MAX_PACKET_SIZE (1500 - 40)
 
+static int getcode(const uint8_t *data, size_t data_len, int *code)
+{
+       uint8_t *end, *p;
+
+       end = data + data_len;
+
+       while (p < end) {
+               /*
+                *      End of packet or end of options
+                */
+               if ((p[0] == 0) || (p[0] == 255)) return 0;
+
+               /*
+                *      Not enough room for 0x3501cc
+                */
+               if ((end - p) < 3) return 0; /* t l v */
+
+               /*
+                *      Option is larger than the packet.
+                */
+               if ((p + p[1] + 2) > end) return 0;
+
+               /*
+                *      Found it.  Ensure it's well formed.
+                */
+               if (p[0] == 53) {
+                       if ((p[1] != 1) || (p[2] == 0) || (p[2] > 8)) {
+                               return 0;
+                       }
+                       *code = p[2];
+                       return 1;
+               }
+
+               p += 2 + p[1];
+       }
+
+       return 0;
+}
+
 /*
  *     DHCPv4 is only for IPv4.  Broadcast only works if udpfromto is
  *     defined.
@@ -191,10 +230,20 @@ RADIUS_PACKET *fr_dhcp_recv(int sockfd)
            (packet->data[241] != 1) ||
            (packet->data[242] == 0) ||
            (packet->data[242] > 8)) {
-               fprintf(stderr, "Unknown, or badly formatted DHCP packet\n");
-               rad_free(&packet);
-               return NULL;
+               /*
+                *      Some clients send the packet type buried
+                *      inside of the packet...
+                */
+               if (!getcode(packet->data + 240, packet->data_len - 240,
+                            &packet->code)) {
+                       fprintf(stderr, "Unknown, or badly formatted DHCP packet\n");
+                       rad_free(&packet);
+                       return NULL;
+               }
+       } else {
+               packet->code = packet->data[242];
        }
+       packet->code |= PW_DHCP_OFFSET;
 
        /*
         *      Create a unique vector from the MAC address and the
@@ -209,15 +258,13 @@ RADIUS_PACKET *fr_dhcp_recv(int sockfd)
         */
        memset(packet->vector, 0, sizeof(packet->vector));
        memcpy(packet->vector, packet->data + 28, packet->data[2]);
-       packet->vector[packet->data[2]] = packet->data[242];
+       packet->vector[packet->data[2]] = packet->code & 0xff;
 
        /*
         *      FIXME: for DISCOVER / REQUEST: src_port == dst_port + 1
         *      FIXME: for OFFER / ACK       : src_port = dst_port - 1
         */
 
-       packet->code = PW_DHCP_OFFSET | packet->data[242];
-
        /*
         *      Unique keys are xid, client mac, and client ID?
         */