+/* DHCP options */
+enum dhcp_options {
+ DHCP_PAD = 0,
+ DHCP_NETMASK = 1,
+ DHCP_ROUTERS = 3,
+ DHCP_DNS = 6,
+ DHCP_END = 255,
+};
+
+#define DHCP_COOKIE 0x63825363
+#define DHCP_COOKIE_SIZE 4
+
+/*
+ * Process the bootp reply packet's vendor extensions.
+ * Vendor extensions are detailed in: http://www.faqs.org/rfcs/rfc1084.html
+ */
+static void
+extract_vendor_options(struct bootp_packet *packet, struct boot_fspec_t *result)
+{
+ int i = 0;
+ __u32 cookie;
+ __u8 *options = &packet->options[0];
+
+ memcpy(&cookie, &options[i], DHCP_COOKIE_SIZE);
+
+ if (cookie != DHCP_COOKIE) {
+ prom_printf("EEEK! cookie is fubar got %08x expected %08x\n",
+ cookie, DHCP_COOKIE);
+ return;
+ }
+
+ i += DHCP_COOKIE_SIZE;
+
+ /* FIXME: It may be possible to run off the end of a packet here /if/
+ * it's malformed. :( */
+ while (options[i] != DHCP_END) {
+ __u8 tag = options[i++], len;
+ __u32 value;
+
+ if (tag == DHCP_PAD)
+ continue;
+
+ len = options[i++];
+ memcpy(&value, &options[i], len);
+
+#if DEBUG
+{
+ DEBUG_F("tag=%2d, len=%2d, data=", tag, len);
+ int j;
+ for (j=0; j<len; j++)
+ prom_printf("%02x", options[i+j]);
+ prom_printf("\n");
+}
+#endif
+
+ switch (tag) {
+ case DHCP_NETMASK:
+ /* FIXME: do we need to grok the subnet mask? */
+ break;
+ case DHCP_ROUTERS:
+ if ((result->giaddr == NULL || *(result->giaddr) == '\x0')
+ && value != 0) {
+ result->giaddr = ipv4_to_str(value);
+ DEBUG_F("Storing %s as gateway from options\n",
+ result->giaddr);
+ }
+ break;
+ }
+ i += len;
+ }
+}
+