- packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
- for (i = 0; dhcp_options[i].code; i++)
- if (dhcp_options[i].flags & OPTION_REQ)
- packet->options[end + OPT_DATA + len++] = dhcp_options[i].code;
- packet->options[end + OPT_LEN] = len;
- packet->options[end + OPT_DATA + len] = DHCP_END;
+ for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
+ if (((dhcp_options[i].flags & OPTION_REQ)
+ && !client_config.no_default_options)
+ || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
+ ) {
+ packet->options[end + OPT_DATA + len] = c;
+ len++;
+ }
+ }
+ if (len) {
+ packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+ packet->options[end + OPT_LEN] = len;
+ packet->options[end + OPT_DATA + len] = DHCP_END;
+ }
+}
+
+/* RFC 2131
+ * 4.4.4 Use of broadcast and unicast
+ *
+ * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
+ * messages, unless the client knows the address of a DHCP server.
+ * The client unicasts DHCPRELEASE messages to the server. Because
+ * the client is declining the use of the IP address supplied by the server,
+ * the client broadcasts DHCPDECLINE messages.
+ *
+ * When the DHCP client knows the address of a DHCP server, in either
+ * INIT or REBOOTING state, the client may use that address
+ * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
+ * The client may also use unicast to send DHCPINFORM messages
+ * to a known DHCP server. If the client receives no response to DHCP
+ * messages sent to the IP address of a known DHCP server, the DHCP
+ * client reverts to using the IP broadcast address.
+ */