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/* libdhcp/dhcp_common.c - Base definitions for the DHCP protocol
*
* Copyright (C) 2025 Luke T. Shumaker <lukeshu@lukeshu.com>
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#include "dhcp_common.h"
/**
* DHCP Options
* https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml#options
*/
bool dhcp_opt_length_is_valid(uint8_t opt, uint16_t len) {
switch (opt) {
/* RFC 2132 */
case DHCP_OPT_PAD: return len == 0;
case DHCP_OPT_SUBNET_MASK: return len == 4;
case DHCP_OPT_TIME_OFFSET: return len == 4;
case DHCP_OPT_ROUTER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_TIME_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_NAME_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_DOMAIN_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_LOG_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_QUOTES_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_LPR_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_IMPRESS_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_RLP_SERVER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_HOSTNAME: return len >= 1;
case DHCP_OPT_BOOT_FILE_SIZE: return len == 2;
case DHCP_OPT_MERIT_DUMP_FILE: return len >= 1;
case DHCP_OPT_DOMAIN_NAME: return len >= 1;
case DHCP_OPT_SWAP_SERVER: return len == 4; /* IANA says length is "N", but RFC 2132 says "length is 4"; likely releated to errata ID 487 */
case DHCP_OPT_ROOT_PATH: return len >= 1;
case DHCP_OPT_EXTENSION_FILE: return len >= 1;
case DHCP_OPT_FORWARD_ONOFF: return len == 1;
case DHCP_OPT_SRCRTE_ONOFF: return len == 1;
case DHCP_OPT_POLICY_FILTER: return len >= 8 && len % 8 == 0;
case DHCP_OPT_MAX_DG_ASSEMBLY: return len == 2;
case DHCP_OPT_DEFAULT_IP_TTL: return len == 1;
case DHCP_OPT_MTU_TIMEOUT: return len == 4;
case DHCP_OPT_MTU_PLATEAU: return len >= 2 && len % 2 == 0;
case DHCP_OPT_MTU_INTERFACE: return len == 2;
case DHCP_OPT_MTU_SUBNET: return len == 1;
case DHCP_OPT_BROADCAST_ADDRESS: return len == 4;
case DHCP_OPT_MASK_DISCOVERY: return len == 1;
case DHCP_OPT_MASK_SUPPLIER: return len == 1;
case DHCP_OPT_ROUTER_DISCOVERY: return len == 1;
case DHCP_OPT_ROUTER_REQUEST: return len == 4;
case DHCP_OPT_STATIC_ROUTE: return len >= 8 && len % 8 == 0;
case DHCP_OPT_TRAILERS: return len == 1;
case DHCP_OPT_ARP_TIMEOUT: return len == 4;
case DHCP_OPT_ETHERNET: return len == 1;
case DHCP_OPT_DEFAULT_TCP_TTL: return len == 1;
case DHCP_OPT_KEEPALIVE_TIME: return len == 4;
case DHCP_OPT_KEEPALIVE_DATA: return len == 1;
case DHCP_OPT_NIS_DOMAIN: return len >= 1;
case DHCP_OPT_NIS_SERVERS: return len >= 4 && len % 4 == 0;
case DHCP_OPT_NTP_SERVERS: return len >= 4 && len % 4 == 0;
case DHCP_OPT_VENDOR_SPECIFIC: return len >= 1;
case DHCP_OPT_NETBIOS_NAME_SRV: return len >= 4 && len % 4 == 0;
case DHCP_OPT_NETBIOS_DIST_SRV: return len >= 4 && len % 4 == 0;
case DHCP_OPT_NETBIOS_NODE_TYPE: return len == 1;
case DHCP_OPT_NETBIOS_SCOPE: return len >= 1;
case DHCP_OPT_X_WINDOW_FONT: return len >= 4 && len % 4 == 0;
case DHCP_OPT_X_WINDOW_MANAGER: return len >= 4 && len % 4 == 0;
case DHCP_OPT_ADDRESS_REQUEST: return len == 4;
case DHCP_OPT_ADDRESS_TIME: return len == 4;
case DHCP_OPT_OVERLOAD: return len == 1;
case DHCP_OPT_DHCP_MSG_TYPE: return len == 1;
case DHCP_OPT_DHCP_SERVER_ID: return len == 4;
case DHCP_OPT_PARAMETER_LIST: return len >= 1;
case DHCP_OPT_DHCP_MESSAGE: return len >= 1;
case DHCP_OPT_DHCP_MAX_MSG_SIZE: return len == 2;
case DHCP_OPT_RENEWAL_TIME: return len == 4;
case DHCP_OPT_REBINDING_TIME: return len == 4;
case DHCP_OPT_CLASS_ID: return len >= 1;
case DHCP_OPT_CLIENT_ID: return len >= 2;
/* RFC 2132 */
case DHCP_OPT_END: return len == 0;
/* Unrecognized */
default:
return true;
}
}
/**
* DHCP Message Type 53 Values
* https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml#message-type-53
*/
const char *dhcp_msgtyp_str(uint8_t typ) {
switch (typ) {
case DHCP_MSGTYP_DISCOVER: return "DHCP_MSGTYP_DISCOVER";
case DHCP_MSGTYP_OFFER: return "DHCP_MSGTYP_OFFER";
case DHCP_MSGTYP_REQUEST: return "DHCP_MSGTYP_REQUEST";
case DHCP_MSGTYP_DECLINE: return "DHCP_MSGTYP_DECLINE";
case DHCP_MSGTYP_ACK: return "DHCP_MSGTYP_ACK";
case DHCP_MSGTYP_NAK: return "DHCP_MSGTYP_NAK";
case DHCP_MSGTYP_RELEASE: return "DHCP_MSGTYP_RELEASE";
case DHCP_MSGTYP_INFORM: return "DHCP_MSGTYP_INFORM";
default: return const_byte_str(typ);
}
}
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