// SPDX-License-Identifier: MIT
/* nhrp_protocol.h - NHRP protocol definitions
 *
 * Copyright (c) 2007-2012 Timo Teräs <timo.teras@iki.fi>
 */

#ifndef NHRP_PROTOCOL_H
#define NHRP_PROTOCOL_H

#include <stdint.h>

/* NHRP Ethernet protocol number */
#define ETH_P_NHRP				0x2001

/* NHRP Version */
#define NHRP_VERSION_RFC2332			1

/* NHRP Packet Types */
#define NHRP_PACKET_RESOLUTION_REQUEST		1
#define NHRP_PACKET_RESOLUTION_REPLY		2
#define NHRP_PACKET_REGISTRATION_REQUEST	3
#define NHRP_PACKET_REGISTRATION_REPLY		4
#define NHRP_PACKET_PURGE_REQUEST		5
#define NHRP_PACKET_PURGE_REPLY			6
#define NHRP_PACKET_ERROR_INDICATION		7
#define NHRP_PACKET_TRAFFIC_INDICATION		8
#define NHRP_PACKET_MAX				8

/* NHRP Extension Types */
#define NHRP_EXTENSION_FLAG_COMPULSORY		0x8000
#define NHRP_EXTENSION_END			0
#define NHRP_EXTENSION_PAYLOAD			0
#define NHRP_EXTENSION_RESPONDER_ADDRESS	3
#define NHRP_EXTENSION_FORWARD_TRANSIT_NHS	4
#define NHRP_EXTENSION_REVERSE_TRANSIT_NHS	5
#define NHRP_EXTENSION_AUTHENTICATION		7
#define NHRP_EXTENSION_VENDOR			8
#define NHRP_EXTENSION_NAT_ADDRESS		9

/* NHRP Error Indication Codes */
#define NHRP_ERROR_UNRECOGNIZED_EXTENSION	1
#define NHRP_ERROR_LOOP_DETECTED		2
#define NHRP_ERROR_PROTOCOL_ADDRESS_UNREACHABLE	6
#define NHRP_ERROR_PROTOCOL_ERROR		7
#define NHRP_ERROR_SDU_SIZE_EXCEEDED		8
#define NHRP_ERROR_INVALID_EXTENSION		9
#define NHRP_ERROR_INVALID_RESOLUTION_REPLY	10
#define NHRP_ERROR_AUTHENTICATION_FAILURE	11
#define NHRP_ERROR_HOP_COUNT_EXCEEDED		15

/* NHRP CIE Codes */
#define NHRP_CODE_SUCCESS			0
#define NHRP_CODE_ADMINISTRATIVELY_PROHIBITED	4
#define NHRP_CODE_INSUFFICIENT_RESOURCES	5
#define NHRP_CODE_NO_BINDING_EXISTS		11
#define NHRP_CODE_BINDING_NON_UNIQUE		13
#define NHRP_CODE_UNIQUE_ADDRESS_REGISTERED     14

/* NHRP Flags for Resolution request/reply */
#define NHRP_FLAG_RESOLUTION_SOURCE_IS_ROUTER	0x8000
#define NHRP_FLAG_RESOLUTION_AUTHORATIVE	0x4000
#define NHRP_FLAG_RESOLUTION_DESTINATION_STABLE	0x2000
#define NHRP_FLAG_RESOLUTION_UNIQUE		0x1000
#define NHRP_FLAG_RESOLUTION_SOURCE_STABLE	0x0800
#define NHRP_FLAG_RESOLUTION_NAT		0x0002

/* NHRP Flags for Registration request/reply */
#define NHRP_FLAG_REGISTRATION_UNIQUE		0x8000
#define NHRP_FLAG_REGISTRATION_NAT		0x0002

/* NHRP Flags for Purge request/reply */
#define NHRP_FLAG_PURGE_NO_REPLY		0x8000

/* NHRP Authentication extension types (ala Cisco) */
#define NHRP_AUTHENTICATION_PLAINTEXT		0x00000001

/* NHRP Packet Structures */
struct nhrp_packet_header {
	/* Fixed header */
	uint16_t afnum;
	uint16_t protocol_type;
	uint8_t snap[5];
	uint8_t hop_count;
	uint16_t packet_size;
	uint16_t checksum;
	uint16_t extension_offset;
	uint8_t version;
	uint8_t type;
	uint8_t src_nbma_address_len;
	uint8_t src_nbma_subaddress_len;

	/* Mandatory header */
	uint8_t src_protocol_address_len;
	uint8_t dst_protocol_address_len;
	uint16_t flags;
	union {
		uint32_t request_id;
		struct {
			uint16_t code;
			uint16_t offset;
		} error;
	} u;
} __attribute__((packed));

struct nhrp_cie_header {
	uint8_t code;
	uint8_t prefix_length;
	uint16_t unused;
	uint16_t mtu;
	uint16_t holding_time;
	uint8_t nbma_address_len;
	uint8_t nbma_subaddress_len;
	uint8_t protocol_address_len;
	uint8_t preference;
} __attribute__((packed));

struct nhrp_extension_header {
	uint16_t type;
	uint16_t length;
} __attribute__((packed));

struct nhrp_cisco_authentication_extension {
	uint32_t type;
	uint8_t secret[8];
} __attribute__((packed));

#endif
