/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * Copyright (c) 2013
 * Guillaume Subiron, Yann Bordenave, Serigne Modou Wagne.
 */

#ifndef SLIRP_IP6_ICMP_H
#define SLIRP_IP6_ICMP_H

/*
 * Interface Control Message Protocol version 6 Definitions.
 * Per RFC 4443, March 2006.
 *
 * Network Discover Protocol Definitions.
 * Per RFC 4861, September 2007.
 */

struct icmp6_echo { /* Echo Messages */
    uint16_t id;
    uint16_t seq_num;
};

union icmp6_error_body {
    uint32_t unused;
    uint32_t pointer;
    uint32_t mtu;
};

/*
 * NDP Messages
 */
struct ndp_rs { /* Router Solicitation Message */
    uint32_t reserved;
};

struct ndp_ra { /* Router Advertisement Message */
    uint8_t chl; /* Cur Hop Limit */
#if (G_BYTE_ORDER == G_BIG_ENDIAN) && !defined(_MSC_VER)
    uint8_t M : 1, O : 1, reserved : 6;
#else
    uint8_t reserved : 6, O : 1, M : 1;
#endif
    uint16_t lifetime; /* Router Lifetime */
    uint32_t reach_time; /* Reachable Time */
    uint32_t retrans_time; /* Retrans Timer */
};

G_STATIC_ASSERT(sizeof(struct ndp_ra) == 12);

struct ndp_ns { /* Neighbor Solicitation Message */
    uint32_t reserved;
    struct in6_addr target; /* Target Address */
};

G_STATIC_ASSERT(sizeof(struct ndp_ns) == 20);

struct ndp_na { /* Neighbor Advertisement Message */
#if (G_BYTE_ORDER == G_BIG_ENDIAN) && !defined(_MSC_VER)
    uint8_t R : 1, /* Router Flag */
        S : 1, /* Solicited Flag */
        O : 1, /* Override Flag */
        reserved_1 : 5;
#else
    uint8_t reserved_1 : 5, O : 1, S : 1, R : 1;
#endif
    uint8_t reserved_2;
    uint16_t reserved_3;
    struct in6_addr target; /* Target Address */
};

G_STATIC_ASSERT(sizeof(struct ndp_na) == 20);

struct ndp_redirect {
    uint32_t reserved;
    struct in6_addr target; /* Target Address */
    struct in6_addr dest; /* Destination Address */
};

G_STATIC_ASSERT(sizeof(struct ndp_redirect) == 36);

/*
 * Structure of an icmpv6 header.
 */
struct icmp6 {
    uint8_t icmp6_type; /* type of message, see below */
    uint8_t icmp6_code; /* type sub code */
    uint16_t icmp6_cksum; /* ones complement cksum of struct */
    union {
        union icmp6_error_body error_body;
        struct icmp6_echo echo;
        struct ndp_rs ndp_rs;
        struct ndp_ra ndp_ra;
        struct ndp_ns ndp_ns;
        struct ndp_na ndp_na;
        struct ndp_redirect ndp_redirect;
    } icmp6_body;
#define icmp6_err icmp6_body.error_body
#define icmp6_echo icmp6_body.echo
#define icmp6_id icmp6_body.echo.id
#define icmp6_seq icmp6_body.echo.seq_num
#define icmp6_nrs icmp6_body.ndp_rs
#define icmp6_nra icmp6_body.ndp_ra
#define icmp6_nns icmp6_body.ndp_ns
#define icmp6_nna icmp6_body.ndp_na
#define icmp6_redirect icmp6_body.ndp_redirect
};

G_STATIC_ASSERT(sizeof(struct icmp6) == 40);

#define ICMP6_MINLEN 4
#define ICMP6_ERROR_MINLEN 8
#define ICMP6_ECHO_MINLEN 8
#define ICMP6_NDP_RS_MINLEN 8
#define ICMP6_NDP_RA_MINLEN 16
#define ICMP6_NDP_NS_MINLEN 24
#define ICMP6_NDP_NA_MINLEN 24
#define ICMP6_NDP_REDIRECT_MINLEN 40

/*
 * NDP Options
 */
SLIRP_PACKED_BEGIN
struct ndpopt {
    uint8_t ndpopt_type; /* Option type */
    uint8_t ndpopt_len; /* /!\ In units of 8 octets */
    union {
        unsigned char linklayer_addr[6]; /* Source/Target Link-layer */
#define ndpopt_linklayer ndpopt_body.linklayer_addr
        SLIRP_PACKED_BEGIN
            struct prefixinfo { /* Prefix Information */
            uint8_t prefix_length;
#if (G_BYTE_ORDER == G_BIG_ENDIAN) && !defined(_MSC_VER)
            uint8_t L : 1, A : 1, reserved1 : 6;
#else
            uint8_t reserved1 : 6, A : 1, L : 1;
#endif
            uint32_t valid_lt; /* Valid Lifetime */
            uint32_t pref_lt; /* Preferred Lifetime */
            uint32_t reserved2;
            struct in6_addr prefix;
        } SLIRP_PACKED_END prefixinfo;
#define ndpopt_prefixinfo ndpopt_body.prefixinfo
        SLIRP_PACKED_BEGIN
            struct rdnss {
            uint16_t reserved;
            uint32_t lifetime;
            struct in6_addr addr;
        } SLIRP_PACKED_END rdnss;
#define ndpopt_rdnss ndpopt_body.rdnss
    } ndpopt_body;
} SLIRP_PACKED_END;

/* NDP options type */
#define NDPOPT_LINKLAYER_SOURCE 1 /* Source Link-Layer Address */
#define NDPOPT_LINKLAYER_TARGET 2 /* Target Link-Layer Address */
#define NDPOPT_PREFIX_INFO 3 /* Prefix Information */
#define NDPOPT_RDNSS 25 /* Recursive DNS Server Address */

/* NDP options size, in octets. */
#define NDPOPT_LINKLAYER_LEN 8
#define NDPOPT_PREFIXINFO_LEN 32
#define NDPOPT_RDNSS_LEN 24

/*
 * Definition of type and code field values.
 * Per https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xml
 * Last Updated 2012-11-12
 */

/* Errors */
#define ICMP6_UNREACH 1 /* Destination Unreachable */
#define ICMP6_UNREACH_NO_ROUTE 0 /* no route to dest */
#define ICMP6_UNREACH_DEST_PROHIB 1 /* com with dest prohibited */
#define ICMP6_UNREACH_SCOPE 2 /* beyond scope of src addr */
#define ICMP6_UNREACH_ADDRESS 3 /* address unreachable */
#define ICMP6_UNREACH_PORT 4 /* port unreachable */
#define ICMP6_UNREACH_SRC_FAIL 5 /* src addr failed */
#define ICMP6_UNREACH_REJECT_ROUTE 6 /* reject route to dest */
#define ICMP6_UNREACH_SRC_HDR_ERROR 7 /* error in src routing header */
#define ICMP6_TOOBIG 2 /* Packet Too Big */
#define ICMP6_TIMXCEED 3 /* Time Exceeded */
#define ICMP6_TIMXCEED_INTRANS 0 /* hop limit exceeded in transit */
#define ICMP6_TIMXCEED_REASS 1 /* ttl=0 in reass */
#define ICMP6_PARAMPROB 4 /* Parameter Problem */
#define ICMP6_PARAMPROB_HDR_FIELD 0 /* err header field */
#define ICMP6_PARAMPROB_NXTHDR_TYPE 1 /* unrecognized Next Header type */
#define ICMP6_PARAMPROB_IPV6_OPT 2 /* unrecognized IPv6 option */

/* Informational Messages */
#define ICMP6_ECHO_REQUEST 128 /* Echo Request */
#define ICMP6_ECHO_REPLY 129 /* Echo Reply */
#define ICMP6_NDP_RS 133 /* Router Solicitation (NDP) */
#define ICMP6_NDP_RA 134 /* Router Advertisement (NDP) */
#define ICMP6_NDP_NS 135 /* Neighbor Solicitation (NDP) */
#define ICMP6_NDP_NA 136 /* Neighbor Advertisement (NDP) */
#define ICMP6_NDP_REDIRECT 137 /* Redirect Message (NDP) */

/*
 * Router Configuration Variables (rfc4861#section-6)
 */
#define NDP_IsRouter 1
#define NDP_AdvSendAdvertisements 1
#define NDP_MaxRtrAdvInterval 600000
#define NDP_MinRtrAdvInterval                                   \
    ((NDP_MaxRtrAdvInterval >= 9) ? NDP_MaxRtrAdvInterval / 3 : \
                                    NDP_MaxRtrAdvInterval)
#define NDP_AdvManagedFlag 0
#define NDP_AdvOtherConfigFlag 0
#define NDP_AdvLinkMTU 0
#define NDP_AdvReachableTime 0
#define NDP_AdvRetransTime 0
#define NDP_AdvCurHopLimit 64
#define NDP_AdvDefaultLifetime ((3 * NDP_MaxRtrAdvInterval) / 1000)
#define NDP_AdvValidLifetime 86400
#define NDP_AdvOnLinkFlag 1
#define NDP_AdvPrefLifetime 14400
#define NDP_AdvAutonomousFlag 1

/* Called from slirp_new, but after other initialization */
void icmp6_post_init(Slirp *slirp);

/* Called from slirp_cleanup */
void icmp6_cleanup(Slirp *slirp);

/* Process an ICMPv6 packet from the guest */
void icmp6_input(struct mbuf *);

/* Send an ICMPv6 error related to the given packet, using the given ICMPv6 type and code, using the given source */
void icmp6_forward_error(struct mbuf *m, uint8_t type, uint8_t code, struct in6_addr *src);

/* Similar to icmp6_forward_error, but use the link-local address as source */
void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code);

/* Forward the ICMP packet to the guest (probably a ping reply) */
void icmp6_reflect(struct mbuf *);

/* Handle ICMP data from the ICMP socket, and forward it to the guest (using so_m as reference) */
void icmp6_receive(struct socket *so);

/* Send a neighbour sollicitation, to resolve the given IPV6 address */
void ndp_send_ns(Slirp *slirp, struct in6_addr addr);

/* Timer handler for router advertisement, to send it and reschedule the timer */
void ra_timer_handler(Slirp *slirp, void *unused);

#endif