icmp.h

#ifndef CURO_ICMP_H
#define CURO_ICMP_H

#include <iostream>

#define ICMP_TYPE_ECHO_REPLY 0
#define ICMP_TYPE_DESTINATION_UNREACHABLE 3
#define ICMP_TYPE_ECHO_REQUEST 8
#define ICMP_TYPE_TIME_EXCEEDED 11

struct icmp_header {
    uint8_t type;
    uint8_t code;
    uint16_t checksum;
} __attribute__((packed));

struct icmp_echo {
    uint16_t identify;
    uint16_t sequence;
    uint8_t data[];
} __attribute__((packed));

struct icmp_dest_unreachable {
    uint32_t unused;
    uint8_t data[];
} __attribute__((packed));

struct icmp_time_exceeded {
    uint32_t unused;
    uint8_t data[];
} __attribute__((packed));

struct icmp_message {
    icmp_header header;
    union {
        icmp_echo echo;
        icmp_dest_unreachable dest_unreachable;
        icmp_time_exceeded time_exceeded;
    };
} __attribute__((packed));

#define ICMP_DEST_UNREACHABLE_CODE_NET_UNREACHABLE 0
#define ICMP_DEST_UNREACHABLE_CODE_HOST_UNREACHABLE 1
#define ICMP_DEST_UNREACHABLE_CODE_PROTOCOL_UNREACHABLE 2
#define ICMP_DEST_UNREACHABLE_CODE_PORT_UNREACHABLE 3
#define ICMP_DEST_UNREACHABLE_CODE_FRAGMENT_NEEDED_AND_DF_SET 4
#define ICMP_DEST_UNREACHABLE_CODE_SOURCE_ROUTE_FAILED 5

#define ICMP_TIME_EXCEEDED_CODE_TIME_TO_LIVE_EXCEEDED 0
#define ICMP_TIME_EXCEEDED_CODE_FRAGMENT_REASSEMBLY_TIME_EXCEEDED 1

void icmp_input(uint32_t source, uint32_t destination, void *buffer,
                size_t len);

void send_icmp_time_exceeded(uint32_t dest_addr, uint32_t src_addr,
                             uint8_t code, void *error_ip_buffer, size_t len);
void send_icmp_destination_unreachable(uint32_t dest_addr, uint32_t src_addr,
                                       uint8_t code, void *error_ip_buffer,
                                       size_t len);

#endif // CURO_ICMP_H