icmp scan

#include "proto-icmp.h"

#include "proto-preprocess.h"

#include "syn-cookie.h"

#include "logger.h"

#include "output.h"

#include "masscan.h"

int

parse_port_unreachable(const unsigned char *px, unsigned length,

        unsigned *r_ip_me, unsigned *r_ip_them,

        unsigned *r_port_me, unsigned *r_port_them)

{

    if (length < 24)

        return -1;

    *r_ip_me = px[12]<<24 | px[13]<<16 | px[14]<<8 | px[15];

    *r_ip_them = px[16]<<24 | px[17]<<16 | px[18]<<8 | px[19];

    px += (px[0]&0xF)<<2;

    length -= (px[0]&0xF)<<2;

    if (length < 4)

        return -1;

    *r_port_me = px[0]<<8 | px[1];

    *r_port_them = px[2]<<8 | px[3];

    return 0;

}

void handle_icmp(struct Output *out, const unsigned char *px, unsigned length, struct PreprocessedInfo *parsed)

{

    unsigned type = parsed->port_src;

    unsigned code = parsed->port_dst;

    unsigned seqno_me;

    unsigned ip_me;

    unsigned ip_them;

    ip_me = parsed->ip_dst[0]<<24 | parsed->ip_dst[1]<<16

            | parsed->ip_dst[2]<< 8 | parsed->ip_dst[3]<<0;

    ip_them = parsed->ip_src[0]<<24 | parsed->ip_src[1]<<16

            | parsed->ip_src[2]<< 8 | parsed->ip_src[3]<<0;

    seqno_me = px[parsed->transport_offset+4]<<24

                | px[parsed->transport_offset+5]<<16

                | px[parsed->transport_offset+6]<<8

                | px[parsed->transport_offset+7]<<0;

    switch (type) {

    case 0: /* ICMP echo reply */

        if (syn_hash(ip_them, 65536*3+0) != seqno_me)

            return; /* not my response */

        /*

         * Report "open" or "existence" of host

         */

        output_report_status(

                            out,

                            Port_IcmpEchoResponse,

                            ip_them,

                            0,

                            0,

                            0);

        break;

    case 3: /* destination unreachable */

        switch (code) {

        case 3: /* port unreachable */

            if (length - parsed->transport_offset > 8) {

                unsigned ip_me2, ip_them2, port_me2, port_them2;

                int err;

                err = parse_port_unreachable(

                    px + parsed->transport_offset + 8,

                    length - parsed->transport_offset + 8,

                    &ip_me2, &ip_them2, &port_me2, &port_them2);

                if (err)

                    return;

                if (ip_me2 != ip_me)

                    return;

                if (port_me2 != out->masscan->adapter_port)

                    return;

                output_report_status(

                                    out,

                                    Port_UdpClosed,

                                    ip_them2,

                                    port_them2,

                                    0,

                                    px[parsed->ip_offset + 8]);

            }

        }

        break;

    default:

        printf(".");

    }

}

#ifndef PROTO_ICMP_H

#define PROTO_ICMP_H

struct PreprocessedInfo;

struct Output;

void handle_icmp(struct Output *out, const unsigned char *px, unsigned length, struct PreprocessedInfo *parsed);

#endif