TCP-Traceroute 核心代码

测试环境:

操作系统: Microsoft Windows 2000 with Service Pack 4

开发环境: Microsoft Visual C++6 with Service Pack 6

其它: Winpcap 3.1 beta 3

代码

//tracer.c

//Copyright (c) 1999 - 2004

//S8S8.net Network Tech. Forum

//written by '13th Floor'

//All rights reserved.

#include <winsock2.h>

#include <ws2tcpip.h>

#include <cstring>

#include <queue>

using namespace std;

#include "pcap.h"

#include "headers.h"

#include "tracer.h"

char* FLT_EXPR = "ip and icmp[icmptype]=icmp-timxceed or tcp[tcpflags]=tcp-rst";

unsigned short checksum(unsigned short *buffer, int size)

{

unsigned long cksum = 0;

while(size > 1) {

cksum += *buffer++;

size -= sizeof(unsigned short);

}

if(size)

cksum += *(unsigned char*)buffer;

cksum = (cksum >> 16) + (cksum & 0xffff);

cksum += (cksum >> 16);

return (unsigned short)(~cksum);

}

int build_packets(

unsigned long local_addr,

unsigned long dst_addr,

char* buf,

unsigned char TTL)

{

static unsigned long SEQ = 0x2344512;

int datasize =0;

IP_HDR ip_header;

TCP_HDR tcp_header;

PSD_HDR psd_header;

ip_header.h_verlen =

(4 << 4 | sizeof(ip_header) / sizeof(unsigned long));

ip_header.total_len = htons(sizeof(IP_HDR) + sizeof(TCP_HDR));

ip_header.ident = 1;

ip_header.frag_and_flags = 0;

ip_header.ttl = TTL;

ip_header.proto = IPPROTO_TCP;

ip_header.checksum = 0;

ip_header.saddr = local_addr;

ip_header.daddr = dst_addr;

tcp_header.th_sport = htons(7000);

tcp_header.th_dport = htons(5000);

tcp_header.th_seq = SEQ++;

tcp_header.th_ack = 0;

tcp_header.th_lenres = (sizeof(TCP_HDR) / 4 << 4 | 0);

tcp_header.th_flag = 16;

tcp_header.th_win = htons(16384);

tcp_header.th_urp = 0;

tcp_header.th_sum = 0;

psd_header.saddr = ip_header.saddr;

psd_header.daddr = ip_header.daddr;

psd_header.mbz = 0;

psd_header.proto = IPPROTO_TCP;

psd_header.tcpl = htons(sizeof(tcp_header));

memcpy(buf, &psd_header, sizeof(psd_header));

memcpy(buf + sizeof(psd_header), &tcp_header, sizeof(tcp_header));

tcp_header.th_sum = checksum((unsigned short *)buf,

sizeof(psd_header) + sizeof(tcp_header));

memcpy(buf, &ip_header, sizeof(ip_header));

memcpy(buf + sizeof(ip_header), &tcp_header, sizeof(tcp_header));

memset(buf + sizeof(ip_header) + sizeof(tcp_header), 0, 4);

datasize = sizeof(ip_header) + sizeof(tcp_header);

ip_header.checksum = checksum((unsigned short*)buf,datasize);

memcpy(buf, &ip_header, sizeof(ip_header));

return 0;

}

int start_trace(

queue<unsigned long>& dst_addr_queue,

unsigned long local_addr,

SOCKET& socket)

{

char snd_buf[128];

int ret;

sockaddr_in dst_addr;

pcap_t* adhandle;

struct pcap_pkthdr *header;

const u_char *pkt_data;

//Setup for winpcap

pcap_if_t *alldevs, *d;

char errbuf[PCAP_ERRBUF_SIZE];

unsigned int netmask;

bpf_program fcode;

if (pcap_findalldevs(&alldevs, errbuf) == -1)

throw ("Error in pcap_findalldevs");

try {

d = alldevs->next;

if ((adhandle= pcap_open_live(

d->name, //adapter

65536,

1,

1000, //time out

errbuf))

== NULL)

throw ("Failed to open adapter!");

if(d->addresses != NULL)

netmask=((struct sockaddr_in *)

(d->addresses->netmask))

->sin_addr.S_un.S_addr;

else

netmask=0xffffff;

if(pcap_compile(adhandle,

&fcode,

FLT_EXPR,

1,

netmask) <0

)

throw ("Failed to compile the filter");

if(pcap_setfilter(adhandle, &fcode)<0) {

throw ("Error setting the filter");

}

}

catch (const char * error) {

pcap_freealldevs(alldevs);

throw (error);

}

pcap_freealldevs(alldevs);

//Setup for Winsock

WSADATA wsaData;

BOOL flag = TRUE;

int time_out = 2000;

socket = INVALID_SOCKET;

if (WSAStartup(MAKEWORD(2, 1), &wsaData) !=0)

throw ("WSAStartup() failed");

try {

socket = WSASocket(AF_INET, SOCK_RAW, IPPROTO_RAW,

NULL,0, WSA_FLAG_OVERLAPPED);

if (socket == INVALID_SOCKET)

throw ("WSASocket() failed");

if (setsockopt(socket, IPPROTO_IP, IP_HDRINCL,

(char*)&flag, sizeof(int)) == SOCKET_ERROR)

throw ("Failed to set IP_HDRINCL");

if (setsockopt(socket, SOL_SOCKET, SO_SNDTIMEO,

(char*)&time_out, sizeof(time_out)) == SOCKET_ERROR)

throw ("Failed to set SO_SNDTIMEO");

}

catch(const char* error) {

if (socket != INVALID_SOCKET)

closesocket(socket);

WSACleanup();

throw error;

}

//Get local address

char name[255];

PHOSTENT hostinfo;

if (gethostname(name, sizeof(name))==0)

if ((hostinfo = gethostbyname(name)) !=NULL)

local_addr = (*(struct in_addr*)

*hostinfo->h_addr_list).s_addr;

//Start Trace

while (dst_addr_queue.empty() == false) {

unsigned long crt_addr = dst_addr_queue.front();

memset(&dst_addr, 0, sizeof(dst_addr));

dst_addr.sin_family = AF_INET;

dst_addr.sin_addr.s_addr = crt_addr;

printf("\n\nTracing: ");

printf("%s\n", inet_ntoa(*(in_addr*)&crt_addr));

for (unsigned char ttl = 1; ttl <= 30; ttl++) {

build_packets(local_addr, crt_addr, snd_buf, ttl);

ret = sendto(socket, snd_buf, sizeof(IP_HDR)+sizeof(TCP_HDR),

0, (sockaddr*)&dst_addr, sizeof(dst_addr));

ret = pcap_next_ex(adhandle, &header, &pkt_data);

if (ret == 0) {

printf("%s\n", "time out");

continue;

}

IP_HDR* iphdr = (IP_HDR*)(pkt_data + 14);

printf("%s\n", inet_ntoa(*(in_addr*)&(iphdr->saddr)));

if (iphdr->proto == IPPROTO_TCP) break;

}

dst_addr_queue.pop();

}

return 0;

}

//headers.h

//Copyright (c) 1999 - 2004

//S8S8.net Network Tech. Forum

//written by '13th Floor'

//All rights reserved.

#ifndef _HEADERS_H

#define _HEADERS_H

//IP Header

typedef struct _iphdr {

unsigned char h_verlen; //IP Version

unsigned char tos; //Type of Service; 8 bits

unsigned short total_len; //total length; 16 bits

unsigned short ident; //Identification; 16 bits

unsigned short frag_and_flags; //Flags

unsigned char ttl; //Time to live; 8 bits

unsigned char proto; //Protocol; 8 bits

unsigned short checksum; //Checksum; 16 bits

unsigned long saddr; //Source IP address; 32 bits

unsigned long daddr; //Destination IP address; 32 bits

} IP_HDR;

//PSD Header

typedef struct _psdhdr {

unsigned long saddr; //Source IP address; 32 bits

unsigned long daddr; //Destination IP address; 32 bits

unsigned char mbz; //padding

unsigned char proto; //Protocol; 8 bits

unsigned short tcpl; //TCP length; 16 bits

} PSD_HDR;

//TCP Header

typedef struct _tcphdr {

unsigned short th_sport; //Source port; 16 bits

unsigned short th_dport; //Destination port; 16 bits

unsigned long th_seq; //Sequence Number; 32 bits

unsigned long th_ack; //Acknowledgment Number; 32 bits

unsigned char th_lenres; //Data Offset / reserved

unsigned char th_flag; //ECN / Control Bits; 6 bits

unsigned short th_win; //Window; 16 bits

unsigned short th_sum; //Checksum; 16 bits

unsigned short th_urp; //Urgent Pointer; 16 bits

} TCP_HDR;

//ICMP Header

typedef struct _icmphdr {

unsigned char i_type; //ICMP Type; 8 bits

unsigned char i_code; //ICMP Code; 8 bits

unsigned short i_cksum; //ICMP header checksum; 16 bits

unsigned short i_id; //Identification; 16 bits

unsigned short i_seq; //Sequence Number; 16 bits

unsigned long timestamp; //Timestamp; 32 bits

} ICMP_HDR;

#endif

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