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Ping的原代码, 网络安全者必看

#pragma pack(4)
#define win32_lean_and_mean
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>

#define icmp_echo 8
#define icmp_echoreply 0

#define icmp_min 8 // minimum 8 byte icmp packet (just header)

/* the ip header */
typedef struct iphdr {
unsigned int h_len:4; // length of the header
unsigned int version:4; // version of ip
unsigned char tos; // type of service
unsigned short total_len; // total length of the packet
unsigned short ident; // unique identifier
unsigned short frag_and_flags; // flags
unsigned char ttl;
unsigned char proto; // protocol (tcp, udp etc)
unsigned short checksum; // ip checksum

unsigned int sourceip;
unsigned int destip;

}ipheader;

//
// icmp header
//
typedef struct _ihdr {
byte i_type;
byte i_code; /* type sub code */
ushort i_cksum;
ushort i_id;
ushort i_seq;
/* this is not the std header, but we reserve space for time */
ulong timestamp;
}icmpheader;

#define status_failed 0xffff
#define def_packet_size 32
#define max_packet 1024

#define xmalloc(s) heapalloc(getprocessheap(),heap_zero_memory,(s))
#define xfree(p) heapfree (getprocessheap(),0,(p))

void fill_icmp_data(char *, int);
ushort checksum(ushort *, int);
void decode_resp(char *,int ,struct sockaddr_in *);

void usage(char *progname){

fprintf(stderr,"usage:\n";
fprintf(stderr,"%s <host> [data_size]\n",progname);
fprintf(stderr,"datasize can be up to 1kb\n";
exitprocess(status_failed);

}
int main(int argc, char **argv){

wsadata wsadata;
socket sockraw;
struct sockaddr_in dest,from;
struct hostent * hp;
int bread,datasize;
int fromlen = sizeof(from);
int timeout = 1000;
char *dest_ip;
char *icmp_data;
char *recvbuf;
unsigned int addr=0;
ushort seq_no = 0;

if (wsastartup(makeword(2,1),&wsadata) != 0){
fprintf(stderr,"wsastartup failed: %d\n",getlasterror());
exitprocess(status_failed);
}

if (argc <2 ) {
usage(argv[0]);
}
sockraw = wsasocket (af_inet,
sock_raw,
ipproto_icmp,
null, 0,0);

if (sockraw == invalid_socket) {
fprintf(stderr,"wsasocket() failed: %d\n",wsagetlasterror());
exitprocess(status_failed);
}
bread = setsockopt(sockraw,sol_socket,so_rcvtimeo,(char*)&timeout,
sizeof(timeout));
if(bread == socket_error) {
fprintf(stderr,"failed to set recv timeout: %d\n",wsagetlasterror());
exitprocess(status_failed);
}
timeout = 1000;
bread = setsockopt(sockraw,sol_socket,so_sndtimeo,(char*)&timeout,
sizeof(timeout));
if(bread == socket_error) {
fprintf(stderr,"failed to set send timeout: %d\n",wsagetlasterror());
exitprocess(status_failed);
}
memset(&dest,0,sizeof(dest));

hp = gethostbyname(argv[1]);

if (!hp){
addr = inet_addr(argv[1]);
}
if ((!hp) && (addr == inaddr_none) ) {
fprintf(stderr,"unable to resolve %s\n",argv[1]);
exitprocess(status_failed);
}

if (hp != null)
memcpy(&(dest.sin_addr),hp->h_addr,hp->h_length);
else
dest.sin_addr.s_addr = addr;

if (hp)
dest.sin_family = hp->h_addrtype;
else
dest.sin_family = af_inet;

dest_ip = inet_ntoa(dest.sin_addr);

if (argc >2) {
datasize = atoi(argv[2]);
if (datasize == 0)
datasize = def_packet_size;

}
else
datasize = def_packet_size;

datasize += sizeof(icmpheader);

icmp_data = xmalloc(max_packet);
recvbuf = xmalloc(max_packet);

if (!icmp_data) {
fprintf(stderr,"heapalloc failed %d\n",getlasterror());
exitprocess(status_failed);
}

memset(icmp_data,0,max_packet);
fill_icmp_data(icmp_data,datasize);

while(1) {
int bwrote;

((icmpheader*)icmp_data)->i_cksum = 0;
((icmpheader*)icmp_data)->timestamp = gettickcount();

((icmpheader*)icmp_data)->i_seq = seq_no++;
((icmpheader*)icmp_data)->i_cksum = checksum((ushort*)icmp_data,
datasize);

bwrote = sendto(sockraw,icmp_data,datasize,0,(struct sockaddr*)&dest,
sizeof(dest));
if (bwrote == socket_error){
if (wsagetlasterror() == wsaetimedout) {
printf("timed out\n";
continue;
}
fprintf(stderr,"sendto failed: %d\n",wsagetlasterror());
exitprocess(status_failed);
}
if (bwrote < datasize ) {
fprintf(stdout,"wrote %d bytes\n",bwrote);
}
bread = recvfrom(sockraw,recvbuf,max_packet,0,(struct sockaddr*)&from,
&fromlen);
if (bread == socket_error){
if (wsagetlasterror() == wsaetimedout) {
printf("timed out\n";
continue;
}
fprintf(stderr,"recvfrom failed: %d\n",wsagetlasterror());
exitprocess(status_failed);
}
decode_resp(recvbuf,bread,&from);
sleep(1000);

}
return 0;

}
/*
the response is an ip packet. we must decode the ip header to locate
the icmp data
*/
void decode_resp(char *buf, int bytes,struct sockaddr_in *from) {

ipheader *iphdr;
icmpheader *icmphdr;
unsigned short iphdrlen;

iphdr = (ipheader *)buf;

iphdrlen = iphdr->h_len * 4 ; // number of 32-bit words *4 = bytes

if (bytes < iphdrlen + icmp_min) {
printf("too few bytes from %s\n",inet_ntoa(from->sin_addr));
}

icmphdr = (icmpheader*)(buf + iphdrlen);

if (icmphdr->i_type != icmp_echoreply) {
fprintf(stderr,"non-echo type %d recvd\n",icmphdr->i_type);
return;
}
if (icmphdr->i_id != (ushort)getcurrentprocessid()) {
fprintf(stderr,"someone else's packet!\n";
return ;
}
printf("%d bytes from %s:",bytes, inet_ntoa(from->sin_addr));
printf(" icmp_seq = %d. ",icmphdr->i_seq);
printf(" time: %d ms ",gettickcount()-icmphdr->timestamp);
printf("\n";

}

ushort checksum(ushort *buffer, int size) {

unsigned long cksum=0;

while(size >1) {
cksum+=*buffer++;
size -=sizeof(ushort);
}

if(size ) {
cksum += *(uchar*)buffer;
}

cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >>16);
return (ushort)(~cksum);
}
/*
helper function to fill in various stuff in our icmp request.
*/
void fill_icmp_data(char * icmp_data, int datasize){

icmpheader *icmp_hdr;
char *datapart;

icmp_hdr = (icmpheader*)icmp_data;

icmp_hdr->i_type = icmp_echo;
icmp_hdr->i_code = 0;
icmp_hdr->i_id = (ushort)getcurrentprocessid();
icmp_hdr->i_cksum = 0;
icmp_hdr->i_seq = 0;

datapart = icmp_data + sizeof(icmpheader);
//
// place some junk in the buffer.
//
memset(datapart,'e', datasize - sizeof(icmpheader));

}

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