代码编程——ping命令流程（图）

不是我写的，找的。

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <time.h>

#define WIN32_LEAN_AND_MEAN

#include <winsock.h>

#pragma comment(lib, "Wsock32.lib")

#define ICMP_ECHO 8

#define ICMP_ECHOREPLY 0

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

#define ICMP_MIN (8 + 4) // minimum 8 byte icmp packet (just header + timestamp)

// IP header

typedef struct _tagX_iphdr

{

unsigned char h_len:4 // length of the header

unsigned char 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 // ttl

unsigned char proto // protocol (TCP, UDP etc)

unsigned short checksum // IP checksum

unsigned int sourceIP

unsigned int destIP

}XIpHeader

// ICMP header

typedef struct _tagX_icmphdr

{

unsigned char i_type

unsigned char i_code

unsigned short i_cksum

unsigned short i_id

unsigned short i_seq

unsigned long i_timestamp

}XIcmpHeader

//puclic code

//网际校验和生产算法

//网际校验和是被校验数据16位值的反码和(ones-complement sum)

unsigned short in_cksum(unsigned short* addr, int len)

{

int nleft = len

int sum = 0

unsigned short* w = addr

unsigned short answer = 0

while(nleft >1) {

sum += *w++

nleft -= 2

}

if(nleft == 1) {

*(unsigned char*)(&answer) = *(unsigned char*)w

sum += answer

}

sum = (sum >>16) + (sum &0xffff)

sum += (sum >>16)

answer = ~sum

return (answer)

}

void fill_IcmpData(char *buf, int datasize)

{

if (buf)

{

char ch = 0

char* icmpdata = buf + sizeof(XIcmpHeader)

fprintf(stdout, "(IcmpData)\r\n")

for (int i = 0i <datasizei++)

{

ch = 'A' + i%('z' - 'A')

*(icmpdata + i) = ch

fprintf(stdout, "%c", ch)

}

fprintf(stdout, "\r\n")

}

}

void fill_IcmpHeader(char *buf, int datasize)

{

static unsigned short seq_no = 0

XIcmpHeader *icmp_hdr = (XIcmpHeader *)buf

if (icmp_hdr)

{

icmp_hdr->i_type = ICMP_ECHO

icmp_hdr->i_code = 0

icmp_hdr->i_cksum = 0

icmp_hdr->i_id = (unsigned short)GetCurrentProcessId()

icmp_hdr->i_seq = seq_no++

icmp_hdr->i_timestamp = (unsigned long)::GetTickCount()

icmp_hdr->i_cksum = in_cksum((unsigned short*)buf, sizeof(XIcmpHeader) + datasize)

fprintf(stdout, "(IcmpHeader)\r\n")

fprintf(stdout, "%02X%02X%04X\r\n", icmp_hdr->i_type, icmp_hdr->i_code, icmp_hdr->i_cksum)

fprintf(stdout, "%04X%04X\r\n", icmp_hdr->i_id, icmp_hdr->i_seq)

fprintf(stdout, "%08X\r\n", icmp_hdr->i_timestamp)

}

}

// decode

void decode_IpIcmp(char *buf, int size)

{

XIpHeader *ip_hdr = (XIpHeader *)buf

unsigned short iphdrlen

if (ip_hdr)

{

fprintf(stdout, "(IpHeader)\r\n")

fprintf(stdout, "%01X%01X%02X%04X\r\n", ip_hdr->version, ip_hdr->h_len, ip_hdr->tos, ip_hdr->total_len)

fprintf(stdout, "%04X%04X\r\n", ip_hdr->ident, ip_hdr->frag_and_flags)

fprintf(stdout, "%02X%02X%04X\r\n", ip_hdr->ttl, ip_hdr->proto, ip_hdr->checksum)

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

iphdrlen = ip_hdr->h_len <<2// number of 32-bit words *4 = bytes

fprintf(stdout, "(IcmpHeader)\r\n")

if (size <iphdrlen + ICMP_MIN)

{

fprintf(stdout, "Reply %d bytes Too few\r\n", size)

}

else

{

XIcmpHeader *icmp_hdr = (XIcmpHeader *)(buf + iphdrlen)

fprintf(stdout, "%02X%02X%04X\r\n", icmp_hdr->i_type, icmp_hdr->i_code, icmp_hdr->i_cksum)

fprintf(stdout, "%04X%04X\r\n", icmp_hdr->i_id, icmp_hdr->i_seq)

fprintf(stdout, "%08X\r\n", icmp_hdr->i_timestamp)

unsigned long timestamp = 0

timestamp = (unsigned long)::GetTickCount()

timestamp -= icmp_hdr->i_timestamp

struct sockaddr_in from

from.sin_addr.s_addr = ip_hdr->sourceIP

fprintf(stdout, "Reply %d bytes from: %s time<%d TTL=%d icmp_seq=%d\r\n",

size,

inet_ntoa(from.sin_addr),

timestamp,

ip_hdr->ttl,

icmp_hdr->i_seq

)

}

}

}

int main(int argc, char **argv)

{

int ret = 0

WSADATA ws

WSAStartup(0x0101,&ws)

int iIcmpDataSize = 0

struct sockaddr_in dest,from

unsigned int addr = 0

struct hostent *hp

char buffer[1024]

char recv_buffer[1024]

if(argc <2)

{

fprintf(stderr, "Usage: %s [host|ip] [datasize]\r\n", argv[0])

return 0

}

if (argc >2)

iIcmpDataSize = atoi(argv[2])

if (iIcmpDataSize <1 || iIcmpDataSize >1024)

iIcmpDataSize = 10

memset(&dest, 0, sizeof dest)

dest.sin_family = AF_INET

hp = gethostbyname(argv[1])

if (!hp)

addr = inet_addr(argv[1])

if ((!hp) &&(addr == INADDR_NONE))

{

fprintf(stderr,"Unable to resolve %s\r\n",argv[1])

return 0

}

if (hp != NULL)

memcpy(&(dest.sin_addr), hp->h_addr,hp->h_length)

else

dest.sin_addr.s_addr = addr

int sockfd

sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)

fprintf(stdout, "XPing...\r\n")

for (int i = 0i <3i++)

{

fprintf(stdout, "Echo...\r\n")

memset(buffer, 0, 1024)

fill_IcmpData(buffer, iIcmpDataSize)

fill_IcmpHeader(buffer, iIcmpDataSize)

XIcmpHeader *icmp_hdr = (XIcmpHeader *)buffer

int iSendSize = sendto(sockfd, buffer, sizeof(XIcmpHeader) + iIcmpDataSize, 0, (struct sockaddr*)&dest, sizeof(dest))

fprintf(stdout, "Reply...\r\n")

memset(&from, 0, sizeof from)

memset(recv_buffer, 0, 1024)

int fromlen = sizeof(from)

int iRecvSize = recvfrom(sockfd, recv_buffer, 1024, 0, (struct sockaddr*)&from, &fromlen)

if (iRecvSize >0)

decode_IpIcmp(recv_buffer, iRecvSize)

}

WSACleanup()

return ret

}

ping其他计算机可按以下步骤 *** 作，以XP系统为例：

1、单击屏幕左下角的“开始”

2、单击“运行”

也可以使用键盘上的组合键调出“运行”栏，如下图：

3、在“运行”栏输入命令“cmd“，点击”确定“

4、出来如下画面：

5、在闪动的光标处输入”ping 119.75.218.77  -t"。其中“119.75.218.77”是对方计算机的IP地址，“-t“是为了一直显示ping的结果，直至按键盘上的ctrl+C终止，也可以在命令行不加“-t“

6、回车即可显示ping对方计算机的结果。

上图显示与对方网络不通

上图显示与对方网络通畅。

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