1.c语言ping程序中文注释
2.如何用C语言实现atoi()函数

c语言ping程序中文注释

       编写自己的函数函数一个ping程序,可以说是许多人迈出网络编程的第一步吧!!这个ping程序的源代码经过我的修改和调试,基本上可以取代windows中自带的ping程序. 各个模块后都有我的详细注释和修改日志,希望能够对大家的学习有所帮助!!

       /* 本程序的主要源代码来自MSDN网站, 笔者只是做了一些改进和注释! 另外需要注意的是在Build之前,必须加入ws2_.lib库文件,否则会提示"error LNK:"的错误！*/

       Version 1.1 修改记录:

        <1> 解决了socket阻塞的源码源码crnn 源码问题,从而能够正确地处理超时的请求!

        <2> 增加了由用户控制发送ICMP包的数目的功能(即命令的第二个参数)

        <3> 增加了对ping结果的统计功能.

       #pragma pack(4)

       #include "winsock2.h"

       #include "stdlib.h"

       #include "stdio.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 icmphdr {

       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

       #define DEF_PACKET_NUMBER 4 /* 发送数据报的个数 */

       #define MAX_PACKET

       #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);

       int decode_resp(char *,int ,struct sockaddr_in *);

       void Usage(char *progname){

       fprintf(stderr,"Usage:\n");

       fprintf(stderr,"%s [number of packets] [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,times;

       int fromlen = sizeof(from);

       int timeout = ;

       int statistic = 0; /* 用于统计结果 */

       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,WSA_FLAG_OVERLAPPED);

       //

       //注：为了使用发送接收超时设置(即设置SO_RCVTIMEO, SO_SNDTIMEO)，

       // 必须将标志位设为WSA_FLAG_OVERLAPPED !

       //

       if (sockRaw == INVALID_SOCKET) {

       fprintf(stderr,函数函数爱源码网址"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 = ;

       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);

       //

       // atoi函数原型是: int atoi( const char *string );

       // The return value is 0 if the input cannot be converted to an integer !

       //

       if(argc>2)

       {

       times=atoi(argv[2]);

       if(times == 0)

        times=DEF_PACKET_NUMBER;

       }

       else

        times=DEF_PACKET_NUMBER;

       if (argc >3)

       {

       datasize = atoi(argv[3]);

        if (datasize == 0)

        datasize = DEF_PACKET_SIZE;

       if (datasize >) /* 用户给出的数据包大小太大 */

       {

        fprintf(stderr,"WARNING : data_size is too large !\n");

        datasize = DEF_PACKET_SIZE;

       }

       }

       else

        datasize = DEF_PACKET_SIZE;

       datasize += sizeof(IcmpHeader);

       icmp_data = (char*)xmalloc(MAX_PACKET);

       recvbuf = (char*)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);

       //

       //显示提示信息

       //

       fprintf(stdout,"\nPinging %s ....\n\n",dest_ip);

       for(int i=0;i{

       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("Request 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("Request timed out.\n");

       continue;

       }

       fprintf(stderr,"recvfrom failed: %d\n",WSAGetLastError());

       ExitProcess(STATUS_FAILED);

       }

       if(!decode_resp(recvbuf,bread,&from))

       statistic++; /* 成功接收的数目++ */

       Sleep();

       }

       /

       Display the statistic result

       */

       fprintf(stdout,"\nPing statistics for %s \n",dest_ip);

       fprintf(stdout," Packets: Sent = %d,Received = %d, Lost = %d (%2.0f%% loss)\n",times,

        statistic,(times-statistic),(float)(times-statistic)/times*);

       WSACleanup();

       return 0;

       }

       /*

       The response is an IP packet. We must decode the IP header to locate

       the ICMP data

       */

       int 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 -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 1;

       }

       if (icmphdr->i_id != (USHORT)GetCurrentProcessId()) {

       fprintf(stderr,"someone else''s packet!\n");

       return 1;

       }

       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");

       return 0;

       }

       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 >> ) + (cksum & 0xffff);

       cksum += (cksum >>);

       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));

       }

       /