【Echo】实验 -- 实现 C/C++下UDP, 服务器/客户端 通讯

本次实验利用UDP协议, 语言环境为 C/C++

利用套接字Socket编程，实现Server/CLient 之间简单的通讯。

结果应为类似所示：

下面贴上代码（参考参考...)

Server 部分：

 /* UDPServer.cpp */

 #include <stdlib.h>
 #include <stdio.h>
 #include <winsock2.h>
 #include <string.h>
 #include "conio.h"
 #include <time.h>

 #define    BUFLEN        2000                  // 缓冲区大小
 #define WSVERS        MAKEWORD(2, 2)        // 指明版本2.2
 #pragma comment(lib,"ws2_32.lib")         // 加载winsock 2.2 Llibrary

 /*------------------------------------------------------------------------
  * main - TCP client for DAYTIME service
  *------------------------------------------------------------------------
  */
 void
 main(int argc, char *argv[])
 {
     char   *host = "127.0.0.1";        /* server IP Address to connect */

     char   *service = "";          /* server port to connect       */
     struct sockaddr_in sin;            /* an Internet endpoint address    */
     struct sockaddr_in from;        /* sender address               */
     int    fromsize = sizeof(from);
     char   buf[BUFLEN+];           /* buffer for one line of text    */
     char   buf1[BUFLEN+];
     SOCKET    sock;                      /* socket descriptor            */
     int    cc;                            /* recv character count            */

     char    *pts;
     time_t    now;

     WSADATA wsadata;
     WSAStartup(WSVERS, &wsadata);   /* 加载winsock library，WSVERS为请求版本,wsadata返回系统实际支持的最高版本。    */
     sock = socket(PF_INET, SOCK_DGRAM,IPPROTO_UDP); // 创建UDP套接字, 参数：因特网协议簇(family)，数据报套接字，UDP协议号， 返回：要监听套接字的描述符或INVALID_SOCKET
     memset(&sin, , sizeof(sin));
     sin.sin_family = AF_INET;
     sin.sin_addr.s_addr = INADDR_ANY;                     // 绑定(监听)所有的接口。
     sin.sin_port = htons((u_short)atoi(service));         // 绑定指定接口。atoi--把ascii转化为int，htons -- 主机序(host)转化为网络序(network), 为short类型。
     bind(sock, (struct sockaddr *)&sin, sizeof(sin));     // 绑定本地端口号（和本地IP地址)

     (void) time(&now);                                      // 取得系统时间
        pts = ctime(&now);                                      // 把时间转换为字符串
        printf("           \t     UDP(Server) Echo增强程序\n\n");
      while(!_kbhit()){                                    //检测是否有按键
 flag1:        cc = recvfrom(sock, buf, BUFLEN, , (SOCKADDR *)&from, &fromsize);  //接收客户数据。返回结果：cc为接收的字符数，from中将包含客户IP地址和端口号。
         sprintf(buf1," \t\t 时间：  %s \t\t Client【IP: %s  端口号： %d  】\n  \t\t  数据：   %s",pts,inet_ntoa(from.sin_addr),from.sin_port,buf);
         if (cc == SOCKET_ERROR){
             printf("recvfrom() failed; %d\n", WSAGetLastError());
             break;
         }
         else if (cc == )
             break;
         else{
             buf[cc] = '\0';
             printf("您收到的数据为：\n   %s\n", buf1);
             printf("将自动把此数据返回给 Client  \n");
             goto flag2;
         }

     }

 flag2:    cc = sendto(sock, buf1, , ,(SOCKADDR *)&from, sizeof(from));
    if (cc == SOCKET_ERROR){
         printf("发送失败，错误号：%d\n", WSAGetLastError());
           }
     else{
         printf("发送成功\n");
         goto flag1;
          }

 //    cc = recvfrom(sock, buf, BUFLEN, 0, (SOCKADDR *)&from, &fromsize);

     closesocket(sock);
     GlobalFree(buf);
     WSACleanup();                     /* 卸载某版本的DLL */
 }

Client 部分：

 /* UDPClient.cpp */

 #include <stdlib.h>
 #include <stdio.h>
 #include <winsock2.h>
 #include <string.h>
 #include <time.h>

 #define    BUFLEN        2000                  // 缓冲区大小
 #define WSVERS        MAKEWORD(2, 2)        // 指明版本2.2
 #pragma comment(lib,"ws2_32.lib")         // 加载winsock 2.2 Llibrary

 void
 main(int argc, char *argv[])
 {
     char    *host = "127.0.0.1";        /* server IP to connect         */

     char    *service = "";          /* server port to connect       */
     struct sockaddr_in toAddr;            /* an Internet endpoint address    */
     char    buf[BUFLEN+];                   /* buffer for one line of text    */
     SOCKET    sock;                          /* socket descriptor            */
     int    cc;                                /* recv character count            */
     char    *pts;                    /* pointer to time string            */
     time_t    now;                    /* current time                        */

     int    toAddrsize = sizeof(toAddr);

     WSADATA wsadata;
     WSAStartup(WSVERS, &wsadata);       /* 启动某版本Socket的DLL        */    

     sock = socket(PF_INET, SOCK_DGRAM,IPPROTO_UDP);

     memset(&toAddr, , sizeof(toAddr));
     toAddr.sin_family = AF_INET;
     toAddr.sin_port = htons((u_short)atoi(service));    //atoi：把ascii转化为int. htons：主机序(host)转化为网络序(network), s--short
     toAddr.sin_addr.s_addr = inet_addr(host);           //如果host为域名，需要先用函数gethostbyname把域名转化为IP地址

 //    memset(buf,' ',1000);  //fill 1000 bytes with 'e'
     buf[] = '\0';
     (void) time(&now);                                      // 取得系统时间
     pts = ctime(&now);                                      // 把时间转换为字符串
 //    memcpy(buf,pts,strlen(pts));
     sprintf(buf,"%s ",pts);
     printf("                        UDP(Client) Echo增强程序\n\n");
      printf("  时间 ：%s",buf);

     cc = sendto(sock, buf, , ,(SOCKADDR *)&toAddr, sizeof(toAddr));
  flag2:   if (cc == SOCKET_ERROR){
         printf("发送失败，错误号：%d\n", WSAGetLastError());
      }
     else{
         printf("       发送成功 \n");
          cc = recvfrom(sock, buf, BUFLEN, , (SOCKADDR *)&toAddr, & toAddrsize);
          printf(" 您接收到的数据为:\n %s \n",buf);
         printf("键入 # 继续发送，键入 @ 停止发送\n");
         scanf("%s",pts);
         if(pts[]=='#')
         {
             printf("    请输入要发送的数据 ：\n");
             goto flag1;
         }
         if(pts[]=='@')
             goto end;

     }

 flag1:
     scanf("%s",pts);
     sprintf(buf,"%s ",pts);
     cc = sendto(sock, buf, , ,(SOCKADDR *)&toAddr, sizeof(toAddr));

     goto flag2;

     getchar();

     closesocket(sock);

 end:    GlobalFree(buf);
     WSACleanup();                     /* 卸载某版本的DLL */  

     getchar();

 }