Linux下tcp通信

目录：

　　　socket 编程

　　　Linux下tcp通信

1、server.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netinet/ip.h>
#include<unistd.h>
#include<arpa/inet.h>
#include <sys/time.h>    
#include <unistd.h>

#define MAXLINE 25

int main(int argc, char** argv){
    int  listenfd, connfd;
    struct sockaddr_in  servaddr;
    char  buff[25];
    int  n,cnt=0,i;
    int res,ret;
    
        char buf111[8] = {0x01,0x03,0x00,0x65,0x00,0x06,0xD5,0xD7};
        struct  timeval    tv1,tv2;    
        
    if( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 ){
        printf("create socket error: %s(errno: %d)
",strerror(errno),errno);
        return 0;
    }

    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(8080);

    if( bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1){
        printf("bind socket error: %s(errno: %d)
",strerror(errno),errno);
        return 0;
    }

    if( listen(listenfd, 10) == -1){
        printf("listen socket error: %s(errno: %d)
",strerror(errno),errno);
        return 0;
    }
        //通过程序获取刚建立连接的socket的客户端的IP地址和端口号
        struct sockaddr_in cin;
        socklen_t addrlen = sizeof(cin);
        if((connfd = accept(listenfd,(struct sockaddr *)&cin,&addrlen)) < 0)
        {
            printf("accept err
");
            exit(1);
        }
        char ipv4_addr[16];
        if(!inet_ntop(AF_INET,(void *)&cin.sin_addr,ipv4_addr,sizeof(cin)))
        {
            printf("inet_ntop
");
            exit(1);
        }
        printf("Client(%s:%d) is connected!
",ipv4_addr,htons(cin.sin_port));
        
    printf("======waiting for client's request======
");
    while(1){
          cnt++;
                printf("%drecv msg from client:",cnt);
                memset(buff, 0, sizeof(buff));
                n = recv(connfd, buff, MAXLINE, 0);
                if(n > 0)
                    {                
                        for(i = 0;i< n;i++)
                       printf("%02X ", buff[i]);              
              }
             
            printf("
"); 
            
            send(connfd, buff, n,MSG_NOSIGNAL);  //将接收到的数据发送回去
                     
        
    }
    close(connfd);
    close(listenfd);
    return 0;
}

2、client.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>

#define MAXLINE 25

int main(int argc, char** argv){
    int   sockfd, n,i,cnt=0;
    char  recvline[25], sendline[25];
    struct sockaddr_in  servaddr;
        char buf111[8]={0x01,0x01,0x00,0x40,0x00,0x18,0x3D,0xD4};
        char  buff[25];
        
    if( argc != 2){
        printf("usage: ./a.out <ipaddress>
");
        return 0;
    }

    if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
        printf("create socket error: %s(errno: %d)
", strerror(errno),errno);
        return 0;
    }

    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(8080);
    if( inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0){
        printf("inet_pton error for %s
",argv[1]);
        return 0;
    }

    if( connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0){
        printf("connect error: %s(errno: %d)
",strerror(errno),errno);
        return 0;
    }
    while(1)
    {
         sleep(1);
         cnt++;                
         send(sockfd, buf111, sizeof(buf111),MSG_NOSIGNAL);
         printf("%dsend ok
",cnt);
        
       　 printf("%drecv msg from client:",cnt);
          memset(buff, 0, sizeof(buff));
          n = recv(sockfd, buff, MAXLINE, 0);
          if(n > 0)
          {                
              for(i = 0;i< n;i++)
                   printf("%02X ", buff[i]);              
          }
             
           printf("
"); 
                     
      }
    close(sockfd);
    return 0;
}