网络通讯-Socket-TCP-demo(C语言版)

流程图

TCP server 服务端

步骤如图所示
1 创建Socket 指定使用什么协议

 socket_fd = socket(AF_INET,SOCK_STREAM,0);

2 将Socket与地址和端口绑定

//set socket address
local_addr.sin_family = AF_INET;
local_addr.sin_port = htons(PORT);
local_addr.sin_addr.s_addr = INADDR_ANY;
bzero(&(local_addr.sin_zero),8);


//bind socket
ret = bind(socket_fd,(struct  sockaddr*)&local_addr,sizeof(struct sockaddr_in));

3 侦听端口（目前Socket和地址 端口绑定了 但是上层应用必须绑定对应的Socket）

ret = listen(socket_fd,backlog);

4 创建新的socket – 每次连接过来以后创建一个新的socket来收发数据 也就是accept socket （之前的socket 一直在侦听 请求连接是数据）

int addr_len = sizeof( struct sockaddr_in );
    //accept an new connection
    accept_fd = accept( socket_fd, (struct sockaddr *)&remote_addr, &addr_len );

5 recv接收数据

 ret = recv( accept_fd ,(void*)in_buf ,MESSAGE_SIZE ,0 );

6 send发送数据

send(accept_fd, (void*)in_buf, MESSAGE_SIZE, 0);

7 close关闭当前socket

 close(accept_fd);
 close(socket_fd);

服务端完整代码

//
// Created by zyc on 2022/5/5.
//


#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define MESSAGE_SIZE 1024
#define PORT 8111
int main(){
    
    
    int ret = 0;

    int socket_fd = -1;
    int accept_fd = -1;

    int curpos = 0;
    int backlog = 10;
    int flag = 1;

    char in_buf[MESSAGE_SIZE] = {
    
    0,};

    struct sockaddr_in local_addr, remote_addr;

    //create a tcp socket
    socket_fd = socket(AF_INET,SOCK_STREAM,0);

    if (socket_fd==-1){
    
    
        perror("create socket error");
        exit(1);
    }

    //set option of socket
    ret = setsockopt(socket_fd,SOL_SOCKET,SO_REUSEADDR,
                     &flag,sizeof(flag));
    if ( ret == -1 ){
    
    
        perror("setsockopt error");
    }

    //set socket address
    local_addr.sin_family = AF_INET;
    local_addr.sin_port = htons(PORT);
    local_addr.sin_addr.s_addr = INADDR_ANY;
    bzero(&(local_addr.sin_zero),8);


    //bind socket
    ret = bind(socket_fd,(struct  sockaddr*)&local_addr,sizeof(struct sockaddr_in));
    if(ret == -1 ) {
    
    
        perror("bind error");
        exit(1);
    }

    ret = listen(socket_fd,backlog);
    if ( ret == -1 ){
    
    
        perror("listen error");
        exit(1);
    }

    //loop
    for(;;){
    
    
        int addr_len = sizeof( struct sockaddr_in );
        //accept an new connection
        accept_fd = accept( socket_fd, (struct sockaddr *)&remote_addr, &addr_len );
        for(;;){
    
    
            memset(in_buf, 0, MESSAGE_SIZE);

            //receive network data and print it
            ret = recv( accept_fd ,(void*)in_buf ,MESSAGE_SIZE ,0 );
            if(ret == 0 ){
    
    
                break;
            }
            printf( "receive message:%s\n", in_buf );
            send(accept_fd, (void*)in_buf, MESSAGE_SIZE, 0);
        }
        printf("close client connection...\n");
        close(accept_fd);
    }

    printf("quit server...\n");
    close(socket_fd);

    return 0;
}

TCP 客户端

客户端 类型 但是少了 绑定和侦听
因为在Connect阶段系统会默认分配

但是需要提前输入服务端的地址 代码如下

serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(SERVER_PORT);

//inet_addr()函数，将点分十进制IP转换成网络字节序IP

serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

if(connect(socket_fd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0)
{
    perror("connect");
    return 1;
}
printf("success to connect server...\n");

客户端完整代码

//
// Created by zyc on 2022/5/5.
//

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#include <fcntl.h>
#include <errno.h>
#include <netdb.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_PORT 8111
#define MESSAGE_LENGTH 1024

int main(){
    
    
    int ret = -1;
    int socket_fd;

    //server addr
    struct sockaddr_in serverAddr;

    char sendbuf[MESSAGE_LENGTH];
    char recvbuf[MESSAGE_LENGTH];

    int data_len;

    if((socket_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
    
    
        perror("socket");
        return 1;
    }

    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(SERVER_PORT);

    //inet_addr()函数，将点分十进制IP转换成网络字节序IP
//    serverAddr.sin_addr.s_addr = inet_addr("39.105.185.198");
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    if(connect(socket_fd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0)
    {
    
    
        perror("connect");
        return 1;
    }
    printf("success to connect server...\n");

    while(1)
    {
    
    
        memset(sendbuf, 0, MESSAGE_LENGTH);

        printf("<<<<send message:");

        gets(sendbuf);
        //printf("\n");
        ret = send(socket_fd, sendbuf, strlen(sendbuf), 0);
        if(ret <= 0 ){
    
    
            printf("the connection is disconnection!\n");
            break;
        }

        if(strcmp(sendbuf, "quit") == 0){
    
    
            break;
        }

        printf(">>> echo message:");

        recvbuf[0] = '\0';
        data_len = recv(socket_fd, recvbuf, MESSAGE_LENGTH, 0);

        recvbuf[data_len] = '\0';

        printf("%s\n", recvbuf);

    }

    close(socket_fd);

    return 0;

}