socket 编程

#include <iostream>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#define PORT 8111
#define MESSAGE_LEN 1024
using namespace std;
int main(int arc, char *argv[]) {
    int ret = -1;
    int socket_fd = -1, accept_fd = -1;
    int on = 1;
    int backlog = 10;
    struct sockaddr_in localaddr,remoteaddr;
    char in_buff[MESSAGE_LEN] = {0,};
  
    //创建一个socket
    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_fd == -1) {
        cout << "Failed to create socket!" << endl;
        exit(-1);
    }
		// SO_REUSEADDR 允许套接口和一个已在使用中的地址捆绑
    ret = setsockopt(socket_fd,
                     SOL_SOCKET,
                     SO_REUSEADDR,
                     &on,
                     sizeof(on));
    if (ret == -1) {
        cout << "Failed to set socket options" << endl;
    }
    localaddr.sin_family = AF_INET;
    localaddr.sin_port = PORT;
    localaddr.sin_addr.s_addr = INADDR_ANY;
//    绑定
    ret = bind(socket_fd, (struct sockaddr *) &localaddr, sizeof(struct sockaddr));
    if (ret == -1) {
        cout << "Failed to bind addr!" << endl;
        exit(-1);
    }
//    侦听
    ret = listen(socket_fd, backlog);
    if (ret == -1) {
        cout << " Failed to listen socket!" << endl;
        exit(-1);
    }
    for (;;) {
        socklen_t addr_len = sizeof(struct sockaddr);
        accept_fd = accept(socket_fd,
               (struct sockaddr *) &remoteaddr,
               &addr_len);
//        开始接受数据
        for (;;) {
//            第一个空从accept_fd接受数据，
            ret = recv(accept_fd, (void *) in_buff, MESSAGE_LEN, 0);
            if (ret == 0)//没有发数据和我们断开连接了
            {
                break;
            }
            cout << "rev:" << in_buff << endl;
            send(accept_fd, (void *) in_buff, MESSAGE_LEN, 0);
        }
        close(accept_fd);
    }
//    把socket关闭
    close(socket_fd);
    return 0;
}

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#define PORT 8111
#define MESSAGE_LEN 1024
using namespace std;
int main(int arc, char *argv[]) {
    int ret = -1;
//   创建socket连接
    int socket_fd;
    char sendbuf[MESSAGE_LEN] = {0,};//输入的buffer
    char recvbuf[MESSAGE_LEN] = {0,};//输出
    struct sockaddr_in serveraddr;
    socket_fd = socket(AF_INET,SOCK_STREAM,0);
    if(socket_fd<0){
        cout<<"Failed to create socket!"<<endl;
        exit(-1);
    }
    //    连接
    serveraddr.sin_family = AF_INET;
    serveraddr.sin_port = PORT;
    serveraddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    ret = connect(socket_fd,
                  (struct sockaddr *)&serveraddr,
                  sizeof(struct sockaddr));
    if (ret < 0){
        cout<<"Failed to connect !"<<endl;
        exit(-1);
    }
    //    进入连接
    while (1){
        memset(sendbuf,0,MESSAGE_LEN);
//        从控制台中获取输入的数据，存储到sendbuf里面
        gets(sendbuf);
        ret = send(socket_fd,sendbuf,strlen(sendbuf),0);
        if(ret<=0){//服务端把信息断开了，无法发送数据
            cout<<"Failed to send data;"<<endl;
            break;
        }
        if (strcmp(sendbuf,"quit")==0){
            break;
        }
//       接受数据
        ret  = recv(socket_fd,recvbuf,MESSAGE_LEN,0);
        recvbuf[ret] = '\0';
        cout<<"recv:"<<recvbuf<<endl;
    }
    close(socket_fd);
    return 0;
}

#include <iostream>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#define PORT 8111
#define MESSAGE_LEN 1024
using namespace std;
int main(int arc, char *argv[]) {
    int ret = -1;
    int socket_fd , accept_fd;
    int on = 1;
    int backlog = 10;
    pid_t pid;
    struct sockaddr_in localaddr,remoteaddr;
    char in_buff[MESSAGE_LEN] = {0,};
    //创建一个socket
    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_fd == -1) {
        cout << "Failed to create socket!" << endl;
        exit(-1);
    }
    // SO_REUSEADDR 允许套接口和一个已在使用中的地址捆绑
    ret = setsockopt(socket_fd,
                     SOL_SOCKET,
                     SO_REUSEADDR,
                     &on,
                     sizeof(on));
    if (ret == -1) {
        cout << "Failed to set socket options" << endl;
    }
    localaddr.sin_family = AF_INET;
    localaddr.sin_port = PORT;
    localaddr.sin_addr.s_addr = INADDR_ANY;
//    绑定
    ret = bind(socket_fd, (struct sockaddr *) &localaddr, sizeof(struct sockaddr));
    if (ret == -1) {
        cout << "Failed to bind addr!" << endl;
        exit(-1);
    }
//    侦听
    ret = listen(socket_fd, backlog);
    if (ret == -1) {
        cout << " Failed to listen socket!" << endl;
        exit(-1);
    }
    for (;;) {
        socklen_t addr_len = sizeof(struct sockaddr);
        accept_fd = accept(socket_fd,
                           (struct sockaddr *) &remoteaddr,
                           &addr_len);
        pid = fork();
        if (pid == 0){//pid是0，说明就是子进程
//        开始接受数据
            for (;;) {
//            第一个空从accept_fd接受数据，
                ret = recv(accept_fd, (void *) in_buff, MESSAGE_LEN, 0);
                if (ret == 0)//没有发数据和我们断开连接了
                {
                    break;
                }
                cout << "rev:" << in_buff << endl;
                send(accept_fd, (void *) in_buff, MESSAGE_LEN, 0);
            }
        }//如果是父进程就不会走这段代码
        if (pid != 0){
            close(accept_fd);
        }
    }
//    把socket关闭
    close(socket_fd);
    return 0;
}