网络编程（一）

一.基于TCP的服务器和客户端之间的通信

    1.服务器端

#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 8888
#define BUF_LEN 100

int main(int argc,char **argv)
{
    int socketfd;
    int ret;
    int len;
    char buf[BUF_LEN] = {0};
    ssize_t clientfd;
    ssize_t buf_len;//接收的数据长度
    struct sockaddr_in server;
    struct sockaddr_in client;
    len = sizeof(client);
    /**
     *socket(int sockfd,const struct aockaddr *addr,)
     * */
    //服务器的创建
    //创建服务器端通信套接口
    socketfd = socket(AF_INET,SOCK_STREAM,0);
    if(socketfd < 0)
    {
        perror("socket");
        return -1;
    }

    bzero(&server,sizeof(server));

    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr.s_addr = inet_addr(argv[1]);

    //绑定地址
    ret = bind(socketfd,(struct sockaddr *)&server,len);
    if(ret < 0)
    {
        perror("bind");
        return -1;
    }
    
    //设置监听队列
    ret = listen(socketfd,4);
    if(ret< 0)
    {
        perror("listen");
        return -1;
    }

    //接收由客户端传来的数据
    while(1)
    {
        printf("1\n");
        clientfd = accept(socketfd,(struct sockaddr *)&client,&len);
        printf("2\n");
        if(clientfd < 0)
        {
            perror("accept");
//            return -1;
        }

        printf("accepted a new connection\n");
        printf("new socket id is %d\n",clientfd);
        printf("Accept client ip is %s\n",inet_ntoa(client.sin_addr));

        printf("start to recv...\n");
        while(1)
        {
            //接收来自客户端的数据
            buf_len = recv(clientfd,buf,BUF_LEN,0);
            if(buf_len < 0)
            {
                perror("recv");
                return -1;
            }
            else if(buf > 0)
            {
                if(strcmp(buf,"exit") == 0)
                {
                    printf("client is closed\n");
                    close(clientfd);
                    break;
                }
                printf("buf %s\n",buf);
            }
        }
    }


    //关闭socket
    close(clientfd);
    close(socketfd);
    return 0;
}       

    2.客户端

#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 8888
#define MAX_LEN 100

int main(int argc,char **argv)
{
    int socketfd;
    int serverfd;
    int ret;
    char buf[MAX_LEN];
    
    struct sockaddr_in server;

    //创建TCP通信socket
    socketfd = socket(AF_INET,SOCK_STREAM,0);
    if(socketfd < 0)
    {
        perror("socket");
        return -1;
    }
    //将空间清零
    bzero(&server,sizeof(server));

    目的地址
    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr.s_addr = inet_addr(argv[1]);

    请求连接目标地址
    serverfd = connect(socketfd,(struct sockaddr *)&server,sizeof(server));
    if(serverfd < 0)
    {
        perror("connect");
        return -1;
    }

    printf("connect success\n");

    while(1)
    {
        //将键盘键入的内容进行传输
        printf("please input buf:");
        scanf("%s",buf);
        //当键入的字符串为exit时，关闭客户端
        if(strcmp(buf,"exit") == 0)
        {
            ret = send(socketfd,buf,sizeof(buf),0);
            if(ret < 0)
            {
                perror("send");
                return -1;
            }
            break;
        }
        ret = send(socketfd,buf,sizeof(buf),0);
        if(ret < 0)
        {
            perror("send");
            return -1;
        }
    }

    return 0;
}

二.基于UDP的服务器和客户端之间的通信

    1.服务器端

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 9999

int main(int argc,char **argv)
{
    int socket_fd;
    int ret;

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    int len = sizeof(struct sockaddr_in);
    char buf[100] = {0};
    int recv_len;

    //创建UDP通信socket
    socket_fd = socket(AF_INET,SOCK_DGRAM,0);
    if(socket_fd < 0)
    {
        perror("socket");
        return -1;
    }
    
    //将空间清空
    bzero(&server_addr,sizeof(server_addr));

    目的地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr((const char *)argv[1]);

    //绑定地址
    ret = bind(socket_fd,(struct sockaddr *)&server_addr,sizeof(server_addr));
    if(ret < 0)
    {
        perror("bind");
        return -1;
    }

    while(1)
    {
        //接收从客户端传输的数据
        recv_len = recvfrom(socket_fd,buf,100,0,(struct sockaddr *)&client_addr,&len);
        if(recv_len < 0)
        {
            perror("recvfrom");
            return -1;
        }
        printf("buf is %s\n",buf);
        memset(buf,0,100);
    }
    close(socket_fd);

    return 0;
}

    2.客户端

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 9999
#define MAX_SIZE 100

int main(int argc,char **argv)
{
    int socket_fd;
    struct sockaddr_in server_addr;
    
    int len = sizeof(struct sockaddr_in);
    char buf[MAX_SIZE] = {0};
    int send_len;

    创建UDP通信socket
    socket_fd = socket(AF_INET,SOCK_DGRAM,0);
    if(socket_fd < 0)
    {
        perror("socket");
        return -1;
    }

    //将空间清空
    bzero(&server_addr,sizeof(struct sockaddr_in));

    //目的地址
    server_addr.sin_family = AF_INET;//IPv4协议
    server_addr.sin_port = htons(PORT);//端口
    server_addr.sin_addr.s_addr = inet_addr((const char *)argv[1]);

    while(1)
    {
        //键盘键入内容进行传输
        printf("input:\n");
        scanf("%s",buf);
        send_len = sendto(socket_fd,buf,MAX_SIZE,0,(struct sockaddr *)&server_addr,len);
    }

    //关闭socket
    close(socket_fd);

    return 0;
}