linux网络编程

复习socket tcp/udp通信

TCP

服务器端：新建socket， 绑定， 监听， 等待接收，发送，关闭。

客户端：新建套接字，绑定，连接，发送/接收， 关闭。

服务器端代码：

#define N 64
int main(int argc, char *argv[])
{
    int listenfd, connectfd;
    struct sockaddr_in serveraddr, clientaddr;
    socklen_t clientlen = sizeof(clientaddr);
    char buf[N] = "";
    
    if (argc < 3) {
        printf("Usage : %s <serverip> <serverport>
", argv[0]);
        exit(-1);
    }
    
    if ((listenfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        perror("fail to socket");
        exit(-1);
    }
    bzero(&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = PF_INET;
    serveraddr.sin_port = htons(atoi(argv[2]));
    serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
    
    if (bind(listenfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0) {
        perror("fail to bind");
        exit(-1);
    }
    
    if (listen(listenfd, 8) < 0) {
        perror("fail to listen");
        exit(-1);
    }
    
    while (1) {
        if ((connectfd = accept(listenfd, (struct sockaddr *)&clientaddr, &clientlen)) < 0) {
            perror("fail to accept");
            exit(-1);
        }
        printf("connection from [%s:%d]
", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
        
        recv(connectfd, buf, N, 0);
        send(connectfd, buf, N, 0);
    
        close(connectfd);
        
    }
}

客户端代码

#define N 64
int main(int argc, char *argv[])
{
    int sockfd;
    struct sockaddr_in serveraddr;
    char buf_send[N] = "hello world";
    char buf_recv[N] = " ";
    
    if (argc < 3) {
        printf("Usage : %s <serverip> <serverport>
", argv[0]);
        exit(-1);
    }
    
    if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        perror("fail to socket");
        exit(-1);
    }
    
    bzero(&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = PF_INET;
    serveraddr.sin_port = htons(atoi(argv[2]));
    serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
    
    if (connect(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0) {
        perror("fail to connect");
        exit(-1);
    }
    
    send(sockfd, buf_send, N, 0);
    recv(sockfd, buf_recv, N, 0);
    printf("receive from server : %s
", buf_recv);
    
    close(sockfd);
    return 0;
}

UDP

服务器端：socket， bind， recvfrom， sendto。

客户端：socket， bind， sendto， recvfrom。

服务器端代码：

#define N 64
int main(int argc, char *argv[])
{
    int sockfd;
    struct sockaddr_in serveraddr, clientaddr;
    socklen_t clientlen = sizeof(clientaddr);
    char buf[N];
    
    if (argc < 3) {
        printf("Usage : %s <serverip> <serverport>
", argv[0]);
        exit(-1);
    }
    
    if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("fail to socket");
        exit(-1);
    }
    
    bzero(&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = PF_INET;
    serveraddr.sin_port = htons(atoi(argv[2]));
    serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
    
    return 0;
}

客户端代码

#define N 64

typedef struct sockaddr SA;
int main(int argc, char *argv[])
{
    int sockfd;
    struct sockaddr_in servaddr;
    char buf[N] = "Hello Server";

    if (argc < 3)
    {
        printf("Usage : %s <ip> <port>
", argv[0]);
        exit(-1);
    }

    // XXX int socket(int domain, int type, int protocol);
    if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
    {
        perror("fail to socket");
        exit(-1);
    }

    // XXX int bind(int sockfd, const struct sockaddr *addr,
    //              socklen_t addrlen);
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = PF_INET;
    servaddr.sin_port = htons(atoi(argv[2]));
    servaddr.sin_addr.s_addr = inet_addr(argv[1]);
    
    while ( 1 )
    {
        printf("client > ");
        fgets(buf, N, stdin);
        if (strncmp(buf, "quit", 4) == 0) break;
        sendto(sockfd, buf, N, 0, (SA *)&servaddr, sizeof(servaddr));
        bzero(buf, N);
        recvfrom(sockfd, buf, N, 0, NULL, NULL);
        printf("recv from server : %s
", buf);
    }

    return 0;
}