linux套接字編程示例

簡單TCP、UDP編程示例。

TCP

TCP通信模型

伺服器代碼

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

int main(void)
{
    const char ip[] = "127.0.0.1";
    const int port = 9006;

    //創建socket，使用IP協議（PF_INET）+TCP協議（SOCK_STREAM）
    int fd_listen = socket(PF_INET, SOCK_STREAM, 0);

    //綁定固定ip:port地址
    in_addr_t ip_num = inet_addr(ip);
    sockaddr_in addr_server = {AF_INET, port, ip_num};
    bind(fd_listen, (sockaddr *)&addr_server, sizeof(addr_server));

    //監聽socket
    listen(fd_listen, 10);

    //接受客戶端連接，並返回連接socket
    sockaddr_in addr_client;
    socklen_t len_client_addr = sizeof(addr_client);
    int fd_conn = accept(fd_listen, (sockaddr *)&addr_client, &len_client_addr);

    //接收客戶端數據
    printf("start receiving data...\n");

    char buf[4096];
    while (true)
    {
        memset(buf, '\0', sizeof(buf));
        int ret = recv(fd_conn, buf, sizeof(buf) - 1, 0);

        // recv返回0，表示客戶端斷開連接
        if (ret == 0)
        {
            printf("connection closed\n");
            break;
        }

        //列印接收的數據
        printf("%s", buf);
    }

    //關閉socket
    close(fd_conn);
    close(fd_listen);
    return 0;
}

客戶端代碼

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

int main(void)
{
    const char ip[] = "127.0.0.1"; //伺服器ip
    const int port = 9006;         //伺服器port

    //創建socket，使用IP協議（PF_INET）+TCP協議（SOCK_STREAM）
    int fd_conn = socket(PF_INET, SOCK_STREAM, 0);

    //連接伺服器
    in_addr_t ip_num = inet_addr(ip);
    sockaddr_in addr_server = {AF_INET, port, ip_num}; //伺服器地址
    connect(fd_conn, (sockaddr *)&addr_server, sizeof(addr_server));

    const char message[] = "hello world!\n";
    for (int i = 0; i < 10; i++)
    {
        send(fd_conn, message, strlen(message), 0);
        sleep(1);
    }

    //關閉socket
    close(fd_conn);
    return 0;
};

UDP

UDP通信模型

伺服器代碼

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

int main(void)
{
    const char ip[] = "127.0.0.1";
    const int port = 9006;

    //創建socket，使用IP協議（PF_INET）+SOCK_DGRAM
    int fd_socket = socket(PF_INET, SOCK_DGRAM, 0);

    //綁定固定ip:port地址
    in_addr_t ip_num = inet_addr(ip);
    sockaddr_in addr_server = {AF_INET, port, ip_num};
    bind(fd_socket, (sockaddr *)&addr_server, sizeof(addr_server));

    //接收客戶端數據
    printf("start receiving data...\n");

    //存放客戶端地址
    sockaddr_in addr_client;
    socklen_t len_addr_client = sizeof(addr_client);

    char buf[4096];
    while (true)
    {
        //接收數據
        memset(buf, '\0', sizeof(buf));
        int ret = recvfrom(fd_socket, buf, sizeof(buf) - 1, 0, (sockaddr *)&addr_client, &len_addr_client);
        char *ip_client = inet_ntoa(addr_client.sin_addr);
        int port_client = addr_client.sin_port;

        //列印接收的數據
        printf("recived from %s:%d: %s\n", ip_client, port_client, buf);
    }

    //關閉socket
    close(fd_socket);
    return 0;
}

客戶端代碼

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

int main(void)
{
    const char ip[] = "127.0.0.1";
    const int port = 9006;

    //創建socket，使用IP協議（PF_INET）+SOCK_DGRAM
    int fd_socket = socket(PF_INET, SOCK_DGRAM, 0);

    //綁定固定ip:port地址
    in_addr_t ip_num = inet_addr(ip);
    sockaddr_in addr_server = {AF_INET, port, ip_num};
    bind(fd_socket, (sockaddr *)&addr_server, sizeof(addr_server));

    //接收客戶端數據
    printf("start receiving data...\n");

    //存放客戶端地址
    sockaddr_in addr_client;
    socklen_t len_addr_client = sizeof(addr_client);

    char buf[4096];
    while (true)
    {
        //接收數據
        memset(buf, '\0', sizeof(buf));
        int ret = recvfrom(fd_socket, buf, sizeof(buf) - 1, 0, (sockaddr *)&addr_client, &len_addr_client);
        char *ip_client = inet_ntoa(addr_client.sin_addr);
        int port_client = addr_client.sin_port;

        //列印接收的數據
        printf("recived from %s:%d: %s\n", ip_client, port_client, buf);
    }

    //關閉socket
    close(fd_socket);
    return 0;
}