【HZ-RK3568开发板免费体验】--TCP通讯

本篇实现客户端(client)与服务端(server)数据通讯收发功能。
一.TCP通讯流程

服务端和客户端程序均可在评估板、PC 机 Ubuntu 系统上运行。本章节采用评估板本地回环测试，即服务端与客户端程序均在评估板上运行，通过 127.0.0.1 进行本地回环测试。

二.代码
1.TCP客户端程序

/* Copyright 2019 Tronlong Elec. Tech. Co. Ltd. All Rights Reserved. */

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

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    // check the arguments.
    if (argc != 3) {
        printf("Usage:\n");
        printf("    %s <server addr> <port number>\n", argv[0]);
        return -1;
    }

    char *addr = argv[1];
    short port = atoi(argv[2]);

    int sock_fd;
    int ret;
    char recv_buf[BUFFER_SIZE], send_buf[BUFFER_SIZE];
    struct sockaddr_in server_addr;

    // initialize address/
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    server_addr.sin_addr.s_addr = inet_addr(addr);

    // create socket fd.
    sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        return -1;
    }

    // connect.
    ret = connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
    if (ret == -1) {
        perror("connect");
        goto err;
    }

    printf("connect server(IP:%s Port: %d).\n", addr, port);

    pid_t pid = fork();
    if (pid > 0) {
        // The parent process is responsible for sending messages.
        while (1) {
            bzero(send_buf, sizeof(send_buf));
            char *str = fgets(send_buf, sizeof(send_buf), stdin);
            if (str == NULL) {
                perror("fgets");
                goto err;
            }

            if (send(sock_fd, send_buf, strlen(send_buf) - 1, 0) < 0) {
                perror("send");
                goto err;
            }
        }
    }
    else if (pid == 0) {
        // The child process is responsible for receiving messages.
        while (1) {
            bzero(recv_buf, sizeof(recv_buf));
            if (sock_fd > 0) {
                if ((recv(sock_fd, recv_buf, BUFFER_SIZE, 0)) <= 0) {
                    perror("recv");
                    goto err;
                }

                printf("[Recv from server %s:%d] : %s\n",
                        inet_ntoa(server_addr.sin_addr),
                        htons(server_addr.sin_port),
                        recv_buf);
            }
        }
    }
    else {
        perror("fork");
        goto err;
    }

    close(sock_fd);
    return 0;

err:
    close(sock_fd);
    return -1;
}

在TCP客户端程序中，使用了socket、connect、send、recv等系统调用的使用。

2.TCP服务端程序

/* Copyright 2019 Tronlong Elec. Tech. Co. Ltd. All Rights Reserved. */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ipc.h>
#include <errno.h>
#include <sys/shm.h>
#include <time.h>
#include <pthread.h>
#include <arpa/inet.h>

#define BUFFER_SIZE     1024    // buf size
#define LISTENQ         1       // the max quote

#define SIZE_SHMADD 2048

int main(int argc, char *argv[]) {
    // check the arguments.
    if (argc != 2) {
        printf("Usage:\n");
        printf("    %s <port number>\n", argv[0]);
        return -1;
    }

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    char recv_buf[BUFFER_SIZE];
    char send_buf[BUFFER_SIZE];

    pid_t pid;
    int sock_fd, conn_fd = -1;
    int optval = 1;
    int port = atoi(argv[1]);

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

    // setting bind port crycled.
    if ((setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR,
                                    (void *)&optval, sizeof(int))) < 0) {
        perror("setsockopt");
        goto err;
    }

    // initized address.
    bzero(&server_addr, sizeof(struct sockaddr_in));
    server_addr.sin_family=AF_INET;
    server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    server_addr.sin_port = htons(port);

    // bind the port.
    if (bind(sock_fd, (struct sockaddr *)(&server_addr),
                                        sizeof(struct sockaddr)) == -1) {
        perror("bind");
        goto err;
    }
    
    // transform the socket into listen socket.
    if (listen(sock_fd, LISTENQ) == -1) {
        perror("listen");
        goto err;
    }

    printf("Waiting for client connectionn...\n");

    socklen_t cli_len = sizeof(struct sockaddr_in);
    conn_fd = accept(sock_fd, (struct sockaddr *)(&client_addr), &cli_len);
    if (conn_fd == -1) {
        perror("accept");
        close(sock_fd);
        return -1;
    }

    printf("Client accepted : %s:%d \n",
            inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

    pid = fork();
    if (pid > 0) {
        // The parent process is responsible for sending messages.
        while (1) {
            bzero(send_buf, sizeof(send_buf));
            char *str = fgets(send_buf, sizeof(send_buf), stdin);
            if (str == NULL) {
                perror("fgets");
                goto err;
            }

            if (send(conn_fd, send_buf, strlen(send_buf) - 1, 0) < 0) {
                perror("send");
                goto err;
            }
        } 
    }
    else if (pid == 0) {
        // The child process is responsible for receiving messages.
        while (1) {
            bzero(recv_buf, sizeof(recv_buf));
            if ((recv(conn_fd, recv_buf, BUFFER_SIZE, 0)) <= 0) {
                perror("recv");
                goto err;
            }

            printf("[Recv from client %s:%d] : %s\n",
                    inet_ntoa(server_addr.sin_addr),
                    htons(server_addr.sin_port),
                    recv_buf);
        }
    }
    else {
        perror("fork");
        goto err;
    }

    close(conn_fd);
    close(sock_fd);
    return 0;

err:
    close(conn_fd);
    close(sock_fd);
    return -1;
}

在TCP服务端程序中，使用了socket、connect、send、recv、bind、listen、accept等系统调用的使用。

三.调试测验
1.开发板上电联网，获取开发板ip.
HZ-wifi.sh -i wlan0 -s "HUAWEI-P" -p password
ifconfig
2.将编译的可执行文件传输到开发板
scp tcp_client root@192.168.3.217:/user_app/
scp tcp_server root@192.168.3.217:/user_app/
输入登录验证密码为root
传输成功在开发板端可看到这些文件。

3.在ubuntu控制台登录开发板，切换到user_app路径下
ssh root@192.168.3.217

4.服务端与客户端分别执行以下命令
TCP服务端命令
./tcp_server 2233
TCP客户端命令
./tcp_client 127.0.0.1 2233、

至此实现TCP通讯功能。