Day01_C语言网络编程20250711

01.思维导图

2：使用服务器和客户端的代码，实现服务器和客户端的互相聊天功能
    同桌之间互相聊天

第一版本:
client
 

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <wait.h>
#include <signal.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <sys/msg.h>
#include <sys/shm.h>
#include <sys/un.h>

typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;

enum Type{
	TYPE_REGIST,
	TYPE_LOGIN
};

typedef struct Pack{
	int size; // 用来记录打算发送的协议包有多大
	enum Type type;
	char buf[4096];
	int used;
}pack_t;

// 写一个函数，功能为 向pack包中，写入一组数据
// 参数1： & pack包 
// 参数2：想要写入的数据本身，暂定为字符串
void pack_append_data(pack_t* pack,const char* val){
	char* buf = pack->buf;

	// 计算准备写入的数据的长度
	short len = strlen(val);

	// 从buf里面，取2个字节，用来存放val的长度
	*(short*)(buf+pack->used) = len;
	// buf + pack->used
	// 含义为：偏移掉已经使用的部分，从buf未使用的部分开始存放数据

	pack->used += 2;

	// 将字符串数据拷贝到紧挨着的内存里面
	strcpy(buf+pack->used,val);
	pack->used += len;

	pack->size = 8 + pack->used;
	// 8个字节是什么？ size 自己的大小 + type 的大小
	// pack->used是什么？ pack.buf 实际使用的大小
}

int main(int argc, const char *argv[])
{
	if(argc < 2){
		printf("请输入端口号\n");
		return 1;
	}
	short port = atoi(argv[1]);// atoi 函数，将字符串类型转换成整形

	int client = socket(AF_INET,SOCK_STREAM,0);

	struct sockaddr_in addr = {0};
	addr.sin_family = AF_INET;	
	addr.sin_port = htons(port);
	addr.sin_addr.s_addr = inet_addr("192.168.201.104");

	connect(client,(struct sockaddr*)&addr,sizeof(addr));

// 	客户端发送账号密码给服务器，实现注册/登录操作

	while(1){
		char name[16] = "";
		char pswd[16] = "";
		printf("请输入账号:");
		scanf("%s",name);
		getchar();

		printf("请输入密码:");
		scanf("%s",pswd);
		getchar();

		pack_t pack = {0};
		pack_append_data(&pack,name);// 将账号name存入pack包中
		pack_append_data(&pack,pswd);// 将密码pswd存入pack包中

		printf("packsize = %d\n",pack.size);
		write(client,&pack,pack.size);
	}
	return 0;
}

server
 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>

int main(int argc, const char *argv[])
{
    if(argc<2)
    {
        printf("请输入端口号!\n");
        return 1;
    }
    short port=atoi(argv[1]);
    int server=socket(AF_INET,SOCK_STREAM,0);

    struct sockaddr_in addr={0};
    addr.sin_family=AF_INET;

    addr.sin_port=htons(port);
    addr.sin_addr.s_addr=inet_addr("0.0.0.0");

    if(bind(server,(struct sockaddr*)&addr,sizeof(addr))==-1)
    {
        perror("bind error..");
        return -1;
    }

    //监听
    listen(server,10);

    printf("服务器已启动，等待客户端连接...\n");

    //接收                                                                                                      
    //准备好客户端结构体
    struct sockaddr_in client_addr;
    socklen_t client_len = sizeof(client_addr);
    //接收客户端,返回客户端套接字
    int client = accept(server,(struct sockaddr*)&client_addr,&client_len);
    
    if(client == -1) {
        perror("accept error");
        close(server);
        return -1;
    }

    printf("客户端已连接\n");

    while(1)
    {
        char buf[128]="";

        int res=read(client,buf,sizeof(buf));
        printf("res=%d\n",res);
        if(res==0)
        {
            printf("客户端断开连接~\n");
            break;  // 修改：使用break而不是return，避免直接退出程序
        }
        else if(res == -1) {
            perror("read error");
            break;  // 处理读取错误
        }
        printf("接收到客户端消息：%s\n",buf);
    }
    
    // 新增：关闭客户端和服务器套接字
    close(client);
    close(server);
    return 0;
}

实现聊天功能的代码: 

01_server
 

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

#define PORT 8888
#define BUFFER_SIZE 1024

// 接收消息线程函数
void *receive_messages(void *arg) 
{
    int sockfd = *(int *)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        ssize_t bytes_received = recv(sockfd, buffer, BUFFER_SIZE - 1, 0);
        if (bytes_received <= 0) {
            printf("对方已断开连接。\n");
            close(sockfd);
            exit(0);
        }
        printf("对方: %s\n", buffer);
    }
    return NULL;
}

// 发送消息线程函数
void *send_messages(void *arg)
{
    int sockfd = *(int *)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        fgets(buffer, BUFFER_SIZE - 1, stdin);
        buffer[strcspn(buffer, "\n")] = 0; // 去掉换行符
        if (send(sockfd, buffer, strlen(buffer), 0) == -1) {
            perror("发送消息失败");
            close(sockfd);
            exit(0);
        }
    }
    return NULL;
}

// 服务器功能函数
void server_function()
{
    int server_fd, new_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);

    // 创建套接字
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置套接字选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    // 绑定套接字
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    // 监听连接
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    printf("等待客户端连接...\n");
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    printf("客户端已连接。\n");

    pthread_t receive_thread, send_thread;
    // 创建接收和发送消息线程
    pthread_create(&receive_thread, NULL, receive_messages, &new_socket);
    pthread_create(&send_thread, NULL, send_messages, &new_socket);

    pthread_join(receive_thread, NULL);
    pthread_join(send_thread, NULL);

    close(new_socket);
    close(server_fd);
}

// 客户端功能函数
void client_function()
{
    int sock = 0;
    struct sockaddr_in serv_addr;

    // 创建套接字
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("\n 套接字创建错误 \n");
        return;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);

    // 将 IPv4 地址从点分十进制转换为二进制形式
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        perror("\n 无效地址/ 地址不支持 \n");
        return;
    }

    // 连接到服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("\n 连接失败 \n");
        return;
    }
    printf("已连接到服务器。\n");

    pthread_t receive_thread, send_thread;
    // 创建接收和发送消息线程
    pthread_create(&receive_thread, NULL, receive_messages, &sock);
    pthread_create(&send_thread, NULL, send_messages, &sock);

    pthread_join(receive_thread, NULL);
    pthread_join(send_thread, NULL);

    close(sock);
}

int main()
{
    char choice;
    printf("选择角色 (s: 服务器, c: 客户端): ");
    scanf(" %c", &choice);
    getchar(); // 消耗掉换行符

    if (choice == 's') {
        server_function();
    } else if (choice == 'c') {
        client_function();
    } else {
        printf("无效选择。\n");
    }

    return 0;
}

01_client
 

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

#define PORT 8888
#define BUFFER_SIZE 1024

// 接收消息线程函数
void *receive_messages(void *arg) 
{
    int sockfd = *(int *)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        ssize_t bytes_received = recv(sockfd, buffer, BUFFER_SIZE - 1, 0);
        if (bytes_received <= 0) {
            printf("对方已断开连接。\n");
            close(sockfd);
            exit(0);
        }
        printf("对方: %s\n", buffer);
    }
    return NULL;
}

// 发送消息线程函数
void *send_messages(void *arg)
{
    int sockfd = *(int *)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        fgets(buffer, BUFFER_SIZE - 1, stdin);
        buffer[strcspn(buffer, "\n")] = 0; // 去掉换行符
        if (send(sockfd, buffer, strlen(buffer), 0) == -1) {
            perror("发送消息失败");
            close(sockfd);
            exit(0);
        }
    }
    return NULL;
}

// 服务器功能函数
void server_function()
{
    int server_fd, new_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);

    // 创建套接字
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置套接字选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    // 绑定套接字
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    // 监听连接
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    printf("等待客户端连接...\n");
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    printf("客户端已连接。\n");

    pthread_t receive_thread, send_thread;
    // 创建接收和发送消息线程
    pthread_create(&receive_thread, NULL, receive_messages, &new_socket);
    pthread_create(&send_thread, NULL, send_messages, &new_socket);

    pthread_join(receive_thread, NULL);
    pthread_join(send_thread, NULL);

    close(new_socket);
    close(server_fd);
}

// 客户端功能函数
void client_function()
{
    int sock = 0;
    struct sockaddr_in serv_addr;

    // 创建套接字
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("\n 套接字创建错误 \n");
        return;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);

    // 将 IPv4 地址从点分十进制转换为二进制形式
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        perror("\n 无效地址/ 地址不支持 \n");
        return;
    }

    // 连接到服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("\n 连接失败 \n");
        return;
    }
    printf("已连接到服务器。\n");

    pthread_t receive_thread, send_thread;
    // 创建接收和发送消息线程
    pthread_create(&receive_thread, NULL, receive_messages, &sock);
    pthread_create(&send_thread, NULL, send_messages, &sock);

    pthread_join(receive_thread, NULL);
    pthread_join(send_thread, NULL);

    close(sock);
}

int main()
{
    char choice;
    printf("选择角色 (s: 服务器, c: 客户端): ");
    scanf(" %c", &choice);
    getchar(); // 消耗掉换行符

    if (choice == 's') {
        server_function();
    } else if (choice == 'c') {
        client_function();
    } else {
        printf("无效选择。\n");
    }

    return 0;
}