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C语言UNIX域套接字CS模型

news 来源：原创 2024/5/9 9:47:39

实验目标:

1 实现基于流的unix域套接字通信cs模型

2 实现基于数据报的unix域套接字通信cs模型

3 可以观察到CS两端的完整启动退出流程,为了实现这一目标仅进行一次通信

实验心得:

1 使用unlink避免地址冲突清理资源

2 传统udp在首次sendto时系统临时分配端口,在套接字关闭|程序终止|显式解绑时端口生命周期结束,而unix域套接字则需要手动绑定,否则客户端无法收到服务器的回信

3 复制文件路径时,sun_path的长度无法更改,容易出现越界的情况

基于流:

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <string.h>
#include <unistd.h>#define SOCK_PATH "/home/u22/socket/addr1"
// 服务端
int main()
{int server_sockfd, client_sockfd;struct sockaddr_un server_sockaddr, client_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));memset(&client_sockaddr, 0, sizeof(client_sockaddr));socklen_t client_sockaddr_len = sizeof(client_sockaddr);ssize_t send_bytes, recv_bytes;char send_buf[1024] = "server say : How can I help you today ?";char recv_buf[1024] = {0};// unix域套接字 使用流式传输,不能叫TCPserver_sockfd = socket(AF_UNIX, SOCK_STREAM, 0);if (server_sockfd == -1){perror("socket");}server_sockaddr.sun_family = AF_UNIX;strcpy(server_sockaddr.sun_path, SOCK_PATH);// 为什么要删除这个文件?因为再次启动代码将无法访问这个文件unlink(SOCK_PATH);if ((bind(server_sockfd, (struct sockaddr *)&server_sockaddr, sizeof(server_sockaddr))) == -1){perror("bind");}if (listen(server_sockfd, 16) == -1){perror("listen");}printf("waiting for connect...\n");// accept返回后将收到客户端地址信息client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_sockaddr, &client_sockaddr_len);if (client_sockfd == -1){perror("accept");}// 同tcp一样 recv send使用accept返回的socket通信recv_bytes = recv(client_sockfd, recv_buf, sizeof(recv_buf), 0);if (recv_bytes == -1){perror("recv");}if (recv_bytes > 0){printf("%s\n", recv_buf);}send_bytes = send(client_sockfd, send_buf, strlen(send_buf), 0);if (send_bytes == -1){perror("send");}if (send_bytes > 0){printf("%s\n", send_buf);}close(client_sockfd);close(server_sockfd);printf("server close\n");//用完了 还要删一遍unlink(SOCK_PATH);return 0;
}

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <string.h>
#include <unistd.h>#define SOCK_PATH "/home/u22/socket/addr1"
//客户端
int main()
{int client_sockfd;struct sockaddr_un server_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));ssize_t send_bytes, recv_bytes;char send_buf[1024] = "client say : hello server !";char recv_buf[1024] = {0};//创建基于流的unix域套接字client_sockfd = socket(AF_UNIX, SOCK_STREAM, 0);if (client_sockfd == -1){perror("socket");}server_sockaddr.sun_family = AF_UNIX;strcpy(server_sockaddr.sun_path, SOCK_PATH);//尝试连接serverprintf("connect server...\n");if ((connect(client_sockfd, (struct sockaddr *)&server_sockaddr, sizeof(server_sockaddr))) == -1){perror("connect");}//与TCP一样 使用socket()返回的socket通信send_bytes = send(client_sockfd, send_buf, strlen(send_buf), 0);if (send_bytes == -1){perror("send");}printf("%s\n", send_buf);recv_bytes = recv(client_sockfd, recv_buf, sizeof(recv_buf), 0);if (recv_bytes == -1){perror("recv");}printf("%s\n", recv_buf);close(client_sockfd);printf("client close\n");return 0;
}

基于数据报:

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <string.h>
#include <unistd.h>#define SOCK_PATH "/home/u22/socket/addr2"int main()
{int server_sockfd;struct sockaddr_un server_sockaddr, client_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));memset(&client_sockaddr, 0, sizeof(client_sockaddr));socklen_t client_sockaddr_len = sizeof(client_sockaddr);ssize_t send_bytes, recv_bytes;char send_buf[1024] = "server say : How can I help you today ?";char recv_buf[1024] = {0};// unix域套接字 使用数据报传输,不能叫UDPserver_sockfd = socket(AF_UNIX, SOCK_DGRAM, 0);if (server_sockfd == -1){perror("socket");}// 无法再次访问此文件,必须删除unlink(SOCK_PATH);server_sockaddr.sun_family = AF_UNIX;// 容易越界,本系统为108字节strncpy(server_sockaddr.sun_path, SOCK_PATH, sizeof(server_sockaddr.sun_path));// 不bind,peer使用sendto也可以正常发送,但是本endpoint无法接收if ((bind(server_sockfd, (struct sockaddr *)&server_sockaddr, sizeof(server_sockaddr))) == -1){perror("bind");}printf("waiting for recv...\n");// 接收的客户端地址信息存在client_sockaddr中,供sendto使用recv_bytes = recvfrom(server_sockfd, recv_buf, sizeof(recv_buf),0, (struct sockaddr *)&client_sockaddr, &client_sockaddr_len);if (recv_bytes == -1){perror("recv");}if (recv_bytes > 0){printf("%s\n", recv_buf);}send_bytes = sendto(server_sockfd, send_buf, strlen(send_buf),0, (struct sockaddr *)&client_sockaddr, client_sockaddr_len);if (send_bytes == -1){perror("send");}if (send_bytes > 0){printf("%s\n", send_buf);}close(server_sockfd);printf("server close\n");// 用完删除SOCK_PATH这个文件unlink(SOCK_PATH);return 0;
}

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <string.h>
#include <unistd.h>
// 客户端使用的socket文件
#define SOCK_PATH_C "/home/u22/socket/addr3"
// 服务器使用的socket文件
#define SOCK_PATH_S "/home/u22/socket/addr2"
// 客户端
int main()
{int client_sockfd;struct sockaddr_un server_sockaddr, client_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));memset(&client_sockaddr, 0, sizeof(client_sockaddr));socklen_t server_sockaddr_len = sizeof(server_sockaddr);ssize_t send_bytes, recv_bytes;char send_buf[1024] = "client say : hello server !";char recv_buf[1024] = {0};// 基于数据报的unix域套接字client_sockfd = socket(AF_UNIX, SOCK_DGRAM, 0);if (client_sockfd == -1){perror("socket");}// 必须删除,否则下次不让用unlink(SOCK_PATH_C);client_sockaddr.sun_family = AF_UNIX;// 容易越界,本系统为108strncpy(client_sockaddr.sun_path, SOCK_PATH_C, sizeof(client_sockaddr.sun_path));// 传统udp在首次sendto时系统临时分配端口,在套接字关闭|程序终止|显式解绑时端口生命周期结束// 而unix域套接字则需要手动绑定if ((bind(client_sockfd, (struct sockaddr *)&client_sockaddr, sizeof(client_sockaddr))) == -1){perror("bind");}server_sockaddr.sun_family = AF_UNIX;// 容易越界,本系统为108strncpy(server_sockaddr.sun_path, SOCK_PATH_S, sizeof(server_sockaddr.sun_path));printf("send message\n");// 向服务器发送信息,由server_sockaddr指定地址send_bytes = sendto(client_sockfd, send_buf, strlen(send_buf),0, (struct sockaddr *)&server_sockaddr, server_sockaddr_len);if (send_bytes == -1){perror("send");}if (send_bytes > 0){printf("%s\n", send_buf);}// 两个null是服务器的地址信息和长度,不需要则设为nullrecv_bytes = recvfrom(client_sockfd, recv_buf, sizeof(recv_buf),0, NULL, NULL);if (recv_bytes == -1){perror("recv");}if (recv_bytes > 0){printf("%s\n", recv_buf);}close(client_sockfd);printf("client close\n");// 用完必须删除文件unlink(SOCK_PATH_C);return 0;
}