客户端（服务器下载文件）

一、客户端代码

        客户端代码

//实现TCP客户端通信
#include<stdio.h>
#include<unistd.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/ip.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<fcntl.h>int main(int argc, const char *argv[])
{//1、创建套接字int sockfd=socket(AF_INET,SOCK_STREAM,0);if(sockfd<0){printf("创建失败\n");return -1;}/*//2、绑定套接字//填写自己的地址信息，不是必要的struct sockaddr_in clientaddr;clientaddr.sin_family=AF_INET;clientaddr.sin_port=htons(10000);clientaddr.sin_addr.s_addr=inet_addr("192.168.124.29");int bind_ret=bind(sockfd,(struct sockaddr *)&clientaddr,sizeof(clientaddr));if(bind_ret<0){printf("绑定失败\n");return -1;}*///3、建立连接connect//填写对方信息struct sockaddr_in destaddr;destaddr.sin_family=AF_INET;destaddr.sin_port=htons(8888);destaddr.sin_addr.s_addr=inet_addr("192.168.124.29");int connect_ret=connect(sockfd,(struct sockaddr*)&destaddr,sizeof(destaddr));if(connect_ret<0){printf("连接失败\n");return -1;}//4、发送数据sendwhile(1){char buf[100];scanf("%s",buf);send(sockfd,buf,100,0);int fd=open(buf,O_WRONLY|O_CREAT|O_TRUNC,0664);if(fd<0){printf("open failed");return -1;}while(1){bzero(buf,100);int ret=recv(sockfd,buf,100,0);printf("%s",buf);if(ret==0)break;write(fd,buf,ret);}}//6、关闭文件close(sockfd);return 0;
}

二、服务器代码

        服务器使用IO多路复用

#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include<fcntl.h>#define SERVERADDR "192.168.124.29"
#define PORT 8888int main(int argc, const char *argv[]) {// 创建套接字int listenfd = socket(AF_INET, SOCK_STREAM, 0);if (listenfd < 0) {perror("socket failed");return -1;}// 绑定套接字struct sockaddr_in serveraddr;serveraddr.sin_family = AF_INET;serveraddr.sin_port = htons(PORT);serveraddr.sin_addr.s_addr = inet_addr(SERVERADDR);if (bind(listenfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0) {perror("bind failed");return -1;}// 监听套接字if (listen(listenfd, 20) < 0) {perror("listen failed");return -1;}//定义文件描述符表fd_set master_fds, read_fds;int max_fd = listenfd;//清空文件描述符表FD_ZERO(&master_fds);//将监听套接字加入文件描述符表FD_SET(listenfd, &master_fds);while (1){read_fds = master_fds;// 监视文件描述符集,进程通知内核监视的内核是否准备就绪(是否有IO事件)int activity = select(max_fd + 1, &read_fds, NULL, NULL, NULL);if (activity < 0) {perror("select failed");return -1;}// 处理新连接if (FD_ISSET(listenfd, &read_fds)){struct sockaddr_in clientaddr;socklen_t len = sizeof(clientaddr);int client_fd = accept(listenfd, (struct sockaddr*)&clientaddr, &len);if (client_fd < 0){perror("accept failed");continue;}printf("New connection from %s:%hu\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));//将新创建的客户端文件描述符加入到文件描述符表当中FD_SET(client_fd, &master_fds);if (client_fd > max_fd){max_fd = client_fd;}}// 处理已连接客户端的数据for (int i = listenfd + 1; i <= max_fd; ++i){if (FD_ISSET(i, &read_fds)){char buf[100];bzero(buf, 100);int ret = read(i, buf, 100);int fd=open(buf,O_RDONLY);if(fd<0){printf("open failed\n");return -1;}char file[100];while(1){bzero(file,100);int read_ret = read(fd,file,100);printf("%d ",read_ret);if(read_ret==0)break;send(i, file, read_ret,0);}printf("download ok\n");}}}close(listenfd);return 0;
}