2022-4-16 sendfile函数的使用《Linux服务器》笔记 ——【为啥发了两次啊？】

客户端代码

//tcp 通信客户端
#include<stdio.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>

int main(void){
    
    
    //1.创建套接字
    int fd = socket(AF_INET,SOCK_STREAM,0);
    if(fd == -1){
    
    
        perror("socket");
        exit(0);
    }

    //2.连接服务器端
    struct sockaddr_in serveraddr;
    serveraddr.sin_family = AF_INET;
    inet_pton(AF_INET,"192.168.131.136",&serveraddr.sin_addr.s_addr);
    serveraddr.sin_port = htons(9999);
    int ret = connect(fd,(struct sockaddr*)&serveraddr,sizeof(serveraddr));
    if(ret == -1){
    
    
        perror("connect");
        exit(0);
    }

    //3.通信
    // char *data = "hello , i am client.";
    // write(fd,data,strlen(data));

    char recvBuf[1024] = {
    
    0}; 
    while(read(fd,recvBuf,sizeof(recvBuf)) > 0){
    
    
        printf("%s\n",recvBuf);
    }
    // int len2 = read(fd,recvBuf,sizeof(recvBuf));
    // if (len2 == -1)
    // {
    
    
    //     perror("read");
    //     exit(-1);
    // }
    // else if(len2 > 0){
    
    
    //     printf("recv client data : %s\n",recvBuf);

    // }else if(len2 == 0){
    
    
    //     //表示服务端断开连接
    //     printf("server closed.\n");
    // }
    close(fd);

    return 0;
}

服务端代码

#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<assert.h>
#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<sys/sendfile.h>
int main(void){
    
    
    //1.以只读形式打开文件
    int filefd = open("daytime.c",O_RDONLY);
    if(filefd == -1){
    
    
        perror("open");
        return -1;
    }
    //2.获取文件的信息
    struct stat stat_buf;
    //fstat和stat有啥区别
    //1)fstat直接接受文件描述符，其他两个接受文件的路径
    fstat(filefd,&stat_buf);
    //3.绑定服务端的地址
    struct sockaddr_in address;
    bzero(&address,sizeof(address));
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(9999);
    int sock = socket(PF_INET,SOCK_STREAM,0);
    if(sock == -1){
    
    
        perror("socket");
        return -1;
    }
    int ret = bind(sock,(struct sockaddr*)&address,sizeof(address));
    if(ret == -1){
    
    
        perror("bind");
        return -1;
    }
    //4.监听服务端的地址
    ret = listen(sock,5);
    if(ret == -1){
    
    
        perror("listen");
        return -1;
    }
    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof(client);
    int connfd = accept(sock,(struct sockaddr*)&client,&client_addrlength);
    if(connfd == -1){
    
    
        perror("accept");
        return -1;
    }else{
    
    
        //输出客户端的信息
        char clientIP[16];
        inet_ntop(AF_INET,&client.sin_addr.s_addr,clientIP,sizeof(clientIP));
        unsigned short port = ntohs(client.sin_port);
        printf("client's ip is %s,port is %d.\n",clientIP,port);
        sendfile(connfd,filefd,NULL,stat_buf.st_size);
        printf("%ld",stat_buf.st_size);
        close(connfd);
    }
    close(sock);
    return 0;
}

服务端结果

客户端结果