c - 如何使用C编程将文本文件从服务器发送到客户端

Question

我正在尝试将文本文件从服务器发送到客户端，但不确定如何继续进行编码。

我一直在阅读一些教程并设法从客户端接收数据，然后向客户端发送确认消息，表示已收到数据。但我想修改它，以便我将整个文本文件发送给客户端。

我是 C 和 TCP 套接字编程的新手，所以任何见解都将不胜感激。

到目前为止，我的服务器代码:

/* A simple server in the internet domain using TCP
   The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>

void error(const char *msg) {
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[]) {

    int sockfd, newsockfd, portno;
    socklen_t clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int n;
    if (argc < 2) {
        fprintf(stderr, "ERROR, no port provided\n");
        exit(1);
    }
    // Create a TCP socket
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
    bzero((char *) &serv_addr, sizeof (serv_addr));
    portno = atoi(argv[1]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);
    // Assign a name/port number to socket
    if (bind(sockfd, (struct sockaddr *) &serv_addr,
            sizeof (serv_addr)) < 0)
        error("ERROR on binding");
    // Establish a queue for connections
    listen(sockfd, 5);
    clilen = sizeof (cli_addr);
    // Extract a connection from the queue
    newsockfd = accept(sockfd,
            (struct sockaddr *) &cli_addr,
            &clilen);
    if (newsockfd < 0)
        error("ERROR on accept");
    bzero(buffer, 256);
    // Read/write
    n = read(newsockfd, buffer, 255);
    if (n < 0) error("ERROR reading from socket");
    printf("Here is the message: %s\n", buffer);
    n = write(newsockfd, "I got your message", 18);
    if (n < 0) error("ERROR writing to socket");
    close(newsockfd);
    close(sockfd);
    return 0;
}

Answer 1

用一个

while ((nread = read(filefd, filebuf, sizeof(filebuf))) > 0) {
     size_t toread = nread, off = 0, wr;
     while (toread > 0) {
         wr = write(connfd, filebuf + off, toread);
         if (wr >= 0) {
             toread -= wr;
             off += wr;
         } else {
             /* handle a write error */
         }
    }
}

环形。