如何通过套接字从服务器向客户端发送文本文件的内容？

Question

I am working on an assignment that would allow the server to grab the contents of a text file via I/O redirection and send to the client line by line which I would then insert into a vector. I have tried using a while loop on both sides, but it isn't working. It only reads the first line of the file (which I was doing separately in order to get the size first) and that's it. Can anyone please advise me on how to fix this issue?

Here's my server code:

listen(sockfd,5);
 clilen = sizeof(cli_addr);
 newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, (socklen_t *)&clilen);

 if (newsockfd < 0){ 
      error("ERROR on accept");
 }
 bzero(buffer,256);
 n = read(newsockfd,buffer,255);

 if (n < 0){
     error("ERROR reading from socket");
 }

 printf("Here is the message: %s\n",buffer);
 std::getline(std::cin, getFile); // I/O Redirection
 n = write(newsockfd,getFile.c_str(),18); //grabs first line of the file which is 3 and sends it to the client

 while (std::getline(std::cin, getFile)) { 
     n = write(newsockfd, getFile.c_str(), 18); //supposed to write every line of the file to the client but isn't working? Should send 0 1 0 0 1 0 1 -1
     if (n < 0){
         error("ERROR writing to socket");
     }
 }

My client code:

std::vector<int> input;

printf("Please enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));

if (n < 0) {
    error("ERROR writing to socket");
}

printf("The ring size is: ");
bzero(buffer,256);
n = read(sockfd,buffer,255); //received first line from server
size = std::atoi(buffer); //ring size converted from char* to int

while (read(sockfd, buffer, 255) > 0) {
    input.push_back(std::atoi(buffer));
    printf("Input contents: %s\n", buffer); //should print 0 1 0 0 1 0 1 -1
}

My text file:

3
0
1
0
0
1
0
1
-1

Answer 1

TCP is a stream-based, not a message based, protocol. That means you need to establish a protocol that separates individual messages if they are intended to be processed as individual messages. read(sockfd, buffer, 255) could easily read 255 bytes of data from the socket which contains multiple messages, possibly even the whole file, but the program only treats it as a single message.

This answer contains a relatively simple protocol for sending strings over a socket