Question

下午，

我在Perl中编写一个小型UDP客户端/服务器，并且在发送文件时遇到了一些问题。我知道我需要将文件分成块（数据报）并将它们发送到服务器。

我很难搞清楚如何将文件分解为数据报并发送它们。截至目前，我可以很好地建立UDP连接，服务器在收到UDP数据包时报告。这是我到目前为止，任何帮助将不胜感激！

服务器：

#!/usr/bin/perl

# Flushing to STDOUT after each write
$| = 1;

use warnings;
use strict;
use IO::Socket;

# Server side information
my $listen_port     = 7070;
my $protocal        = 'udp';
my $received_data   = undef;

# Creating UDP socket for server
my $server = IO::Socket::INET->new (
    LocalPort   => $listen_port,
    Proto       => $protocal,
    Type        => SOCK_DGRAM
) or die "Socket could not be created, failed with error $!\n";

print "Waiting for client connection on port $listen_port\n";

open(FILE, ">output.UDP")
  or die "File can not be opened: $!";

while($server->recv($received_data, 1024)) {
    my $peer_address = $server->peerhost();
    my $peer_port    = $server->peerport();
    print "Message was received from: $peer_address, $peer_port\n";
    print FILE "$received_data";
}
close FILE;

print "Closing socket...\n";
$server->close();

客户端：

#!/usr/bin/perl

# Flushing to STDOUT after each write
$| = 1;

use warnings;
use strict;
use IO::Socket;

# Client side information
my $host        = 'apollo.cselabs.umn.edu';
my $port        = 7070;
my $protocal    = 'udp';
my $datagram    = undef;

# Creating UDP socket for client
my $client = IO::Socket::INET->new (
    PeerAddr    => $host,
    PeerPort    => $port,
    Proto       => $protocal,
    Type        => SOCK_DGRAM
) or die "Socket could not be created, failed with error: $!\n";

# Open and specified file
open(FILE, "10MBfile.dat")
    or die "Fine can not be opened: $!";
$client->send("test");

# Send file line by line
while (<FILE>) {
    $datagram = $_;
    $client->send("$datagram");
}
close FILE;
# sleep(10);
$client->close();

Answer 1

您的代码已经将文件拆分为块。通过调用<FILE>，每个块将是一行。但是有几个问题：

如果该行太长而且不适合数据包，则无法传输
UDP不保证传送，因此您的接收方可能会丢失数据，甚至可能会复制数据
UDP不保证交付顺序，因此您的接收方可能会先获得更晚的数据

文件传输可能无法接受这些缺点，因此您需要在UDP之上添加图层以解决这些问题，例如：用于检测重复的序列号，重新排序和确认以触发对丢失数据的重新提交。或者你可以简单地使用TCP而不是已经内置了所有这些内容。

在Perl中通过UDP发送文件

1 个答案: