perl Socket編程例子

Perl的networking 功能非常強大，基本上用c/c++能做的事perl都能做，而且做得更輕松方便，甚至可以只用10來行代碼就完成了c/c++要幾十上百甚至幾百行才能完成得好的工作。

在networking方面，最基礎的是BSD socket編程，但往往perl入門時在這個方面，最頭疼的無疑是如何開始，如何Step by
step。最好的葯方就是Example，一段完整的可以運行（working）的代碼，通過實踐來感受遠比看枯燥的manual來得深刻。

以下給出幾段使用Socket及IO::Socket編寫的Server/client，他們能實現最簡單但是卻最基本的任務，包括一個forking/accept的模型。可以直接復制這些代碼，然后小加修改即可開發一些小型的tcp/udp應用了。

TCP 客戶端, Socket 模塊

簡介：實現從服務器端讀取一行信息然后返回

#!/usr/bin/perl -w
# tcp_socket_cli.pl
use strict;
use Socket;

my $addr = $ARGV[0] || '127.0.0.1';
my $port = $ARGV[1] || '3000';
my $dest = sockaddr_in($port, inet_aton($addr));
my $buf = undef;

socket(SOCK,PF_INET,SOCK_STREAM,6) or die "Can't create socket: $!";
connect(SOCK,$dest)                or die "Can't connect: $!";

my $bs = sysread(SOCK, $buf, 2048); # try to read 2048
print "Received $bs bytes, content $buf\n"; # actually get $bs bytes
close SOCK;

 

執行結果：

perl tcp_socket_cli.pl localhost 25
Received 41 bytes, content 220 ESMTP Postfix - ExtMail 0.12-hzqbbc

TCP 服務端 Socket模塊, forking/accept模型

簡介：一個多進程的TCP
服務器，sample中實現了daytime的功能

 

#!/usr/bin/perl -w
# tcp_socket_dt_srv.pl
use strict;
use Socket;
use IO::Handle;
use POSIX qw(WNOHANG);

my $port     = $ARGV[0] || '3000';
my $proto    = getprotobyname('tcp');

$SIG{'CHLD'} = sub {
     while((my $pid = waitpid(-1, WNOHANG)) >0) {
          print "Reaped child $pid\n";
      }
};

socket(SOCK, AF_INET, SOCK_STREAM, getprotobyname('tcp'))
    or die "socket() failed: $!";
setsockopt(SOCK,SOL_SOCKET,SO_REUSEADDR,1)
    or die "Can't set SO_REUSADDR: $!" ;

my $my_addr = sockaddr_in($port,INADDR_ANY);
bind(SOCK,$my_addr)    or die "bind() failed: $!";
listen(SOCK,SOMAXCONN) or die "listen() failed: $!";

warn "Starting server on port $port...\n";

while (1) {
     next unless my $remote_addr = accept(SESSION,SOCK);
     defined(my $pid=fork) or die "Can't fork: $!\n";
   
     if($pid==0) {
          my ($port,$hisaddr) = sockaddr_in($remote_addr);
          warn "Connection from [",inet_ntoa($hisaddr),",$port]\n";
          SESSION->autoflush(1);
          print SESSION (my $s = localtime);
          warn "Connection from [",inet_ntoa($hisaddr),",$port] finished\n";
          close SESSION;
          exit 0;
      }else {
          print "Forking child $pid\n";
      }
}

close SOCK;

 

利用上述tcp_socket_cli.pl訪問該server的執行結果：

[hzqbbc@local misc]$ perl tcp_socket_dt_srv.pl 
Starting server on port 3000...
Connection from [127.0.0.1,32888]
Connection from [127.0.0.1,32888] finished
Reaped child 13927
Forking child 13927

TCP 客戶端 ,IO::Sockiet模塊

簡介：同樣為客戶端，不過使用的是IO::Socket 面向對象模塊

#!/usr/bin/perl -w
# tcp_iosocket_cli.pl
use strict;
use IO::Socket;

my $addr = $ARGV[0] || '127.0.0.1';
my $port = $ARGV[1] || '3000';
my $buf = undef;

my $sock = IO::Socket::INET->new(
        PeerAddr => $addr,
        PeerPort => $port,
        Proto    => 'tcp')
    or die "Can't connect: $!\n";
$buf = <$sock>;
my $bs = length($buf);
print "Received $bs bytes, content $buf\n"; # actually get $bs bytes
close $sock;

TCP 服務端, IO::Socket模塊, forking/accept模型

簡介：同樣的一個daytime
服務器，使用IO::Socket重寫。

#!/usr/bin/perl
# tcp_iosocket_dt_srv.pl
use strict;
use IO::Socket;
use POSIX qw(WNOHANG);

$SIG = sub {
     while((my $pid = waitpid(-1, WNOHANG)) >0) {
          print "Reaped child $pid\n";
      }
};

my $port     = $ARGV[0] || '3000';
my $sock = IO::Socket::INET->new( Listen    => 20,
                                  LocalPort => $port,
                                  Timeout   => 60*1,
                                  Reuse     => 1)
  or die "Can't create listening socket: $!\n";

warn "Starting server on port $port...\n";
while (1) {
     next unless my $session = $sock->accept;
     defined (my $pid = fork) or die "Can't fork: $!\n";
 
     if($pid == 0) {
          my $peer = gethostbyaddr($session->peeraddr,AF_INET) || $session->peerhost;
          my $port = $session->peerport;
          warn "Connection from [$peer,$port]\n";
          $session->autoflush(1);
          print $session (my $s = localtime), "\n";
          warn "Connection from [$peer,$port] finished\n";
          close $session;
          exit 0;
      }else {
          print "Forking child $pid\n";
      }
}
close $sock;

 

現在再介紹使用Socket及IO::Socket模塊來進行Unix domain
Socket的client/server開發。Unix Domain Socket（簡稱unix
socket）和TCP/UDP等INET類型socket相比起來有幾個優點：

• 安全性高，unix socket只在單機環境中使用，不支持機器之間通信
• 效率高，執行時的速度約是TCP的兩倍，多用於操作系統內部通信（IPC）
• 支持SOCK_DGRAM，但和UDP不同，前后消息是嚴格有序的

因此使用Unix socket來設計單機的IPC應用是首選。非常實用。大量的Unix應用軟件都使用unix socket來進行程序間通信。

Unix Domain Socket客戶端, Socket模塊

簡介：使用Unix domain socket的客戶端。

#!/usr/bin/perl -w
use strict;
use Socket;
use IO::Handle;

my $path = $ARGV[0] || '/tmp/daytime.sock';

socket(my $sock, PF_UNIX, SOCK_STREAM, 0);
my $sun = sockaddr_un($path);
connect($sock, $sun) or die "Connect: $!\n";
$sock->autoflush(1);
my $buf = <$sock>;
my $bs = length($buf);
print "Received $bs bytes, content $buf\n";
close $sock;

 

Unix Domain Socket 服務端, Socket模塊

簡介：使用Unix domain socket實現的daytime服務器。

#!/usr/bin/perl -w
# tcp_socket_dt_srv.pl
use strict;
use Socket;
use IO::Handle;
use POSIX qw(WNOHANG);

my $path     = $ARGV[0] || '/tmp/daytime.sock';

$SIG{'CHLD'} = sub {
      while((my $pid = waitpid(-1, WNOHANG)) >0) {
            print "Reaped child $pid\n";
        }
};

socket(SOCK, PF_UNIX, SOCK_STREAM, 0)
    or die "socket() failed: $!";
setsockopt(SOCK,SOL_SOCKET,SO_REUSEADDR,1)
    or die "Can't set SO_REUSADDR: $!" ;

unlink $path if -r $path;

bind(SOCK,sockaddr_un($path))    or die "bind() failed: $!";
listen(SOCK,SOMAXCONN)           or die "listen() failed: $!";

warn "Starting server on path $path...\n";

while (1) {
      next unless my $sockname = accept(SESSION,SOCK);
      defined (my $pid=fork) or die "Can't fork: $!\n";
 
      if($pid==0) {
          SESSION->autoflush(1);
          print SESSION (my $s = localtime);
          close SESSION;
          exit 0;
       }else {
          print "Forking child $pid\n";
       }
}

close SOCK;