在networking方面，最基础的是BSD socket编程，但往往perl入门时在这个方面，最头疼的无疑是如何开始，如何Step by step。最好的药方就是Example，一段完整的可以运行（working）的代码，通过实践来感受远比看枯燥的manual来得深刻。

以下给出几段使用Socket及IO::Socket编写的Server/client，他们能实现最简单但是却最基本的任务，包括一个forking/accept的模型。可以直接复制这些代码，然后小加修改即可开发一些小型的tcp/udp应用了。

TCP 客户端, Socket 模块

简介：实现从服务器端读取一行信息然后返回

复制代码 代码如下:

#!/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 $bufn"; # actually get $bs bytes

close SOCK;

执行结果：

perl tcp_socket_cli.pl localhost 25

Received 41 bytes, content 220 ESMTP Postfix - ExtMail 0.12-hzqbbc

TCP 服务端 Socket模块, forking/accept模型

简介：一个多进程的TCP服务器，sample中实现了daytime的功能

复制代码 代码如下:

#!/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 $pidn";

}

};

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] finishedn";

close SESSION;

exit 0;

}else {

print "Forking child $pidn";

}

}

close SOCK;

利用上述tcp_socket_cli.pl访问该server的执行结果：

[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 客户端 ,IO::Sockiet模块

简介：同样为客户端，不过使用的是IO::Socket 面向对象模块

复制代码 代码如下:

#!/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 $bufn"; # actually get $bs bytes

close $sock;

TCP 服务端, IO::Socket模块, forking/accept模型

简介：同样的一个daytime

服务器，使用IO::Socket重写。

复制代码 代码如下:

#!/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 $pidn";

}

};

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] finishedn";

close $session;

exit 0;

}else {

print "Forking child $pidn";

}

}

close $sock;

现在再介绍使用Socket及IO::Socket模块来进行Unix domain Socket的client/server开发。Unix Domain Socket（简称unix socket）和TCP/UDP等INET类型socket相比起来有几个优点：

1）、安全性高，unix socket只在单机环境中使用，不支持机器之间通信

2）、效率高，执行时的速度约是TCP的两倍，多用于操作系统内部通信（IPC）

3）、支持SOCK_DGRAM，但和UDP不同，前后消息是严格有序的

因此使用Unix socket来设计单机的IPC应用是首选。非常实用。大量的Unix应用软件都使用unix socket来进行程序间通信。

Unix Domain Socket客户端, Socket模块

简介：使用Unix domain socket的客户端。

复制代码 代码如下:

#!/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 $bufn";

close $sock;

Unix Domain Socket 服务端, Socket模块

简介：使用Unix domain socket实现的daytime服务器。

复制代码 代码如下:

#!/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 $pidn";

}

};

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 $pidn";

}

}

close SOCK;