7

我正在尝试使用无效端口连接到某个主机，并且我想在 X 秒后超时。怎么做 ？

我的代码：

 $sock = new IO::Socket::INET(
                  PeerAddr => $_[0],
    PeerPort => $_[1],
    Proto => 'tcp',
    Timeout => 2
    );
4

2 回答 2

19

如果你检查你会看到的代码（我从我的 Ubuntu 10.04 复制它）：

        my $timeout = ${*$sock}{'io_socket_timeout'};
#       my $before = time() if $timeout;

        undef $@;
        if ($sock->connect(pack_sockaddr_in($rport, $raddr))) {
#            ${*$sock}{'io_socket_timeout'} = $timeout;
            return $sock;
        }

        return _error($sock, $!, $@ || "Timeout")
            unless @raddr;

#       if ($timeout) {
#           my $new_timeout = $timeout - (time() - $before);
#           return _error($sock,
#                         (exists(&Errno::ETIMEDOUT) ? Errno::ETIMEDOUT() : $EINVAL),
#                         "Timeout") if $new_timeout <= 0;
#           ${*$sock}{'io_socket_timeout'} = $new_timeout;
#        }

显然，超时的东西被注释掉了，以便解释它被忽略的原因。

我发现一篇2003 年的帖子讨论了这个问题。一个建议（在底部）是在一个被警报信号终止的 eval 块中打开套接字：

eval { 
  local $SIG{ALRM} = sub { die 'Timed Out'; }; 
  alarm 3; 
  my $sock = IO::Socket::INET->new( 
    PeerAddr => inet_ntoa( gethostbyname($host) ), 
    PeerPort => 'whois', 
    Proto => 'tcp', 
    ## timeout => , 
  );
  $sock->autoflush;   
  print $sock "$qry\015\012"; 
  undef $/; $data = <$sock>; $/ = "\n"; 
  alarm 0; 
}; 
alarm 0; # race condition protection 
return "Error: timeout." if ( $@ && $@ =~ /Timed Out/ ); 
return "Error: Eval corrupted: $@" if $@;

不是很优雅，但如果它有效......

让我们用慢速服务器和不耐烦的客户端来验证：

# Impatient Client
use IO::Socket::INET;

$sock = new IO::Socket::INET(
    PeerAddr => "localhost",
    PeerPort => "10007",
    Proto => 'tcp',
    Timeout => 2,
    );  

print <$sock>;

close($sock);


# SlowServer
use IO::Socket::INET;

$sock = new IO::Socket::INET(
    LocalAddr => "localhost",
    LocalPort => "10007",
    Proto => 'tcp',
    Listen => 1,
    Reuse => 1,
    );

$newsock = $sock->accept();
sleep 5;

#while (<$newsock>) {
#    print $_;
#}
print $newsock "Some Stuff";
close($newsock);
close($sock);

如果我们运行这个：

pti@pti-laptop:~/playpen$ perl server.pl&
[1] 9130
pti@pti-laptop:~/playpen$ time perl test.pl
Some Stuff[1]+  Done                    perl server.pl

real    0m5.039s
user    0m0.050s
sys     0m0.030s

所以它忽略了 2 秒超时并运行了整整 5 秒。

现在另一个不耐烦的客户：

use IO::Socket::INET;
eval {
  local $SIG{ALRM} = sub { die 'Timed Out'; };
  alarm 2;
  $sock = new IO::Socket::INET(
    PeerAddr => "localhost",
    PeerPort => "10007",
    Proto => 'tcp',
    Timeout => 2,
    );

  print <$sock>;

  close($sock);
  alarm 0;
};
alarm 0; # race condition protection 
print "Error: timeout." if ( $@ && $@ =~ /Timed Out/ );
print "Error: Eval corrupted: $@" if $@;

~

并运行它：

pti@pti-laptop:~/playpen$ perl server.pl&
[1] 9175
pti@pti-laptop:~/playpen$ time perl test2.pl
Error: timeout.Error: Eval corrupted: Timed Out at test2.pl line 3.

real    0m2.040s
user    0m0.020s
sys         0m0.010s

是的，这在 2 秒后按预期超时。

于 2010-08-25T22:05:28.053 回答
1

使用 IO::Socket::Timeout 容易得多

如下所示，它就像一个魅力。

use IO::Socket::Timeout;
my $socket = IO::Socket::INET->new( Timeout => 2 );
IO::Socket::Timeout->enable_timeouts_on($socket);
$socket->read_timeout(0.5);    # These will work
$socket->write_timeout(0.5);   # These will work
于 2020-12-23T08:22:27.967 回答