ЭЛЕКТРОННАЯ БИБЛИОТЕКА КОАПП |
Сборники Художественной, Технической, Справочной, Английской, Нормативной, Исторической, и др. литературы. |
17.1. Writing a TCP ClientProblemYou want to connect to a socket on a remote machine. SolutionThis solution assumes you're using the Internet to communicate. For TCP-like communication within a single machine, see Recipe 17.6. Either use the standard (as of 5.004) IO::Socket::INET class: use IO::Socket; $socket = IO::Socket::INET->new(PeerAddr => $remote_host, PeerPort => $remote_port, Proto => "tcp", Type => SOCK_STREAM) or die "Couldn't connect to $remote_host:$remote_port : $@\n"; # ... do something with the socket print $socket "Why don't you call me anymore?\n"; $answer = <$socket>; # and terminate the connection when we're done close($socket); or create a socket by hand for better control: use Socket; # create a socket socket(TO_SERVER, PF_INET, SOCK_STREAM, getprotobyname('tcp')); # build the address of the remote machine $internet_addr = inet_aton($remote_host) or die "Couldn't convert $remote_host into an Internet address: $!\n"; $paddr = sockaddr_in($remote_port, $internet_addr); # connect connect(TO_SERVER, $paddr) or die "Couldn't connect to $remote_host:$remote_port : $!\n"; # ... do something with the socket print TO_SERVER "Why don't you call me anymore?\n"; # and terminate the connection when we're done close(TO_SERVER); DiscussionWhile coding this by hand requires a lot of steps, the IO::Socket::INET class wraps them all in a convenient constructor. The important things to know are where you're going (the PeerAddr and PeerPort parameters) and how you're getting there (the Type parameter). IO::Socket::INET tries to determine these things from what you've given it. It deduces Proto from the Type and Port if possible, and assumes PeerAddr is a string containing either a hostname ( If you want a SOCK_STREAM connection to a port on a particular machine with no other options, pass a single string to $client = IO::Socket::INET->new("www.yahoo.com:80") or die $@; If an error occurs, IO::Socket::INET will return $s = IO::Socket::INET->new(PeerAddr => "Does not Exist", Peerport => 80, Type => SOCK_STREAM ) or die $@; If your packets are disappearing into a network void, it can take a while for your inability to connect to a port to be recognized. You can decrease this time by specifying a $s = IO::Socket::INET->new(PeerAddr => "bad.host.com", PeerPort => 80, Type => SOCK_STREAM, Timeout => 5 ) or die $@; If you do this, though, there's no way to tell from INADDR_ANY is a special address, meaning "listen on any interface." If you want to restrict it to a particular IP address, add a $inet_addr = inet_aton("208.146.240.1"); $paddr = sockaddr_in($port, $inet_addr); bind(SOCKET, $paddr) or die "bind: $!"; If you know only the name, do this: $inet_addr = gethostbyname("www.yahoo.com") or die "Can't resolve www.yahoo.com: $!"; $paddr = sockaddr_in($port, $inet_addr); bind(SOCKET, $paddr) or die "bind: $!"; See AlsoThe
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