Free Ebook Network Programming : Network Programming with Perl.pdf

Introduction

• Perl provides direct access to the C library routines for socket communication. Often, arguments and return values are constants defined in the C header files, or are data structures which Perl will pass in a packed binary format.
• The Socket module provides these constants and also many functions for packing and unpacking these data structures
• The IO::Socket module provides a higher level access to creating a socket
• CPAN contains many modules that provide a very high level access to specific application protocols. e.g. Net::FTP, Net::SMTP, Net::DNS, etc.

Binding the socket

• bind takes two arguments, the first is the socket and the second is a packed address.
• The Socket module provides functions for packing and unpacking addresses.
• sockaddr_in allows you to either pack or unpack an AF_INET socket address. In a scalar context it packs and in a list context it will unpack.
  $paddr = sockaddr_in($port, $inaddr);
  ($port, $inaddr) = sockaddr_in($paddr);
• If the use of context here disturbs you then you can explicitly call pack_sockaddr_in and unpack_sockaddr_in