Net::Write::Layer - base class and constants

   use Net::Write::Layer qw(:constants);

#
# $Id: Layer.pm 1636 2009-06-10 18:38:24Z gomor $
#
package Net::Write::Layer;
use strict;
use warnings;

require Exporter;
require Class::Gomor::Array;
our @ISA = qw(Exporter Class::Gomor::Array);
our @AS = qw(
   dev
   dst
   protocol
   family
   _io
   _sockaddr
);
__PACKAGE__->cgBuildIndices;
__PACKAGE__->cgBuildAccessorsScalar(\@AS);

sub _setIpProtoIpConstant {
   my $val = 0;
   if (defined(&IPPROTO_IP)) {
      $val = &IPPROTO_IP;
   }
   elsif ($^O eq 'darwin'
      ||  $^O eq 'linux'
      ||  $^O eq 'freebsd'
      ||  $^O eq 'openbsd'
      ||  $^O eq 'netbsd'
      ||  $^O eq 'aix') {
      $val = 0;
   }
   eval "use constant NW_IPPROTO_IP => $val;";
}

sub _setIpProtoIpv6Constant {
   my $val = 0;
   if (defined(&IPPROTO_IPv6)) {
      $val = &IPPROTO_IPv6;
   }
   elsif ($^O eq 'linux'
      ||  $^O eq 'freebsd') {
      $val = 41;
   }
   eval "use constant NW_IPPROTO_IPv6 => $val;";
}

sub _setIpProtoRawConstant {
   my $val = 255;
   if (defined(&IPPROTO_RAW)) {
      $val = &IPPROTO_RAW;
   }
   elsif ($^O eq 'darwin'
      ||  $^O eq 'linux'
      ||  $^O eq 'freebsd'
      ||  $^O eq 'openbsd'
      ||  $^O eq 'netbsd'
      ||  $^O eq 'aix') {
      $val = 255;
   }
   eval "use constant NW_IPPROTO_RAW => $val;";
}

sub _setIpHdrInclConstant {
   my $val = 2;
   if (defined(&IP_HDRINCL)) {
      $val = &IP_HDRINCL;
   }
   elsif ($^O eq 'darwin'
      ||  $^O eq 'freebsd'
      ||  $^O eq 'openbsd'
      ||  $^O eq 'netbsd'
      ||  $^O eq 'linux'
      ||  $^O eq 'aix'
      ||  $^O eq 'cygwin') {
      $val = 2;
   }
   elsif ($^O eq 'hpux') {
      $val = 0x1002;
   }
   eval "use constant NW_IP_HDRINCL => $val;";
}

sub _setAfinet6Constant {
   require Socket6;
   require Socket;
   my $val = 0;
   if (defined(&Socket6::AF_INET6)) {
      $val = &Socket6::AF_INET6;
   }
   elsif (defined(&Socket::AF_INET6)) {
      $val = &Socket::AF_INET6;
   }
   eval "use constant NW_AF_INET6  => $val;";
}

BEGIN {
   my $osname = {
      cygwin  => \&_checkWin32,
      MSWin32 => \&_checkWin32,
   };

   *_check  = $osname->{$^O} || \&_checkOther;
   _setIpProtoIpConstant();
   _setIpProtoIpv6Constant();
   _setIpProtoRawConstant();
   _setIpHdrInclConstant();
   _setAfinet6Constant();
}

no strict 'vars';

use Socket;
use Socket6 qw(getaddrinfo);
use IO::Socket;
use Net::Pcap;
use Carp;

use constant NW_AF_INET   => AF_INET();
use constant NW_AF_UNSPEC => AF_UNSPEC();

use constant NW_IPPROTO_ICMPv4 => 1;
use constant NW_IPPROTO_TCP    => 6;
use constant NW_IPPROTO_UDP    => 17;
use constant NW_IPPROTO_ICMPv6 => 58;

our %EXPORT_TAGS = (
   constants => [qw(
      NW_AF_INET
      NW_AF_INET6
      NW_AF_UNSPEC
      NW_IPPROTO_IP
      NW_IPPROTO_IPv6
      NW_IPPROTO_ICMPv4
      NW_IPPROTO_TCP
      NW_IPPROTO_UDP
      NW_IPPROTO_ICMPv6
      NW_IP_HDRINCL
      NW_IPPROTO_RAW
   )],
);

our @EXPORT_OK = (
   @{$EXPORT_TAGS{constants}},
);

sub _checkWin32 { }

sub _checkOther {
   croak("Must be EUID 0 (or equivalent) to open a device for writing.\n")
      if $>;
}

sub new { _check(); shift->SUPER::new(@_) }

sub open {
   my $self = shift;
   my ($hdrincl) = @_;

   my @res = getaddrinfo($self->[$__dst], 0, $self->[$__family], SOCK_STREAM)
      or croak("@{[(caller(0))[3]]}: getaddrinfo: $!\n");

   my ($family, $saddr) = @res[0, 3] if @res >= 5;
   $self->[$___sockaddr] = $saddr;

   socket(my $s, $family, SOCK_RAW, $self->[$__protocol])
      or croak("@{[(caller(0))[3]]}: socket: $!\n");

   my $fd = fileno($s) or croak("@{[(caller(0))[3]]}: fileno: $!\n");

   if ($hdrincl) {
      $self->_setIpHdrincl($s, $self->[$__family])
         or croak("@{[(caller(0))[3]]}: setsockopt: $!\n");
   }

   my $io = IO::Socket->new;
   $io->fdopen($fd, 'w') or croak("@{[(caller(0))[3]]}: fdopen: $!\n");

   $self->[$___io] = $io;

   1;
}

sub send {
   my $self = shift;
   my ($raw) = @_;

   while (1) {
      my $ret = CORE::send($self->_io, $raw, 0, $self->_sockaddr);
      unless ($ret) {
         if ($!{ENOBUFS}) {
            $self->cgDebugPrint(2, "ENOBUFS returned, sleeping for 1 second");
            sleep 1;
            next;
         }
         elsif ($!{EHOSTDOWN}) {
            $self->cgDebugPrint(2, "host is down");
            last;
         }
         carp("@{[(caller(0))[3]]}: $!\n");
         return undef;
      }
      last;
   }

   1;
}

sub close { shift->_io->close }

1;

__END__