Here's a basic sample of connecting to the P2P interface in Perl, this just connects and spits out any new blocks in raw format on STDOUT and debug information about the connection on STDERR but once you've got the connection running you can send any commands through it, just need to be careful about the network byte orders that bitcoin uses.
#!/usr/bin/perl
use IO::Socket;use IO::Select;
use Digest::SHA;$|=1;
$btc=IO::Socket::INET->new(PeerAddr=>"localhost",PeerPort=>'8333',Proto=>'tcp') or die "Socket";
$sel=IO::Select->new();$sel->add($btc);
$p="\x2c\x7e\x00\x00"; # Version
$p.="\x01\x00\x00\x00\x00\x00\x00\x00"; # Services
$h=sprintf('%x',time());while(length($h)<16){$h="0".$h;}
$h=reverse($h);$p.=pack('h*',$h); # Unix Timestamp
$p.="\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF"; # To IP
$p.="\x7f\x00\x00\x01\x20\x8d"; # 127.0.0.1 - Port 8333
$p.="\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF"; # From IP
$p.="\x00\x00\x00\x00\x20\x8d"; # 0.0.0.0 - Port 8333
@chars=('a'..'f', 0..9);$rr=join '',map {$chars[rand @chars]} 1..16;
$p.=pack('H*',$rr); # Random Unique ID
$p.="\x00\x00\x00\x00\x00"; # No UA/Blocks
sendpacket('version',$p);
while($gotver==0){
($c,$p)=readpacket();
if($c eq 'version'){$gotver=1;}
sleep(1);}
sendpacket('verack','');
while(1){
($c,$p)=readpacket();
if($c eq 'inv'){
sendpacket('getdata',$p);
}
if($c eq 'block'){
$blk=unpack('H*',$p);print $blk."\n";
}
sleep(1);}
close($btc);
sub sendpacket{my $c=shift(@_);my $p=shift(@_);
my $o="\xf9\xbe\xb4\xd9"; # Magic for main network
while(length($c)<12){$c.="\x00";}$o.=$c; #Command
my $h=sprintf('%x',length($p));while(length($h)<8){$h="0".$h;}
$h=reverse($h);$o.=pack('h*',$h); # Payload length
$h=Digest::SHA::sha256(Digest::SHA::sha256($p));
$h=unpack('H*',$h);$o.=pack('H*',substr($h,0,8)); # Checksum
$o.=$p; # Payload
print $btc $o;print STDERR "Sent $c (".length($p)." byte payload)\n";
}
sub readpacket{
if(!$sel->can_read(1)){return 0;}
my @x;my $x;while(1){read($btc,$x,1);$x=unpack('H*',$x);
push(@x,$x);if($#x>3){shift(@x);}
if(join('.',@x) eq "f9.be.b4.d9"){
my $cmd;my $len;
read($btc,$cmd,12);read($btc,$len,4);read($btc,$x,4);
$x=unpack('h*',$len);$x=reverse($x);$len=hex($x);
$x=chop($cmd);while($x eq "\x00"){$x=chop($cmd);}$cmd.=$x;
print STDERR "Read $cmd ($len byte payload)\n";
if($len>0){read($btc,$x,$len);return ($cmd,$x);}
else{return ($cmd,'');}
}
}
}
