Magnet Link

This PHP function return the urn (Uniform Resource Name) formed from the content hash of a particular torrent file. The urn refering to the Base32 encoded hash of the file.

function base32_encode ($hash)
{
$outString = '';
$compBits = '';
$BASE32_TABLE = array(
                         '00000' => 0x61,
                         '00001' => 0x62,
                         '00010' => 0x63,
                         '00011' => 0x64,
                         '00100' => 0x65,
                         '00101' => 0x66,
                         '00110' => 0x67,
                         '00111' => 0x68,
                         '01000' => 0x69,
                         '01001' => 0x6a,
                         '01010' => 0x6b,
                         '01011' => 0x6c,
                         '01100' => 0x6d,
                         '01101' => 0x6e,
                         '01110' => 0x6f,
                         '01111' => 0x70,
                         '10000' => 0x71,
                         '10001' => 0x72,
                         '10010' => 0x73,
                         '10011' => 0x74,
                         '10100' => 0x75,
                         '10101' => 0x76,
                         '10110' => 0x77,
                         '10111' => 0x78,
                         '11000' => 0x79,
                         '11001' => 0x7a,
                         '11010' => 0x32,
                         '11011' => 0x33,
                         '11100' => 0x34,
                         '11101' => 0x35,
                         '11110' => 0x36,
                         '11111' => 0x37,
                         );

   /* Turn the compressed string into a string that represents the bits as 0 and 1. */
   for ($i = 0; $i < strlen($hash); $i++) {
       $compBits .= str_pad(decbin(ord(substr($hash,$i,1))), 8, '0', STR_PAD_LEFT);
   }

   /* Pad the value with enough 0's to make it a multiple of 5 */
   if((strlen($compBits) % 5) != 0) {
       $compBits = str_pad($compBits, strlen($compBits)+(5-(strlen($compBits)%5)), '0', STR_PAD_RIGHT);
   }

   /* Create an array by chunking it every 5 chars */
   $fiveBitsArray = split("\n",rtrim(chunk_split($compBits, 5, "\n")));

   /* Look-up each chunk and add it to $outstring */
   foreach($fiveBitsArray as $fiveBitsString) {
       $outString .= chr($BASE32_TABLE[$fiveBitsString]);
   }

   return $outString;

}

Parametres:

dn - Filename

xl - Size in bytes

xt - urn containing file hash

as - Web link to the file online

xs - P2P link

kt - Key words for search

mt - link to the metafile that contains a list of magneto

xt is the most important part of magnet links.