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Diffstat (limited to 'Html/includes/BDecode.php')
| -rw-r--r-- | Html/includes/BDecode.php | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/Html/includes/BDecode.php b/Html/includes/BDecode.php new file mode 100644 index 0000000..fbf12bc --- /dev/null +++ b/Html/includes/BDecode.php @@ -0,0 +1,172 @@ +<?php +/* + Programming info + +All functions output a small array, which we'll call $return for now. + +$return[0] is the data expected of the function +$return[1] is the offset over the whole bencoded data of the next + piece of data. + +numberdecode returns [0] as the integer read, and [1]-1 points to the +symbol that was interprented as the end of the interger (either "e" or +":"). +numberdecode is used for integer decodes both for i11e and 11:hello there +so it is tolerant of the ending symbol. + +decodelist returns $return[0] as an integer indexed array like you would use in C +for all the entries. $return[1]-1 is the "e" that ends the list, so [1] is the next +useful byte. + +decodeDict returns $return[0] as an array of text-indexed entries. For example, +$return[0]["announce"] = "http://www.whatever.com:6969/announce"; +$return[1]-1 again points to the "e" that ends the dictionary. + +decodeEntry returns [0] as an integer in the case $offset points to +i12345e or a string if $offset points to 11:hello there style strings. +It also calls decodeDict or decodeList if it encounters a d or an l. + +Known bugs: +- The program doesn't pay attention to the string it's working on. + A zero-sized or truncated data block will cause string offset errors + before they get rejected by the decoder. This is worked around by + suppressing errors. +*/ + +// Protect our namespace using a class +class BDecode { + function numberdecode($wholefile, $offset) { + // Funky handling of negative numbers and zero + $negative = false; + if ($wholefile[$offset] == '-') { + $negative = true; + $offset++; + } + if ($wholefile[$offset] == '0') { + $offset++; + if ($negative) + return array(false); + if ($wholefile[$offset] == ':' || $wholefile[$offset] == 'e'){ + + return array(0, ++$offset); + } + + return array(false); + } + $ret[0] = 0; + for(;;) { + if ($wholefile[$offset] >= '0' && $wholefile[$offset] <= '9') { + $ret[0] *= 10; + //Added 2005.02.21 - VisiGod + //Changing the type of variable from integer to double to prevent a numeric overflow + settype($ret[0],'double'); + //Added 2005.02.21 - VisiGod + $ret[0] += ord($wholefile[$offset]) - ord('0'); + $offset++; + } else if ($wholefile[$offset] == 'e' || $wholefile[$offset] == ':') { + // Tolerate : or e because this is a multiuse function + $ret[1] = $offset+1; + if ($negative) { + if ($ret[0] == 0) + return array(false); + $ret[0] = - $ret[0]; + } + return $ret; + } else return array(false); + } + } + + function decodeEntry($wholefile, $offset=0) { + if ($wholefile[$offset] == 'd') + return $this->decodeDict($wholefile, $offset); + if ($wholefile[$offset] == 'l') + return $this->decodelist($wholefile, $offset); + if ($wholefile[$offset] == 'i') + return $this->numberdecode($wholefile, ++$offset); + // String value: decode number, then grab substring + + $info = $this->numberdecode($wholefile, $offset); + + if ($info[0] === false) + return array(false); + $ret[0] = substr($wholefile, $info[1], $info[0]); + $ret[1] = $info[1]+strlen($ret[0]); + + + return $ret; + } + + function decodeList($wholefile, $offset) { + if ($wholefile[$offset] != 'l') + return array(false); + $offset++; + $ret = array(); + for ($i=0;;$i++) { + if ($wholefile[$offset] == 'e') + break; + $value = $this->decodeEntry($wholefile, $offset); + if ($value[0] === false) + return array(false); + $ret[$i] = $value[0]; + $offset = $value[1]; + } + // The empty list is an empty array. Seems fine. + return array(0=>$ret, 1=>++$offset); + } + + // Tries to construct an array + function decodeDict($wholefile, $offset=0) { + if ($wholefile[$offset] == 'l') + return $this->decodeList($wholefile, $offset); + if ($wholefile[$offset] != 'd') + return false; + $ret=array(); + $offset++; + for (;;) { + if ($wholefile[$offset] == 'e') { + $offset++; + break; + } + $left = $this->decodeEntry($wholefile, $offset); + if ($left[0]===false) { + die("stop...".$left[1]); + return false; + } + + $offset = $left[1]; + if ($wholefile[$offset] == 'd') { + // Recurse + $value = $this->decodedict($wholefile, $offset); + if ($value[0]) { + $ret[addslashes($left[0])] = $value[0]; + $offset= $value[1]; + } + continue; + } + if ($wholefile[$offset] == 'l') { + $value = $this->decodeList($wholefile, $offset); + if (!$value[0] && is_bool($value[0])) + return false; + $ret[addslashes($left[0])] = $value[0]; + $offset = $value[1]; + continue; + } + $value = $this->decodeEntry($wholefile, $offset); + if ($value[0] === false) + return false; + $ret[addslashes($left[0])] = $value[0]; + $offset = $value[1]; + + } + + return array(0=>(empty($ret)?true:$ret), 1=>$offset); + } +} // End of class declaration. + +// Use this function. eg: BDecode("d8:announce44:http://www. ... e"); +function BDecode($wholefile) { + $decoder = new BDecode; + $return = $decoder->decodeEntry($wholefile); + return $return[0]; +} +?>
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