Decoder::prematureEndOfDataError() - Code Metrics - Inspection of "WiP" - s9e/Bencode - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — Exceptions ( 69c4e2...90da39 )

by Josh

created 2020-09-24 09:46 UTC

Decoder::prematureEndOfDataError() A

↳ Parent: Project

Complexity

Conditions	1
Paths	1

Size

Total Lines	3
Code Lines	1

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	2
CRAP Score	1

Importance

Changes

Metric	Value
cc	1
eloc	1
nc	1
nop	0
dl	0
loc	3
ccs	2
cts	2
cp	1
crap	1
rs	10
c	0
b	0
f	0

<?php declare(strict_types=1);

/**
* @package   s9e\Bencode
* @copyright Copyright (c) 2014-2020 The s9e authors
* @license   http://www.opensource.org/licenses/mit-license.php The MIT License
*/
namespace s9e\Bencode;

use ArrayObject;
use InvalidArgumentException;
use RuntimeException;
use s9e\Bencode\Exceptions\ComplianceError;
use s9e\Bencode\Exceptions\DecodingException;

class Decoder
{
	/**
	* @var string Bencoded string being decoded
	*/
	protected string $bencoded;

	/**
	* @var int Length of the bencoded string
	*/
	protected int $len;

	/**
	* @var int Safe rightmost boundary
	*/
	protected int $max;

	/**
	* @var int Position of the cursor while decoding
	*/
	protected int $offset;

	public static function decode(string $bencoded)
	{
		$decoder = new static($bencoded);
		$value   = $decoder->decodeAnything();

		$decoder->checkCursorPosition();

		return $value;
	}

	protected function __construct(string $bencoded)
	{
		$this->bencoded = $bencoded;
		$this->len      = strlen($bencoded);
		$this->offset   = 0;

		if ($bencoded === '')
		{
			throw new DecodingException('Premature end of data', 0);
		}
		$this->computeSafeBoundary();
	}

	protected function checkBoundary(): void
	{
		if ($this->max < 1)
		{
			if (strpos('-e', $this->bencoded[0]) !== false)
			{
				throw new DecodingException('Illegal character', 0);
			}

			throw new DecodingException('Premature end of data', $this->len - 1);
		}
	}

	/**
	* Check the cursor's position after decoding is done
	*/
	protected function checkCursorPosition(): void
	{
		if ($this->offset !== $this->len)
		{
			if ($this->offset > $this->len)
			{
				throw new DecodingException('Premature end of data', $this->len - 1);
			}

			$this->complianceError('Superfluous content', $this->offset);
		}
	}

	protected function complianceError(string $message, int $offset): void
	{
		throw new ComplianceError($message, $offset);
	}

	/**
	* Adjust the rightmost boundary to the last safe character that can start a value
	*
	* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
	*/
	protected function computeSafeBoundary(): void
	{
		$boundary = $this->len - 1;
		$c = $this->bencoded[$boundary];
		while (is_numeric($c) && --$boundary >= 0)
		{
			$c = $this->bencoded[$boundary];
		}
		if ($c === '-')
		{
			$boundary -= 2;
		}
		elseif ($c === 'i')
		{
			--$boundary;
		}

		$this->max = $boundary;
		$this->checkBoundary();
	}

	protected function decodeAnything()
	{
		$c = $this->bencoded[$this->offset];
		if ($c === 'i')
		{
			return $this->decodeInteger();
		}
		if ($c === 'd')
		{
			return $this->decodeDictionary();
		}
		if ($c === 'l')
		{
			return $this->decodeList();
		}

		return $this->decodeString();
	}

	protected function decodeDictionary(): ArrayObject
	{
		$values  = [];
		$lastKey = null;

		++$this->offset;
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
			}

			$offset = $this->offset;
			$key    = $this->decodeString();
			if ($key <= $lastKey)
			{
				$this->dictionaryComplianceError($offset, $key, $lastKey);
			}
			if ($this->offset > $this->max)
			{
				break;
			}
			$values[$key] = $this->decodeAnything();
			$lastKey      = $key;
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeDigits(string $terminator): int
	{
		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
		$spn = strspn($this->bencoded, '4615302879', $this->offset);
		if (!$spn)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		if ($this->bencoded[$this->offset] === '0' && $spn > 1)
		{
			$this->complianceError('Illegal character', 1 + $this->offset);
		}

		// Capture the value and cast it as an integer
		$value = (int) substr($this->bencoded, $this->offset, $spn);

		$this->offset += $spn;
		if ($this->bencoded[$this->offset] !== $terminator)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		++$this->offset;

		return $value;
	}

	protected function decodeInteger(): int
	{
		$negative = ($this->bencoded[++$this->offset] === '-');
		if ($negative && $this->bencoded[++$this->offset] === '0')
		{
			$this->complianceError('Illegal character', $this->offset);
		}

		$value = $this->decodeDigits('e');

		return ($negative) ? -$value : $value;
	}

	protected function decodeList(): array
	{
		++$this->offset;

		$list = [];
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return $list;
			}

			$list[] = $this->decodeAnything();
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeString(): string
	{
		$len           = $this->decodeDigits(':');
		$string        = substr($this->bencoded, $this->offset, $len);
		$this->offset += $len;

		return $string;
	}

	protected function dictionaryComplianceError(int $offset, string $key, ?string $lastKey): void
	{
		if ($key === $lastKey)
		{
			$this->complianceError("Duplicate dictionary entry '" . $key . "'", $offset);
		}
		elseif ($key < $lastKey)
		{
			$this->complianceError("Out of order dictionary entry '" . $key . "'", $offset);
		}
	}
}

1		<?php declare(strict_types=1);
2
3		/**
4		* @package s9e\Bencode
5		* @copyright Copyright (c) 2014-2020 The s9e authors
6		* @license http://www.opensource.org/licenses/mit-license.php The MIT License
7		*/
8		namespace s9e\Bencode;
9
10		use ArrayObject;
11		use InvalidArgumentException;
12		use RuntimeException;
13		use s9e\Bencode\Exceptions\ComplianceError;
14		use s9e\Bencode\Exceptions\DecodingException;
15
16		class Decoder
17		{
18		/**
19		* @var string Bencoded string being decoded
20		*/
21		protected string $bencoded;
22
23		/**
24		* @var int Length of the bencoded string
25		*/
26		protected int $len;
27
28		/**
29		* @var int Safe rightmost boundary
30		*/
31		protected int $max;
32
33		/**
34		* @var int Position of the cursor while decoding
35		*/
36		protected int $offset;
37
38	61	public static function decode(string $bencoded)
39		{
40	61	$decoder = new static($bencoded);
41	50	$value = $decoder->decodeAnything();
42
43	26	$decoder->checkCursorPosition();
44
45	18	return $value;
46		}
47
48	61	protected function __construct(string $bencoded)
49		{
50	61	$this->bencoded = $bencoded;
51	61	$this->len = strlen($bencoded);
52	61	$this->offset = 0;
53
54	61	if ($bencoded === '')
55		{
56	1	throw new DecodingException('Premature end of data', 0);
57		}
58	60	$this->computeSafeBoundary();
59		}
60
61	60	protected function checkBoundary(): void
62		{
63	60	if ($this->max < 1)
64		{
65	10	if (strpos('-e', $this->bencoded[0]) !== false)
66		{
67	2	throw new DecodingException('Illegal character', 0);
68		}
69
70	8	throw new DecodingException('Premature end of data', $this->len - 1);
71		}
72		}
73
74		/**
75		* Check the cursor's position after decoding is done
76		*/
77	26	protected function checkCursorPosition(): void
78		{
79	26	if ($this->offset !== $this->len)
80		{
81	8	if ($this->offset > $this->len)
82		{
83	3	throw new DecodingException('Premature end of data', $this->len - 1);
84		}
85
86	5	$this->complianceError('Superfluous content', $this->offset);
87		}
88		}
89
90	12	protected function complianceError(string $message, int $offset): void
91		{
92	12	throw new ComplianceError($message, $offset);
93		}
94
95		/**
96		* Adjust the rightmost boundary to the last safe character that can start a value
97		*
98		* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
99		*/
100	60	protected function computeSafeBoundary(): void
101		{
102	60	$boundary = $this->len - 1;
103	60	$c = $this->bencoded[$boundary];
104	60	while (is_numeric($c) && --$boundary >= 0)
105		{
106	7	$c = $this->bencoded[$boundary];
107		}
108	60	if ($c === '-')
109		{
110	6	$boundary -= 2;
111		}
112	54	elseif ($c === 'i')
113		{
114	6	--$boundary;
115		}
116
117	60	$this->max = $boundary;
118	60	$this->checkBoundary();
119		}
120
121	50	protected function decodeAnything()
122		{
123	50	$c = $this->bencoded[$this->offset];
124	50	if ($c === 'i')
125		{
126	17	return $this->decodeInteger();
127		}
128	41	if ($c === 'd')
129		{
130	15	return $this->decodeDictionary();
131		}
132	32	if ($c === 'l')
133		{
134	12	return $this->decodeList();
135		}
136
137	25	return $this->decodeString();
138		}
139
140	15	protected function decodeDictionary(): ArrayObject
141		{
142	15	$values = [];
143	15	$lastKey = null;
144
145	15	++$this->offset;
146	15	while ($this->offset <= $this->max)
147		{
148	15	if ($this->bencoded[$this->offset] === 'e')
149		{
150	7	++$this->offset;
151
152	7	return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
153		}
154
155	14	$offset = $this->offset;
156	14	$key = $this->decodeString();
157	13	if ($key <= $lastKey)
158		{
159	4	$this->dictionaryComplianceError($offset, $key, $lastKey);
160		}
161	13	if ($this->offset > $this->max)
162		{
163	1	break;
164		}
165	12	$values[$key] = $this->decodeAnything();
166	9	$lastKey = $key;
167		}
168
169	1	throw new DecodingException('Premature end of data', $this->len - 1);
170		}
171
172	43	protected function decodeDigits(string $terminator): int
173		{
174		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
175	43	$spn = strspn($this->bencoded, '4615302879', $this->offset);
176	43	if (!$spn)
177		{
178	7	throw new DecodingException('Illegal character', $this->offset);
179		}
180	38	if ($this->bencoded[$this->offset] === '0' && $spn > 1)
181		{
182	3	$this->complianceError('Illegal character', 1 + $this->offset);
183		}
184
185		// Capture the value and cast it as an integer
186	35	$value = (int) substr($this->bencoded, $this->offset, $spn);
187
188	35	$this->offset += $spn;
189	35	if ($this->bencoded[$this->offset] !== $terminator)
190		{
191	5	throw new DecodingException('Illegal character', $this->offset);
192		}
193	30	++$this->offset;
194
195	30	return $value;
196		}
197
198	17	protected function decodeInteger(): int
199		{
200	17	$negative = ($this->bencoded[++$this->offset] === '-');
201	17	if ($negative && $this->bencoded[++$this->offset] === '0')
202		{
203	1	$this->complianceError('Illegal character', $this->offset);
204		}
205
206	16	$value = $this->decodeDigits('e');
207
208	11	return ($negative) ? -$value : $value;
209		}
210
211	12	protected function decodeList(): array
212		{
213	12	++$this->offset;
214
215	12	$list = [];
216	12	while ($this->offset <= $this->max)
217		{
218	11	if ($this->bencoded[$this->offset] === 'e')
219		{
220	7	++$this->offset;
221
222	7	return $list;
223		}
224
225	8	$list[] = $this->decodeAnything();
226		}
227
228	4	throw new DecodingException('Premature end of data', $this->len - 1);
229		}
230
231	34	protected function decodeString(): string
232		{
233	34	$len = $this->decodeDigits(':');
234	26	$string = substr($this->bencoded, $this->offset, $len);
235	26	$this->offset += $len;
236
237	26	return $string;
238		}
239
240	4	protected function dictionaryComplianceError(int $offset, string $key, ?string $lastKey): void
241		{
242	4	if ($key === $lastKey)
243		{
244	2	$this->complianceError("Duplicate dictionary entry '" . $key . "'", $offset);
245		}
246	2	elseif ($key < $lastKey)
247		{
248	1	$this->complianceError("Out of order dictionary entry '" . $key . "'", $offset);
249		}
250		}
251		}

s9e / Bencode

Push — Exceptions ( 69c4e2...90da39 )

Decoder::prematureEndOfDataError() A

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