Length::expectFromDER() - Code Metrics - Inspection of "Reduce complexity" - sop/asn1 - Measure and Improve Code Quality continuously with Scrutinizer

Completed

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by Joni

created 2016-06-03 08:40 UTC

Length::expectFromDER() B

↳ Parent: Length

Complexity

Conditions	5
Paths	4

Size

Total Lines	21
Code Lines	14

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	14
CRAP Score	5

Importance

Changes

Metric	Value
dl	0
loc	21
ccs	14
cts	14
cp	1
rs	8.7624
c	0
b	0
f	0
cc	5
eloc	14
nc	4
nop	3
crap	5

<?php

namespace ASN1\Component;

use ASN1\Exception\DecodeException;
use ASN1\Feature\Encodable;


/**
 * Class to represent BER/DER length octets.
 */
class Length implements Encodable
{
	/**
	 * Length.
	 *
	 * @var int|string
	 */
	private $_length;
	
	/**
	 * Whether length is indefinite.
	 *
	 * @var boolean
	 */
	private $_indefinite;
	
	/**
	 * Constructor
	 *
	 * @param int|string $length Length
	 * @param boolean $indefinite Whether length is indefinite
	 */
	public function __construct($length, $indefinite = false) {
		$this->_length = $length;
		$this->_indefinite = $indefinite;
	}
	
	/**
	 * Decode length component from DER data.
	 *
	 * @param string $data DER encoded data
	 * @param int|null $offset Reference to the variable that contains offset
	 *        into the data where to start parsing. Variable is updated to
	 *        the offset next to the parsed length component. If null, start
	 *        from offset 0.
	 * @throws DecodeException If decoding fails
	 * @return self
	 */
	public static function fromDER($data, &$offset = null) {
		assert('is_string($data)', "got " . gettype($data));
		$idx = $offset ? $offset : 0;
		$datalen = strlen($data);
		if ($idx >= $datalen) {
			throw new DecodeException("Invalid offset.");
		}
		$indefinite = false;
		$byte = ord($data[$idx++]);
		// bits 7 to 1
		$length = (0x7f & $byte);
		// long form
		if (0x80 & $byte) {
			if (!$length) {
				$indefinite = true;
			} else {
				if ($idx + $length > $datalen) {
					throw new DecodeException("Too many length octets.");
				}
				$length = self::_decodeLongFormLength($length, $data, $idx);
			}
		}
		if (isset($offset)) {
			$offset = $idx;
		}
		return new self($length, $indefinite);
	}
	
	/**
	 * Decode long form length.
	 *
	 * @param int $length Number of octets
	 * @param string $data Data
	 * @param int $offset Reference to the variable containing offset to the
	 *        data.
	 * @throws DecodeException If decoding fails
	 * @return int|string
	 */
	private static function _decodeLongFormLength($length, $data, &$offset) {
		// first octet must not be 0xff (spec 8.1.3.5c)
		if ($length == 127) {
			throw new DecodeException("Invalid number of length octets.");
		}
		$num = gmp_init(0, 10);
		while (--$length >= 0) {
			$byte = ord($data[$offset++]);
			$num <<= 8;
			$num |= $byte;
		}
		return gmp_strval($num);
	}
	
	/**
	 * Decode length from DER.
	 *
	 * Throws an exception if length doesn't match with expected or if data
	 * doesn't contain enough bytes.
	 *
	 * @see self::fromDER
	 * @param string $data DER data
	 * @param int $offset Reference to the offset variable
	 * @param int|null $expected Expected length, null to bypass checking
	 * @throws DecodeException If decoding or expectation fails
	 * @return self
	 */
	public static function expectFromDER($data, &$offset, $expected = null) {
		$idx = $offset;
		$length = self::fromDER($data, $idx);
		// DER encoding must have definite length (spec 10.1)
		if ($length->isIndefinite()) {
			throw new DecodeException("DER encoding must have definite length.");
		}
		// if certain length was expected
		if (isset($expected) && $expected != $length->_length) {
			throw new DecodeException(
				"Expected length $expected, got {$length->_length}.");
		}
		// check that enough data is available
		if (strlen($data) < $idx + $length->_length) {
			throw new DecodeException(
				"Length {$length->_length} overflows data, " .
					 (strlen($data) - $idx) . " bytes left.");
		}
		$offset = $idx;
		return $length;
	}
	
	/**
	 *
	 * @see Encodable::toDER()
	 * @throws \DomainException If length is too large to encode
	 * @return string
	 */
	public function toDER() {
		$bytes = array();
		if ($this->_indefinite) {
			$bytes[] = 0x80;
		} else {
			$num = gmp_init($this->_length, 10);
			// long form
			if ($num > 127) {
				$octets = array();
				for (; $num > 0; $num >>= 8) {
					$octets[] = gmp_intval(0xff & $num);
				}
				$count = count($octets);
				// first octet must not be 0xff
				if ($count >= 127) {
					throw new \DomainException("Too many length octets.");
				}
				$bytes[] = 0x80 | $count;
				foreach (array_reverse($octets) as $octet) {
					$bytes[] = $octet;
				}
			} else { // short form
				$bytes[] = gmp_intval($num);
			}
		}
		return pack("C*", ...$bytes);
	}
	
	/**
	 * Get the length.
	 *
	 * @throws \LogicException If length is indefinite
	 * @return int|string
	 */
	public function length() {
		if ($this->_indefinite) {
			throw new \LogicException("Length is indefinite.");
		}
		return $this->_length;
	}
	
	/**
	 * Whether length is indefinite.
	 *
	 * @return boolean
	 */
	public function isIndefinite() {
		return $this->_indefinite;
	}
}


1		<?php
2
3		namespace ASN1\Component;
4
5		use ASN1\Exception\DecodeException;
6		use ASN1\Feature\Encodable;
7
8
9		/**
10		* Class to represent BER/DER length octets.
11		*/
12		class Length implements Encodable
13		{
14		/**
15		* Length.
16		*
17		* @var int\|string
18		*/
19		private $_length;
20
21		/**
22		* Whether length is indefinite.
23		*
24		* @var boolean
25		*/
26		private $_indefinite;
27
28		/**
29		* Constructor
30		*
31		* @param int\|string $length Length
32		* @param boolean $indefinite Whether length is indefinite
33		*/
34	307	public function __construct($length, $indefinite = false) {
35	307	$this->_length = $length;
36	307	$this->_indefinite = $indefinite;
37	307	}
38
39		/**
40		* Decode length component from DER data.
41		*
42		* @param string $data DER encoded data
43		* @param int\|null $offset Reference to the variable that contains offset
44		* into the data where to start parsing. Variable is updated to
45		* the offset next to the parsed length component. If null, start
46		* from offset 0.
47		* @throws DecodeException If decoding fails
48		* @return self
49		*/
50	211	public static function fromDER($data, &$offset = null) {
51	211	assert('is_string($data)', "got " . gettype($data));
52	210	$idx = $offset ? $offset : 0;
53	210	$datalen = strlen($data);
54	210	if ($idx >= $datalen) {
55	1	throw new DecodeException("Invalid offset.");
56		}
57	209	$indefinite = false;
58	209	$byte = ord($data[$idx++]);
59		// bits 7 to 1
60	209	$length = (0x7f & $byte);
61		// long form
62	209	if (0x80 & $byte) {
63	10	if (!$length) {
64	3	$indefinite = true;
65	3	} else {
66	7	if ($idx + $length > $datalen) {
67	1	throw new DecodeException("Too many length octets.");
68		}
69	6	$length = self::_decodeLongFormLength($length, $data, $idx);
70		}
71	8	}
72	207	if (isset($offset)) {
73	199	$offset = $idx;
74	199	}
75	207	return new self($length, $indefinite);
76		}
77
78		/**
79		* Decode long form length.
80		*
81		* @param int $length Number of octets
82		* @param string $data Data
83		* @param int $offset Reference to the variable containing offset to the
84		* data.
85		* @throws DecodeException If decoding fails
86		* @return int\|string
87		*/
88	6	private static function _decodeLongFormLength($length, $data, &$offset) {
89		// first octet must not be 0xff (spec 8.1.3.5c)
90	6	if ($length == 127) {
91	1	throw new DecodeException("Invalid number of length octets.");
92		}
93	5	$num = gmp_init(0, 10);
94	5	while (--$length >= 0) {
95	5	$byte = ord($data[$offset++]);
96	5	$num <<= 8;
97	5	$num \|= $byte;
98	5	}
99	5	return gmp_strval($num);
100		}
101
102		/**
103		* Decode length from DER.
104		*
105		* Throws an exception if length doesn't match with expected or if data
106		* doesn't contain enough bytes.
107		*
108		* @see self::fromDER
109		* @param string $data DER data
110		* @param int $offset Reference to the offset variable
111		* @param int\|null $expected Expected length, null to bypass checking
112		* @throws DecodeException If decoding or expectation fails
113		* @return self
114		*/
115	199	public static function expectFromDER($data, &$offset, $expected = null) {
116	199	$idx = $offset;
117	199	$length = self::fromDER($data, $idx);
118		// DER encoding must have definite length (spec 10.1)
119	199	if ($length->isIndefinite()) {
120	1	throw new DecodeException("DER encoding must have definite length.");
121		}
122		// if certain length was expected
123	198	if (isset($expected) && $expected != $length->_length) {
124	3	throw new DecodeException(
125	3	"Expected length $expected, got {$length->_length}.");
126		}
127		// check that enough data is available
128	195	if (strlen($data) < $idx + $length->_length) {
129	4	throw new DecodeException(
130	4	"Length {$length->_length} overflows data, " .
131	4	(strlen($data) - $idx) . " bytes left.");
132		}
133	191	$offset = $idx;
134	191	return $length;
135		}
136
137		/**
138		*
139		* @see Encodable::toDER()
140		* @throws \DomainException If length is too large to encode
141		* @return string
142		*/
143	118	public function toDER() {
144	118	$bytes = array();
145	118	if ($this->_indefinite) {
146	1	$bytes[] = 0x80;
147	1	} else {
148	117	$num = gmp_init($this->_length, 10);
149		// long form
150	117	if ($num > 127) {
151	7	$octets = array();
152	7	for (; $num > 0; $num >>= 8) {
153	7	$octets[] = gmp_intval(0xff & $num);
154	7	}
155	7	$count = count($octets);
156		// first octet must not be 0xff
157	7	if ($count >= 127) {
158	2	throw new \DomainException("Too many length octets.");
159		}
160	5	$bytes[] = 0x80 \| $count;
161	5	foreach (array_reverse($octets) as $octet) {
162	5	$bytes[] = $octet;
163	5	}
164	5	} else { // short form
165	110	$bytes[] = gmp_intval($num);
166		}
167		}
168	116	return pack("C*", ...$bytes);
169		}
170
171		/**
172		* Get the length.
173		*
174		* @throws \LogicException If length is indefinite
175		* @return int\|string
176		*/
177	179	public function length() {
178	179	if ($this->_indefinite) {
179	1	throw new \LogicException("Length is indefinite.");
180		}
181	178	return $this->_length;
182		}
183
184		/**
185		* Whether length is indefinite.
186		*
187		* @return boolean
188		*/
189	201	public function isIndefinite() {
190	201	return $this->_indefinite;
191		}
192		}
193

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Length::expectFromDER() B

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