Length::fromDER() - Code Metrics - Inspection of "Add private tagging support" - sop/asn1 - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 9e3709...6a1987 )

by Joni

created 2017-12-20 08:56 UTC

Length::fromDER() B

↳ Parent: Length

Complexity

Conditions	6
Paths	8

Size

Total Lines	27
Code Lines	18

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	17
CRAP Score	6

Importance

Changes

Metric	Value
dl	0
loc	27
ccs	17
cts	17
cp	1
rs	8.439
c	0
b	0
f	0
cc	6
eloc	18
nc	8
nop	2
crap	6

<?php

declare(strict_types = 1);

namespace ASN1\Component;

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

/**
 * Class to represent BER/DER length octets.
 */
class Length implements Encodable
{
    /**
     * Length.
     *
     * @var BigInt
     */
    private $_length;
    
    /**
     * Whether length is indefinite.
     *
     * @var bool
     */
    private $_indefinite;
    
    /**
     * Constructor.
     *
     * @param int|string $length Length
     * @param bool $indefinite Whether length is indefinite
     */
    public function __construct($length, bool $indefinite = false)
    {
        $this->_length = new BigInt($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(string $data, int &$offset = null): self
    {
        $idx = $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 string Integer as a string
     */
    private static function _decodeLongFormLength(int $length, string $data,
        int &$offset): string
    {
        // 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(string $data, int &$offset,
        int $expected = null): self
    {
        $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->intLength()) {
            throw new DecodeException(
                sprintf("Expected length %d, got %d.", $expected,
                    $length->intLength()));
        }
        // check that enough data is available
        if (strlen($data) < $idx + $length->intLength()) {
            throw new DecodeException(
                sprintf("Length %d overflows data, %d bytes left.",
                    $length->intLength(), strlen($data) - $idx));
        }
        $offset = $idx;
        return $length;
    }
    
    /**
     *
     * @see Encodable::toDER()
     * @throws \DomainException If length is too large to encode
     * @return string
     */
    public function toDER(): string
    {
        $bytes = [];
        if ($this->_indefinite) {
            $bytes[] = 0x80;
        } else {
            $num = $this->_length->gmpObj();
            // long form
            if ($num > 127) {
                $octets = [];
                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 string Length as an integer string
     */
    public function length(): string
    {
        if ($this->_indefinite) {
            throw new \LogicException("Length is indefinite.");
        }
        return $this->_length->base10();
    }
    
    /**
     * Get the length as an integer.
     *
     * @throws \LogicException If length is indefinite
     * @throws \RuntimeException If length overflows integer size
     * @return int
     */
    public function intLength(): int
    {
        if ($this->_indefinite) {
            throw new \LogicException("Length is indefinite.");
        }
        return $this->_length->intVal();
    }
    
    /**
     * Whether length is indefinite.
     *
     * @return bool
     */
    public function isIndefinite(): bool
    {
        return $this->_indefinite;
    }
}


1		<?php
2
3		declare(strict_types = 1);
4
5		namespace ASN1\Component;
6
7		use ASN1\Exception\DecodeException;
8		use ASN1\Feature\Encodable;
9		use ASN1\Util\BigInt;
10
11		/**
12		* Class to represent BER/DER length octets.
13		*/
14		class Length implements Encodable
15		{
16		/**
17		* Length.
18		*
19		* @var BigInt
20		*/
21		private $_length;
22
23		/**
24		* Whether length is indefinite.
25		*
26		* @var bool
27		*/
28		private $_indefinite;
29
30		/**
31		* Constructor.
32		*
33		* @param int\|string $length Length
34		* @param bool $indefinite Whether length is indefinite
35		*/
36	328	public function __construct($length, bool $indefinite = false)
37		{
38	328	$this->_length = new BigInt($length);
39	328	$this->_indefinite = $indefinite;
40	328	}
41
42		/**
43		* Decode length component from DER data.
44		*
45		* @param string $data DER encoded data
46		* @param int\|null $offset Reference to the variable that contains offset
47		* into the data where to start parsing. Variable is updated to
48		* the offset next to the parsed length component. If null, start
49		* from offset 0.
50		* @throws DecodeException If decoding fails
51		* @return self
52		*/
53	227	public static function fromDER(string $data, int &$offset = null): self
54		{
55	227	$idx = $offset ?? 0;
56	227	$datalen = strlen($data);
57	227	if ($idx >= $datalen) {
58	1	throw new DecodeException("Invalid offset.");
59		}
60	226	$indefinite = false;
61	226	$byte = ord($data[$idx++]);
62		// bits 7 to 1
63	226	$length = (0x7f & $byte);
64		// long form
65	226	if (0x80 & $byte) {
66	12	if (!$length) {
67	4	$indefinite = true;
68		} else {
69	8	if ($idx + $length > $datalen) {
70	1	throw new DecodeException("Too many length octets.");
71		}
72	7	$length = self::_decodeLongFormLength($length, $data, $idx);
73		}
74		}
75	224	if (isset($offset)) {
76	214	$offset = $idx;
77		}
78	224	return new self($length, $indefinite);
79		}
80
81		/**
82		* Decode long form length.
83		*
84		* @param int $length Number of octets
85		* @param string $data Data
86		* @param int $offset Reference to the variable containing offset to the
87		* data.
88		* @throws DecodeException If decoding fails
89		* @return string Integer as a string
90		*/
91	7	private static function _decodeLongFormLength(int $length, string $data,
92		int &$offset): string
93		{
94		// first octet must not be 0xff (spec 8.1.3.5c)
95	7	if ($length == 127) {
96	1	throw new DecodeException("Invalid number of length octets.");
97		}
98	6	$num = gmp_init(0, 10);
99	6	while (--$length >= 0) {
100	6	$byte = ord($data[$offset++]);
101	6	$num <<= 8;
102	6	$num \|= $byte;
103		}
104	6	return gmp_strval($num);
105		}
106
107		/**
108		* Decode length from DER.
109		*
110		* Throws an exception if length doesn't match with expected or if data
111		* doesn't contain enough bytes.
112		*
113		* @see self::fromDER
114		* @param string $data DER data
115		* @param int $offset Reference to the offset variable
116		* @param int\|null $expected Expected length, null to bypass checking
117		* @throws DecodeException If decoding or expectation fails
118		* @return self
119		*/
120	214	public static function expectFromDER(string $data, int &$offset,
121		int $expected = null): self
122		{
123	214	$idx = $offset;
124	214	$length = self::fromDER($data, $idx);
125		// DER encoding must have definite length (spec 10.1)
126	214	if ($length->isIndefinite()) {
127	1	throw new DecodeException("DER encoding must have definite length.");
128		}
129		// if certain length was expected
130	213	if (isset($expected) && $expected != $length->intLength()) {
131	3	throw new DecodeException(
132	3	sprintf("Expected length %d, got %d.", $expected,
133	3	$length->intLength()));
134		}
135		// check that enough data is available
136	210	if (strlen($data) < $idx + $length->intLength()) {
137	4	throw new DecodeException(
138	4	sprintf("Length %d overflows data, %d bytes left.",
139	4	$length->intLength(), strlen($data) - $idx));
140		}
141	206	$offset = $idx;
142	206	return $length;
143		}
144
145		/**
146		*
147		* @see Encodable::toDER()
148		* @throws \DomainException If length is too large to encode
149		* @return string
150		*/
151	124	public function toDER(): string
152		{
153	124	$bytes = [];
154	124	if ($this->_indefinite) {
155	1	$bytes[] = 0x80;
156		} else {
157	123	$num = $this->_length->gmpObj();
158		// long form
159	123	if ($num > 127) {
160	7	$octets = [];
161	7	for (; $num > 0; $num >>= 8) {
162	7	$octets[] = gmp_intval(0xff & $num);
163		}
164	7	$count = count($octets);
165		// first octet must not be 0xff
166	7	if ($count >= 127) {
167	2	throw new \DomainException("Too many length octets.");
168		}
169	5	$bytes[] = 0x80 \| $count;
170	5	foreach (array_reverse($octets) as $octet) {
171	5	$bytes[] = $octet;
172		}
173		} else { // short form
174	116	$bytes[] = gmp_intval($num);
175		}
176		}
177	122	return pack("C*", ...$bytes);
178		}
179
180		/**
181		* Get the length.
182		*
183		* @throws \LogicException If length is indefinite
184		* @return string Length as an integer string
185		*/
186	5	public function length(): string
187		{
188	5	if ($this->_indefinite) {
189	1	throw new \LogicException("Length is indefinite.");
190		}
191	4	return $this->_length->base10();
192		}
193
194		/**
195		* Get the length as an integer.
196		*
197		* @throws \LogicException If length is indefinite
198		* @throws \RuntimeException If length overflows integer size
199		* @return int
200		*/
201	217	public function intLength(): int
202		{
203	217	if ($this->_indefinite) {
204	1	throw new \LogicException("Length is indefinite.");
205		}
206	216	return $this->_length->intVal();
207		}
208
209		/**
210		* Whether length is indefinite.
211		*
212		* @return bool
213		*/
214	216	public function isIndefinite(): bool
215		{
216	216	return $this->_indefinite;
217		}
218		}
219

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Length::fromDER() B

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