APILengthCoDec::decodeLength() - Code Metrics - Inspection of "Streamrefactor" - EvilFreelancer/routeros-api-php - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#8)

by Mr

created 2019-03-24 14:04 UTC

APILengthCoDec::decodeLength() B

↳ Parent: APILengthCoDec

Complexity

Conditions	7
Paths	7

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	32
CRAP Score	7

Importance

Changes

Metric	Value
dl	0
loc	93
ccs	32
cts	32
cp	1
rs	7.2193
c	0
b	0
f	0
cc	7
nc	7
nop	1
crap	7

How to fix Long Method

<?php

namespace RouterOS;

use RouterOS\Interfaces\StreamInterface;
use RouterOS\Helpers\BinaryStringHelper;

/**
 * class APILengthCoDec
 *
 * Coder / Decoder for length field in mikrotik API communication protocol
 *
 * @package RouterOS
 * @since   0.9
 */
class APILengthCoDec
{
    /**
     * Encode string to length of string
     *
     * @param   int|float $length
     * @return  string
     */
    public static function encodeLength($length): string
    {
        // Encode the length :
        // - if length <= 0x7F (binary : 01111111 => 7 bits set to 1)
        //      - encode length with one byte
        //      - set the byte to length value, as length maximal value is 7 bits set to 1, the most significant bit is always 0
        //      - end
        // - length <= 0x3FFF (binary : 00111111 11111111 => 14 bits set to 1)
        //      - encode length with two bytes
        //      - set length value to 0x8000 (=> 10000000 00000000)
        //      - add length : as length maximumal value is 14 bits to 1, this does not modify the 2 most significance bits (10)
        //      - end
        //      => minimal encoded value is 10000000 10000000
        // - length <= 0x1FFFFF (binary : 00011111 11111111 11111111 => 21 bits set to 1)
        //      - encode length with three bytes
        //      - set length value to 0xC00000 (binary : 11000000 00000000 00000000)
        //      - add length : as length maximal vlaue is 21 bits to 1, this does not modify the 3 most significance bits (110)
        //      - end
        //      => minimal encoded value is 11000000 01000000 00000000
        // - length <= 0x0FFFFFFF (binary : 00001111 11111111 11111111 11111111 => 28 bits set to 1)
        //      - encode length with four bytes
        //      - set length value to 0xE0000000 (binary : 11100000 00000000 00000000 00000000)
        //      - add length : as length maximal vlaue is 28 bits to 1, this does not modify the 4 most significance bits (1110)
        //      - end
        //      => minimal encoded value is 11100000 00100000 00000000 00000000
        // - length <= 0x7FFFFFFFFF (binary : 00000111 11111111 11111111 11111111 11111111 => 35 bits set to 1)
        //      - encode length with five bytes
        //      - set length value to 0xF000000000 (binary : 11110000 00000000 00000000 00000000 00000000)
        //      - add length : as length maximal vlaue is 35 bits to 1, this does not modify the 5 most significance bits (11110)
        //      - end
        // - length > 0x7FFFFFFFFF : not supported

        if ($length < 0) {
            throw new \DomainException("Length of word could not to be negative ($length)");
        }

        if ($length <= 0x7F) {
            return BinaryStringHelper::IntegerToNBOBinaryString($length);
        }

        if ($length <= 0x3FFF) {
            return BinaryStringHelper::IntegerToNBOBinaryString(0x8000 + $length);
        }

        if ($length <= 0x1FFFFF) {
            return BinaryStringHelper::IntegerToNBOBinaryString(0xC00000 + $length);
        }

        if ($length <= 0x0FFFFFFF) {
            return BinaryStringHelper::IntegerToNBOBinaryString(0xE0000000 + $length);
        }

        // https://wiki.mikrotik.com/wiki/Manual:API#API_words
        // If len >= 0x10000000 then 0xF0 and len as four bytes
        return BinaryStringHelper::IntegerToNBOBinaryString(0xF000000000 + $length);
    }

    // Decode length of data when reading :
    // The 5 firsts bits of the first byte specify how the length is encoded.
    // The position of the first 0 value bit, starting from the most significant postion. 
    // - 0xxxxxxx => The 7 remainings bits of the first byte is the length : 
    //            => min value of length is 0x00 
    //            => max value of length is 0x7F (127 bytes)
    // - 10xxxxxx => The 6 remainings bits of the first byte plus the next byte represent the lenght
    //            NOTE : the next byte MUST be at least 0x80 !!
    //            => min value of length is 0x80 
    //            => max value of length is 0x3FFF (16,383 bytes, near 16 KB)
    // - 110xxxxx => The 5 remainings bits of th first byte and the two next bytes represent the length
    //             => max value of length is 0x1FFFFF (2,097,151 bytes, near 2 MB)
    // - 1110xxxx => The 4 remainings bits of the first byte and the three next bytes represent the length
    //            => max value of length is 0xFFFFFFF (268,435,455 bytes, near 270 MB)
    // - 11110xxx => The 3 remainings bits of the first byte and the four next bytes represent the length
    //            => max value of length is 0x7FFFFFFF (2,147,483,647 byes, 2GB)
    // - 11111xxx => This byte is not a length-encoded word but a control byte.
    //          =>  Extracted from Mikrotik API doc : 
    //              it is a reserved control byte. 
    //              After receiving unknown control byte API client cannot proceed, because it cannot know how to interpret following bytes
    //              Currently control bytes are not used

    public static function decodeLength(StreamInterface $stream): int
    {
        // if (false === is_resource($stream)) {
        //     throw new \InvalidArgumentException(
        //         sprintf(
        //             'Argument must be a stream resource type. %s given.',
        //             gettype($stream)
        //         )
        //     );
        // }

        // Read first byte
        $firstByte = ord($stream->read(1));

        // If first byte is not set, length is the value of the byte
        if (0 === ($firstByte & 0x80)) {
            return $firstByte;
        }

        // if 10xxxxxx, length is 2 bytes encoded
        if (0x80 === ($firstByte & 0xC0)) {
            // Set 2 most significands bits to 0
            $result = $firstByte & 0x3F;

            // shift left 8 bits to have 2 bytes
            $result <<= 8;

            // read next byte and use it as least significant
            $result |= ord($stream->read(1));
            return $result;
        }

        // if 110xxxxx, length is 3 bytes encoded
        if (0xC0 === ($firstByte & 0xE0)) {
            // Set 3 most significands bits to 0
            $result = $firstByte & 0x1F;

            // shift left 16 bits to have 3 bytes
            $result <<= 16;

            // read next 2 bytes as value and use it as least significant position
            $result |= (ord($stream->read(1)) << 8);
            $result |= ord($stream->read(1));
            return $result;
        }

        // if 1110xxxx, length is 4 bytes encoded
        if (0xE0 === ($firstByte & 0xF0)) {
            // Set 4 most significance bits to 0
            $result = $firstByte & 0x0F;

            // shift left 24 bits to have 4 bytes
            $result <<= 24;

            // read next 3 bytes as value and use it as least significant position
            $result |= (ord($stream->read(1)) << 16);
            $result |= (ord($stream->read(1)) << 8);
            $result |= ord($stream->read(1));
            return $result;
        }

        // if 11110xxx, length is 5 bytes encoded
        if (0xF0 === ($firstByte & 0xF8)) {
            // Not possible on 32 bits systems
            if (PHP_INT_SIZE < 8) {
                // Cannot be done on 32 bits systems
                // PHP5 windows versions of php, even on 64 bits systems was impacted
                // see : https://stackoverflow.com/questions/27865340/php-int-size-returns-4-but-my-operating-system-is-64-bit
                // How can we test it ?

                // @codeCoverageIgnoreStart
                throw new \OverflowException("Your system is using 32 bits integers, cannot decode this value ($firstByte) on this system");
                // @codeCoverageIgnoreEnd
            }

            // Set 5 most significance bits to 0
            $result = $firstByte & 0x07;

            // shift left 232 bits to have 5 bytes
            $result <<= 32;

            // read next 4 bytes as value and use it as least significant position
            $result |= (ord($stream->read(1)) << 24);
            $result |= (ord($stream->read(1)) << 16);
            $result |= (ord($stream->read(1)) << 8);
            $result |= ord($stream->read(1));
            return $result;
        }

        // Now the only solution is 5 most significance bits are set to 1 (11111xxx)
        // This is a control word, not implemented by Mikrotik for the moment 
        throw new \UnexpectedValueException('Control Word found');
    }
}


1		<?php
2
3		namespace RouterOS;
4
5		use RouterOS\Interfaces\StreamInterface;
6		use RouterOS\Helpers\BinaryStringHelper;
7
8		/**
9		* class APILengthCoDec
10		*
11		* Coder / Decoder for length field in mikrotik API communication protocol
12		*
13		* @package RouterOS
14		* @since 0.9
15		*/
16		class APILengthCoDec
17		{
18		/**
19		* Encode string to length of string
20		*
21		* @param int\|float $length
22		* @return string
23		*/
24	29	public static function encodeLength($length): string
25		{
26		// Encode the length :
27		// - if length <= 0x7F (binary : 01111111 => 7 bits set to 1)
28		// - encode length with one byte
29		// - set the byte to length value, as length maximal value is 7 bits set to 1, the most significant bit is always 0
30		// - end
31		// - length <= 0x3FFF (binary : 00111111 11111111 => 14 bits set to 1)
32		// - encode length with two bytes
33		// - set length value to 0x8000 (=> 10000000 00000000)
34		// - add length : as length maximumal value is 14 bits to 1, this does not modify the 2 most significance bits (10)
35		// - end
36		// => minimal encoded value is 10000000 10000000
37		// - length <= 0x1FFFFF (binary : 00011111 11111111 11111111 => 21 bits set to 1)
38		// - encode length with three bytes
39		// - set length value to 0xC00000 (binary : 11000000 00000000 00000000)
40		// - add length : as length maximal vlaue is 21 bits to 1, this does not modify the 3 most significance bits (110)
41		// - end
42		// => minimal encoded value is 11000000 01000000 00000000
43		// - length <= 0x0FFFFFFF (binary : 00001111 11111111 11111111 11111111 => 28 bits set to 1)
44		// - encode length with four bytes
45		// - set length value to 0xE0000000 (binary : 11100000 00000000 00000000 00000000)
46		// - add length : as length maximal vlaue is 28 bits to 1, this does not modify the 4 most significance bits (1110)
47		// - end
48		// => minimal encoded value is 11100000 00100000 00000000 00000000
49		// - length <= 0x7FFFFFFFFF (binary : 00000111 11111111 11111111 11111111 11111111 => 35 bits set to 1)
50		// - encode length with five bytes
51		// - set length value to 0xF000000000 (binary : 11110000 00000000 00000000 00000000 00000000)
52		// - add length : as length maximal vlaue is 35 bits to 1, this does not modify the 5 most significance bits (11110)
53		// - end
54		// - length > 0x7FFFFFFFFF : not supported
55
56	29	if ($length < 0) {
57	2	throw new \DomainException("Length of word could not to be negative ($length)");
58		}
59
60	27	if ($length <= 0x7F) {
61	15	return BinaryStringHelper::IntegerToNBOBinaryString($length);
62		}
63
64	12	if ($length <= 0x3FFF) {
65	3	return BinaryStringHelper::IntegerToNBOBinaryString(0x8000 + $length);
66		}
67
68	9	if ($length <= 0x1FFFFF) {
69	3	return BinaryStringHelper::IntegerToNBOBinaryString(0xC00000 + $length);
70		}
71
72	6	if ($length <= 0x0FFFFFFF) {
73	3	return BinaryStringHelper::IntegerToNBOBinaryString(0xE0000000 + $length);
74		}
75
76		// https://wiki.mikrotik.com/wiki/Manual:API#API_words
77		// If len >= 0x10000000 then 0xF0 and len as four bytes
78	3	return BinaryStringHelper::IntegerToNBOBinaryString(0xF000000000 + $length);
79		}
80
81		// Decode length of data when reading :
82		// The 5 firsts bits of the first byte specify how the length is encoded.
83		// The position of the first 0 value bit, starting from the most significant postion.
84		// - 0xxxxxxx => The 7 remainings bits of the first byte is the length :
85		// => min value of length is 0x00
86		// => max value of length is 0x7F (127 bytes)
87		// - 10xxxxxx => The 6 remainings bits of the first byte plus the next byte represent the lenght
88		// NOTE : the next byte MUST be at least 0x80 !!
89		// => min value of length is 0x80
90		// => max value of length is 0x3FFF (16,383 bytes, near 16 KB)
91		// - 110xxxxx => The 5 remainings bits of th first byte and the two next bytes represent the length
92		// => max value of length is 0x1FFFFF (2,097,151 bytes, near 2 MB)
93		// - 1110xxxx => The 4 remainings bits of the first byte and the three next bytes represent the length
94		// => max value of length is 0xFFFFFFF (268,435,455 bytes, near 270 MB)
95		// - 11110xxx => The 3 remainings bits of the first byte and the four next bytes represent the length
96		// => max value of length is 0x7FFFFFFF (2,147,483,647 byes, 2GB)
97		// - 11111xxx => This byte is not a length-encoded word but a control byte.
98		// => Extracted from Mikrotik API doc :
99		// it is a reserved control byte.
100		// After receiving unknown control byte API client cannot proceed, because it cannot know how to interpret following bytes
101		// Currently control bytes are not used
102
103	30	public static function decodeLength(StreamInterface $stream): int
104		{
105		// if (false === is_resource($stream)) {
106		// throw new \InvalidArgumentException(
107		// sprintf(
108		// 'Argument must be a stream resource type. %s given.',
109		// gettype($stream)
110		// )
111		// );
112		// }
113
114		// Read first byte
115	30	$firstByte = ord($stream->read(1));
116
117		// If first byte is not set, length is the value of the byte
118	30	if (0 === ($firstByte & 0x80)) {
119	15	return $firstByte;
120		}
121
122		// if 10xxxxxx, length is 2 bytes encoded
123	15	if (0x80 === ($firstByte & 0xC0)) {
124		// Set 2 most significands bits to 0
125	3	$result = $firstByte & 0x3F;
126
127		// shift left 8 bits to have 2 bytes
128	3	$result <<= 8;
129
130		// read next byte and use it as least significant
131	3	$result \|= ord($stream->read(1));
132	3	return $result;
133		}
134
135		// if 110xxxxx, length is 3 bytes encoded
136	12	if (0xC0 === ($firstByte & 0xE0)) {
137		// Set 3 most significands bits to 0
138	3	$result = $firstByte & 0x1F;
139
140		// shift left 16 bits to have 3 bytes
141	3	$result <<= 16;
142
143		// read next 2 bytes as value and use it as least significant position
144	3	$result \|= (ord($stream->read(1)) << 8);
145	3	$result \|= ord($stream->read(1));
146	3	return $result;
147		}
148
149		// if 1110xxxx, length is 4 bytes encoded
150	9	if (0xE0 === ($firstByte & 0xF0)) {
151		// Set 4 most significance bits to 0
152	3	$result = $firstByte & 0x0F;
153
154		// shift left 24 bits to have 4 bytes
155	3	$result <<= 24;
156
157		// read next 3 bytes as value and use it as least significant position
158	3	$result \|= (ord($stream->read(1)) << 16);
159	3	$result \|= (ord($stream->read(1)) << 8);
160	3	$result \|= ord($stream->read(1));
161	3	return $result;
162		}
163
164		// if 11110xxx, length is 5 bytes encoded
165	6	if (0xF0 === ($firstByte & 0xF8)) {
166		// Not possible on 32 bits systems
167	3	if (PHP_INT_SIZE < 8) {
168		// Cannot be done on 32 bits systems
169		// PHP5 windows versions of php, even on 64 bits systems was impacted
170		// see : https://stackoverflow.com/questions/27865340/php-int-size-returns-4-but-my-operating-system-is-64-bit
171		// How can we test it ?
172
173		// @codeCoverageIgnoreStart
174		throw new \OverflowException("Your system is using 32 bits integers, cannot decode this value ($firstByte) on this system");
175		// @codeCoverageIgnoreEnd
176		}
177
178		// Set 5 most significance bits to 0
179	3	$result = $firstByte & 0x07;
180
181		// shift left 232 bits to have 5 bytes
182	3	$result <<= 32;
183
184		// read next 4 bytes as value and use it as least significant position
185	3	$result \|= (ord($stream->read(1)) << 24);
186	3	$result \|= (ord($stream->read(1)) << 16);
187	3	$result \|= (ord($stream->read(1)) << 8);
188	3	$result \|= ord($stream->read(1));
189	3	return $result;
190		}
191
192		// Now the only solution is 5 most significance bits are set to 1 (11111xxx)
193		// This is a control word, not implemented by Mikrotik for the moment
194	3	throw new \UnexpectedValueException('Control Word found');
195		}
196		}
197

EvilFreelancer / routeros-api-php

Pull Request — master (#8)

APILengthCoDec::decodeLength() B

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Size

Duplication

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How to fix Long Method

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