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independent-analytics / vendor / mlocati / ip-lib / src / Service / UnsignedIntegerMath.php

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UnsignedIntegerMath.php

148 lines

1	<?php
2
3	namespace IAWPSCOPED\IPLib\Service;
4
5	/**
6	* Helper class to work with unsigned integers.
7	*
8	* @internal
9	*/
10	class UnsignedIntegerMath
11	{
12	/**
13	* Convert a string containing a decimal, octal or hexadecimal number into its bytes.
14	*
15	* @param string $value
16	* @param int $numBytes the wanted number of bytes
17	* @param bool $onlyDecimal Only parse decimal numbers
18	*
19	* @return int[]\|null
20	*/
21	public function getBytes($value, $numBytes, $onlyDecimal = \false)
22	{
23	$m = null;
24	if ($onlyDecimal) {
25	if (\preg_match('/^0*(\\d+)$/', $value, $m)) {
26	return $this->getBytesFromDecimal($m[1], $numBytes);
27	}
28	} else {
29	if (\preg_match('/^0[Xx]0*([0-9A-Fa-f]+)$/', $value, $m)) {
30	return $this->getBytesFromHexadecimal($m[1], $numBytes);
31	}
32	if (\preg_match('/^0+([0-7]*)$/', $value, $m)) {
33	return $this->getBytesFromOctal($m[1], $numBytes);
34	}
35	if (\preg_match('/^[1-9][0-9]*$/', $value)) {
36	return $this->getBytesFromDecimal($value, $numBytes);
37	}
38	}
39	// Not a valid number
40	return null;
41	}
42	/**
43	* @return int
44	*/
45	protected function getMaxSignedInt()
46	{
47	return \PHP_INT_MAX;
48	}
49	/**
50	* @param string $value never zero-length, never extra leading zeroes
51	* @param int $numBytes
52	*
53	* @return int[]\|null
54	*/
55	private function getBytesFromBits($value, $numBytes)
56	{
57	$valueLength = \strlen($value);
58	if ($valueLength > $numBytes << 3) {
59	// overflow
60	return null;
61	}
62	$remainderBits = $valueLength % 8;
63	if ($remainderBits !== 0) {
64	$value = \str_pad($value, $valueLength + 8 - $remainderBits, '0', \STR_PAD_LEFT);
65	}
66	$bytes = \array_map('bindec', \str_split($value, 8));
67	/** @var int[] $bytes */
68	return \array_pad($bytes, -$numBytes, 0);
69	}
70	/**
71	* @param string $value may be zero-length, never extra leading zeroes
72	* @param int $numBytes
73	*
74	* @return int[]\|null
75	*/
76	private function getBytesFromOctal($value, $numBytes)
77	{
78	if ($value === '') {
79	return \array_fill(0, $numBytes, 0);
80	}
81	$bits = \implode('', \array_map(function ($octalDigit) {
82	return \str_pad(\decbin((int) \octdec($octalDigit)), 3, '0', \STR_PAD_LEFT);
83	}, \str_split($value, 1)));
84	$bits = \ltrim($bits, '0');
85	return $bits === '' ? \array_fill(0, $numBytes, 0) : self::getBytesFromBits($bits, $numBytes);
86	}
87	/**
88	* @param string $value never zero-length, never extra leading zeroes
89	* @param int $numBytes
90	*
91	* @return int[]\|null
92	*/
93	private function getBytesFromDecimal($value, $numBytes)
94	{
95	$valueLength = \strlen($value);
96	$maxSignedIntLength = \strlen((string) $this->getMaxSignedInt());
97	if ($valueLength < $maxSignedIntLength) {
98	return $this->getBytesFromBits(\decbin((int) $value), $numBytes);
99	}
100	// Divide by two, so that we have 1 less bit
101	$carry = 0;
102	$halfValue = \ltrim(\implode('', \array_map(function ($digit) use(&$carry) {
103	$number = $carry + (int) $digit;
104	$carry = $number % 2 * 10;
105	return (string) $number >> 1;
106	}, \str_split($value, 1))), '0');
107	$halfValueBytes = $this->getBytesFromDecimal($halfValue, $numBytes);
108	if ($halfValueBytes === null) {
109	return null;
110	}
111	$carry = $carry === 0 ? 0 : 1;
112	$result = \array_fill(0, $numBytes, 0);
113	for ($index = $numBytes - 1; $index >= 0; $index--) {
114	$byte = $carry + ($halfValueBytes[$index] << 1);
115	if ($byte <= 0xff) {
116	$carry = 0;
117	} else {
118	$carry = ($byte & ~0xff) >> 8;
119	$byte -= 0x100;
120	}
121	$result[$index] = $byte;
122	}
123	if ($carry !== 0) {
124	// Overflow
125	return null;
126	}
127	return $result;
128	}
129	/**
130	* @param string $value never zero-length, never extra leading zeroes
131	* @param int $numBytes
132	*
133	* @return int[]\|null
134	*/
135	private function getBytesFromHexadecimal($value, $numBytes)
136	{
137	$valueLength = \strlen($value);
138	if ($valueLength > $numBytes << 1) {
139	// overflow
140	return null;
141	}
142	$value = \str_pad($value, $valueLength + $valueLength % 2, '0', \STR_PAD_LEFT);
143	$bytes = \array_map('hexdec', \str_split($value, 2));
144	/** @var int[] $bytes */
145	return \array_pad($bytes, -$numBytes, 0);
146	}
147	}
148