xref: /dokuwiki/inc/Ip32.php (revision 91da8d440c37d90167dc8ee25e6de7f854a11f1e) 
1<?php
2
3/**
4 * DokuWiki 32bit shims for IP address functions.
5 *
6 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
7 */
8
9namespace dokuwiki;
10
11class Ip32
12{
13    /**
14     * slow and ugly bitwise_and for 32bit arch
15     * @param $u64 unsigned 64bit integer as string
16     *            likely from ipv6_upper_lower_32
17     * @param $pow 0-64 power of 2 for bitmask
18     */
19    public static function bitmask64_32(string $u64, int $pow) : string {
20        //$u64 = sprintf("%.0f", $u65);
21        $b32 = '4294967296';
22        $bin = sprintf("%032b%032b",
23                bcdiv($u64, $b32, 0),
24                bcmod($u64, $b32));
25
26        $mask = Ip32::make_bitmask_32(64-$pow);
27
28        // most right is lowest bit
29        $res='0';
30        for ($i=0; $i<64; $i++){
31            if (bcmul($bin[$i], $mask[$i]) == 1) {
32                $res = bcadd($res, bcpow(2, 63-$i));
33            }
34        }
35        return $res;
36    }
37
38
39    /**
40     * modeling bitshift like  ~0 << $pow for 32-bit arch
41     * @param pow power of 2 for mask
42     * @return 64-char string of 1 and 0s
43     * pow=1
44     * 1111111111111111111111111111111111111111111111111111111111111110
45     * pow=63
46     * 1000000000000000000000000000000000000000000000000000000000000000
47     * pow=64
48     * 0000000000000000000000000000000000000000000000000000000000000000
49     */
50    private static function make_bitmask_32(int $pow) : string {
51        $pow = $pow < 0 ? 64 - $pow : $pow;
52        $mask = sprintf("%064d",0);
53        for ($i=0; $i<64; $i++) {
54            if ($i >= $pow) {
55                $mask[63 - $i] = '1';
56            }
57        }
58        return $mask;
59    }
60
61    /**
62     * conversion of inet_pton ipv6 into 64-bit upper and lower
63     * bcmath version for 32-bit architecture
64     * w/o no unpack('J') - unsigned long long (always 64 bit, big endian byte order)
65     *
66     * results match unpack('Jupper/Jlower', $binary)
67     *
68     * @param string $binary inet_pton's ipv6 16 element binary
69     *
70     * @return int[] upper 64 and lower 64 for ipToNumber
71     */
72    public static function ipv6_upper_lower_32(string $binary) {
73       // unpack into four 32-bit unsigned ints to recombine as 2 64-bit
74       $b32 = 4294967296; // bcpow(2, 32)
75       $parts = unpack('N4', $binary);
76       $upper = bcadd(bcmul($parts[1], $b32),
77                      $parts[2]);
78       $lower = bcadd(bcmul($parts[3], $b32),
79                      $parts[4]);
80       return ['upper' => $upper, 'lower' => $lower];
81    }
82 }
83