Serializer::readInt() - Code Metrics - Inspection of "Refactor reading of ints from the byte array" - carlosafonso/php-dns-client - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 4f6108...97a3dc )

by Carlos

created 2020-04-18 18:49 UTC

Serializer::readInt() A

↳ Parent: Serializer

Complexity

Conditions	2
Paths	2

Size

Total Lines	7
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	5
CRAP Score	2

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	2
eloc	4
c	1
b	0
f	0
nc	2
nop	3
dl	0
loc	7
ccs	5
cts	5
cp	1
crap	2
rs	10

<?php

declare(strict_types=1);

namespace Afonso\Dns;

class Serializer
{
    public function serializeRequest(Request $request): string
    {
        $bytes = [];

        /*
         * Header
         */
        // ID (0x00 - 0x15)
        $bytes = array_merge($bytes, [0xAA, 0xAA]);

        // QR, OPCODE, AA, TC, RD, RA, RCODE (0x16 - 0x31)
        $bytes += array_merge($bytes, [0x01, 0x00]);

        // QDCOUNT (0x32 - 0x47)
        $bytes += array_merge($bytes, [0x00, 0x01]);

        // ANCOUNT (0x48 - 0x63)
        $bytes += array_merge($bytes, [0x00, 0x00]);

        // NSCOUNT (0x64 - 0x79)
        $bytes += array_merge($bytes, [0x00, 0x00]);

        // ARCOUNT (0x80 - 0x95)
        $bytes += array_merge($bytes, [0x00, 0x00]);

        /*
         * Question
         */
        // QNAME
        $qname = [];
        $labels = explode('.', $request->getName());
        foreach ($labels as $label) {
            $labelLength = strlen($label);
            if ($labelLength > 63) {
                throw new \InvalidArgumentException(
                    'At least one of the labels of the specified domain exceeds the allowed maximum length'
                );
            }
            $qname = array_merge($qname, [$labelLength]);
            $qname = array_merge($qname, array_map('ord', str_split($label)));
        }
        $qname = array_merge($qname, [0x00]);
        $bytes += array_merge($bytes, $qname);

        // QTYPE
        $bytes += array_merge($bytes, [0x00, $request->getType()]);

        // QCLASS
        $bytes += array_merge($bytes, [0x00, 0x01]);

        return implode(array_map('chr', $bytes));
    }

    public function deserializeResponse(string $response): Response
    {
        $responseObj = new Response();

        $bytes = array_map('ord', str_split($response));

        // To-Do: check that response is actually a response (QR)

        /*
         * Header
         */
        $isAuthoritative = (bool) ($bytes[2] & 0x04);
        $isRecursionAvailable = (bool) ($bytes[3] & 0x80);
        $type = $bytes[3] & 0x0F;

        [$_, $qdCount] = $this->readInt($bytes, 4, 2);

        [$_, $anCount] = $this->readInt($bytes, 6, 2);
        [$_, $nsCount] = $this->readInt($bytes, 8, 2);

        [$_, $arCount] = $this->readInt($bytes, 10, 2);


        $responseObj->setAuthoritative($isAuthoritative);
        $responseObj->setRecursionAvailable($isRecursionAvailable);
        $responseObj->setType($type);

        // From now on there are variable-length fields, so we need to keep
        // track of the current byte position.
        $ptr = 12;

        /*
         * Question
         */
        // QNAME
        while ($bytes[$ptr] > 0x00) {
            $labelLength = $bytes[$ptr];
            // Just skip the label for the time being
            // $label = implode('', array_map('chr', array_slice($bytes, $ptr + 1, $labelLength)));
            $ptr += $labelLength + 1;
        }
        $ptr++; // End of field

        // QTYPE
        $ptr += 2;

        // CLASS
        $ptr += 2;

        /*
         * Answer
         */
        for ($i = 0; $i < $anCount; $i++) {
            // NAME
            [$ptr, $name] = $this->readNameField($bytes, $ptr);

            // TYPE
            [$ptr, $type] = $this->readInt($bytes, $ptr, 2);

            // CLASS
            $ptr += 2;

            // TTL
            [$ptr, $ttl] = $this->readInt($bytes, $ptr, 4);

            // RDATA
            [$ptr, $rdLength] = $this->readInt($bytes, $ptr, 2);
            switch ($type) {
                case Request::RR_TYPE_A:
                    $value = $bytes[$ptr++] . '.' . $bytes[$ptr++] . '.' . $bytes[$ptr++] . '.' . $bytes[$ptr++];
                    break;
                case Request::RR_TYPE_NS:
                    [$ptr, $value] = $this->readNameField($bytes, $ptr);
                    break;
                case Request::RR_TYPE_CNAME:
                    [$ptr, $value] = $this->readNameField($bytes, $ptr);
                    break;
                case Request::RR_TYPE_SOA:
                    [$ptr, $primaryNs] = $this->readNameField($bytes, $ptr);
                    [$ptr, $adminMb] = $this->readNameField($bytes, $ptr);
                    [$ptr, $serialNo] = $this->readInt($bytes, $ptr, 4);
                    [$ptr, $refreshInterval] = $this->readInt($bytes, $ptr, 4);
                    [$ptr, $retryInterval] = $this->readInt($bytes, $ptr, 4);
                    [$ptr, $expirationLimit] = $this->readInt($bytes, $ptr, 4);
                    [$ptr, $minimumTtl] = $this->readInt($bytes, $ptr, 4);
                    $value = "{$primaryNs} {$adminMb} {$serialNo} {$refreshInterval}"
                        . " {$retryInterval} {$expirationLimit} {$minimumTtl}";
                    break;
                case Request::RR_TYPE_PTR:
                    [$ptr, $value] = $this->readNameField($bytes, $ptr);
                    break;
                case Request::RR_TYPE_MX:
                    [$ptr, $preference] = $this->readInt($bytes, $ptr, 2);
                    [$ptr, $exchanger] = $this->readNameField($bytes, $ptr);
                    $value = "{$preference} {$exchanger}";
                    break;
                case Request::RR_TYPE_AAAA:
                    $packed = '';
                    for ($i = 0; $i < 16; $i++) {
                        $packed .= chr($bytes[$ptr++]);
                    }
                    $value = inet_ntop($packed);
                    break;
                default:
                    throw new \RuntimeException("Reading responses for resource type '{$type}' is not implemented");
            }

            $record = new ResourceRecord($name, $type, $ttl, $value);
            $responseObj->addResourceRecord($record);
        }

        /*
         * Authority
         */
        // Intentionally skipped

        /*
         * Additional
         */
        // Intentionally skipped

        return $responseObj;
    }

    private function readNameField(array $bytes, int $ptr): array
    {
        while (true) {
            // Zero byte means we hit end of name field. Break the loop.
            if ($bytes[$ptr] == 0) {
                $ptr++;
                break;
            }

            $format = $bytes[$ptr] & 0xC0;
            $length = $offset = 0;


            if ($format == 0xC0) { // Pointer format
                $offset = ($bytes[$ptr++] << 8 | $bytes[$ptr++]) & 0x3F;
                [$_, $label] = $this->readNameField($bytes, $offset);
                $labels[] = $label;
                // Pointer ends the name field. Break the loop.
                break;
            } elseif ($format == 0x00) {  // Label format
                $length = $bytes[$ptr++] & 0x3F;
                $labels[] = implode('', array_map('chr', array_slice($bytes, $ptr, $length)));
                $ptr += $length;
            } else {
                throw new \RuntimeException("Unrecognized format '${format}' in response");
            }
        }

        return [$ptr, implode('.', $labels)];

    }

    /**
     * Reads and returns an integer from the given byte array, at the specified
     * offset and with the specified length in bytes.
     *
     * @param int[] $byteArray
     * @param int $ptr
     * @param int $bytes
     * @return int[] An array of size 2, the first item being the updated
     * pointer (after the read operation) and the second item being the actual
     * integer that was read.
     */
    private function readInt(array $byteArray, int $ptr, int $bytes): array
    {
        $int = 0;
        for ($i = $bytes - 1; $i >= 0; $i--) {
            $int |= $byteArray[$ptr++] << 8 * $i;
        }
        return [$ptr, $int];
    }
}


1		<?php
2
3		declare(strict_types=1);
4
5		namespace Afonso\Dns;
6
7		class Serializer
8		{
9	6	public function serializeRequest(Request $request): string
10		{
11	6	$bytes = [];
12
13		/*
14		* Header
15		*/
16		// ID (0x00 - 0x15)
17	6	$bytes = array_merge($bytes, [0xAA, 0xAA]);
18
19		// QR, OPCODE, AA, TC, RD, RA, RCODE (0x16 - 0x31)
20	6	$bytes += array_merge($bytes, [0x01, 0x00]);
21
22		// QDCOUNT (0x32 - 0x47)
23	6	$bytes += array_merge($bytes, [0x00, 0x01]);
24
25		// ANCOUNT (0x48 - 0x63)
26	6	$bytes += array_merge($bytes, [0x00, 0x00]);
27
28		// NSCOUNT (0x64 - 0x79)
29	6	$bytes += array_merge($bytes, [0x00, 0x00]);
30
31		// ARCOUNT (0x80 - 0x95)
32	6	$bytes += array_merge($bytes, [0x00, 0x00]);
33
34		/*
35		* Question
36		*/
37		// QNAME
38	6	$qname = [];
39	6	$labels = explode('.', $request->getName());
40	6	foreach ($labels as $label) {
41	6	$labelLength = strlen($label);
42	6	if ($labelLength > 63) {
43	3	throw new \InvalidArgumentException(
44	3	'At least one of the labels of the specified domain exceeds the allowed maximum length'
45		);
46		}
47	3	$qname = array_merge($qname, [$labelLength]);
48	3	$qname = array_merge($qname, array_map('ord', str_split($label)));
49		}
50	3	$qname = array_merge($qname, [0x00]);
51	3	$bytes += array_merge($bytes, $qname);
52
53		// QTYPE
54	3	$bytes += array_merge($bytes, [0x00, $request->getType()]);
55
56		// QCLASS
57	3	$bytes += array_merge($bytes, [0x00, 0x01]);
58
59	3	return implode(array_map('chr', $bytes));
60		}
61
62	21	public function deserializeResponse(string $response): Response
63		{
64	21	$responseObj = new Response();
65
66	21	$bytes = array_map('ord', str_split($response));
67
68		// To-Do: check that response is actually a response (QR)
69
70		/*
71		* Header
72		*/
73	21	$isAuthoritative = (bool) ($bytes[2] & 0x04);
74	21	$isRecursionAvailable = (bool) ($bytes[3] & 0x80);
75	21	$type = $bytes[3] & 0x0F;
76
77	21	[$_, $qdCount] = $this->readInt($bytes, 4, 2);
		0 ignored issues – show Comprehensibility Best Practice introduced 2020-04-18 18:51 UTC by Report Bug Copy Issue Report This list assign is not used and could be removed. Loading history...
78	21	[$_, $anCount] = $this->readInt($bytes, 6, 2);
79	21	[$_, $nsCount] = $this->readInt($bytes, 8, 2);
		0 ignored issues – show Comprehensibility Best Practice introduced 2020-04-18 18:51 UTC by Report Bug Copy Issue Report This list assign is not used and could be removed. Loading history...
80	21	[$_, $arCount] = $this->readInt($bytes, 10, 2);
		0 ignored issues – show Comprehensibility Best Practice introduced 2020-04-18 18:51 UTC by Report Bug Copy Issue Report This list assign is not used and could be removed. Loading history...
81
82	21	$responseObj->setAuthoritative($isAuthoritative);
83	21	$responseObj->setRecursionAvailable($isRecursionAvailable);
84	21	$responseObj->setType($type);
85
86		// From now on there are variable-length fields, so we need to keep
87		// track of the current byte position.
88	21	$ptr = 12;
89
90		/*
91		* Question
92		*/
93		// QNAME
94	21	while ($bytes[$ptr] > 0x00) {
95	21	$labelLength = $bytes[$ptr];
96		// Just skip the label for the time being
97		// $label = implode('', array_map('chr', array_slice($bytes, $ptr + 1, $labelLength)));
98	21	$ptr += $labelLength + 1;
99		}
100	21	$ptr++; // End of field
101
102		// QTYPE
103	21	$ptr += 2;
104
105		// CLASS
106	21	$ptr += 2;
107
108		/*
109		* Answer
110		*/
111	21	for ($i = 0; $i < $anCount; $i++) {
112		// NAME
113	21	[$ptr, $name] = $this->readNameField($bytes, $ptr);
114
115		// TYPE
116	21	[$ptr, $type] = $this->readInt($bytes, $ptr, 2);
117
118		// CLASS
119	21	$ptr += 2;
120
121		// TTL
122	21	[$ptr, $ttl] = $this->readInt($bytes, $ptr, 4);
123
124		// RDATA
125	21	[$ptr, $rdLength] = $this->readInt($bytes, $ptr, 2);
126	21	switch ($type) {
127		case Request::RR_TYPE_A:
128	3	$value = $bytes[$ptr++] . '.' . $bytes[$ptr++] . '.' . $bytes[$ptr++] . '.' . $bytes[$ptr++];
129	3	break;
130		case Request::RR_TYPE_NS:
131	3	[$ptr, $value] = $this->readNameField($bytes, $ptr);
132	3	break;
133		case Request::RR_TYPE_CNAME:
134	3	[$ptr, $value] = $this->readNameField($bytes, $ptr);
135	3	break;
136		case Request::RR_TYPE_SOA:
137	3	[$ptr, $primaryNs] = $this->readNameField($bytes, $ptr);
138	3	[$ptr, $adminMb] = $this->readNameField($bytes, $ptr);
139	3	[$ptr, $serialNo] = $this->readInt($bytes, $ptr, 4);
140	3	[$ptr, $refreshInterval] = $this->readInt($bytes, $ptr, 4);
141	3	[$ptr, $retryInterval] = $this->readInt($bytes, $ptr, 4);
142	3	[$ptr, $expirationLimit] = $this->readInt($bytes, $ptr, 4);
143	3	[$ptr, $minimumTtl] = $this->readInt($bytes, $ptr, 4);
144	3	$value = "{$primaryNs} {$adminMb} {$serialNo} {$refreshInterval}"
145	3	. " {$retryInterval} {$expirationLimit} {$minimumTtl}";
146	3	break;
147		case Request::RR_TYPE_PTR:
148	3	[$ptr, $value] = $this->readNameField($bytes, $ptr);
149	3	break;
150		case Request::RR_TYPE_MX:
151	3	[$ptr, $preference] = $this->readInt($bytes, $ptr, 2);
152	3	[$ptr, $exchanger] = $this->readNameField($bytes, $ptr);
153	3	$value = "{$preference} {$exchanger}";
154	3	break;
155		case Request::RR_TYPE_AAAA:
156	3	$packed = '';
157	3	for ($i = 0; $i < 16; $i++) {
158	3	$packed .= chr($bytes[$ptr++]);
159		}
160	3	$value = inet_ntop($packed);
161	3	break;
162		default:
163		throw new \RuntimeException("Reading responses for resource type '{$type}' is not implemented");
164		}
165
166	21	$record = new ResourceRecord($name, $type, $ttl, $value);
167	21	$responseObj->addResourceRecord($record);
168		}
169
170		/*
171		* Authority
172		*/
173		// Intentionally skipped
174
175		/*
176		* Additional
177		*/
178		// Intentionally skipped
179
180	21	return $responseObj;
181		}
182
183	21	private function readNameField(array $bytes, int $ptr): array
184		{
185	21	while (true) {
186		// Zero byte means we hit end of name field. Break the loop.
187	21	if ($bytes[$ptr] == 0) {
188	21	$ptr++;
189	21	break;
190		}
191
192	21	$format = $bytes[$ptr] & 0xC0;
193	21	$length = $offset = 0;
		0 ignored issues – show Unused Code introduced 2020-04-18 18:30 UTC by Report Bug Copy Issue Report The assignment to `$length` is dead and can be removed. Loading history...
194
195	21	if ($format == 0xC0) { // Pointer format
196	21	$offset = ($bytes[$ptr++] << 8 \| $bytes[$ptr++]) & 0x3F;
197	21	[$_, $label] = $this->readNameField($bytes, $offset);
198	21	$labels[] = $label;
199		// Pointer ends the name field. Break the loop.
200	21	break;
201	21	} elseif ($format == 0x00) { // Label format
202	21	$length = $bytes[$ptr++] & 0x3F;
203	21	$labels[] = implode('', array_map('chr', array_slice($bytes, $ptr, $length)));
204	21	$ptr += $length;
205		} else {
206		throw new \RuntimeException("Unrecognized format '${format}' in response");
207		}
208		}
209
210	21	return [$ptr, implode('.', $labels)];
		0 ignored issues – show Comprehensibility Best Practice introduced 2020-04-18 18:30 UTC by Report Bug Copy Issue Report The variable `$labels` does not seem to be defined for all execution paths leading up to this point. Loading history...
211		}
212
213		/**
214		* Reads and returns an integer from the given byte array, at the specified
215		* offset and with the specified length in bytes.
216		*
217		* @param int[] $byteArray
218		* @param int $ptr
219		* @param int $bytes
220		* @return int[] An array of size 2, the first item being the updated
221		* pointer (after the read operation) and the second item being the actual
222		* integer that was read.
223		*/
224	21	private function readInt(array $byteArray, int $ptr, int $bytes): array
225		{
226	21	$int = 0;
227	21	for ($i = $bytes - 1; $i >= 0; $i--) {
228	21	$int \|= $byteArray[$ptr++] << 8 * $i;
229		}
230	21	return [$ptr, $int];
231		}
232		}
233

carlosafonso / php-dns-client

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Serializer::readInt() A

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