feat: add sniffing functionality (WIP)

src/Sniff/SniffAgent.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Neoncitylights\MediaType\Sniff;
+
+use Neoncitylights\MediaType\MediaType;
+
+final class SniffAgent {
+	/**
+	 * @see https://mimesniff.spec.whatwg.org/#supplied-mime-type
+	 */
+	public readonly MediaType $suppliedMediaType;
+
+	/**
+	 * @see https://mimesniff.spec.whatwg.org/#check-for-apache-bug-flag
+	 */
+	public readonly bool $checkForApacheFlag;
+
+	/**
+	 * @see https://mimesniff.spec.whatwg.org/#no-sniff-flag
+	 */
+	public readonly bool $noSniffFlag;
+
+	/**
+	 * https://mimesniff.spec.whatwg.org/#computed-mime-type
+	 */
+	public MediaType|null $computedMimeType;
+
+	public function __construct(
+		MediaType $suppliedMediaType,
+		bool $checkForApacheFlag,
+		bool $noSniffFlag
+	) {
+		$this->suppliedMediaType = $suppliedMediaType;
+		$this->computedMimeType = null;
+		$this->checkForApacheFlag = $checkForApacheFlag;
+		$this->noSniffFlag = $noSniffFlag;
+	}
+}

src/Sniff/SniffTableLookup.php

@@ -0,0 +1,64 @@
+<?php
+
+namespace Neoncitylights\MediaType\Sniff;
+
+use Neoncitylights\MediaType\MediaType;
+
+final class SniffTableLookup {
+	public const IMAGE = [
+		[
+			[ 0x00, 0x00, 0x01, 0x00 ],
+			[ 0xFF, 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'x-icon' ],
+		],
+		[
+			[ 0x00, 0x00, 0x02, 0x00 ],
+			[ 0xFF, 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'x-icon' ],
+		],
+		[
+			[ 0x42, 0x4D ],
+			[ 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'bmp' ],
+		],
+		[
+			[ 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 ],
+			[ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'gif' ],
+		],
+		[
+			[ 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 ],
+			[ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'gif' ],
+		],
+		[
+			[
+				0x52, 0x49, 0x46, 0x46, 0x00, 0x00, 0x00,
+				0x00, 0x57, 0x45, 0x42, 0x50, 0x56, 0x50
+			],
+			[
+				0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00,
+				0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+			],
+			[ ],
+			[ 'image', 'png' ],
+		],
+		[
+			[ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A ],
+			[ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'png' ],
+		],
+		[
+			[ 0xFF, 0xD8, 0xFF ],
+			[ 0xFF, 0xFF, 0xFF ],
+			[ ],
+			[ 'image', 'jpeg' ],
+		],
+	];
+}

src/Sniff/SniffTableValue.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Neoncitylights\MediaType\Sniff;
+
+use Neoncitylights\MediaType\MediaType;
+
+final class SniffTableValue {
+    /**
+     * @see https://mimesniff.spec.whatwg.org/#byte-pattern
+     * @var int[]
+     */
+    public readonly array $pattern;
+
+    /**
+     * @see https://mimesniff.spec.whatwg.org/#pattern-mask
+     * @var int[]
+     */
+    public readonly array $patternMask;
+
+    /**
+     * @see https://mimesniff.spec.whatwg.org/#bytes-ignored
+     * @var int[]
+     */
+    public readonly array $bytesIgnored;
+
+    public readonly MediaType $mediaType;
+
+    public function __construct(
+        array $pattern,
+        array $patternMask,
+        array $bytesIgnored,
+        MediaType $mediaType
+    ) {
+        $this->pattern = $pattern;
+        $this->patternMask = $patternMask;
+        $this->bytesIgnored = $bytesIgnored;
+        $this->mediaType = $mediaType;
+    }
+}

src/Sniff/Sniffer.php

@@ -0,0 +1,117 @@
+<?php
+
+namespace Neoncitylights\MediaType\Sniff;
+
+use Neoncitylights\MediaType\MediaType;
+
+final class Sniffer {
+	/**
+	 * Undocumented function
+	 *
+	 * @param array $tableLookup
+	 * @param array $sequence
+	 * @return void
+	 */
+	public function performTableLookup( array $tableLookup, array $sequence ) {
+		$imageTable = SniffTableLookup::IMAGE;
+		foreach( $imageTable as $tableRecord ) {
+			$lookupValue = new SniffTableValue(
+				$tableRecord[0],
+				$tableRecord[1],
+				$tableRecord[2],
+				new MediaType( $tableRecord[3][0], $tableRecord[3][1], [] )
+			);
+
+			$patternMatched = $this->doesByteSequenceMatchPattern(
+				$sequence,
+				$lookupValue->pattern,
+				$lookupValue->patternMask,
+				$lookupValue->bytesIgnored
+			);
+
+			if ( $patternMatched ) {
+				return $lookupValue->mediaType;
+			}
+		}
+	}
+
+	private function matchesSignatureForMP4( array $input ) {
+		$length = count( $input );
+		if ( $length < 12 ) {
+			return false;
+		}
+
+		$boxSize = \intval(\pack( "L*", ...\array_slice( $input, 0, 4 ) ));
+		if ( $length < $boxSize || $boxSize % 4 !== 0 ) {
+			return false;
+		}
+
+		$bytes4to7 = \array_slice( $input, 4, 4 );
+		if( $bytes4to7 !== [ 0x66, 0x74, 0x79, 0x70 ] ) {
+			return false;
+		}
+
+		$bytes8to10 = \array_slice( $input, 8, 3 );
+		$mp4Signature = [ 0x6D, 0x70, 0x34 ];
+		if ( $bytes8to10 === $mp4Signature ) {
+			return true;
+		}
+
+		$bytesRead = 16;
+		while ( $bytesRead < $boxSize ) {
+			$byteSlice = [ $input[$bytesRead], $input[$bytesRead + 1], $input[$bytesRead + 2] ];
+			if ( $byteSlice === $mp4Signature ) {
+				return true;
+			}
+			$bytesRead += 4;
+		}
+
+		return false;
+	}
+
+	private function matchesSignatureForWebM() {
+
+	}
+
+	/**
+	 * @see https://mimesniff.spec.whatwg.org/#pattern-matching-algorithm
+	 * @param int[] $input
+	 * @param int[] $pattern
+	 * @param int[] $patternMask
+	 * @param int[] $bytesIgnored
+	 * @return boolean
+	 */
+	private function doesByteSequenceMatchPattern(
+		array $input,
+		array $pattern,
+		array $patternMask,
+		array $bytesIgnored
+	): bool {
+		$inputLen = count( $input );
+		$patternLen = count( $pattern );
+
+		if ( $inputLen < $patternLen ) {
+			return false;
+		}
+
+		$s = 0;
+		while( $s < $inputLen ) {
+			if ( !in_array( $input[$s], $bytesIgnored ) ) {
+				return false;
+			}
+			$s++;
+		}
+
+		$p = 0;
+		while ( $p < $patternLen ) {
+			$maskedData = $input[$s] & $patternMask[$p];
+			if ( $maskedData !== $pattern[$p] ) {
+				return false;
+			}
+			$s++;
+			$p++;
+		}
+
+		return true;
+	}
+}