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denoland-deno/ext/web/01_mimesniff.js

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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// @ts-check
/// <reference path="../../core/internal.d.ts" />
/// <reference path="../../core/lib.deno_core.d.ts" />
/// <reference path="../web/internal.d.ts" />
/// <reference path="../web/lib.deno_web.d.ts" />
import { primordials } from "ext:core/mod.js";
const {
ArrayPrototypeIncludes,
MapPrototypeGet,
MapPrototypeHas,
MapPrototypeSet,
RegExpPrototypeTest,
RegExpPrototypeExec,
SafeMap,
SafeMapIterator,
StringPrototypeReplaceAll,
StringPrototypeToLowerCase,
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StringPrototypeEndsWith,
Uint8Array,
TypedArrayPrototypeGetLength,
TypedArrayPrototypeIncludes,
} = primordials;
import {
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assert,
collectHttpQuotedString,
collectSequenceOfCodepoints,
HTTP_QUOTED_STRING_TOKEN_POINT_RE,
HTTP_TOKEN_CODE_POINT_RE,
HTTP_WHITESPACE,
HTTP_WHITESPACE_PREFIX_RE,
HTTP_WHITESPACE_SUFFIX_RE,
} from "./00_infra.js";
/**
* @typedef MimeType
* @property {string} type
* @property {string} subtype
* @property {Map<string,string>} parameters
*/
/**
* @param {string} input
* @returns {MimeType | null}
*/
function parseMimeType(input) {
// 1.
input = StringPrototypeReplaceAll(input, HTTP_WHITESPACE_PREFIX_RE, "");
input = StringPrototypeReplaceAll(input, HTTP_WHITESPACE_SUFFIX_RE, "");
// 2.
let position = 0;
const endOfInput = input.length;
// 3.
const res1 = collectSequenceOfCodepoints(
input,
position,
(c) => c != "\u002F",
);
const type = res1.result;
position = res1.position;
// 4.
if (type === "" || !RegExpPrototypeTest(HTTP_TOKEN_CODE_POINT_RE, type)) {
return null;
}
// 5.
if (position >= endOfInput) return null;
// 6.
position++;
// 7.
const res2 = collectSequenceOfCodepoints(
input,
position,
(c) => c != "\u003B",
);
let subtype = res2.result;
position = res2.position;
// 8.
subtype = StringPrototypeReplaceAll(subtype, HTTP_WHITESPACE_SUFFIX_RE, "");
// 9.
if (
subtype === "" || !RegExpPrototypeTest(HTTP_TOKEN_CODE_POINT_RE, subtype)
) {
return null;
}
// 10.
const mimeType = {
type: StringPrototypeToLowerCase(type),
subtype: StringPrototypeToLowerCase(subtype),
/** @type {Map<string, string>} */
parameters: new SafeMap(),
};
// 11.
while (position < endOfInput) {
// 11.1.
position++;
// 11.2.
const res1 = collectSequenceOfCodepoints(
input,
position,
(c) => ArrayPrototypeIncludes(HTTP_WHITESPACE, c),
);
position = res1.position;
// 11.3.
const res2 = collectSequenceOfCodepoints(
input,
position,
(c) => c !== "\u003B" && c !== "\u003D",
);
let parameterName = res2.result;
position = res2.position;
// 11.4.
parameterName = StringPrototypeToLowerCase(parameterName);
// 11.5.
if (position < endOfInput) {
if (input[position] == "\u003B") continue;
position++;
}
// 11.6.
if (position >= endOfInput) break;
// 11.7.
let parameterValue = null;
// 11.8.
if (input[position] === "\u0022") {
// 11.8.1.
const res = collectHttpQuotedString(input, position, true);
parameterValue = res.result;
position = res.position;
// 11.8.2.
position++;
} else { // 11.9.
// 11.9.1.
const res = collectSequenceOfCodepoints(
input,
position,
(c) => c !== "\u003B",
);
parameterValue = res.result;
position = res.position;
// 11.9.2.
parameterValue = StringPrototypeReplaceAll(
parameterValue,
HTTP_WHITESPACE_SUFFIX_RE,
"",
);
// 11.9.3.
if (parameterValue === "") continue;
}
// 11.10.
if (
parameterName !== "" &&
RegExpPrototypeTest(HTTP_TOKEN_CODE_POINT_RE, parameterName) &&
RegExpPrototypeTest(
HTTP_QUOTED_STRING_TOKEN_POINT_RE,
parameterValue,
) &&
!MapPrototypeHas(mimeType.parameters, parameterName)
) {
MapPrototypeSet(mimeType.parameters, parameterName, parameterValue);
}
}
// 12.
return mimeType;
}
/**
* @param {MimeType} mimeType
* @returns {string}
*/
function essence(mimeType) {
return `${mimeType.type}/${mimeType.subtype}`;
}
/**
* @param {MimeType} mimeType
* @returns {string}
*/
function serializeMimeType(mimeType) {
let serialization = essence(mimeType);
for (const param of new SafeMapIterator(mimeType.parameters)) {
serialization += `;${param[0]}=`;
let value = param[1];
if (RegExpPrototypeExec(HTTP_TOKEN_CODE_POINT_RE, value) === null) {
value = StringPrototypeReplaceAll(value, "\\", "\\\\");
value = StringPrototypeReplaceAll(value, '"', '\\"');
value = `"${value}"`;
}
serialization += value;
}
return serialization;
}
/**
* Part of the Fetch spec's "extract a MIME type" algorithm
* (https://fetch.spec.whatwg.org/#concept-header-extract-mime-type).
* @param {string[] | null} headerValues The result of getting, decoding and
* splitting the "Content-Type" header.
* @returns {MimeType | null}
*/
function extractMimeType(headerValues) {
if (headerValues === null) return null;
let charset = null;
let essence_ = null;
let mimeType = null;
for (let i = 0; i < headerValues.length; ++i) {
const value = headerValues[i];
const temporaryMimeType = parseMimeType(value);
if (
temporaryMimeType === null ||
essence(temporaryMimeType) == "*/*"
) {
continue;
}
mimeType = temporaryMimeType;
if (essence(mimeType) !== essence_) {
charset = null;
const newCharset = MapPrototypeGet(mimeType.parameters, "charset");
if (newCharset !== undefined) {
charset = newCharset;
}
essence_ = essence(mimeType);
} else {
if (
!MapPrototypeHas(mimeType.parameters, "charset") &&
charset !== null
) {
MapPrototypeSet(mimeType.parameters, "charset", charset);
}
}
}
return mimeType;
}
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/**
* Ref: https://mimesniff.spec.whatwg.org/#xml-mime-type
* @param {MimeType} mimeType
* @returns {boolean}
*/
function isXML(mimeType) {
return StringPrototypeEndsWith(mimeType.subtype, "+xml") ||
essence(mimeType) === "text/xml" || essence(mimeType) === "application/xml";
}
/**
* Ref: https://mimesniff.spec.whatwg.org/#pattern-matching-algorithm
* @param {Uint8Array} input
* @param {Uint8Array} pattern
* @param {Uint8Array} mask
* @param {Uint8Array} ignored
* @returns {boolean}
*/
function patternMatchingAlgorithm(input, pattern, mask, ignored) {
assert(
TypedArrayPrototypeGetLength(pattern) ===
TypedArrayPrototypeGetLength(mask),
);
if (
TypedArrayPrototypeGetLength(input) < TypedArrayPrototypeGetLength(pattern)
) {
return false;
}
let s = 0;
for (; s < TypedArrayPrototypeGetLength(input); s++) {
if (!TypedArrayPrototypeIncludes(ignored, input[s])) {
break;
}
}
let p = 0;
for (; p < TypedArrayPrototypeGetLength(pattern); p++, s++) {
const maskedData = input[s] & mask[p];
if (maskedData !== pattern[p]) {
return false;
}
}
return true;
}
const ImageTypePatternTable = [
// A Windows Icon signature.
[
new Uint8Array([0x00, 0x00, 0x01, 0x00]),
new Uint8Array([0xFF, 0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/x-icon",
],
// A Windows Cursor signature.
[
new Uint8Array([0x00, 0x00, 0x02, 0x00]),
new Uint8Array([0xFF, 0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/x-icon",
],
// The string "BM", a BMP signature.
[
new Uint8Array([0x42, 0x4D]),
new Uint8Array([0xFF, 0xFF]),
new Uint8Array(),
"image/bmp",
],
// The string "GIF87a", a GIF signature.
[
new Uint8Array([0x47, 0x49, 0x46, 0x38, 0x37, 0x61]),
new Uint8Array([0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/gif",
],
// The string "GIF89a", a GIF signature.
[
new Uint8Array([0x47, 0x49, 0x46, 0x38, 0x39, 0x61]),
new Uint8Array([0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/gif",
],
// The string "RIFF" followed by four bytes followed by the string "WEBPVP".
[
new Uint8Array([
0x52,
0x49,
0x46,
0x46,
0x00,
0x00,
0x00,
0x00,
0x57,
0x45,
0x42,
0x50,
0x56,
0x50,
]),
new Uint8Array([
0xFF,
0xFF,
0xFF,
0xFF,
0x00,
0x00,
0x00,
0x00,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
]),
new Uint8Array(),
"image/webp",
],
// An error-checking byte followed by the string "PNG" followed by CR LF SUB LF, the PNG signature.
[
new Uint8Array([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]),
new Uint8Array([0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/png",
],
// The JPEG Start of Image marker followed by the indicator byte of another marker.
[
new Uint8Array([0xFF, 0xD8, 0xFF]),
new Uint8Array([0xFF, 0xFF, 0xFF]),
new Uint8Array(),
"image/jpeg",
],
];
/**
* Ref: https://mimesniff.spec.whatwg.org/#image-type-pattern-matching-algorithm
* @param {Uint8Array} input
* @returns {string | undefined}
*/
function imageTypePatternMatchingAlgorithm(input) {
for (let i = 0; i < ImageTypePatternTable.length; i++) {
const row = ImageTypePatternTable[i];
const patternMatched = patternMatchingAlgorithm(
input,
row[0],
row[1],
row[2],
);
if (patternMatched) {
return row[3];
}
}
return undefined;
}
/**
* Ref: https://mimesniff.spec.whatwg.org/#rules-for-sniffing-images-specifically
* @param {string} mimeTypeString
* @returns {string}
*/
function sniffImage(mimeTypeString) {
const mimeType = parseMimeType(mimeTypeString);
if (mimeType === null) {
return mimeTypeString;
}
if (isXML(mimeType)) {
return mimeTypeString;
}
const imageTypeMatched = imageTypePatternMatchingAlgorithm(
new TextEncoder().encode(mimeTypeString),
);
if (imageTypeMatched !== undefined) {
return imageTypeMatched;
}
return mimeTypeString;
}
export {
essence,
extractMimeType,
parseMimeType,
serializeMimeType,
sniffImage,
};