pdf.js/src/display/content_disposition.js
Jonas Jenwald d642d34500 Remove the UTF-8 fallback, when TextDecoder is missing, from the Content-Disposition parser
Given that `TextDecoder` is now supported by all modern browsers/environments, please see https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder#browser_compatibility, there's no longer any good reason to keep a UTF-8 fallback in the Content-Disposition parser.
2022-02-12 10:30:25 +01:00

220 lines
7.7 KiB
JavaScript

/* Copyright 2017 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { stringToBytes } from "../shared/util.js";
// This getFilenameFromContentDispositionHeader function is adapted from
// https://github.com/Rob--W/open-in-browser/blob/7e2e35a38b8b4e981b11da7b2f01df0149049e92/extension/content-disposition.js
// with the following changes:
// - Modified to conform to PDF.js's coding style.
// - Move return to the end of the function to prevent Babel from dropping the
// function declarations.
/**
* Extract file name from the Content-Disposition HTTP response header.
*
* @param {string} contentDisposition
* @returns {string} Filename, if found in the Content-Disposition header.
*/
function getFilenameFromContentDispositionHeader(contentDisposition) {
let needsEncodingFixup = true;
// filename*=ext-value ("ext-value" from RFC 5987, referenced by RFC 6266).
let tmp = toParamRegExp("filename\\*", "i").exec(contentDisposition);
if (tmp) {
tmp = tmp[1];
let filename = rfc2616unquote(tmp);
filename = unescape(filename);
filename = rfc5987decode(filename);
filename = rfc2047decode(filename);
return fixupEncoding(filename);
}
// Continuations (RFC 2231 section 3, referenced by RFC 5987 section 3.1).
// filename*n*=part
// filename*n=part
tmp = rfc2231getparam(contentDisposition);
if (tmp) {
// RFC 2047, section
const filename = rfc2047decode(tmp);
return fixupEncoding(filename);
}
// filename=value (RFC 5987, section 4.1).
tmp = toParamRegExp("filename", "i").exec(contentDisposition);
if (tmp) {
tmp = tmp[1];
let filename = rfc2616unquote(tmp);
filename = rfc2047decode(filename);
return fixupEncoding(filename);
}
// After this line there are only function declarations. We cannot put
// "return" here for readability because babel would then drop the function
// declarations...
function toParamRegExp(attributePattern, flags) {
return new RegExp(
"(?:^|;)\\s*" +
attributePattern +
"\\s*=\\s*" +
// Captures: value = token | quoted-string
// (RFC 2616, section 3.6 and referenced by RFC 6266 4.1)
"(" +
'[^";\\s][^;\\s]*' +
"|" +
'"(?:[^"\\\\]|\\\\"?)+"?' +
")",
flags
);
}
function textdecode(encoding, value) {
if (encoding) {
if (!/^[\x00-\xFF]+$/.test(value)) {
return value;
}
try {
const decoder = new TextDecoder(encoding, { fatal: true });
const buffer = stringToBytes(value);
value = decoder.decode(buffer);
needsEncodingFixup = false;
} catch (e) {
// TextDecoder constructor threw - unrecognized encoding.
}
}
return value;
}
function fixupEncoding(value) {
if (needsEncodingFixup && /[\x80-\xff]/.test(value)) {
// Maybe multi-byte UTF-8.
value = textdecode("utf-8", value);
if (needsEncodingFixup) {
// Try iso-8859-1 encoding.
value = textdecode("iso-8859-1", value);
}
}
return value;
}
function rfc2231getparam(contentDispositionStr) {
const matches = [];
let match;
// Iterate over all filename*n= and filename*n*= with n being an integer
// of at least zero. Any non-zero number must not start with '0'.
const iter = toParamRegExp("filename\\*((?!0\\d)\\d+)(\\*?)", "ig");
while ((match = iter.exec(contentDispositionStr)) !== null) {
let [, n, quot, part] = match; // eslint-disable-line prefer-const
n = parseInt(n, 10);
if (n in matches) {
// Ignore anything after the invalid second filename*0.
if (n === 0) {
break;
}
continue;
}
matches[n] = [quot, part];
}
const parts = [];
for (let n = 0; n < matches.length; ++n) {
if (!(n in matches)) {
// Numbers must be consecutive. Truncate when there is a hole.
break;
}
let [quot, part] = matches[n]; // eslint-disable-line prefer-const
part = rfc2616unquote(part);
if (quot) {
part = unescape(part);
if (n === 0) {
part = rfc5987decode(part);
}
}
parts.push(part);
}
return parts.join("");
}
function rfc2616unquote(value) {
if (value.startsWith('"')) {
const parts = value.slice(1).split('\\"');
// Find the first unescaped " and terminate there.
for (let i = 0; i < parts.length; ++i) {
const quotindex = parts[i].indexOf('"');
if (quotindex !== -1) {
parts[i] = parts[i].slice(0, quotindex);
parts.length = i + 1; // Truncates and stop the iteration.
}
parts[i] = parts[i].replace(/\\(.)/g, "$1");
}
value = parts.join('"');
}
return value;
}
function rfc5987decode(extvalue) {
// Decodes "ext-value" from RFC 5987.
const encodingend = extvalue.indexOf("'");
if (encodingend === -1) {
// Some servers send "filename*=" without encoding 'language' prefix,
// e.g. in https://github.com/Rob--W/open-in-browser/issues/26
// Let's accept the value like Firefox (57) (Chrome 62 rejects it).
return extvalue;
}
const encoding = extvalue.slice(0, encodingend);
const langvalue = extvalue.slice(encodingend + 1);
// Ignore language (RFC 5987 section 3.2.1, and RFC 6266 section 4.1 ).
const value = langvalue.replace(/^[^']*'/, "");
return textdecode(encoding, value);
}
function rfc2047decode(value) {
// RFC 2047-decode the result. Firefox tried to drop support for it, but
// backed out because some servers use it - https://bugzil.la/875615
// Firefox's condition for decoding is here: https://searchfox.org/mozilla-central/rev/4a590a5a15e35d88a3b23dd6ac3c471cf85b04a8/netwerk/mime/nsMIMEHeaderParamImpl.cpp#742-748
// We are more strict and only recognize RFC 2047-encoding if the value
// starts with "=?", since then it is likely that the full value is
// RFC 2047-encoded.
// Firefox also decodes words even where RFC 2047 section 5 states:
// "An 'encoded-word' MUST NOT appear within a 'quoted-string'."
if (!value.startsWith("=?") || /[\x00-\x19\x80-\xff]/.test(value)) {
return value;
}
// RFC 2047, section 2.4
// encoded-word = "=?" charset "?" encoding "?" encoded-text "?="
// charset = token (but let's restrict to characters that denote a
// possibly valid encoding).
// encoding = q or b
// encoded-text = any printable ASCII character other than ? or space.
// ... but Firefox permits ? and space.
return value.replace(
/=\?([\w-]*)\?([QqBb])\?((?:[^?]|\?(?!=))*)\?=/g,
function (matches, charset, encoding, text) {
if (encoding === "q" || encoding === "Q") {
// RFC 2047 section 4.2.
text = text.replace(/_/g, " ");
text = text.replace(/=([0-9a-fA-F]{2})/g, function (match, hex) {
return String.fromCharCode(parseInt(hex, 16));
});
return textdecode(charset, text);
} // else encoding is b or B - base64 (RFC 2047 section 4.1)
try {
text = atob(text);
} catch (e) {}
return textdecode(charset, text);
}
);
}
return "";
}
export { getFilenameFromContentDispositionHeader };