JS: Modernize SignedSource
Reviewed By: cpojer Differential Revision: D4271506 fbshipit-source-id: b3eff94de9ce2c179d62d57eace9a40797aed397
This commit is contained in:
Tim Yung
Facebook Github Bot
parent
dd97443f2b
commit
ebe0c85fbe
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@ -8,93 +8,110 @@
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*/
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'use strict';
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var TOKEN = '<<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@IsG>>',
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OLDTOKEN = '<<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@I>>',
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TOKENS = [TOKEN, OLDTOKEN],
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PATTERN = new RegExp('@' + 'generated (?:SignedSource<<([a-f0-9]{32})>>)');
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const crypto = require('crypto');
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exports.SIGN_OK = {message:'ok'};
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exports.SIGN_UNSIGNED = new Error('unsigned');
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exports.SIGN_INVALID = new Error('invalid');
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const GENERATED = '@' + 'generated';
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const OLDTOKEN = '<<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@I>>';
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const NEWTOKEN = '<<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@IsG>>';
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const TOKENS = [NEWTOKEN, OLDTOKEN];
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const PATTERN = new RegExp(`${GENERATED} (?:SignedSource<<([a-f0-9]{32})>>)`);
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// Thrown by sign(). Primarily for unit tests.
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exports.TokenNotFoundError = new Error(
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'Code signing placeholder not found (expected to find \'' + TOKEN + '\')');
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const TokenNotFoundError = new Error(
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`SignedSource.signFile(...): Cannot sign file without token: ${NEWTOKEN}`
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);
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var md5_hash_hex;
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// MD5 hash function for Node.js. To port this to other platforms, provide an
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// alternate code path for defining the md5_hash_hex function.
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var crypto = require('crypto');
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// eslint-disable-next-line no-shadow
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md5_hash_hex = function md5_hash_hex(data, input_encoding) {
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var md5sum = crypto.createHash('md5');
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md5sum.update(data, input_encoding);
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function hash(data, encoding) {
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const md5sum = crypto.createHash('md5');
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md5sum.update(data, encoding);
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return md5sum.digest('hex');
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}
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/**
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* Utility for signing and verifying the signature of a file. This is useful for
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* ensuring that the contents of a generated file are not contaminated by manual
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* changes. Example usage:
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*
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* const myFile = `
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* // ${SignedSource.getSigningToken()}
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*
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* console.log('My generated file.');
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* `;
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* const mySignedFile = SignedSource.signFile(myFile);
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*
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*/
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const SignedSource = {
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TokenNotFoundError,
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/**
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* Gets the signing token to be embedded in the file you wish to be signed.
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*/
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getSigningToken() {
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return `${GENERATED} ${NEWTOKEN}`;
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},
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/**
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* Checks whether a file is signed *without* verifying the signature.
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*/
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isSigned(data) {
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return !PATTERN.exec(data);
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},
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/**
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* Signs a source file which contains a signing token. Signing modifies only
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* the signing token, so the token should be placed inside a comment in order
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* for signing to not change code semantics.
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*/
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signFile(data) {
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if (!data.includes(NEWTOKEN)) {
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if (SignedSource.isSigned(data)) {
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// Signing a file that was previously signed.
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data = data.replace(PATTERN, SignedSource.getSigningToken());
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} else {
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throw TokenNotFoundError;
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}
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}
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return data.replace(NEWTOKEN, `SignedSource<<${hash(data, 'utf8')}>>`);
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},
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/**
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* Verifies the signature in a signed file.
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*/
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verifySignature(data) {
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const matches = PATTERN.exec(data);
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if (!matches) {
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throw new Error(
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'SignedSource.verifySignature(...): Cannot verify signature of an ' +
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'unsigned file.'
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);
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}
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const actual = matches[1];
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// Replace signature with `NEWTOKEN` and hash to see if it matches the hash
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// in the file. For backwards compatibility, also try `OLDTOKEN`.
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return TOKENS.some(token => {
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const unsigned = data.replace(PATTERN, `${GENERATED} ${token}`);
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return hash(unsigned, 'utf8') === actual;
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});
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},
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};
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// Returns the signing token to be embedded, generally in a header comment,
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// in the file you wish to be signed.
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//
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// @return str to be embedded in to-be-signed file
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function signing_token() {
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return '@' + 'generated ' + TOKEN;
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}
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exports.signing_token = signing_token;
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// Determine whether a file is signed. This does NOT verify the signature.
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//
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// @param str File contents as a string.
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// @return bool True if the file has a signature.
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function is_signed(file_data) {
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return !!PATTERN.exec(file_data);
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}
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exports.is_signed = is_signed;
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// Sign a source file which you have previously embedded a signing token
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// into. Signing modifies only the signing token, so the semantics of the
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// file will not change if you've put it in a comment.
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//
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// @param str File contents as a string (with embedded token).
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// @return str Signed data.
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function sign(file_data) {
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var first_time = file_data.indexOf(TOKEN) !== -1;
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if (!first_time) {
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if (is_signed(file_data)) {
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file_data = file_data.replace(PATTERN, signing_token());
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} else {
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throw exports.TokenNotFoundError;
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}
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// @deprecated
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SignedSource.SIGN_OK = {message: 'ok'};
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SignedSource.SIGN_INVALID = new Error('invalid');
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SignedSource.SIGN_UNSIGNED = new Error('unsigned');
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SignedSource.signing_token = SignedSource.getSigningToken;
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SignedSource.is_signed = SignedSource.isSigned;
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SignedSource.sign = data => ({
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first_time: data.includes(NEWTOKEN),
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signed_data: SignedSource.signFile(data),
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});
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SignedSource.verify_signature = data => {
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try {
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return SignedSource.verifySignature(data)
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? SignedSource.SIGN_OK
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: SignedSource.SIGN_INVALID;
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} catch (_) {
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return SignedSource.SIGN_UNSIGNED;
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}
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var signature = md5_hash_hex(file_data, 'utf8');
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var signed_data = file_data.replace(TOKEN, 'SignedSource<<' + signature + '>>');
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return { first_time: first_time, signed_data: signed_data };
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}
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exports.sign = sign;
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};
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// Verify a file's signature.
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//
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// @param str File contents as a string.
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// @return Returns SIGN_OK if the data contains a valid signature,
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// SIGN_UNSIGNED if it contains no signature, or SIGN_INVALID if
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// it contains an invalid signature.
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function verify_signature(file_data) {
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var match = PATTERN.exec(file_data);
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if (!match) {
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return exports.SIGN_UNSIGNED;
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}
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// Replace the signature with the TOKEN, then hash and see if it matches
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// the value in the file. For backwards compatibility, also try with
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// OLDTOKEN if that doesn't match.
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var k, token, with_token, actual_md5, expected_md5 = match[1];
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for (k in TOKENS) {
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token = TOKENS[k];
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with_token = file_data.replace(PATTERN, '@' + 'generated ' + token);
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actual_md5 = md5_hash_hex(with_token, 'utf8');
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if (expected_md5 === actual_md5) {
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return exports.SIGN_OK;
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}
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}
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return exports.SIGN_INVALID;
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}
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exports.verify_signature = verify_signature;
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module.exports = SignedSource;
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