// Copyright 2012 Mark Cavage, Inc. All rights reserved.
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'use strict';
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var errors = require('restify-errors');
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///--- Globals
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var BadRequestError = errors.BadRequestError;
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var PreconditionFailedError = errors.PreconditionFailedError;
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var IF_MATCH_FAIL = "if-match '%s' didn't match etag '%s'";
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var IF_NO_MATCH_FAIL = "if-none-match '%s' matched etag '%s'";
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var IF_MOD_FAIL = "object was modified at '%s'; if-modified-since '%s'";
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var IF_UNMOD_FAIL = "object was modified at '%s'; if-unmodified-since '%s'";
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///--- API
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// Reference RFC2616 section 14 for an explanation of what this all does.
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function checkIfMatch(req, res, next) {
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var clientETags;
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var cur;
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var etag = res.etag || res.getHeader('etag') || '';
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var ifMatch;
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var matched = false;
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if ((ifMatch = req.headers['if-match'])) {
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clientETags = ifMatch.split(/\s*,\s*/);
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for (var i = 0; i < clientETags.length; i++) {
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cur = clientETags[i];
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// only strong comparison
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cur = cur.replace(/^W\//, '');
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cur = cur.replace(/^"(\w*)"$/, '$1');
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if (cur === '*' || cur === etag) {
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matched = true;
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break;
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}
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}
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if (!matched) {
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var err = new PreconditionFailedError(IF_MATCH_FAIL, ifMatch, etag);
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return next(err);
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}
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}
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return next();
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}
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function checkIfNoneMatch(req, res, next) {
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var clientETags;
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var cur;
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var etag = res.etag || res.getHeader('etag') || '';
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var ifNoneMatch;
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var matched = false;
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if ((ifNoneMatch = req.headers['if-none-match'])) {
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clientETags = ifNoneMatch.split(/\s*,\s*/);
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for (var i = 0; i < clientETags.length; i++) {
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cur = clientETags[i];
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// ignore weak validation
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cur = cur.replace(/^W\//, '');
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cur = cur.replace(/^"(\w*)"$/, '$1');
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if (cur === '*' || cur === etag) {
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matched = true;
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break;
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}
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}
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if (!matched) {
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return next();
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}
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if (req.method !== 'GET' && req.method !== 'HEAD') {
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var err = new PreconditionFailedError(
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IF_NO_MATCH_FAIL,
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ifNoneMatch,
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etag
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);
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return next(err);
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}
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res.send(304);
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return next(false);
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}
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return next();
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}
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function checkIfModified(req, res, next) {
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var code;
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var err;
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var ctime = req.header('if-modified-since');
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var mtime = res.mtime || res.header('Last-Modified') || '';
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if (!mtime || !ctime) {
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next();
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return;
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}
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try {
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//
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// TODO handle Range header modifications
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//
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// Note: this is not technically correct as per 2616 -
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// 2616 only specifies semantics for GET requests, not
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// any other method - but using if-modified-since with a
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// PUT or DELETE seems like returning 412 is sane
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//
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if (Date.parse(mtime) <= Date.parse(ctime)) {
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switch (req.method) {
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case 'GET':
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case 'HEAD':
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code = 304;
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break;
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default:
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err = new PreconditionFailedError(
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IF_MOD_FAIL,
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mtime,
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ctime
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);
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break;
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}
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}
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} catch (e) {
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next(new BadRequestError(e.message));
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return;
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}
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if (code !== undefined) {
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res.send(code);
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next(false);
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return;
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}
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next(err);
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}
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function checkIfUnmodified(req, res, next) {
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var err;
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var ctime = req.headers['if-unmodified-since'];
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var mtime = res.mtime || res.header('Last-Modified') || '';
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if (!mtime || !ctime) {
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next();
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return;
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}
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try {
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if (Date.parse(mtime) > Date.parse(ctime)) {
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err = new PreconditionFailedError(IF_UNMOD_FAIL, mtime, ctime);
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}
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} catch (e) {
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next(new BadRequestError(e.message));
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return;
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}
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next(err);
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}
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///--- Exports
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/**
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* Returns a set of plugins that will compare an already set `ETag` header with
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* the client's `If-Match` and `If-None-Match` header, and an already set
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* Last-Modified header with the client's `If-Modified-Since` and
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* `If-Unmodified-Since` header.
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*
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* You can use this handler to let clients do nice HTTP semantics with the
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* "match" headers. Specifically, with this plugin in place, you would set
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* `res.etag=$yourhashhere`, and then this plugin will do one of:
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*
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* - return `304` (Not Modified) [and stop the handler chain]
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* - return `412` (Precondition Failed) [and stop the handler chain]
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* - Allow the request to go through the handler chain.
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*
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* The specific headers this plugin looks at are:
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*
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* - `Last-Modified`
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* - `If-Match`
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* - `If-None-Match`
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* - `If-Modified-Since`
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* - `If-Unmodified-Since`
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*
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* @public
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* @throws {BadRequestError}
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* @throws {PreconditionFailedError}
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* @function conditionalRequest
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* @returns {Function[]} Handlers
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* @example
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* server.use(restify.plugins.conditionalRequest());
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* @example
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* server.use(function setETag(req, res, next) {
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* res.header('ETag', 'myETag');
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* res.header('Last-Modified', new Date());
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* });
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*
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* server.use(restify.plugins.conditionalRequest());
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*
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* server.get('/hello/:name', function(req, res, next) {
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* res.send('hello ' + req.params.name);
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* });
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*/
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function conditionalRequest() {
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var chain = [
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checkIfMatch,
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checkIfNoneMatch,
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checkIfModified,
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checkIfUnmodified
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];
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return chain;
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}
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module.exports = conditionalRequest;
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