1/*
2 * Copyright (C) 2008, 2009 Apple Inc. All Rights Reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 */
26
27#include "config.h"
28#include "CrossOriginPreflightResultCache.h"
29
30#include "CrossOriginAccessControl.h"
31#include "ResourceResponse.h"
32#include <wtf/CurrentTime.h>
33#include <wtf/MainThread.h>
34#include <wtf/StdLibExtras.h>
35
36namespace WebCore {
37
38using namespace std;
39
40// These values are at the discretion of the user agent.
41static const unsigned defaultPreflightCacheTimeoutSeconds = 5;
42static const unsigned maxPreflightCacheTimeoutSeconds = 600; // Should be short enough to minimize the risk of using a poisoned cache after switching to a secure network.
43
44static bool parseAccessControlMaxAge(const String& string, unsigned& expiryDelta)
45{
46    // FIXME: this will not do the correct thing for a number starting with a '+'
47    bool ok = false;
48    expiryDelta = string.toUIntStrict(&ok);
49    return ok;
50}
51
52template<class HashType>
53static void addToAccessControlAllowList(const String& string, unsigned start, unsigned end, HashSet<String, HashType>& set)
54{
55    StringImpl* stringImpl = string.impl();
56    if (!stringImpl)
57        return;
58
59    // Skip white space from start.
60    while (start <= end && isSpaceOrNewline((*stringImpl)[start]))
61        ++start;
62
63    // only white space
64    if (start > end)
65        return;
66
67    // Skip white space from end.
68    while (end && isSpaceOrNewline((*stringImpl)[end]))
69        --end;
70
71    set.add(string.substring(start, end - start + 1));
72}
73
74template<class HashType>
75static bool parseAccessControlAllowList(const String& string, HashSet<String, HashType>& set)
76{
77    unsigned start = 0;
78    size_t end;
79    while ((end = string.find(',', start)) != notFound) {
80        if (start != end)
81            addToAccessControlAllowList(string, start, end - 1, set);
82        start = end + 1;
83    }
84    if (start != string.length())
85        addToAccessControlAllowList(string, start, string.length() - 1, set);
86
87    return true;
88}
89
90bool CrossOriginPreflightResultCacheItem::parse(const ResourceResponse& response, String& errorDescription)
91{
92    m_methods.clear();
93    if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Methods"), m_methods)) {
94        errorDescription = "Cannot parse Access-Control-Allow-Methods response header field.";
95        return false;
96    }
97
98    m_headers.clear();
99    if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Headers"), m_headers)) {
100        errorDescription = "Cannot parse Access-Control-Allow-Headers response header field.";
101        return false;
102    }
103
104    unsigned expiryDelta;
105    if (parseAccessControlMaxAge(response.httpHeaderField("Access-Control-Max-Age"), expiryDelta)) {
106        if (expiryDelta > maxPreflightCacheTimeoutSeconds)
107            expiryDelta = maxPreflightCacheTimeoutSeconds;
108    } else
109        expiryDelta = defaultPreflightCacheTimeoutSeconds;
110
111    m_absoluteExpiryTime = currentTime() + expiryDelta;
112    return true;
113}
114
115bool CrossOriginPreflightResultCacheItem::allowsCrossOriginMethod(const String& method, String& errorDescription) const
116{
117    if (m_methods.contains(method) || isOnAccessControlSimpleRequestMethodWhitelist(method))
118        return true;
119
120    errorDescription = "Method " + method + " is not allowed by Access-Control-Allow-Methods.";
121    return false;
122}
123
124bool CrossOriginPreflightResultCacheItem::allowsCrossOriginHeaders(const HTTPHeaderMap& requestHeaders, String& errorDescription) const
125{
126    HTTPHeaderMap::const_iterator end = requestHeaders.end();
127    for (HTTPHeaderMap::const_iterator it = requestHeaders.begin(); it != end; ++it) {
128        if (!m_headers.contains(it->key) && !isOnAccessControlSimpleRequestHeaderWhitelist(it->key, it->value)) {
129            errorDescription = "Request header field " + it->key.string() + " is not allowed by Access-Control-Allow-Headers.";
130            return false;
131        }
132    }
133    return true;
134}
135
136bool CrossOriginPreflightResultCacheItem::allowsRequest(StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders) const
137{
138    String ignoredExplanation;
139    if (m_absoluteExpiryTime < currentTime())
140        return false;
141    if (includeCredentials == AllowStoredCredentials && m_credentials == DoNotAllowStoredCredentials)
142        return false;
143    if (!allowsCrossOriginMethod(method, ignoredExplanation))
144        return false;
145    if (!allowsCrossOriginHeaders(requestHeaders, ignoredExplanation))
146        return false;
147    return true;
148}
149
150CrossOriginPreflightResultCache& CrossOriginPreflightResultCache::shared()
151{
152    DEFINE_STATIC_LOCAL(CrossOriginPreflightResultCache, cache, ());
153    ASSERT(isMainThread());
154    return cache;
155}
156
157void CrossOriginPreflightResultCache::appendEntry(const String& origin, const KURL& url, PassOwnPtr<CrossOriginPreflightResultCacheItem> preflightResult)
158{
159    ASSERT(isMainThread());
160    m_preflightHashMap.set(make_pair(origin, url), preflightResult);
161}
162
163bool CrossOriginPreflightResultCache::canSkipPreflight(const String& origin, const KURL& url, StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders)
164{
165    ASSERT(isMainThread());
166    CrossOriginPreflightResultHashMap::iterator cacheIt = m_preflightHashMap.find(make_pair(origin, url));
167    if (cacheIt == m_preflightHashMap.end())
168        return false;
169
170    if (cacheIt->value->allowsRequest(includeCredentials, method, requestHeaders))
171        return true;
172
173    m_preflightHashMap.remove(cacheIt);
174    return false;
175}
176
177void CrossOriginPreflightResultCache::empty()
178{
179    ASSERT(isMainThread());
180    m_preflightHashMap.clear();
181}
182
183} // namespace WebCore
184