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 "core/loader/CrossOriginPreflightResultCache.h"
29
30#include "core/fetch/FetchUtils.h"
31#include "platform/network/ResourceResponse.h"
32#include "wtf/CurrentTime.h"
33#include "wtf/MainThread.h"
34#include "wtf/StdLibExtras.h"
35
36namespace blink {
37
38// These values are at the discretion of the user agent.
39static const unsigned defaultPreflightCacheTimeoutSeconds = 5;
40static const unsigned maxPreflightCacheTimeoutSeconds = 600; // Should be short enough to minimize the risk of using a poisoned cache after switching to a secure network.
41
42static bool parseAccessControlMaxAge(const String& string, unsigned& expiryDelta)
43{
44    // FIXME: this will not do the correct thing for a number starting with a '+'
45    bool ok = false;
46    expiryDelta = string.toUIntStrict(&ok);
47    return ok;
48}
49
50template<class HashType>
51static void addToAccessControlAllowList(const String& string, unsigned start, unsigned end, HashSet<String, HashType>& set)
52{
53    StringImpl* stringImpl = string.impl();
54    if (!stringImpl)
55        return;
56
57    // Skip white space from start.
58    while (start <= end && isSpaceOrNewline((*stringImpl)[start]))
59        ++start;
60
61    // only white space
62    if (start > end)
63        return;
64
65    // Skip white space from end.
66    while (end && isSpaceOrNewline((*stringImpl)[end]))
67        --end;
68
69    set.add(string.substring(start, end - start + 1));
70}
71
72template<class HashType>
73static bool parseAccessControlAllowList(const String& string, HashSet<String, HashType>& set)
74{
75    unsigned start = 0;
76    size_t end;
77    while ((end = string.find(',', start)) != kNotFound) {
78        if (start != end)
79            addToAccessControlAllowList(string, start, end - 1, set);
80        start = end + 1;
81    }
82    if (start != string.length())
83        addToAccessControlAllowList(string, start, string.length() - 1, set);
84
85    return true;
86}
87
88bool CrossOriginPreflightResultCacheItem::parse(const ResourceResponse& response, String& errorDescription)
89{
90    m_methods.clear();
91    if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Methods"), m_methods)) {
92        errorDescription = "Cannot parse Access-Control-Allow-Methods response header field.";
93        return false;
94    }
95
96    m_headers.clear();
97    if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Headers"), m_headers)) {
98        errorDescription = "Cannot parse Access-Control-Allow-Headers response header field.";
99        return false;
100    }
101
102    unsigned expiryDelta;
103    if (parseAccessControlMaxAge(response.httpHeaderField("Access-Control-Max-Age"), expiryDelta)) {
104        if (expiryDelta > maxPreflightCacheTimeoutSeconds)
105            expiryDelta = maxPreflightCacheTimeoutSeconds;
106    } else {
107        expiryDelta = defaultPreflightCacheTimeoutSeconds;
108    }
109
110    m_absoluteExpiryTime = currentTime() + expiryDelta;
111    return true;
112}
113
114bool CrossOriginPreflightResultCacheItem::allowsCrossOriginMethod(const String& method, String& errorDescription) const
115{
116    if (m_methods.contains(method) || FetchUtils::isSimpleMethod(method))
117        return true;
118
119    errorDescription = "Method " + method + " is not allowed by Access-Control-Allow-Methods.";
120    return false;
121}
122
123bool CrossOriginPreflightResultCacheItem::allowsCrossOriginHeaders(const HTTPHeaderMap& requestHeaders, String& errorDescription) const
124{
125    HTTPHeaderMap::const_iterator end = requestHeaders.end();
126    for (HTTPHeaderMap::const_iterator it = requestHeaders.begin(); it != end; ++it) {
127        if (!m_headers.contains(it->key) && !FetchUtils::isSimpleHeader(it->key, it->value) && !FetchUtils::isForbiddenHeaderName(it->key)) {
128            errorDescription = "Request header field " + it->key.string() + " is not allowed by Access-Control-Allow-Headers.";
129            return false;
130        }
131    }
132    return true;
133}
134
135bool CrossOriginPreflightResultCacheItem::allowsRequest(StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders) const
136{
137    String ignoredExplanation;
138    if (m_absoluteExpiryTime < currentTime())
139        return false;
140    if (includeCredentials == AllowStoredCredentials && m_credentials == DoNotAllowStoredCredentials)
141        return false;
142    if (!allowsCrossOriginMethod(method, ignoredExplanation))
143        return false;
144    if (!allowsCrossOriginHeaders(requestHeaders, ignoredExplanation))
145        return false;
146    return true;
147}
148
149CrossOriginPreflightResultCache& CrossOriginPreflightResultCache::shared()
150{
151    DEFINE_STATIC_LOCAL(CrossOriginPreflightResultCache, cache, ());
152    ASSERT(isMainThread());
153    return cache;
154}
155
156void CrossOriginPreflightResultCache::appendEntry(const String& origin, const KURL& url, PassOwnPtr<CrossOriginPreflightResultCacheItem> preflightResult)
157{
158    ASSERT(isMainThread());
159    m_preflightHashMap.set(std::make_pair(origin, url), preflightResult);
160}
161
162bool CrossOriginPreflightResultCache::canSkipPreflight(const String& origin, const KURL& url, StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders)
163{
164    ASSERT(isMainThread());
165    CrossOriginPreflightResultHashMap::iterator cacheIt = m_preflightHashMap.find(std::make_pair(origin, url));
166    if (cacheIt == m_preflightHashMap.end())
167        return false;
168
169    if (cacheIt->value->allowsRequest(includeCredentials, method, requestHeaders))
170        return true;
171
172    m_preflightHashMap.remove(cacheIt);
173    return false;
174}
175
176} // namespace blink
177