1 // Copyright 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "components/precache/core/precache_fetcher.h"
6
7 #include <string>
8
9 #include "base/bind.h"
10 #include "base/callback.h"
11 #include "base/command_line.h"
12 #include "base/compiler_specific.h"
13 #include "base/containers/hash_tables.h"
14 #include "components/precache/core/precache_switches.h"
15 #include "components/precache/core/proto/precache.pb.h"
16 #include "net/base/escape.h"
17 #include "net/base/load_flags.h"
18 #include "net/url_request/url_fetcher.h"
19 #include "net/url_request/url_fetcher_delegate.h"
20 #include "net/url_request/url_request_context_getter.h"
21 #include "net/url_request/url_request_status.h"
22
23 using net::URLFetcher;
24
25 namespace precache {
26
27 namespace {
28
GetConfigURL()29 GURL GetConfigURL() {
30 const CommandLine& command_line = *CommandLine::ForCurrentProcess();
31 if (command_line.HasSwitch(switches::kPrecacheConfigSettingsURL)) {
32 return GURL(
33 command_line.GetSwitchValueASCII(switches::kPrecacheConfigSettingsURL));
34 }
35
36 #if defined(PRECACHE_CONFIG_SETTINGS_URL)
37 return GURL(PRECACHE_CONFIG_SETTINGS_URL);
38 #else
39 // The precache config settings URL could not be determined, so return an
40 // empty, invalid GURL.
41 return GURL();
42 #endif
43 }
44
GetManifestURLPrefix()45 std::string GetManifestURLPrefix() {
46 const CommandLine& command_line = *CommandLine::ForCurrentProcess();
47 if (command_line.HasSwitch(switches::kPrecacheManifestURLPrefix)) {
48 return command_line.GetSwitchValueASCII(
49 switches::kPrecacheManifestURLPrefix);
50 }
51
52 #if defined(PRECACHE_MANIFEST_URL_PREFIX)
53 return PRECACHE_MANIFEST_URL_PREFIX;
54 #else
55 // The precache manifest URL prefix could not be determined, so return an
56 // empty string.
57 return std::string();
58 #endif
59 }
60
61 // Construct the URL of the precache manifest for the given starting URL.
62 // The server is expecting a request for a URL consisting of the manifest URL
63 // prefix followed by the doubly escaped starting URL.
ConstructManifestURL(const GURL & starting_url)64 GURL ConstructManifestURL(const GURL& starting_url) {
65 return GURL(
66 GetManifestURLPrefix() +
67 net::EscapeQueryParamValue(
68 net::EscapeQueryParamValue(starting_url.spec(), false), false));
69 }
70
71 // Attempts to parse a protobuf message from the response string of a
72 // URLFetcher. If parsing is successful, the message parameter will contain the
73 // parsed protobuf and this function will return true. Otherwise, returns false.
ParseProtoFromFetchResponse(const URLFetcher & source,::google::protobuf::MessageLite * message)74 bool ParseProtoFromFetchResponse(const URLFetcher& source,
75 ::google::protobuf::MessageLite* message) {
76 std::string response_string;
77
78 if (!source.GetStatus().is_success()) {
79 DLOG(WARNING) << "Fetch failed: " << source.GetOriginalURL().spec();
80 return false;
81 }
82 if (!source.GetResponseAsString(&response_string)) {
83 DLOG(WARNING) << "No response string present: "
84 << source.GetOriginalURL().spec();
85 return false;
86 }
87 if (!message->ParseFromString(response_string)) {
88 DLOG(WARNING) << "Unable to parse proto served from "
89 << source.GetOriginalURL().spec();
90 return false;
91 }
92 return true;
93 }
94
95 } // namespace
96
97 // Class that fetches a URL, and runs the specified callback when the fetch is
98 // complete. This class exists so that a different method can be run in
99 // response to different kinds of fetches, e.g. OnConfigFetchComplete when
100 // configuration settings are fetched, OnManifestFetchComplete when a manifest
101 // is fetched, etc.
102 class PrecacheFetcher::Fetcher : public net::URLFetcherDelegate {
103 public:
104 // Construct a new Fetcher. This will create and start a new URLFetcher for
105 // the specified URL using the specified request context.
106 Fetcher(net::URLRequestContextGetter* request_context, const GURL& url,
107 const base::Callback<void(const URLFetcher&)>& callback);
~Fetcher()108 virtual ~Fetcher() {}
109 virtual void OnURLFetchComplete(const URLFetcher* source) OVERRIDE;
110
111 private:
112 const base::Callback<void(const URLFetcher&)> callback_;
113 scoped_ptr<URLFetcher> url_fetcher_;
114
115 DISALLOW_COPY_AND_ASSIGN(Fetcher);
116 };
117
Fetcher(net::URLRequestContextGetter * request_context,const GURL & url,const base::Callback<void (const URLFetcher &)> & callback)118 PrecacheFetcher::Fetcher::Fetcher(
119 net::URLRequestContextGetter* request_context, const GURL& url,
120 const base::Callback<void(const URLFetcher&)>& callback)
121 : callback_(callback) {
122 url_fetcher_.reset(URLFetcher::Create(url, URLFetcher::GET, this));
123 url_fetcher_->SetRequestContext(request_context);
124 url_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_PROMPT_FOR_LOGIN);
125 url_fetcher_->Start();
126 }
127
OnURLFetchComplete(const URLFetcher * source)128 void PrecacheFetcher::Fetcher::OnURLFetchComplete(const URLFetcher* source) {
129 callback_.Run(*source);
130 }
131
PrecacheFetcher(const std::list<GURL> & starting_urls,net::URLRequestContextGetter * request_context,PrecacheFetcher::PrecacheDelegate * precache_delegate)132 PrecacheFetcher::PrecacheFetcher(
133 const std::list<GURL>& starting_urls,
134 net::URLRequestContextGetter* request_context,
135 PrecacheFetcher::PrecacheDelegate* precache_delegate)
136 : starting_urls_(starting_urls),
137 request_context_(request_context),
138 precache_delegate_(precache_delegate) {
139 DCHECK(request_context_); // Request context must be non-NULL.
140 DCHECK(precache_delegate_); // Precache delegate must be non-NULL.
141
142 DCHECK_NE(GURL(), GetConfigURL())
143 << "Could not determine the precache config settings URL.";
144 DCHECK_NE(std::string(), GetManifestURLPrefix())
145 << "Could not determine the precache manifest URL prefix.";
146 }
147
~PrecacheFetcher()148 PrecacheFetcher::~PrecacheFetcher() {
149 }
150
Start()151 void PrecacheFetcher::Start() {
152 DCHECK(!fetcher_); // Start shouldn't be called repeatedly.
153
154 GURL config_url = GetConfigURL();
155 DCHECK(config_url.is_valid());
156
157 // Fetch the precache configuration settings from the server.
158 fetcher_.reset(new Fetcher(request_context_, config_url,
159 base::Bind(&PrecacheFetcher::OnConfigFetchComplete,
160 base::Unretained(this))));
161 }
162
StartNextFetch()163 void PrecacheFetcher::StartNextFetch() {
164 if (!resource_urls_to_fetch_.empty()) {
165 // Fetch the next resource URL.
166 fetcher_.reset(
167 new Fetcher(request_context_, resource_urls_to_fetch_.front(),
168 base::Bind(&PrecacheFetcher::OnResourceFetchComplete,
169 base::Unretained(this))));
170
171 resource_urls_to_fetch_.pop_front();
172 return;
173 }
174
175 if (!manifest_urls_to_fetch_.empty()) {
176 // Fetch the next manifest URL.
177 fetcher_.reset(
178 new Fetcher(request_context_, manifest_urls_to_fetch_.front(),
179 base::Bind(&PrecacheFetcher::OnManifestFetchComplete,
180 base::Unretained(this))));
181
182 manifest_urls_to_fetch_.pop_front();
183 return;
184 }
185
186 // There are no more URLs to fetch, so end the precache cycle.
187 precache_delegate_->OnDone();
188 // OnDone may have deleted this PrecacheFetcher, so don't do anything after it
189 // is called.
190 }
191
OnConfigFetchComplete(const URLFetcher & source)192 void PrecacheFetcher::OnConfigFetchComplete(const URLFetcher& source) {
193 PrecacheConfigurationSettings config;
194
195 if (ParseProtoFromFetchResponse(source, &config)) {
196 // Keep track of starting URLs that manifests are being fetched for, in
197 // order to remove duplicates. This is a hash set on strings, and not GURLs,
198 // because there is no hash function defined for GURL.
199 base::hash_set<std::string> unique_starting_urls;
200
201 // Attempt to fetch manifests for starting URLs up to the maximum top sites
202 // count. If a manifest does not exist for a particular starting URL, then
203 // the fetch will fail, and that starting URL will be ignored.
204 int64 rank = 0;
205 for (std::list<GURL>::const_iterator it = starting_urls_.begin();
206 it != starting_urls_.end() && rank < config.top_sites_count();
207 ++it, ++rank) {
208 if (unique_starting_urls.find(it->spec()) == unique_starting_urls.end()) {
209 // Only add a fetch for the manifest URL if this manifest isn't already
210 // going to be fetched.
211 manifest_urls_to_fetch_.push_back(ConstructManifestURL(*it));
212 unique_starting_urls.insert(it->spec());
213 }
214 }
215
216 for (int i = 0; i < config.forced_starting_url_size(); ++i) {
217 // Convert the string URL into a GURL and take the spec() of it so that
218 // the URL string gets canonicalized.
219 GURL url(config.forced_starting_url(i));
220 if (unique_starting_urls.find(url.spec()) == unique_starting_urls.end()) {
221 // Only add a fetch for the manifest URL if this manifest isn't already
222 // going to be fetched.
223 manifest_urls_to_fetch_.push_back(ConstructManifestURL(url));
224 unique_starting_urls.insert(url.spec());
225 }
226 }
227 }
228
229 StartNextFetch();
230 }
231
OnManifestFetchComplete(const URLFetcher & source)232 void PrecacheFetcher::OnManifestFetchComplete(const URLFetcher& source) {
233 PrecacheManifest manifest;
234
235 if (ParseProtoFromFetchResponse(source, &manifest)) {
236 for (int i = 0; i < manifest.resource_size(); ++i) {
237 if (manifest.resource(i).has_url()) {
238 resource_urls_to_fetch_.push_back(GURL(manifest.resource(i).url()));
239 }
240 }
241 }
242
243 StartNextFetch();
244 }
245
OnResourceFetchComplete(const URLFetcher & source)246 void PrecacheFetcher::OnResourceFetchComplete(const URLFetcher& source) {
247 // The resource has already been put in the cache during the fetch process, so
248 // nothing more needs to be done for the resource.
249 StartNextFetch();
250 }
251
252 } // namespace precache
253