net/proxy/dhcp_proxy_script_fetcher_win.cc

   1 // Copyright (c) 2012 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 "net/proxy/dhcp_proxy_script_fetcher_win.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/metrics/histogram.h"
  10 #include "base/threading/sequenced_worker_pool.h"
  11 #include "base/timer/elapsed_timer.h"
  12 #include "net/base/net_errors.h"
  13 #include "net/proxy/dhcp_proxy_script_adapter_fetcher_win.h"
  14
  15 #include <winsock2.h>
  16 #include <iphlpapi.h>
  17 #pragma comment(lib, "iphlpapi.lib")
  18
  19 namespace {
  20
  21 // How many threads to use at maximum to do DHCP lookups. This is
  22 // chosen based on the following UMA data:
  23 // - When OnWaitTimer fires, ~99.8% of users have 6 or fewer network
  24 //   adapters enabled for DHCP in total.
  25 // - At the same measurement point, ~99.7% of users have 3 or fewer pending
  26 //   DHCP adapter lookups.
  27 // - There is however a very long and thin tail of users who have
  28 //   systems reporting up to 100+ adapters (this must be some very weird
  29 //   OS bug (?), probably the cause of http://crbug.com/240034).
  30 //
  31 // The maximum number of threads is chosen such that even systems that
  32 // report a huge number of network adapters should not run out of
  33 // memory from this number of threads, while giving a good chance of
  34 // getting back results for any responsive adapters.
  35 //
  36 // The ~99.8% of systems that have 6 or fewer network adapters will
  37 // not grow the thread pool to its maximum size (rather, they will
  38 // grow it to 6 or fewer threads) so setting the limit lower would not
  39 // improve performance or memory usage on those systems.
  40 const int kMaxDhcpLookupThreads = 12;
  41
  42 // How long to wait at maximum after we get results (a PAC file or
  43 // knowledge that no PAC file is configured) from whichever network
  44 // adapter finishes first.
  45 const int kMaxWaitAfterFirstResultMs = 400;
  46
  47 const int kGetAdaptersAddressesErrors[] = {
  48   ERROR_ADDRESS_NOT_ASSOCIATED,
  49   ERROR_BUFFER_OVERFLOW,
  50   ERROR_INVALID_PARAMETER,
  51   ERROR_NOT_ENOUGH_MEMORY,
  52   ERROR_NO_DATA,
  53 };
  54
  55 }  // namespace
  56
  57 namespace net {
  58
  59 DhcpProxyScriptFetcherWin::DhcpProxyScriptFetcherWin(
  60     URLRequestContext* url_request_context)
  61     : state_(STATE_START),
  62       num_pending_fetchers_(0),
  63       destination_string_(NULL),
  64       url_request_context_(url_request_context) {
  65   DCHECK(url_request_context_);
  66
  67   worker_pool_ = new base::SequencedWorkerPool(kMaxDhcpLookupThreads,
  68                                                "PacDhcpLookup");
  69 }
  70
  71 DhcpProxyScriptFetcherWin::~DhcpProxyScriptFetcherWin() {
  72   // Count as user-initiated if we are not yet in STATE_DONE.
  73   Cancel();
  74
  75   worker_pool_->Shutdown();
  76 }
  77
  78 int DhcpProxyScriptFetcherWin::Fetch(base::string16* utf16_text,
  79                                      const CompletionCallback& callback) {
  80   DCHECK(CalledOnValidThread());
  81   if (state_ != STATE_START && state_ != STATE_DONE) {
  82     NOTREACHED();
  83     return ERR_UNEXPECTED;
  84   }
  85
  86   fetch_start_time_ = base::TimeTicks::Now();
  87
  88   state_ = STATE_WAIT_ADAPTERS;
  89   callback_ = callback;
  90   destination_string_ = utf16_text;
  91
  92   last_query_ = ImplCreateAdapterQuery();
  93   GetTaskRunner()->PostTaskAndReply(
  94       FROM_HERE,
  95       base::Bind(
  96           &DhcpProxyScriptFetcherWin::AdapterQuery::GetCandidateAdapterNames,
  97           last_query_.get()),
  98       base::Bind(
  99           &DhcpProxyScriptFetcherWin::OnGetCandidateAdapterNamesDone,
 100           AsWeakPtr(),
 101           last_query_));
 102
 103   return ERR_IO_PENDING;
 104 }
 105
 106 void DhcpProxyScriptFetcherWin::Cancel() {
 107   DCHECK(CalledOnValidThread());
 108
 109   if (state_ != STATE_DONE) {
 110     // We only count this stat if the cancel was explicitly initiated by
 111     // our client, and if we weren't already in STATE_DONE.
 112     UMA_HISTOGRAM_TIMES("Net.DhcpWpadCancelTime",
 113                         base::TimeTicks::Now() - fetch_start_time_);
 114   }
 115
 116   CancelImpl();
 117 }
 118
 119 void DhcpProxyScriptFetcherWin::CancelImpl() {
 120   DCHECK(CalledOnValidThread());
 121
 122   if (state_ != STATE_DONE) {
 123     callback_.Reset();
 124     wait_timer_.Stop();
 125     state_ = STATE_DONE;
 126
 127     for (FetcherVector::iterator it = fetchers_.begin();
 128          it != fetchers_.end();
 129          ++it) {
 130       (*it)->Cancel();
 131     }
 132
 133     fetchers_.clear();
 134   }
 135 }
 136
 137 void DhcpProxyScriptFetcherWin::OnGetCandidateAdapterNamesDone(
 138     scoped_refptr<AdapterQuery> query) {
 139   DCHECK(CalledOnValidThread());
 140
 141   // This can happen if this object is reused for multiple queries,
 142   // and a previous query was cancelled before it completed.
 143   if (query.get() != last_query_.get())
 144     return;
 145   last_query_ = NULL;
 146
 147   // Enable unit tests to wait for this to happen; in production this function
 148   // call is a no-op.
 149   ImplOnGetCandidateAdapterNamesDone();
 150
 151   // We may have been cancelled.
 152   if (state_ != STATE_WAIT_ADAPTERS)
 153     return;
 154
 155   state_ = STATE_NO_RESULTS;
 156
 157   const std::set<std::string>& adapter_names = query->adapter_names();
 158
 159   if (adapter_names.empty()) {
 160     TransitionToDone();
 161     return;
 162   }
 163
 164   for (std::set<std::string>::const_iterator it = adapter_names.begin();
 165        it != adapter_names.end();
 166        ++it) {
 167     DhcpProxyScriptAdapterFetcher* fetcher(ImplCreateAdapterFetcher());
 168     fetcher->Fetch(
 169         *it, base::Bind(&DhcpProxyScriptFetcherWin::OnFetcherDone,
 170                         base::Unretained(this)));
 171     fetchers_.push_back(fetcher);
 172   }
 173   num_pending_fetchers_ = fetchers_.size();
 174 }
 175
 176 std::string DhcpProxyScriptFetcherWin::GetFetcherName() const {
 177   DCHECK(CalledOnValidThread());
 178   return "win";
 179 }
 180
 181 const GURL& DhcpProxyScriptFetcherWin::GetPacURL() const {
 182   DCHECK(CalledOnValidThread());
 183   DCHECK_EQ(state_, STATE_DONE);
 184
 185   return pac_url_;
 186 }
 187
 188 void DhcpProxyScriptFetcherWin::OnFetcherDone(int result) {
 189   DCHECK(state_ == STATE_NO_RESULTS || state_ == STATE_SOME_RESULTS);
 190
 191   if (--num_pending_fetchers_ == 0) {
 192     TransitionToDone();
 193     return;
 194   }
 195
 196   // If the only pending adapters are those less preferred than one
 197   // with a valid PAC script, we do not need to wait any longer.
 198   for (FetcherVector::iterator it = fetchers_.begin();
 199        it != fetchers_.end();
 200        ++it) {
 201     bool did_finish = (*it)->DidFinish();
 202     int result = (*it)->GetResult();
 203     if (did_finish && result == OK) {
 204       TransitionToDone();
 205       return;
 206     }
 207     if (!did_finish || result != ERR_PAC_NOT_IN_DHCP) {
 208       break;
 209     }
 210   }
 211
 212   // Once we have a single result, we set a maximum on how long to wait
 213   // for the rest of the results.
 214   if (state_ == STATE_NO_RESULTS) {
 215     state_ = STATE_SOME_RESULTS;
 216     wait_timer_.Start(FROM_HERE,
 217         ImplGetMaxWait(), this, &DhcpProxyScriptFetcherWin::OnWaitTimer);
 218   }
 219 }
 220
 221 void DhcpProxyScriptFetcherWin::OnWaitTimer() {
 222   DCHECK_EQ(state_, STATE_SOME_RESULTS);
 223
 224   // These are intended to help us understand whether our timeout may
 225   // be too aggressive or not aggressive enough.
 226   UMA_HISTOGRAM_COUNTS_100("Net.DhcpWpadNumAdaptersAtWaitTimer",
 227                            fetchers_.size());
 228   UMA_HISTOGRAM_COUNTS_100("Net.DhcpWpadNumPendingAdaptersAtWaitTimer",
 229                            num_pending_fetchers_);
 230
 231   TransitionToDone();
 232 }
 233
 234 void DhcpProxyScriptFetcherWin::TransitionToDone() {
 235   DCHECK(state_ == STATE_NO_RESULTS || state_ == STATE_SOME_RESULTS);
 236
 237   int result = ERR_PAC_NOT_IN_DHCP;  // Default if no fetchers.
 238   if (!fetchers_.empty()) {
 239     // Scan twice for the result; once through the whole list for success,
 240     // then if no success, return result for most preferred network adapter,
 241     // preferring "real" network errors to the ERR_PAC_NOT_IN_DHCP error.
 242     // Default to ERR_ABORTED if no fetcher completed.
 243     result = ERR_ABORTED;
 244     for (FetcherVector::iterator it = fetchers_.begin();
 245          it != fetchers_.end();
 246          ++it) {
 247       if ((*it)->DidFinish() && (*it)->GetResult() == OK) {
 248         result = OK;
 249         *destination_string_ = (*it)->GetPacScript();
 250         pac_url_ = (*it)->GetPacURL();
 251         break;
 252       }
 253     }
 254     if (result != OK) {
 255       destination_string_->clear();
 256       for (FetcherVector::iterator it = fetchers_.begin();
 257            it != fetchers_.end();
 258            ++it) {
 259         if ((*it)->DidFinish()) {
 260           result = (*it)->GetResult();
 261           if (result != ERR_PAC_NOT_IN_DHCP) {
 262             break;
 263           }
 264         }
 265       }
 266     }
 267   }
 268
 269   CompletionCallback callback = callback_;
 270   CancelImpl();
 271   DCHECK_EQ(state_, STATE_DONE);
 272   DCHECK(fetchers_.empty());
 273   DCHECK(callback_.is_null());  // Invariant of data.
 274
 275   UMA_HISTOGRAM_TIMES("Net.DhcpWpadCompletionTime",
 276                       base::TimeTicks::Now() - fetch_start_time_);
 277
 278   if (result != OK) {
 279     UMA_HISTOGRAM_CUSTOM_ENUMERATION(
 280         "Net.DhcpWpadFetchError", std::abs(result), GetAllErrorCodesForUma());
 281   }
 282
 283   // We may be deleted re-entrantly within this outcall.
 284   callback.Run(result);
 285 }
 286
 287 int DhcpProxyScriptFetcherWin::num_pending_fetchers() const {
 288   return num_pending_fetchers_;
 289 }
 290
 291 URLRequestContext* DhcpProxyScriptFetcherWin::url_request_context() const {
 292   return url_request_context_;
 293 }
 294
 295 scoped_refptr<base::TaskRunner> DhcpProxyScriptFetcherWin::GetTaskRunner() {
 296   return worker_pool_->GetTaskRunnerWithShutdownBehavior(
 297       base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
 298 }
 299
 300 DhcpProxyScriptAdapterFetcher*
 301     DhcpProxyScriptFetcherWin::ImplCreateAdapterFetcher() {
 302   return new DhcpProxyScriptAdapterFetcher(url_request_context_,
 303                                            GetTaskRunner());
 304 }
 305
 306 DhcpProxyScriptFetcherWin::AdapterQuery*
 307     DhcpProxyScriptFetcherWin::ImplCreateAdapterQuery() {
 308   return new AdapterQuery();
 309 }
 310
 311 base::TimeDelta DhcpProxyScriptFetcherWin::ImplGetMaxWait() {
 312   return base::TimeDelta::FromMilliseconds(kMaxWaitAfterFirstResultMs);
 313 }
 314
 315 bool DhcpProxyScriptFetcherWin::GetCandidateAdapterNames(
 316     std::set<std::string>* adapter_names) {
 317   DCHECK(adapter_names);
 318   adapter_names->clear();
 319
 320   // The GetAdaptersAddresses MSDN page recommends using a size of 15000 to
 321   // avoid reallocation.
 322   ULONG adapters_size = 15000;
 323   scoped_ptr<IP_ADAPTER_ADDRESSES, base::FreeDeleter> adapters;
 324   ULONG error = ERROR_SUCCESS;
 325   int num_tries = 0;
 326
 327   base::ElapsedTimer time_api_access;
 328   do {
 329     adapters.reset(static_cast<IP_ADAPTER_ADDRESSES*>(malloc(adapters_size)));
 330     // Return only unicast addresses, and skip information we do not need.
 331     error = GetAdaptersAddresses(AF_UNSPEC,
 332                                  GAA_FLAG_SKIP_ANYCAST |
 333                                  GAA_FLAG_SKIP_MULTICAST |
 334                                  GAA_FLAG_SKIP_DNS_SERVER |
 335                                  GAA_FLAG_SKIP_FRIENDLY_NAME,
 336                                  NULL,
 337                                  adapters.get(),
 338                                  &adapters_size);
 339     ++num_tries;
 340   } while (error == ERROR_BUFFER_OVERFLOW && num_tries <= 3);
 341
 342   // This is primarily to validate our belief that the GetAdaptersAddresses API
 343   // function is fast enough to call synchronously from the network thread.
 344   UMA_HISTOGRAM_TIMES("Net.DhcpWpadGetAdaptersAddressesTime",
 345                       time_api_access.Elapsed());
 346
 347   if (error != ERROR_SUCCESS) {
 348     UMA_HISTOGRAM_CUSTOM_ENUMERATION(
 349         "Net.DhcpWpadGetAdaptersAddressesError",
 350         error,
 351         base::CustomHistogram::ArrayToCustomRanges(
 352             kGetAdaptersAddressesErrors,
 353             arraysize(kGetAdaptersAddressesErrors)));
 354   }
 355
 356   if (error == ERROR_NO_DATA) {
 357     // There are no adapters that we care about.
 358     return true;
 359   }
 360
 361   if (error != ERROR_SUCCESS) {
 362     LOG(WARNING) << "Unexpected error retrieving WPAD configuration from DHCP.";
 363     return false;
 364   }
 365
 366   IP_ADAPTER_ADDRESSES* adapter = NULL;
 367   for (adapter = adapters.get(); adapter; adapter = adapter->Next) {
 368     if (adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK)
 369       continue;
 370     if ((adapter->Flags & IP_ADAPTER_DHCP_ENABLED) == 0)
 371       continue;
 372
 373     DCHECK(adapter->AdapterName);
 374     adapter_names->insert(adapter->AdapterName);
 375   }
 376
 377   return true;
 378 }
 379
 380 DhcpProxyScriptFetcherWin::AdapterQuery::AdapterQuery() {
 381 }
 382
 383 DhcpProxyScriptFetcherWin::AdapterQuery::~AdapterQuery() {
 384 }
 385
 386 void DhcpProxyScriptFetcherWin::AdapterQuery::GetCandidateAdapterNames() {
 387   ImplGetCandidateAdapterNames(&adapter_names_);
 388 }
 389
 390 const std::set<std::string>&
 391     DhcpProxyScriptFetcherWin::AdapterQuery::adapter_names() const {
 392   return adapter_names_;
 393 }
 394
 395 bool DhcpProxyScriptFetcherWin::AdapterQuery::ImplGetCandidateAdapterNames(
 396     std::set<std::string>* adapter_names) {
 397   return DhcpProxyScriptFetcherWin::GetCandidateAdapterNames(adapter_names);
 398 }
 399
 400 }  // namespace net