printing/backend/print_backend_cups.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 "printing/backend/print_backend.h"
   6
   7 #include "build/build_config.h"
   8
   9 #include <dlfcn.h>
  10 #include <errno.h>
  11 #include <pthread.h>
  12
  13 #if defined(OS_MACOSX)
  14 #include <AvailabilityMacros.h>
  15 #else
  16 #include <gcrypt.h>
  17 #endif
  18
  19 #include "base/file_util.h"
  20 #include "base/lazy_instance.h"
  21 #include "base/logging.h"
  22 #include "base/string_number_conversions.h"
  23 #include "base/synchronization/lock.h"
  24 #include "base/values.h"
  25 #include "googleurl/src/gurl.h"
  26 #include "printing/backend/cups_helper.h"
  27 #include "printing/backend/print_backend_consts.h"
  28
  29 #if (CUPS_VERSION_MAJOR == 1 && CUPS_VERSION_MINOR < 4)
  30 const int CUPS_PRINTER_SCANNER = 0x2000000;  // Scanner-only device
  31 #endif
  32
  33 #if !defined(OS_MACOSX)
  34 GCRY_THREAD_OPTION_PTHREAD_IMPL;
  35
  36 namespace {
  37
  38 // Init GCrypt library (needed for CUPS) using pthreads.
  39 // There exists a bug in CUPS library, where it crashed with: "ath.c:184:
  40 // _gcry_ath_mutex_lock: Assertion `*lock == ((ath_mutex_t) 0)' failed."
  41 // It happened when multiple threads tried printing simultaneously.
  42 // Google search for 'gnutls thread safety' provided a solution that
  43 // initialized gcrypt and gnutls.
  44
  45 // TODO(phajdan.jr): Remove this after https://bugs.g10code.com/gnupg/issue1197
  46 // gets fixed on all Linux distros we support (i.e. when they ship libgcrypt
  47 // with the fix).
  48
  49 // Initially, we linked with -lgnutls and simply called gnutls_global_init(),
  50 // but this did not work well since we build one binary on Ubuntu Hardy and
  51 // expect it to run on many Linux distros. (See http://crbug.com/46954)
  52 // So instead we use dlopen() and dlsym() to dynamically load and call
  53 // gnutls_global_init().
  54
  55 class GcryptInitializer {
  56  public:
  57   GcryptInitializer() {
  58     Init();
  59   }
  60
  61  private:
  62   void Init() {
  63     const char* kGnuTlsFiles[] = {
  64       "libgnutls.so.28",
  65       "libgnutls.so.26",
  66       "libgnutls.so",
  67     };
  68     gcry_control(GCRYCTL_SET_THREAD_CBS, &gcry_threads_pthread);
  69     for (size_t i = 0; i < arraysize(kGnuTlsFiles); ++i) {
  70       void* gnutls_lib = dlopen(kGnuTlsFiles[i], RTLD_NOW);
  71       if (!gnutls_lib) {
  72         VLOG(1) << "Cannot load " << kGnuTlsFiles[i];
  73         continue;
  74       }
  75       const char* kGnuTlsInitFuncName = "gnutls_global_init";
  76       int (*pgnutls_global_init)(void) = reinterpret_cast<int(*)()>(
  77           dlsym(gnutls_lib, kGnuTlsInitFuncName));
  78       if (!pgnutls_global_init) {
  79         VLOG(1) << "Could not find " << kGnuTlsInitFuncName
  80                 << " in " << kGnuTlsFiles[i];
  81         continue;
  82       }
  83       if ((*pgnutls_global_init)() != 0)
  84         LOG(ERROR) << "gnutls_global_init() failed";
  85       return;
  86     }
  87     LOG(ERROR) << "Cannot find libgnutls";
  88   }
  89 };
  90
  91 base::LazyInstance<GcryptInitializer> g_gcrypt_initializer =
  92     LAZY_INSTANCE_INITIALIZER;
  93
  94 }  // namespace
  95 #endif  // !defined(OS_MACOSX)
  96
  97 namespace printing {
  98
  99 static const char kCUPSPrinterInfoOpt[] = "printer-info";
 100 static const char kCUPSPrinterStateOpt[] = "printer-state";
 101 static const char kCUPSPrinterTypeOpt[] = "printer-type";
 102 static const char kCUPSPrinterMakeModelOpt[] = "printer-make-and-model";
 103
 104 class PrintBackendCUPS : public PrintBackend {
 105  public:
 106   PrintBackendCUPS(const GURL& print_server_url,
 107                    http_encryption_t encryption, bool blocking);
 108
 109   // PrintBackend implementation.
 110   virtual bool EnumeratePrinters(PrinterList* printer_list) OVERRIDE;
 111   virtual std::string GetDefaultPrinterName() OVERRIDE;
 112   virtual bool GetPrinterSemanticCapsAndDefaults(
 113       const std::string& printer_name,
 114       PrinterSemanticCapsAndDefaults* printer_info) OVERRIDE;
 115   virtual bool GetPrinterCapsAndDefaults(
 116       const std::string& printer_name,
 117       PrinterCapsAndDefaults* printer_info) OVERRIDE;
 118   virtual std::string GetPrinterDriverInfo(
 119       const std::string& printer_name) OVERRIDE;
 120   virtual bool IsValidPrinter(const std::string& printer_name) OVERRIDE;
 121
 122  protected:
 123   virtual ~PrintBackendCUPS() {}
 124
 125  private:
 126   // Following functions are wrappers around corresponding CUPS functions.
 127   // <functions>2()  are called when print server is specified, and plain
 128   // version in another case. There is an issue specifing CUPS_HTTP_DEFAULT
 129   // in the <functions>2(), it does not work in CUPS prior to 1.4.
 130   int GetDests(cups_dest_t** dests);
 131   base::FilePath GetPPD(const char* name);
 132
 133   GURL print_server_url_;
 134   http_encryption_t cups_encryption_;
 135   bool blocking_;
 136 };
 137
 138 PrintBackendCUPS::PrintBackendCUPS(const GURL& print_server_url,
 139                                    http_encryption_t encryption,
 140                                    bool blocking)
 141     : print_server_url_(print_server_url),
 142       cups_encryption_(encryption),
 143       blocking_(blocking) {
 144 }
 145
 146 bool PrintBackendCUPS::EnumeratePrinters(PrinterList* printer_list) {
 147   DCHECK(printer_list);
 148   printer_list->clear();
 149
 150   cups_dest_t* destinations = NULL;
 151   int num_dests = GetDests(&destinations);
 152   if ((num_dests == 0) && (cupsLastError() > IPP_OK_EVENTS_COMPLETE)) {
 153     VLOG(1) << "CUPS: Error getting printers from CUPS server"
 154             << ", server: " << print_server_url_
 155             << ", error: " << static_cast<int>(cupsLastError());
 156     return false;
 157   }
 158
 159   for (int printer_index = 0; printer_index < num_dests; printer_index++) {
 160     const cups_dest_t& printer = destinations[printer_index];
 161
 162     // CUPS can have 'printers' that are actually scanners. (not MFC)
 163     // At least on Mac. Check for scanners and skip them.
 164     const char* type_str = cupsGetOption(kCUPSPrinterTypeOpt,
 165         printer.num_options, printer.options);
 166     if (type_str != NULL) {
 167       int type;
 168       if (base::StringToInt(type_str, &type) && (type & CUPS_PRINTER_SCANNER))
 169         continue;
 170     }
 171
 172     PrinterBasicInfo printer_info;
 173     printer_info.printer_name = printer.name;
 174     printer_info.is_default = printer.is_default;
 175
 176     const char* info = cupsGetOption(kCUPSPrinterInfoOpt,
 177         printer.num_options, printer.options);
 178     if (info != NULL)
 179       printer_info.printer_description = info;
 180
 181     const char* state = cupsGetOption(kCUPSPrinterStateOpt,
 182         printer.num_options, printer.options);
 183     if (state != NULL)
 184       base::StringToInt(state, &printer_info.printer_status);
 185
 186     const char* drv_info = cupsGetOption(kCUPSPrinterMakeModelOpt,
 187                                          printer.num_options,
 188                                          printer.options);
 189     if (drv_info)
 190       printer_info.options[kDriverInfoTagName] = *drv_info;
 191
 192     // Store printer options.
 193     for (int opt_index = 0; opt_index < printer.num_options; opt_index++) {
 194       printer_info.options[printer.options[opt_index].name] =
 195           printer.options[opt_index].value;
 196     }
 197
 198     printer_list->push_back(printer_info);
 199   }
 200
 201   cupsFreeDests(num_dests, destinations);
 202
 203   VLOG(1) << "CUPS: Enumerated printers"
 204           << ", server: " << print_server_url_
 205           << ", # of printers: " << printer_list->size();
 206   return true;
 207 }
 208
 209 std::string PrintBackendCUPS::GetDefaultPrinterName() {
 210   // Not using cupsGetDefault() because it lies about the default printer.
 211   cups_dest_t* dests;
 212   int num_dests = GetDests(&dests);
 213   cups_dest_t* dest = cupsGetDest(NULL, NULL, num_dests, dests);
 214   std::string name = dest ? std::string(dest->name) : std::string();
 215   cupsFreeDests(num_dests, dests);
 216   return name;
 217 }
 218
 219 bool PrintBackendCUPS::GetPrinterSemanticCapsAndDefaults(
 220     const std::string& printer_name,
 221     PrinterSemanticCapsAndDefaults* printer_info) {
 222   PrinterCapsAndDefaults info;
 223   if (!GetPrinterCapsAndDefaults(printer_name, &info) )
 224     return false;
 225
 226   return parsePpdCapabilities(
 227       printer_name, info.printer_capabilities, printer_info);
 228 }
 229
 230 bool PrintBackendCUPS::GetPrinterCapsAndDefaults(
 231     const std::string& printer_name,
 232     PrinterCapsAndDefaults* printer_info) {
 233   DCHECK(printer_info);
 234
 235   VLOG(1) << "CUPS: Getting caps and defaults"
 236           << ", printer name: " << printer_name;
 237
 238   base::FilePath ppd_path(GetPPD(printer_name.c_str()));
 239   // In some cases CUPS failed to get ppd file.
 240   if (ppd_path.empty()) {
 241     LOG(ERROR) << "CUPS: Failed to get PPD"
 242                << ", printer name: " << printer_name;
 243     return false;
 244   }
 245
 246   std::string content;
 247   bool res = file_util::ReadFileToString(ppd_path, &content);
 248
 249   file_util::Delete(ppd_path, false);
 250
 251   if (res) {
 252     printer_info->printer_capabilities.swap(content);
 253     printer_info->caps_mime_type = "application/pagemaker";
 254     // In CUPS, printer defaults is a part of PPD file. Nothing to upload here.
 255     printer_info->printer_defaults.clear();
 256     printer_info->defaults_mime_type.clear();
 257   }
 258
 259   return res;
 260 }
 261
 262 std::string PrintBackendCUPS::GetPrinterDriverInfo(
 263     const std::string& printer_name) {
 264   cups_dest_t* destinations = NULL;
 265   int num_dests = GetDests(&destinations);
 266   std::string result;
 267   for (int printer_index = 0; printer_index < num_dests; printer_index++) {
 268     const cups_dest_t& printer = destinations[printer_index];
 269     if (printer_name == printer.name) {
 270       const char* info = cupsGetOption(kCUPSPrinterMakeModelOpt,
 271                                        printer.num_options,
 272                                        printer.options);
 273       if (info)
 274         result = *info;
 275     }
 276   }
 277
 278   cupsFreeDests(num_dests, destinations);
 279   return result;
 280 }
 281
 282 bool PrintBackendCUPS::IsValidPrinter(const std::string& printer_name) {
 283   // This is not very efficient way to get specific printer info. CUPS 1.4
 284   // supports cupsGetNamedDest() function. However, CUPS 1.4 is not available
 285   // everywhere (for example, it supported from Mac OS 10.6 only).
 286   PrinterList printer_list;
 287   EnumeratePrinters(&printer_list);
 288
 289   PrinterList::iterator it;
 290   for (it = printer_list.begin(); it != printer_list.end(); ++it)
 291     if (it->printer_name == printer_name)
 292       return true;
 293   return false;
 294 }
 295
 296 scoped_refptr<PrintBackend> PrintBackend::CreateInstance(
 297     const DictionaryValue* print_backend_settings) {
 298 #if !defined(OS_MACOSX)
 299   // Initialize gcrypt library.
 300   g_gcrypt_initializer.Get();
 301 #endif
 302
 303   std::string print_server_url_str, cups_blocking;
 304   int encryption = HTTP_ENCRYPT_NEVER;
 305   if (print_backend_settings) {
 306     print_backend_settings->GetString(kCUPSPrintServerURL,
 307                                       &print_server_url_str);
 308
 309     print_backend_settings->GetString(kCUPSBlocking,
 310                                       &cups_blocking);
 311
 312     print_backend_settings->GetInteger(kCUPSEncryption, &encryption);
 313   }
 314   GURL print_server_url(print_server_url_str.c_str());
 315   return new PrintBackendCUPS(print_server_url,
 316                               static_cast<http_encryption_t>(encryption),
 317                               cups_blocking == kValueTrue);
 318 }
 319
 320 int PrintBackendCUPS::GetDests(cups_dest_t** dests) {
 321   if (print_server_url_.is_empty()) {  // Use default (local) print server.
 322     return cupsGetDests(dests);
 323   } else {
 324     HttpConnectionCUPS http(print_server_url_, cups_encryption_);
 325     http.SetBlocking(blocking_);
 326     return cupsGetDests2(http.http(), dests);
 327   }
 328 }
 329
 330 base::FilePath PrintBackendCUPS::GetPPD(const char* name) {
 331   // cupsGetPPD returns a filename stored in a static buffer in CUPS.
 332   // Protect this code with lock.
 333   CR_DEFINE_STATIC_LOCAL(base::Lock, ppd_lock, ());
 334   base::AutoLock ppd_autolock(ppd_lock);
 335   base::FilePath ppd_path;
 336   const char* ppd_file_path = NULL;
 337   if (print_server_url_.is_empty()) {  // Use default (local) print server.
 338     ppd_file_path = cupsGetPPD(name);
 339     if (ppd_file_path)
 340       ppd_path = base::FilePath(ppd_file_path);
 341   } else {
 342     // cupsGetPPD2 gets stuck sometimes in an infinite time due to network
 343     // configuration/issues. To prevent that, use non-blocking http connection
 344     // here.
 345     // Note: After looking at CUPS sources, it looks like non-blocking
 346     // connection will timeout after 10 seconds of no data period. And it will
 347     // return the same way as if data was completely and sucessfully downloaded.
 348     HttpConnectionCUPS http(print_server_url_, cups_encryption_);
 349     http.SetBlocking(blocking_);
 350     ppd_file_path = cupsGetPPD2(http.http(), name);
 351     // Check if the get full PPD, since non-blocking call may simply return
 352     // normally after timeout expired.
 353     if (ppd_file_path) {
 354       // There is no reliable way right now to detect full and complete PPD
 355       // get downloaded. If we reach http timeout, it may simply return
 356       // downloaded part as a full response. It might be good enough to check
 357       // http->data_remaining or http->_data_remaining, unfortunately http_t
 358       // is an internal structure and fields are not exposed in CUPS headers.
 359       // httpGetLength or httpGetLength2 returning the full content size.
 360       // Comparing file size against that content length might be unreliable
 361       // since some http reponses are encoded and content_length > file size.
 362       // Let's just check for the obvious CUPS and http errors here.
 363       ppd_path = base::FilePath(ppd_file_path);
 364       ipp_status_t error_code = cupsLastError();
 365       int http_error = httpError(http.http());
 366       if (error_code > IPP_OK_EVENTS_COMPLETE || http_error != 0) {
 367         LOG(ERROR) << "Error downloading PPD file"
 368                    << ", name: " << name
 369                    << ", CUPS error: " << static_cast<int>(error_code)
 370                    << ", HTTP error: " << http_error;
 371         file_util::Delete(ppd_path, false);
 372         ppd_path.clear();
 373       }
 374     }
 375   }
 376   return ppd_path;
 377 }
 378
 379 }  // namespace printing