src/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 #include "base/debug/leak_annotations.h"
  14 #include "base/files/file_util.h"
  15 #include "base/lazy_instance.h"
  16 #include "base/logging.h"
  17 #include "base/strings/string_number_conversions.h"
  18 #include "base/synchronization/lock.h"
  19 #include "base/values.h"
  20 #include "printing/backend/cups_helper.h"
  21 #include "printing/backend/print_backend_consts.h"
  22 #include "url/gurl.h"
  23
  24 namespace printing {
  25
  26 static const char kCUPSPrinterInfoOpt[] = "printer-info";
  27 static const char kCUPSPrinterStateOpt[] = "printer-state";
  28 static const char kCUPSPrinterTypeOpt[] = "printer-type";
  29 static const char kCUPSPrinterMakeModelOpt[] = "printer-make-and-model";
  30
  31 class PrintBackendCUPS : public PrintBackend {
  32  public:
  33   PrintBackendCUPS(const GURL& print_server_url,
  34                    http_encryption_t encryption, bool blocking);
  35
  36   // PrintBackend implementation.
  37   bool EnumeratePrinters(PrinterList* printer_list) override;
  38   std::string GetDefaultPrinterName() override;
  39   bool GetPrinterSemanticCapsAndDefaults(
  40       const std::string& printer_name,
  41       PrinterSemanticCapsAndDefaults* printer_info) override;
  42   bool GetPrinterCapsAndDefaults(const std::string& printer_name,
  43                                  PrinterCapsAndDefaults* printer_info) override;
  44   std::string GetPrinterDriverInfo(const std::string& printer_name) override;
  45   bool IsValidPrinter(const std::string& printer_name) override;
  46
  47  protected:
  48   ~PrintBackendCUPS() override {}
  49
  50  private:
  51   // Following functions are wrappers around corresponding CUPS functions.
  52   // <functions>2()  are called when print server is specified, and plain
  53   // version in another case. There is an issue specifing CUPS_HTTP_DEFAULT
  54   // in the <functions>2(), it does not work in CUPS prior to 1.4.
  55   int GetDests(cups_dest_t** dests);
  56   base::FilePath GetPPD(const char* name);
  57
  58   GURL print_server_url_;
  59   http_encryption_t cups_encryption_;
  60   bool blocking_;
  61 };
  62
  63 PrintBackendCUPS::PrintBackendCUPS(const GURL& print_server_url,
  64                                    http_encryption_t encryption,
  65                                    bool blocking)
  66     : print_server_url_(print_server_url),
  67       cups_encryption_(encryption),
  68       blocking_(blocking) {
  69 }
  70
  71 bool PrintBackendCUPS::EnumeratePrinters(PrinterList* printer_list) {
  72   DCHECK(printer_list);
  73   printer_list->clear();
  74
  75   cups_dest_t* destinations = NULL;
  76   int num_dests = GetDests(&destinations);
  77   if ((num_dests == 0) && (cupsLastError() > IPP_OK_EVENTS_COMPLETE)) {
  78     VLOG(1) << "CUPS: Error getting printers from CUPS server"
  79             << ", server: " << print_server_url_
  80             << ", error: " << static_cast<int>(cupsLastError());
  81     return false;
  82   }
  83
  84   for (int printer_index = 0; printer_index < num_dests; ++printer_index) {
  85     const cups_dest_t& printer = destinations[printer_index];
  86
  87     // CUPS can have 'printers' that are actually scanners. (not MFC)
  88     // At least on Mac. Check for scanners and skip them.
  89     const char* type_str = cupsGetOption(kCUPSPrinterTypeOpt,
  90         printer.num_options, printer.options);
  91     if (type_str != NULL) {
  92       int type;
  93       if (base::StringToInt(type_str, &type) && (type & CUPS_PRINTER_SCANNER))
  94         continue;
  95     }
  96
  97     PrinterBasicInfo printer_info;
  98     printer_info.printer_name = printer.name;
  99     printer_info.is_default = printer.is_default;
 100
 101     const char* info = cupsGetOption(kCUPSPrinterInfoOpt,
 102         printer.num_options, printer.options);
 103     if (info != NULL)
 104       printer_info.printer_description = info;
 105
 106     const char* state = cupsGetOption(kCUPSPrinterStateOpt,
 107         printer.num_options, printer.options);
 108     if (state != NULL)
 109       base::StringToInt(state, &printer_info.printer_status);
 110
 111     const char* drv_info = cupsGetOption(kCUPSPrinterMakeModelOpt,
 112                                          printer.num_options,
 113                                          printer.options);
 114     if (drv_info)
 115       printer_info.options[kDriverInfoTagName] = *drv_info;
 116
 117     // Store printer options.
 118     for (int opt_index = 0; opt_index < printer.num_options; ++opt_index) {
 119       printer_info.options[printer.options[opt_index].name] =
 120           printer.options[opt_index].value;
 121     }
 122
 123     printer_list->push_back(printer_info);
 124   }
 125
 126   cupsFreeDests(num_dests, destinations);
 127
 128   VLOG(1) << "CUPS: Enumerated printers"
 129           << ", server: " << print_server_url_
 130           << ", # of printers: " << printer_list->size();
 131   return true;
 132 }
 133
 134 std::string PrintBackendCUPS::GetDefaultPrinterName() {
 135   // Not using cupsGetDefault() because it lies about the default printer.
 136   cups_dest_t* dests;
 137   int num_dests = GetDests(&dests);
 138   cups_dest_t* dest = cupsGetDest(NULL, NULL, num_dests, dests);
 139   std::string name = dest ? std::string(dest->name) : std::string();
 140   cupsFreeDests(num_dests, dests);
 141   return name;
 142 }
 143
 144 bool PrintBackendCUPS::GetPrinterSemanticCapsAndDefaults(
 145     const std::string& printer_name,
 146     PrinterSemanticCapsAndDefaults* printer_info) {
 147   PrinterCapsAndDefaults info;
 148   if (!GetPrinterCapsAndDefaults(printer_name, &info) )
 149     return false;
 150
 151   return ParsePpdCapabilities(
 152       printer_name, info.printer_capabilities, printer_info);
 153 }
 154
 155 bool PrintBackendCUPS::GetPrinterCapsAndDefaults(
 156     const std::string& printer_name,
 157     PrinterCapsAndDefaults* printer_info) {
 158   DCHECK(printer_info);
 159
 160   VLOG(1) << "CUPS: Getting caps and defaults"
 161           << ", printer name: " << printer_name;
 162
 163   base::FilePath ppd_path(GetPPD(printer_name.c_str()));
 164   // In some cases CUPS failed to get ppd file.
 165   if (ppd_path.empty()) {
 166     LOG(ERROR) << "CUPS: Failed to get PPD, printer name: " << printer_name;
 167     return false;
 168   }
 169
 170   std::string content;
 171   bool res = base::ReadFileToString(ppd_path, &content);
 172
 173   base::DeleteFile(ppd_path, false);
 174
 175   if (res) {
 176     printer_info->printer_capabilities.swap(content);
 177     printer_info->caps_mime_type = "application/pagemaker";
 178     // In CUPS, printer defaults is a part of PPD file. Nothing to upload here.
 179     printer_info->printer_defaults.clear();
 180     printer_info->defaults_mime_type.clear();
 181   }
 182
 183   return res;
 184 }
 185
 186 std::string PrintBackendCUPS::GetPrinterDriverInfo(
 187     const std::string& printer_name) {
 188   cups_dest_t* destinations = NULL;
 189   int num_dests = GetDests(&destinations);
 190   std::string result;
 191   for (int printer_index = 0; printer_index < num_dests; ++printer_index) {
 192     const cups_dest_t& printer = destinations[printer_index];
 193     if (printer_name == printer.name) {
 194       const char* info = cupsGetOption(kCUPSPrinterMakeModelOpt,
 195                                        printer.num_options,
 196                                        printer.options);
 197       if (info)
 198         result = *info;
 199     }
 200   }
 201
 202   cupsFreeDests(num_dests, destinations);
 203   return result;
 204 }
 205
 206 bool PrintBackendCUPS::IsValidPrinter(const std::string& printer_name) {
 207   // This is not very efficient way to get specific printer info. CUPS 1.4
 208   // supports cupsGetNamedDest() function. However, CUPS 1.4 is not available
 209   // everywhere (for example, it supported from Mac OS 10.6 only).
 210   PrinterList printer_list;
 211   EnumeratePrinters(&printer_list);
 212
 213   PrinterList::iterator it;
 214   for (it = printer_list.begin(); it != printer_list.end(); ++it)
 215     if (it->printer_name == printer_name)
 216       return true;
 217   return false;
 218 }
 219
 220 scoped_refptr<PrintBackend> PrintBackend::CreateInstance(
 221     const base::DictionaryValue* print_backend_settings) {
 222   std::string print_server_url_str, cups_blocking;
 223   int encryption = HTTP_ENCRYPT_NEVER;
 224   if (print_backend_settings) {
 225     print_backend_settings->GetString(kCUPSPrintServerURL,
 226                                       &print_server_url_str);
 227
 228     print_backend_settings->GetString(kCUPSBlocking,
 229                                       &cups_blocking);
 230
 231     print_backend_settings->GetInteger(kCUPSEncryption, &encryption);
 232   }
 233   GURL print_server_url(print_server_url_str.c_str());
 234   return new PrintBackendCUPS(print_server_url,
 235                               static_cast<http_encryption_t>(encryption),
 236                               cups_blocking == kValueTrue);
 237 }
 238
 239 int PrintBackendCUPS::GetDests(cups_dest_t** dests) {
 240   if (print_server_url_.is_empty()) {  // Use default (local) print server.
 241     // GnuTLS has a genuine small memory leak that is easier to annotate
 242     // than suppress. See http://crbug.com/176888#c7
 243     // In theory any CUPS function can trigger this leak, but in
 244     // PrintBackendCUPS, this is the most likely spot.
 245     // TODO(earthdok): remove this once the leak is fixed.
 246     ANNOTATE_SCOPED_MEMORY_LEAK;
 247     return cupsGetDests(dests);
 248   } else {
 249     HttpConnectionCUPS http(print_server_url_, cups_encryption_);
 250     http.SetBlocking(blocking_);
 251     return cupsGetDests2(http.http(), dests);
 252   }
 253 }
 254
 255 base::FilePath PrintBackendCUPS::GetPPD(const char* name) {
 256   // cupsGetPPD returns a filename stored in a static buffer in CUPS.
 257   // Protect this code with lock.
 258   CR_DEFINE_STATIC_LOCAL(base::Lock, ppd_lock, ());
 259   base::AutoLock ppd_autolock(ppd_lock);
 260   base::FilePath ppd_path;
 261   const char* ppd_file_path = NULL;
 262   if (print_server_url_.is_empty()) {  // Use default (local) print server.
 263     ppd_file_path = cupsGetPPD(name);
 264     if (ppd_file_path)
 265       ppd_path = base::FilePath(ppd_file_path);
 266   } else {
 267     // cupsGetPPD2 gets stuck sometimes in an infinite time due to network
 268     // configuration/issues. To prevent that, use non-blocking http connection
 269     // here.
 270     // Note: After looking at CUPS sources, it looks like non-blocking
 271     // connection will timeout after 10 seconds of no data period. And it will
 272     // return the same way as if data was completely and sucessfully downloaded.
 273     HttpConnectionCUPS http(print_server_url_, cups_encryption_);
 274     http.SetBlocking(blocking_);
 275     ppd_file_path = cupsGetPPD2(http.http(), name);
 276     // Check if the get full PPD, since non-blocking call may simply return
 277     // normally after timeout expired.
 278     if (ppd_file_path) {
 279       // There is no reliable way right now to detect full and complete PPD
 280       // get downloaded. If we reach http timeout, it may simply return
 281       // downloaded part as a full response. It might be good enough to check
 282       // http->data_remaining or http->_data_remaining, unfortunately http_t
 283       // is an internal structure and fields are not exposed in CUPS headers.
 284       // httpGetLength or httpGetLength2 returning the full content size.
 285       // Comparing file size against that content length might be unreliable
 286       // since some http reponses are encoded and content_length > file size.
 287       // Let's just check for the obvious CUPS and http errors here.
 288       ppd_path = base::FilePath(ppd_file_path);
 289       ipp_status_t error_code = cupsLastError();
 290       int http_error = httpError(http.http());
 291       if (error_code > IPP_OK_EVENTS_COMPLETE || http_error != 0) {
 292         LOG(ERROR) << "Error downloading PPD file"
 293                    << ", name: " << name
 294                    << ", CUPS error: " << static_cast<int>(error_code)
 295                    << ", HTTP error: " << http_error;
 296         base::DeleteFile(ppd_path, false);
 297         ppd_path.clear();
 298       }
 299     }
 300   }
 301   return ppd_path;
 302 }
 303
 304 }  // namespace printing