Add a method to query IPP printers for attributes.

printing/backend/cups_jobs.h

Index: printing/backend/cups_jobs.h
diff --git a/printing/backend/cups_jobs.h b/printing/backend/cups_jobs.h
index b1ca693c82858288fdf01ebffc2f41eda426e141..b6e5b116b1f9311a2b00401d7fe1be03fdb57188 100644
--- a/printing/backend/cups_jobs.h
+++ b/printing/backend/cups_jobs.h
@@ -10,10 +10,15 @@
 #include <cups/cups.h>
 
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "printing/printing_export.h"
 
+// This file contains a collection of functions used to query IPP printers or
+// print servers and the related code to parse these responses.  All Get*
+// operations block on the network request and cannot be run on the UI thread.
+
 namespace printing {
 
 // Represents a print job sent to the queue.
@@ -110,6 +115,27 @@ struct PRINTING_EXPORT PrinterStatus {
   std::string message;
 };
 
+struct PRINTING_EXPORT PrinterInfo {
+  PrinterInfo();
+  PrinterInfo(const PrinterInfo& info);
+
+  ~PrinterInfo();
+
+  // printer-make-and-model
+  std::string make_and_model;
+
+  // document-format-supported
+  // MIME types for supported formats.
+  std::vector<std::string> document_formats;
+
+  // ipp-versions-supported
+  // A collection of major, minor pairs.
+  std::vector<std::pair<int, int>> ipp_versions;
+
+  // Does ipp-features-supported contain 'ipp-everywhere'.
+  bool ipp_everywhere = false;
+};
+
 // Specifies classes of jobs.
 enum JobCompletionState {
   COMPLETED,  // only completed jobs
@@ -125,6 +151,13 @@ void ParseJobsResponse(ipp_t* response,
 // Attempts to extract a PrinterStatus object out of |response|.
 void ParsePrinterStatus(ipp_t* response, PrinterStatus* printer_status);
 
+// Queries the printer at |address| on |port| with a Get-Printer-Attributes

[Lei Zhang, 2017/05/31 00:48:03]

Curious why this take [address, port] rather than a http_t* like the other
functions.

[skau, 2017/05/31 18:37:51]

The other functions can reuse http_t since they're querying the same IPP server
repeatedly.  This function builds its own http_t because the connection isn't
reused right now.

+// request to populate |printer_info|.  Returns false if the request failed.
+bool PRINTING_EXPORT GetPrinterInfo(const std::string& address,
+                                    const int port,
+                                    const std::string& resource,
+                                    PrinterInfo* printer_info);
+
 // Attempts to retrieve printer status using connection |http| for |printer_id|.
 // Returns true if succcssful and updates the fields in |printer_status| as
 // appropriate.  Returns false if the request failed.