[cups.general] Getting capability info from IPP printers

[Till Kamppeter]

Attached is the output of

sudo tcpdump -s0 -U -w <file>.tcp tcp port ipp

for both cases.

ipptool.tcp is of ipptool, cups-browsed.tcp of my C program.

   Till


On 02/19/2013 04:47 PM, Till Kamppeter wrote:
> Hi,
> 
> to allow driverless printiung on network-connected printers, especially
> from mobile devices I want to poll capability information from the
> printer, where I want to support IPP printers with known PDLs, like
> PostScript, PCL, IPP Everywhere, ... The program should then
> automatically generate a PPD file or at least select the most suitable
> generic one, depending on how much info the printer provides.
> 
> Using ipptool of CUPS I have no problem to poll info from IPP printers,
> running
> 
> ipptool -X <IPP URI of the printer> cap.ipptool
> 
> cap.ipptool contains:
> 
> ----------
> IGNORE-ERRORS yes
> {
>         NAME "Get printer attributes using Get-Printer-Attributes"
>         OPERATION Get-Printer-Attributes
>         GROUP operation-attributes-tag
>         ATTR charset attributes-charset utf-8
>         ATTR language attributes-natural-language en
>         ATTR uri printer-uri $uri
>         ATTR keyword requested-attributes
> job-template,printer-description,printer-resolution-supported,print-color-mode-supported,print-quality-supported,media-supported,media-default,media-ready,output-bin-supported,finishings-supported,color-supported,sides-supported,number-up-supported,page-ranges-supported,all,media-col-database
> }
> ----------
> 
> Now I want to poll with my own C program. It contains:
> 
> ----------
>   char *uri;
>   http_t *http;
>   ipp_t *request, *response;
>   int i;
>   char scheme[10], userpass[1024], host_name[1024], resource[1024];
>   static const char * const requested_attrs[] =
>     {
>       "printer-description",
>       "document-format-supported",
>       "color-supported",
>       "pages-per-minute",
>       "pages-per-minute-color",
>       "media-supported",
>       "media-ready",
>       "media-default",
>       "media-type-supported",
>       "media-source-supported",
>       "media-col-database",
>       "sides-supported",
>       "sides-default",
>       "output-bin-supported",
>       "output-bin-default",
>       "finishings-supported",
>       "finishings-default",
>       "print-color-mode-supported",
>       "print-color-mode-default",
>       "output-mode-supported",
>       "output-mode-default",
>       "print-quality-supported",
>       "print-quality-default",
>       "printer-resolution-supported",
>       "printer-resolution-default",
>       "copies-supported",
>       "copies-default",
>       "all"
>     };
>     uri_status = httpSeparateURI(HTTP_URI_CODING_ALL, uri,
> 				 scheme, sizeof(scheme),
> 				 userpass, sizeof(userpass),
> 				 host_name, sizeof(host_name),
> 				 &(port),
> 				 resource, sizeof(resource));
>     if (uri_status != HTTP_URI_OK)
>       goto fail;
>     if ((http = httpConnect(host_name, port)) ==
> 	NULL) {
>       goto fail;
>     }
>     request = ippNewRequest(IPP_GET_PRINTER_ATTRIBUTES);
>     /*ippSetRequestId(request, (CUPS_RAND() % 1000) * 137 + 1);*/
>     /*ippAddSeparator(request);*/
>     /*ippSetVersion(request, 1, 1);*/
>     /*ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_CHARSET,
>       "attributes-charset", NULL, "utf-8");*/
>     /*ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_LANGUAGE,
>       "attributes-natural-language", NULL, "en");*/
>     ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI,
> 		 "printer-uri", NULL, p->uri);
>     /*ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_NAME,
>       "requesting-user-name", NULL, cupsUser());*/
>     ippAddStrings(request, IPP_TAG_OPERATION, IPP_TAG_NAME,
> 		  "requested-attributes",
> 		  sizeof(requested_attrs) / sizeof(requested_attrs[0]),
> 		  NULL, requested_attrs);
>      /*int status = cupsSendRequest(http, request, resource,
> ippLength(request));
>       response = cupsGetResponse(http, resource);*/
>     response = cupsDoRequest(http, request, resource);
>     if (response == NULL) {
>       httpClose(http);
>       goto fail;
>     }
>     printf("cups-browsed: Remote printer %s: %s (%s)\n",
>            p->uri, ippErrorString(cupsLastError()),
> 	   cupsLastErrorString());
>     ipp_attribute_t *attr;
>     attr = ippFirstAttribute(response);
>     while (attr) {
>       printf("Attr: %s\n",
>              ippGetName(attr));
>       for (i = 0; i < ippGetCount(attr); i ++)
> 	printf("Value: %s\n",
> 	       ippGetString(attr, i, NULL));
>       attr = ippNextAttribute(response);
>     }
>     attr = ippFindAttribute(response,
> 			    "document-format-supported",
> 			    IPP_TAG_ZERO);
>     if (attr)
>       for (i = 0; i < ippGetCount(attr); i ++)
> 	printf("Format: %s\n",
> 	       ippGetString(attr, i, NULL));
>     else
>       printf("Not found.\n");
> 
>     /* Clean up */
>     ippDelete(response);
>     httpClose(http);
>   fail:
> ----------
> 
> With this I always get client-error-bad-request, independent whwther I
> run it as shown here or whatever combination of lines which are
> currently commented out I activated. I tried with several HP printers
> (HP Color LaserJet CM3530 MFP, HP LaserJet P3005, HP OfficeJet Pro 8500
> A910) and the Canon iR-ADV C5000s-B1, all with the same result, and all
> work with ipptool. I also tried to remove and re-add items from the list
> of requested attributes.
> 
> Note: I am using this code only for directly talking with network
> printers, not for remote CUPS queues.
> 
> Any idea what I am doing wrong?
> 
>    Till
> 
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: cups-browsed.tcp
Type: application/octet-stream
Size: 1722 bytes
Desc: not available
URL: <https://lists.cups.org/pipermail/cups/attachments/20130219/e84cfe30/attachment-0002.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ipptool.tcp
Type: application/octet-stream
Size: 3740 bytes
Desc: not available
URL: <https://lists.cups.org/pipermail/cups/attachments/20130219/e84cfe30/attachment-0003.obj>