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5a738aea | 251 | --></style> |
ef416fc2 | 252 | </head> |
253 | <body> | |
5a738aea | 254 | <div class='body'> |
ef416fc2 | 255 | <!-- |
ac884b6a | 256 | "$Id: api-filter.header 7285 2008-02-01 23:57:39Z mike $" |
ef416fc2 | 257 | |
5a738aea MS |
258 | Filter and backend programming header for the Common UNIX Printing System |
259 | (CUPS). | |
ef416fc2 | 260 | |
5a738aea | 261 | Copyright 2008 by Apple Inc. |
ef416fc2 | 262 | |
263 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 264 | property of Apple Inc. and are protected by Federal copyright |
265 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
266 | which should have been included with this file. If this file is | |
267 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 268 | --> |
269 | ||
5a738aea | 270 | <h1 class="title">Filter and Backend Programming</h1> |
ef416fc2 | 271 | |
5a738aea MS |
272 | <div class='summary'><table summary='General Information'> |
273 | <thead> | |
274 | <tr> | |
ac884b6a | 275 | <th>Headers</th> |
5a738aea | 276 | <th>cups/backend.h<br> |
ac884b6a MS |
277 | cups/sidechannel.h<br> |
278 | cups/snmp.h</th> | |
5a738aea MS |
279 | </tr> |
280 | </thead> | |
281 | <tbody> | |
282 | <tr> | |
283 | <th>Library</th> | |
284 | <td>-lcups</td> | |
285 | </tr> | |
286 | <tr> | |
287 | <th>See Also</th> | |
288 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
289 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
290 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
291 | Programming: <a href='api-raster.html' target='_top'>Raster API</a></td> | |
292 | </tr> | |
293 | </tbody> | |
294 | </table></div> | |
295 | <h2 class="title">Contents</h2> | |
296 | <ul class="contents"> | |
297 | </li> | |
298 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> | |
ac884b6a MS |
299 | <li><a href="#SECURITY">Security Considerations</a></li> |
300 | <li><a href="#TEMPFILES">Temporary Files</a></li> | |
301 | <li><a href="#COPIES">Copy Generation</a></li> | |
5a738aea MS |
302 | <li><a href="#EXITCODES">Exit Codes</a></li> |
303 | <li><a href="#ENVIRONMENT">Environment Variables</a></li> | |
304 | <li><a href="#MESSAGES">Communicating with the Scheduler</a></li> | |
305 | <li><a href="#COMMUNICATING">Communicating with the Backend</a></li> | |
ac884b6a | 306 | <li><a href="#SNMP">Doing SNMP Queries with Network Printers</a></li> |
5a738aea MS |
307 | </ul></li> |
308 | <li><a href="#FUNCTIONS">Functions</a><ul class="code"> | |
309 | <li><a href="#cupsBackChannelRead" title="Read data from the backchannel.">cupsBackChannelRead</a></li> | |
310 | <li><a href="#cupsBackChannelWrite" title="Write data to the backchannel.">cupsBackChannelWrite</a></li> | |
ac884b6a MS |
311 | <li><a href="#cupsBackendDeviceURI" title="Get the device URI for a backend.">cupsBackendDeviceURI</a></li> |
312 | <li><a href="#cupsSNMPClose" title="Close a SNMP socket.">cupsSNMPClose</a></li> | |
313 | <li><a href="#cupsSNMPCopyOID" title="Copy an OID.">cupsSNMPCopyOID</a></li> | |
314 | <li><a href="#cupsSNMPDefaultCommunity" title="Get the default SNMP community name.">cupsSNMPDefaultCommunity</a></li> | |
315 | <li><a href="#cupsSNMPIsOID" title="Test whether a SNMP response contains the specified OID.">cupsSNMPIsOID</a></li> | |
316 | <li><a href="#cupsSNMPIsOIDPrefixed" title="Test whether a SNMP response uses the specified | |
317 | OID prefix.">cupsSNMPIsOIDPrefixed</a></li> | |
318 | <li><a href="#cupsSNMPOpen" title="Open a SNMP socket.">cupsSNMPOpen</a></li> | |
319 | <li><a href="#cupsSNMPRead" title="Read and parse a SNMP response.">cupsSNMPRead</a></li> | |
320 | <li><a href="#cupsSNMPSetDebug" title="Enable/disable debug logging to stderr.">cupsSNMPSetDebug</a></li> | |
321 | <li><a href="#cupsSNMPWalk" title="Enumerate a group of OIDs.">cupsSNMPWalk</a></li> | |
322 | <li><a href="#cupsSNMPWrite" title="Send an SNMP query packet.">cupsSNMPWrite</a></li> | |
5a738aea MS |
323 | <li><a href="#cupsSideChannelDoRequest" title="Send a side-channel command to a backend and wait for a response.">cupsSideChannelDoRequest</a></li> |
324 | <li><a href="#cupsSideChannelRead" title="Read a side-channel message.">cupsSideChannelRead</a></li> | |
325 | <li><a href="#cupsSideChannelWrite" title="Write a side-channel message.">cupsSideChannelWrite</a></li> | |
326 | </ul> | |
327 | <li><a href="#TYPES">Data Types</a><ul class="code"> | |
ac884b6a | 328 | <li><a href="#cups_asn1_t" title="ASN1 request/object types">cups_asn1_t</a></li> |
5a738aea MS |
329 | <li><a href="#cups_backend_t" title="Backend exit codes">cups_backend_t</a></li> |
330 | <li><a href="#cups_sc_bidi_t" title="Bidirectional capabilities">cups_sc_bidi_t</a></li> | |
331 | <li><a href="#cups_sc_command_t" title="Request command codes">cups_sc_command_t</a></li> | |
332 | <li><a href="#cups_sc_state_t" title="Printer state bits">cups_sc_state_t</a></li> | |
333 | <li><a href="#cups_sc_status_t" title="Response status codes">cups_sc_status_t</a></li> | |
ac884b6a MS |
334 | <li><a href="#cups_snmp_cb_t" title="Prototypes...">cups_snmp_cb_t</a></li> |
335 | <li><a href="#cups_snmp_t" title="SNMP data packet">cups_snmp_t</a></li> | |
336 | </ul></li> | |
337 | <li><a href="#STRUCTURES">Structures</a><ul class="code"> | |
338 | <li><a href="#cups_snmp_hexstring_s" title="Hex-STRING value">cups_snmp_hexstring_s</a></li> | |
339 | <li><a href="#cups_snmp_s" title="SNMP data packet">cups_snmp_s</a></li> | |
340 | </ul></li> | |
341 | <li><a href="#UNIONS">Unions</a><ul class="code"> | |
342 | <li><a href="#cups_snmp_value_u" title="Object value">cups_snmp_value_u</a></li> | |
5a738aea MS |
343 | </ul></li> |
344 | <li><a href="#ENUMERATIONS">Constants</a><ul class="code"> | |
ac884b6a | 345 | <li><a href="#cups_asn1_e" title="ASN1 request/object types">cups_asn1_e</a></li> |
5a738aea MS |
346 | <li><a href="#cups_backend_e" title="Backend exit codes">cups_backend_e</a></li> |
347 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capabilities">cups_sc_bidi_e</a></li> | |
348 | <li><a href="#cups_sc_command_e" title="Request command codes">cups_sc_command_e</a></li> | |
349 | <li><a href="#cups_sc_state_e" title="Printer state bits">cups_sc_state_e</a></li> | |
350 | <li><a href="#cups_sc_status_e" title="Response status codes">cups_sc_status_e</a></li> | |
351 | </ul></li> | |
352 | </ul> | |
353 | <!-- | |
ac884b6a | 354 | "$Id: api-filter.shtml 7288 2008-02-06 01:39:05Z mike $" |
ef416fc2 | 355 | |
5a738aea MS |
356 | Filter and backend programming introduction for the Common UNIX Printing |
357 | System (CUPS). | |
ef416fc2 | 358 | |
5a738aea MS |
359 | Copyright 2007-2008 by Apple Inc. |
360 | Copyright 1997-2006 by Easy Software Products, all rights reserved. | |
ef416fc2 | 361 | |
5a738aea MS |
362 | These coded instructions, statements, and computer programs are the |
363 | property of Apple Inc. and are protected by Federal copyright | |
364 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
365 | which should have been included with this file. If this file is | |
366 | file is missing or damaged, see the license at "http://www.cups.org/". | |
367 | --> | |
f7deaa1a | 368 | |
5a738aea | 369 | <h2 class='title'><a name="OVERVIEW">Overview</a></h2> |
ef416fc2 | 370 | |
5a738aea MS |
371 | <p>Filters, printer drivers, port monitors, and backends use a common interface |
372 | for processing print jobs and communicating status information to the scheduler. | |
373 | Each filter is run with a standard set of command-line arguments:<p> | |
ef416fc2 | 374 | |
5a738aea | 375 | <dl class="code"> |
f7deaa1a | 376 | |
5a738aea MS |
377 | <dt>argv[1]</dt> |
378 | <dd>The job ID</dd> | |
ef416fc2 | 379 | |
5a738aea MS |
380 | <dt>argv[2]</dt> |
381 | <dd>The user printing the job</dd> | |
f7deaa1a | 382 | |
5a738aea MS |
383 | <dt>argv[3]</dt> |
384 | <dd>The job name/title</dd> | |
f7deaa1a | 385 | |
5a738aea MS |
386 | <dt>argv[4]</dt> |
387 | <dd>The number of copies to print</dd> | |
f7deaa1a | 388 | |
5a738aea MS |
389 | <dt>argv[5]</dt> |
390 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 391 | |
5a738aea MS |
392 | <dt>argv[6]</dt> |
393 | <dd>The file to print (first filter only)</dd> | |
394 | </dl> | |
f7deaa1a | 395 | |
5a738aea MS |
396 | <p>The scheduler runs one or more of these programs to print any given job. The |
397 | first filter reads from the print file and writes to the standard output, while | |
398 | the remaining filters read from the standard input and write to the standard | |
399 | output. The backend is the last filter in the chain and writes to the | |
400 | device.</p> | |
f7deaa1a | 401 | |
ac884b6a MS |
402 | <h3><a name="SECURITY">Security Considerations</a></h3> |
403 | ||
404 | <p>It is always important to use security programming practices. Filters and | |
405 | most backends are run as a non-priviledged user, so the major security | |
406 | consideration is resource utilization - filters should not depend on unlimited | |
407 | amounts of CPU, memory, or disk space, and should protect against conditions | |
408 | that could lead to excess usage of any resource like infinite loops and | |
409 | unbounded recursion. In addition, filters must <em>never</em> allow the user to | |
410 | specify an arbitrary file path to a separator page, template, or other file | |
411 | used by the filter since that can lead to an unauthorized disclosure of | |
412 | information. <em>Always</em> treat input as suspect and validate it!</p> | |
413 | ||
414 | <p>If you are developing a backend that runs as root, make sure to check for | |
415 | potential buffer overflows, integer under/overflow conditions, and file | |
416 | accesses since these can lead to privilege escalations. When writing files, | |
417 | always validate the file path and <em>never</em> allow a user to determine | |
418 | where to store a file.</p> | |
419 | ||
420 | <blockquote><b>Note:</b> | |
421 | ||
422 | <p><em>Never</em> write files to a user's home directory. Aside from the | |
423 | security implications, CUPS is a network print service and as such the network | |
424 | user may not be the same as the local user and/or there may not be a local home | |
425 | directory to write to.</p> | |
426 | ||
427 | <p>In addition, some operating systems provide additional security mechanisms | |
428 | that further limit file system access, even for backends running as root. On | |
429 | Mac OS X, for example, no backend may write to a user's home directory.</p> | |
430 | </blockquote> | |
431 | ||
432 | <h3><a name="TEMPFILES">Temporary Files</a></h3> | |
433 | ||
434 | <p>Temporary files should be created in the directory specified by the | |
435 | "TMPDIR" environment variable. The | |
436 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
437 | used to safely create temporary files in this directory.</p> | |
438 | ||
439 | <h3><a name="COPIES">Copy Generation</a></h3> | |
440 | ||
441 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
442 | of the input file. In general, you should only generate copies if the | |
443 | <em>filename</em> argument is supplied. The only exception to this are | |
444 | filters that produce device-independent PostScript output, since the PostScript | |
445 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
446 | files.</p> | |
447 | ||
5a738aea | 448 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 449 | |
5a738aea MS |
450 | <p>Filters must exit with status 0 when they successfully generate print data |
451 | or 1 when they encounter an error. Backends can return any of the | |
452 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 453 | |
5a738aea | 454 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 455 | |
5a738aea | 456 | <p>The following environment variables are defined by the printing system:</p> |
f7deaa1a | 457 | |
5a738aea | 458 | <dl class="code"> |
f7deaa1a | 459 | |
5a738aea MS |
460 | <dt>APPLE_LANGUAGES</dt> |
461 | <dd>The Apple language identifier associated with the job | |
462 | (Mac OS X only).</dd> | |
f7deaa1a | 463 | |
5a738aea MS |
464 | <dt>CHARSET</dt> |
465 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 466 | |
5a738aea MS |
467 | <dt>CLASS</dt> |
468 | <dd>When a job is submitted to a printer class, contains the name of | |
469 | the destination printer class. Otherwise this environment | |
470 | variable will not be set.</dd> | |
f7deaa1a | 471 | |
5a738aea MS |
472 | <dt>CONTENT_TYPE</dt> |
473 | <dd>The MIME type associated with the file (e.g. | |
474 | application/postscript).</dd> | |
f7deaa1a | 475 | |
5a738aea MS |
476 | <dt>CUPS_CACHEDIR</dt> |
477 | <dd>The directory where cache files can be stored.</dd> | |
f7deaa1a | 478 | |
5a738aea MS |
479 | <dt>CUPS_DATADIR</dt> |
480 | <dd>The directory where data files can be found.</dd> | |
f7deaa1a | 481 | |
5a738aea MS |
482 | <dt>CUPS_SERVERROOT</dt> |
483 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 484 | |
5a738aea MS |
485 | <dt>DEVICE_URI</dt> |
486 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 487 | |
5a738aea MS |
488 | <dt>FINAL_CONTENT_TYPE</dt> |
489 | <dd>The MIME type associated with the printer (e.g. | |
490 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 491 | |
5a738aea MS |
492 | <dt>LANG</dt> |
493 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 494 | |
5a738aea MS |
495 | <dt>PPD</dt> |
496 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
497 | file for this printer.</dd> | |
f7deaa1a | 498 | |
5a738aea MS |
499 | <dt>PRINTER</dt> |
500 | <dd>The name of the printer.</dd> | |
f7deaa1a | 501 | |
5a738aea MS |
502 | <dt>RIP_CACHE</dt> |
503 | <dd>The recommended amount of memory to use for Raster Image | |
504 | Processors (RIPs).</dd> | |
f7deaa1a | 505 | |
5a738aea | 506 | </dl> |
f7deaa1a | 507 | |
5a738aea | 508 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 509 | |
5a738aea MS |
510 | <p>Filters and backends communicate wih the scheduler by writing messages |
511 | to the standard error file. For example, the following code sets the current | |
512 | printer state message to "Printing page 5":</p> | |
f7deaa1a | 513 | |
5a738aea MS |
514 | <pre class="example"> |
515 | int page = 5; | |
f7deaa1a | 516 | |
5a738aea | 517 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 518 | </pre> |
519 | ||
5a738aea MS |
520 | <p>Each message is a single line of text starting with one of the following |
521 | prefix strings:</p> | |
522 | ||
523 | <dl class="code"> | |
524 | ||
525 | <dt>ALERT: message</dt> | |
526 | <dd>Sets the printer-state-message attribute and adds the specified | |
527 | message to the current error log file using the "alert" log level.</dd> | |
528 | ||
529 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
530 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
531 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
532 | <code>marker-names</code>, <code>marker-types</code>, | |
533 | <code>printer-alert</code>, and <code>printer-alert-description</code> | |
534 | printer attributes.</dd> | |
535 | ||
536 | <dt>CRIT: message</dt> | |
537 | <dd>Sets the printer-state-message attribute and adds the specified | |
538 | message to the current error log file using the "critical" log | |
539 | level.</dd> | |
540 | ||
541 | <dt>DEBUG: message</dt> | |
542 | <dd>Sets the printer-state-message attribute and adds the specified | |
543 | message to the current error log file using the "debug" log level.</dd> | |
544 | ||
545 | <dt>DEBUG2: message</dt> | |
546 | <dd>Sets the printer-state-message attribute and adds the specified | |
547 | message to the current error log file using the "debug2" log level.</dd> | |
548 | ||
549 | <dt>EMERG: message</dt> | |
550 | <dd>Sets the printer-state-message attribute and adds the specified | |
551 | message to the current error log file using the "emergency" log | |
552 | level.</dd> | |
553 | ||
554 | <dt>ERROR: message</dt> | |
555 | <dd>Sets the printer-state-message attribute and adds the specified | |
556 | message to the current error log file using the "error" log level.</dd> | |
557 | ||
558 | <dt>INFO: message</dt> | |
559 | <dd>Sets the printer-state-message attribute. If the current log level | |
560 | is set to "debug2", also adds the specified message to the current error | |
561 | log file using the "info" log level.</dd> | |
562 | ||
563 | <dt>NOTICE: message</dt> | |
564 | <dd>Sets the printer-state-message attribute and adds the specified | |
565 | message to the current error log file using the "notice" log level.</dd> | |
566 | ||
567 | <dt>PAGE: page-number #-copies</dt> | |
568 | <dt>PAGE: total #-pages</dt> | |
569 | <dd>Adds an entry to the current page log file. The first form adds | |
570 | #-copies to the job-media-sheets-completed attribute. The second | |
571 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
572 | ||
573 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> | |
574 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
575 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
576 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
577 | current queue. Typically this is used to indicate media, ink, and | |
578 | toner conditions on a printer.</dd> | |
579 | ||
580 | <dt>WARNING: message</dt> | |
581 | <dd>Sets the printer-state-message attribute and adds the specified | |
582 | message to the current error log file using the "warning" log | |
583 | level.</dd> | |
584 | ||
585 | </dl> | |
586 | ||
587 | <p>Messages without one of these prefixes are treated as if they began with | |
588 | the "DEBUG:" prefix string.</p> | |
589 | ||
590 | <h3><a name="COMMUNICATING">Communicating with the Backend</a></h3> | |
591 | ||
592 | <p>Filters can communicate with the backend via the | |
593 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
594 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
595 | functions. The | |
596 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function | |
597 | reads data that has been sent back from the device and is typically used to | |
598 | obtain status and configuration information. For example, the following code | |
599 | polls the backend for back-channel data:</p> | |
600 | ||
601 | <pre class="example"> | |
602 | #include <cups/cups.h> | |
603 | ||
604 | char buffer[8192]; | |
605 | ssize_t bytes; | |
606 | ||
607 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
608 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
609 | </pre> | |
f7deaa1a | 610 | |
5a738aea MS |
611 | The |
612 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
613 | function allows you to get out-of-band status information and do synchronization | |
614 | with the device. For example, the following code gets the current IEEE-1284 | |
615 | device ID string from the backend:</p> | |
616 | ||
617 | <pre class="example"> | |
f7deaa1a | 618 | #include <cups/sidechannel.h> |
619 | ||
620 | char data[2049]; | |
621 | int datalen; | |
5a738aea | 622 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 623 | |
624 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for nul-termination... */ | |
625 | datalen = sizeof(data) - 1; | |
626 | ||
627 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 628 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 629 | |
630 | /* Use the returned value if OK was returned and the length is non-zero */ | |
631 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
632 | data[datalen] = '\0'; | |
633 | else | |
634 | data[0] = '\0'; | |
635 | </pre> | |
636 | ||
5a738aea MS |
637 | <p>Backends communicate with filters using the reciprocal functions |
638 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
639 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
640 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
641 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 642 | |
5a738aea MS |
643 | <pre class="example"> |
644 | #include <cups/cups.h> | |
f7deaa1a | 645 | |
5a738aea MS |
646 | char buffer[8192]; |
647 | ssize_t bytes; | |
f7deaa1a | 648 | |
5a738aea MS |
649 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
650 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 651 | </pre> |
652 | ||
5a738aea MS |
653 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
654 | function reads a side-channel command from a filter, driver, or port monitor. | |
655 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
656 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
657 | separate thread for that purpose), or use <code>select</code> or | |
658 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
659 | input and output on several file descriptors at the same time. Backends can pass | |
660 | <code>NULL</code> for the <code>data</code> and <code>datalen</code> parameters | |
661 | since none of the commands sent by upstream filters contain any data at this | |
662 | time.</p> | |
663 | ||
664 | <p>Once a command is processed, the backend uses the | |
665 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
666 | to send its response. For example, the following code shows how to poll for a | |
667 | side-channel command and respond to it:</p> | |
668 | ||
669 | <pre class="example"> | |
f7deaa1a | 670 | #include <cups/sidechannel.h> |
671 | ||
5a738aea MS |
672 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
673 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
f7deaa1a | 674 | |
675 | /* Poll for a command... */ | |
5a738aea | 676 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, NULL, NULL, 0.0)) |
f7deaa1a | 677 | { |
678 | char data[2048]; | |
679 | int datalen; | |
680 | ||
681 | switch (command) | |
682 | { | |
5a738aea | 683 | /* handle supported commands, file data/datalen/status with values as needed */ |
f7deaa1a | 684 | |
685 | default : | |
686 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
687 | datalen = 0; | |
688 | break; | |
689 | } | |
690 | ||
691 | /* Send a response... */ | |
5a738aea | 692 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 693 | } |
694 | </pre> | |
ac884b6a MS |
695 | |
696 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
697 | ||
698 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
699 | status, page counter, and supply levels from most network printers. Every | |
700 | piece of information is associated with an Object Identifier (OID), and | |
701 | every printer has a <em>community</em> name associated with it. OIDs can be | |
702 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
703 | ||
704 | <p>The CUPS SNMP functions provide a simple API for querying network printers. | |
705 | Queries are made using a datagram socket that is created using | |
706 | <a href="#cupsSNMPOpen"><code>cupsSNMPOpen</code></a> and destroyed using | |
707 | <a href="#cupsSNMPClose"><code>cupsSNMPClose</code></a>:</p> | |
708 | ||
709 | <pre class="example"> | |
710 | #include <cups/snmp.h> | |
711 | ||
712 | int snmp = <a href="#cupsSNMPOpen">cupsSNMPOpen</a>(AF_INET); | |
713 | ||
714 | /* do some queries */ | |
715 | ||
716 | <a href="#cupsSNMPClose">cupsSNMPClose</a>(snmp); | |
717 | </pre> | |
718 | ||
719 | <p>OIDs are simple C arrays of integers, terminated by a value of -1. For | |
720 | example, the page counter OID .1.3.6.1.2.1.43.10.2.1.4.1.1 would be:</p> | |
721 | ||
722 | <pre class="example"> | |
723 | int page_counter_oid[] = { 1, 3, 6, 1, 2, 1, 43, 10, 2, 1, 4, 1, 1, -1 }; | |
724 | </pre> | |
725 | ||
726 | <p>You send a query using | |
727 | <a href="#cupsSNMPWrite"><code>cupsSNMPWrite</code></a> and read the value back | |
728 | using <a href="#cupsSNMPRead"><code>cupsSNMPRead</code></a>. The value is read | |
729 | into a structure called <a href="#cups_snmp_t"><code>cups_snmp_t</code></a>:</p> | |
730 | ||
731 | <pre class="example"> | |
732 | #include <cups/snmp.h> | |
733 | ||
734 | int page_counter_oid[] = { 1, 3, 6, 1, 2, 1, 43, 10, 2, 1, 4, 1, 1, -1 }; | |
735 | http_addrlist_t *host = httpAddrGetList("myprinter", AF_UNSPEC, "161"); | |
736 | int snmp = <a href="#cupsSNMPOpen">cupsSNMPOpen</a>(host->addr.addr.sa_family); | |
737 | <a href="#cups_snmp_t">cups_snmp_t</a> packet; | |
738 | ||
739 | <a href="#cupsSNMPWrite">cupsSNMPWrite</a>(snmp, &(host->addr), CUPS_SNMP_VERSION_1, | |
740 | <a href="#cupsSNMPDefaultCommunity">cupsSNMPDefaultCommunity</a>(), CUPS_ASN1_GET_REQUEST, 1, | |
741 | page_counter_oid); | |
742 | if (<a href="#cupsSNMPRead">cupsSNMPRead</a>(snmp, &packet, 5000)) | |
743 | { | |
744 | /* Do something with the value */ | |
745 | printf("Page counter is: %d\n", packet.object_value.integer); | |
746 | } | |
747 | </pre> | |
748 | ||
749 | <p>The <a href="#cupsSNMPWalk"><code>cupsSNMPWalk</code></a> function allows you | |
750 | to query a whole group of OIDs, calling a function of your choice for each OID | |
751 | that is found:</p> | |
752 | ||
753 | <pre class="example"> | |
754 | #include <cups/snmp.h> | |
755 | ||
756 | void | |
757 | my_callback(<a href="#cups_snmp_t">cups_snmp_t</a> *packet, void *data) | |
758 | { | |
759 | /* Do something with the value */ | |
760 | } | |
761 | ||
762 | int printer_mib_oid[] = { 1, 3, 6, 1, 2, 1, 43, -1 }; | |
763 | http_addrlist_t *host = httpAddrGetList("myprinter", AF_UNSPEC, "161"); | |
764 | int snmp = <a href="#cupsSNMPOpen">cupsSNMPOpen</a>(host->addr.addr.sa_family); | |
765 | void *my_data; | |
766 | ||
767 | <a href="#cupsSNMPWalk">cupsSNMPWalk</a>(snmp, &(host->addr), CUPS_SNMP_VERSION_1, | |
768 | <a href="#cupsSNMPDefaultCommunity">cupsSNMPDefaultCommunity</a>(), printer_mib_oid, my_callback, my_data); | |
769 | </pre> | |
5a738aea MS |
770 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
771 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> | |
772 | <p class="description">Read data from the backchannel.</p> | |
773 | <p class="code"> | |
774 | ssize_t cupsBackChannelRead (<br> | |
775 | char *buffer,<br> | |
776 | size_t bytes,<br> | |
777 | double timeout<br> | |
778 | );</p> | |
779 | <h4 class="parameters">Parameters</h4> | |
780 | <dl> | |
781 | <dt>buffer</dt> | |
782 | <dd class="description">Buffer to read</dd> | |
783 | <dt>bytes</dt> | |
784 | <dd class="description">Bytes to read</dd> | |
785 | <dt>timeout</dt> | |
786 | <dd class="description">Timeout in seconds</dd> | |
787 | </dl> | |
788 | <h4 class="returnvalue">Return Value</h4> | |
789 | <p class="description">Bytes read or -1 on error</p> | |
790 | <h4 class="discussion">Discussion</h4> | |
791 | <p class="discussion">Reads up to "bytes" bytes from the backchannel. The "timeout" | |
ef416fc2 | 792 | parameter controls how many seconds to wait for the data - use |
793 | 0.0 to return immediately if there is no data, -1.0 to wait | |
794 | for data indefinitely. | |
795 | ||
5a738aea MS |
796 | </p> |
797 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> | |
798 | <p class="description">Write data to the backchannel.</p> | |
799 | <p class="code"> | |
800 | ssize_t cupsBackChannelWrite (<br> | |
801 | const char *buffer,<br> | |
802 | size_t bytes,<br> | |
803 | double timeout<br> | |
804 | );</p> | |
805 | <h4 class="parameters">Parameters</h4> | |
806 | <dl> | |
807 | <dt>buffer</dt> | |
808 | <dd class="description">Buffer to write</dd> | |
809 | <dt>bytes</dt> | |
810 | <dd class="description">Bytes to write</dd> | |
811 | <dt>timeout</dt> | |
812 | <dd class="description">Timeout in seconds</dd> | |
813 | </dl> | |
814 | <h4 class="returnvalue">Return Value</h4> | |
815 | <p class="description">Bytes written or -1 on error</p> | |
816 | <h4 class="discussion">Discussion</h4> | |
817 | <p class="discussion">Writes "bytes" bytes to the backchannel. The "timeout" parameter | |
ef416fc2 | 818 | controls how many seconds to wait for the data to be written - use |
819 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
820 | indefinitely. | |
821 | ||
ac884b6a MS |
822 | </p> |
823 | <h3 class="function"><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> | |
824 | <p class="description">Get the device URI for a backend.</p> | |
825 | <p class="code"> | |
826 | const char *cupsBackendDeviceURI (<br> | |
827 | char **argv<br> | |
828 | );</p> | |
829 | <h4 class="parameters">Parameters</h4> | |
830 | <dl> | |
831 | <dt>argv</dt> | |
832 | <dd class="description">Command-line arguments</dd> | |
833 | </dl> | |
834 | <h4 class="returnvalue">Return Value</h4> | |
835 | <p class="description">Device URI or <code>NULL</code></p> | |
836 | <h4 class="discussion">Discussion</h4> | |
837 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
838 | function returns the device URI passed in the DEVICE_URI environment | |
839 | variable or the device URI passed in argv[0], whichever is found | |
840 | first.</p> | |
841 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPClose">cupsSNMPClose</a></h3> | |
842 | <p class="description">Close a SNMP socket.</p> | |
843 | <p class="code"> | |
844 | void cupsSNMPClose (<br> | |
845 | int fd<br> | |
846 | );</p> | |
847 | <h4 class="parameters">Parameters</h4> | |
848 | <dl> | |
849 | <dt>fd</dt> | |
850 | <dd class="description">SNMP socket file descriptor</dd> | |
851 | </dl> | |
852 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPCopyOID">cupsSNMPCopyOID</a></h3> | |
853 | <p class="description">Copy an OID.</p> | |
854 | <p class="code"> | |
855 | int *cupsSNMPCopyOID (<br> | |
856 | int *dst,<br> | |
857 | const int *src,<br> | |
858 | int dstsize<br> | |
859 | );</p> | |
860 | <h4 class="parameters">Parameters</h4> | |
861 | <dl> | |
862 | <dt>dst</dt> | |
863 | <dd class="description">Destination OID</dd> | |
864 | <dt>src</dt> | |
865 | <dd class="description">Source OID</dd> | |
866 | <dt>dstsize</dt> | |
867 | <dd class="description">Number of integers in dst</dd> | |
868 | </dl> | |
869 | <h4 class="returnvalue">Return Value</h4> | |
870 | <p class="description">New OID</p> | |
871 | <h4 class="discussion">Discussion</h4> | |
872 | <p class="discussion">The array pointed to by "src" is terminated by the value -1. | |
873 | ||
874 | </p> | |
875 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPDefaultCommunity">cupsSNMPDefaultCommunity</a></h3> | |
876 | <p class="description">Get the default SNMP community name.</p> | |
877 | <p class="code"> | |
878 | const char *cupsSNMPDefaultCommunity (void);</p> | |
879 | <h4 class="returnvalue">Return Value</h4> | |
880 | <p class="description">Default community name</p> | |
881 | <h4 class="discussion">Discussion</h4> | |
882 | <p class="discussion">The default community name is the first community name found in the | |
883 | snmp.conf file. If no community name is defined there, "public" is used. | |
884 | ||
885 | </p> | |
886 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPIsOID">cupsSNMPIsOID</a></h3> | |
887 | <p class="description">Test whether a SNMP response contains the specified OID.</p> | |
888 | <p class="code"> | |
889 | int cupsSNMPIsOID (<br> | |
890 | <a href="#cups_snmp_t">cups_snmp_t</a> *packet,<br> | |
891 | const int *oid<br> | |
892 | );</p> | |
893 | <h4 class="parameters">Parameters</h4> | |
894 | <dl> | |
895 | <dt>packet</dt> | |
896 | <dd class="description">Response packet</dd> | |
897 | <dt>oid</dt> | |
898 | <dd class="description">OID</dd> | |
899 | </dl> | |
900 | <h4 class="returnvalue">Return Value</h4> | |
901 | <p class="description">1 if equal, 0 if not equal</p> | |
902 | <h4 class="discussion">Discussion</h4> | |
903 | <p class="discussion">The array pointed to by "oid" is terminated by the value -1. | |
904 | ||
905 | </p> | |
906 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPIsOIDPrefixed">cupsSNMPIsOIDPrefixed</a></h3> | |
907 | <p class="description">Test whether a SNMP response uses the specified | |
908 | OID prefix.</p> | |
909 | <p class="code"> | |
910 | int cupsSNMPIsOIDPrefixed (<br> | |
911 | <a href="#cups_snmp_t">cups_snmp_t</a> *packet,<br> | |
912 | const int *prefix<br> | |
913 | );</p> | |
914 | <h4 class="parameters">Parameters</h4> | |
915 | <dl> | |
916 | <dt>packet</dt> | |
917 | <dd class="description">Response packet</dd> | |
918 | <dt>prefix</dt> | |
919 | <dd class="description">OID prefix</dd> | |
920 | </dl> | |
921 | <h4 class="returnvalue">Return Value</h4> | |
922 | <p class="description">1 if prefixed, 0 if not prefixed</p> | |
923 | <h4 class="discussion">Discussion</h4> | |
924 | <p class="discussion">The array pointed to by "prefix" is terminated by the value -1. | |
925 | ||
926 | </p> | |
927 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPOpen">cupsSNMPOpen</a></h3> | |
928 | <p class="description">Open a SNMP socket.</p> | |
929 | <p class="code"> | |
930 | int cupsSNMPOpen (<br> | |
931 | int family<br> | |
932 | );</p> | |
933 | <h4 class="parameters">Parameters</h4> | |
934 | <dl> | |
935 | <dt>family</dt> | |
936 | <dd class="description">Address family - <code>AF_INET</code> or <code>AF_INET6</code></dd> | |
937 | </dl> | |
938 | <h4 class="returnvalue">Return Value</h4> | |
939 | <p class="description">SNMP socket file descriptor</p> | |
940 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPRead">cupsSNMPRead</a></h3> | |
941 | <p class="description">Read and parse a SNMP response.</p> | |
942 | <p class="code"> | |
943 | <a href="#cups_snmp_t">cups_snmp_t</a> *cupsSNMPRead (<br> | |
944 | int fd,<br> | |
945 | <a href="#cups_snmp_t">cups_snmp_t</a> *packet,<br> | |
568fa3fa | 946 | double timeout<br> |
ac884b6a MS |
947 | );</p> |
948 | <h4 class="parameters">Parameters</h4> | |
949 | <dl> | |
950 | <dt>fd</dt> | |
951 | <dd class="description">SNMP socket file descriptor</dd> | |
952 | <dt>packet</dt> | |
953 | <dd class="description">SNMP packet buffer</dd> | |
568fa3fa MS |
954 | <dt>timeout</dt> |
955 | <dd class="description">Timeout in seconds</dd> | |
ac884b6a MS |
956 | </dl> |
957 | <h4 class="returnvalue">Return Value</h4> | |
958 | <p class="description">SNMP packet or <code>NULL</code> if none</p> | |
959 | <h4 class="discussion">Discussion</h4> | |
960 | <p class="discussion">If "timeout" is negative, <code>cupsSNMPRead</code> will wait for a response | |
961 | indefinitely. | |
962 | ||
963 | </p> | |
964 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPSetDebug">cupsSNMPSetDebug</a></h3> | |
965 | <p class="description">Enable/disable debug logging to stderr.</p> | |
966 | <p class="code"> | |
967 | void cupsSNMPSetDebug (<br> | |
968 | int level<br> | |
969 | );</p> | |
970 | <h4 class="parameters">Parameters</h4> | |
971 | <dl> | |
972 | <dt>level</dt> | |
973 | <dd class="description">1 to enable debug output, 0 otherwise</dd> | |
974 | </dl> | |
975 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPWalk">cupsSNMPWalk</a></h3> | |
976 | <p class="description">Enumerate a group of OIDs.</p> | |
977 | <p class="code"> | |
978 | int cupsSNMPWalk (<br> | |
979 | int fd,<br> | |
980 | http_addr_t *address,<br> | |
981 | int version,<br> | |
982 | const char *community,<br> | |
983 | const int *prefix,<br> | |
568fa3fa | 984 | double timeout,<br> |
ac884b6a MS |
985 | <a href="#cups_snmp_cb_t">cups_snmp_cb_t</a> cb,<br> |
986 | void *data<br> | |
987 | );</p> | |
988 | <h4 class="parameters">Parameters</h4> | |
989 | <dl> | |
990 | <dt>fd</dt> | |
991 | <dd class="description">SNMP socket</dd> | |
992 | <dt>address</dt> | |
993 | <dd class="description">Address to query</dd> | |
994 | <dt>version</dt> | |
995 | <dd class="description">SNMP version</dd> | |
996 | <dt>community</dt> | |
997 | <dd class="description">Community name</dd> | |
998 | <dt>prefix</dt> | |
999 | <dd class="description">OID prefix</dd> | |
568fa3fa MS |
1000 | <dt>timeout</dt> |
1001 | <dd class="description">Timeout for each response in seconds</dd> | |
ac884b6a MS |
1002 | <dt>cb</dt> |
1003 | <dd class="description">Function to call for each response</dd> | |
1004 | <dt>data</dt> | |
1005 | <dd class="description">User data pointer that is passed to the callback function</dd> | |
1006 | </dl> | |
1007 | <h4 class="returnvalue">Return Value</h4> | |
1008 | <p class="description">Number of OIDs found or -1 on error</p> | |
1009 | <h4 class="discussion">Discussion</h4> | |
1010 | <p class="discussion">This function queries all of the OIDs with the specified OID prefix, | |
1011 | calling the "cb" function for every response that is received.<br> | |
1012 | <br> | |
568fa3fa MS |
1013 | The array pointed to by "prefix" is terminated by the value -1.<br> |
1014 | <br> | |
1015 | If "timeout" is negative, <code>cupsSNMPWalk</code> will wait for a response | |
1016 | indefinitely. | |
ac884b6a MS |
1017 | |
1018 | </p> | |
1019 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSNMPWrite">cupsSNMPWrite</a></h3> | |
1020 | <p class="description">Send an SNMP query packet.</p> | |
1021 | <p class="code"> | |
1022 | int cupsSNMPWrite (<br> | |
1023 | int fd,<br> | |
1024 | http_addr_t *address,<br> | |
1025 | int version,<br> | |
1026 | const char *community,<br> | |
1027 | <a href="#cups_asn1_t">cups_asn1_t</a> request_type,<br> | |
1028 | const unsigned request_id,<br> | |
1029 | const int *oid<br> | |
1030 | );</p> | |
1031 | <h4 class="parameters">Parameters</h4> | |
1032 | <dl> | |
1033 | <dt>fd</dt> | |
1034 | <dd class="description">SNMP socket</dd> | |
1035 | <dt>address</dt> | |
1036 | <dd class="description">Address to send to</dd> | |
1037 | <dt>version</dt> | |
1038 | <dd class="description">SNMP version</dd> | |
1039 | <dt>community</dt> | |
1040 | <dd class="description">Community name</dd> | |
1041 | <dt>request_type</dt> | |
1042 | <dd class="description">Request type</dd> | |
1043 | <dt>request_id</dt> | |
1044 | <dd class="description">Request ID</dd> | |
1045 | <dt>oid</dt> | |
1046 | <dd class="description">OID</dd> | |
1047 | </dl> | |
1048 | <h4 class="returnvalue">Return Value</h4> | |
1049 | <p class="description">1 on success, 0 on error</p> | |
1050 | <h4 class="discussion">Discussion</h4> | |
1051 | <p class="discussion">The array pointed to by "oid" is terminated by the value -1. | |
1052 | ||
5a738aea MS |
1053 | </p> |
1054 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> | |
1055 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> | |
1056 | <p class="code"> | |
1057 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
1058 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1059 | char *data,<br> | |
1060 | int *datalen,<br> | |
1061 | double timeout<br> | |
1062 | );</p> | |
1063 | <h4 class="parameters">Parameters</h4> | |
1064 | <dl> | |
1065 | <dt>command</dt> | |
1066 | <dd class="description">Command to send</dd> | |
1067 | <dt>data</dt> | |
1068 | <dd class="description">Response data buffer pointer</dd> | |
1069 | <dt>datalen</dt> | |
1070 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1071 | <dt>timeout</dt> | |
1072 | <dd class="description">Timeout in seconds</dd> | |
1073 | </dl> | |
1074 | <h4 class="returnvalue">Return Value</h4> | |
1075 | <p class="description">Status of command</p> | |
1076 | <h4 class="discussion">Discussion</h4> | |
1077 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 1078 | monitors in order to communicate with the backend used by the current |
1079 | printer. Programs must be prepared to handle timeout or "not | |
1080 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
1081 | do not support the specified side-channel command.<br> |
1082 | <br> | |
1083 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1084 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1085 | update the value to contain the number of data bytes in the buffer. | |
1086 | ||
5a738aea MS |
1087 | </p> |
1088 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> | |
1089 | <p class="description">Read a side-channel message.</p> | |
1090 | <p class="code"> | |
1091 | int cupsSideChannelRead (<br> | |
1092 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
1093 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
1094 | char *data,<br> | |
1095 | int *datalen,<br> | |
1096 | double timeout<br> | |
1097 | );</p> | |
1098 | <h4 class="parameters">Parameters</h4> | |
1099 | <dl> | |
1100 | <dt>command</dt> | |
1101 | <dd class="description">Command code</dd> | |
1102 | <dt>status</dt> | |
1103 | <dd class="description">Status code</dd> | |
1104 | <dt>data</dt> | |
1105 | <dd class="description">Data buffer pointer</dd> | |
1106 | <dt>datalen</dt> | |
1107 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1108 | <dt>timeout</dt> | |
1109 | <dd class="description">Timeout in seconds</dd> | |
1110 | </dl> | |
1111 | <h4 class="returnvalue">Return Value</h4> | |
1112 | <p class="description">0 on success, -1 on error</p> | |
1113 | <h4 class="discussion">Discussion</h4> | |
1114 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 1115 | commands from a filter, driver, or port monitor program. The |
1116 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
1117 | and return the corresponding status codes.<br> |
1118 | <br> | |
1119 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1120 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1121 | update the value to contain the number of data bytes in the buffer. | |
1122 | ||
5a738aea MS |
1123 | </p> |
1124 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> | |
1125 | <p class="description">Write a side-channel message.</p> | |
1126 | <p class="code"> | |
1127 | int cupsSideChannelWrite (<br> | |
1128 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1129 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
1130 | const char *data,<br> | |
1131 | int datalen,<br> | |
1132 | double timeout<br> | |
1133 | );</p> | |
1134 | <h4 class="parameters">Parameters</h4> | |
1135 | <dl> | |
1136 | <dt>command</dt> | |
1137 | <dd class="description">Command code</dd> | |
1138 | <dt>status</dt> | |
1139 | <dd class="description">Status code</dd> | |
1140 | <dt>data</dt> | |
1141 | <dd class="description">Data buffer pointer</dd> | |
1142 | <dt>datalen</dt> | |
1143 | <dd class="description">Number of bytes of data</dd> | |
1144 | <dt>timeout</dt> | |
1145 | <dd class="description">Timeout in seconds</dd> | |
1146 | </dl> | |
1147 | <h4 class="returnvalue">Return Value</h4> | |
1148 | <p class="description">0 on success, -1 on error</p> | |
1149 | <h4 class="discussion">Discussion</h4> | |
1150 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 1151 | responses to a filter, driver, or port monitor program. |
1152 | ||
5a738aea MS |
1153 | </p> |
1154 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
ac884b6a MS |
1155 | <h3 class="typedef"><a name="cups_asn1_t">cups_asn1_t</a></h3> |
1156 | <p class="description">ASN1 request/object types</p> | |
1157 | <p class="code"> | |
1158 | typedef enum <a href="#cups_asn1_e">cups_asn1_e</a> cups_asn1_t; | |
1159 | </p> | |
5a738aea MS |
1160 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> |
1161 | <p class="description">Backend exit codes</p> | |
1162 | <p class="code"> | |
1163 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
1164 | </p> | |
1165 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
1166 | <p class="description">Bidirectional capabilities</p> | |
1167 | <p class="code"> | |
1168 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1169 | </p> | |
1170 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1171 | <p class="description">Request command codes</p> | |
1172 | <p class="code"> | |
1173 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1174 | </p> | |
1175 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> | |
1176 | <p class="description">Printer state bits</p> | |
1177 | <p class="code"> | |
1178 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1179 | </p> | |
1180 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1181 | <p class="description">Response status codes</p> | |
1182 | <p class="code"> | |
1183 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1184 | </p> | |
ac884b6a MS |
1185 | <h3 class="typedef"><a name="cups_snmp_cb_t">cups_snmp_cb_t</a></h3> |
1186 | <p class="description">Prototypes...</p> | |
1187 | <p class="code"> | |
1188 | typedef void (*cups_snmp_cb_t)(<a href="#cups_snmp_t">cups_snmp_t</a> *packet, void *data); | |
1189 | </p> | |
1190 | <h3 class="typedef"><a name="cups_snmp_t">cups_snmp_t</a></h3> | |
1191 | <p class="description">SNMP data packet</p> | |
1192 | <p class="code"> | |
1193 | typedef struct <a href="#cups_snmp_s">cups_snmp_s</a> cups_snmp_t; | |
1194 | </p> | |
1195 | <h2 class="title"><a name="STRUCTURES">Structures</a></h2> | |
1196 | <h3 class="struct"><a name="cups_snmp_hexstring_s">cups_snmp_hexstring_s</a></h3> | |
1197 | <p class="description">Hex-STRING value</p> | |
1198 | <p class="code">struct cups_snmp_hexstring_s {<br> | |
1199 | unsigned char bytes[CUPS_SNMP_MAX_STRING];<br> | |
1200 | int num_bytes;<br> | |
1201 | };</p> | |
1202 | <h4 class="members">Members</h4> | |
1203 | <dl> | |
1204 | <dt>bytes[CUPS_SNMP_MAX_STRING] </dt> | |
1205 | <dd class="description">Bytes in string</dd> | |
1206 | <dt>num_bytes </dt> | |
1207 | <dd class="description">Number of bytes</dd> | |
1208 | </dl> | |
1209 | <h3 class="struct"><a name="cups_snmp_s">cups_snmp_s</a></h3> | |
1210 | <p class="description">SNMP data packet</p> | |
1211 | <p class="code">struct cups_snmp_s {<br> | |
1212 | http_addr_t address;<br> | |
1213 | char community[CUPS_SNMP_MAX_STRING];<br> | |
1214 | const char *error;<br> | |
1215 | int error_index;<br> | |
1216 | int error_status;<br> | |
1217 | int object_name[CUPS_SNMP_MAX_OID];<br> | |
1218 | <a href="#cups_asn1_t">cups_asn1_t</a> object_type;<br> | |
1219 | union <a href="#cups_snmp_value_u">cups_snmp_value_u</a> object_value;<br> | |
1220 | int request_id;<br> | |
1221 | <a href="#cups_asn1_t">cups_asn1_t</a> request_type;<br> | |
1222 | int version;<br> | |
1223 | };</p> | |
1224 | <h4 class="members">Members</h4> | |
1225 | <dl> | |
1226 | <dt>address </dt> | |
1227 | <dd class="description">Source address</dd> | |
1228 | <dt>community[CUPS_SNMP_MAX_STRING] </dt> | |
1229 | <dd class="description">Community name</dd> | |
1230 | <dt>error </dt> | |
1231 | <dd class="description">Encode/decode error</dd> | |
1232 | <dt>error_index </dt> | |
1233 | <dd class="description">error-index value</dd> | |
1234 | <dt>error_status </dt> | |
1235 | <dd class="description">error-status value</dd> | |
1236 | <dt>object_name[CUPS_SNMP_MAX_OID] </dt> | |
1237 | <dd class="description">object-name value</dd> | |
1238 | <dt>object_type </dt> | |
1239 | <dd class="description">object-value type</dd> | |
1240 | <dt>object_value </dt> | |
1241 | <dd class="description">object-value value</dd> | |
1242 | <dt>request_id </dt> | |
1243 | <dd class="description">request-id value</dd> | |
1244 | <dt>request_type </dt> | |
1245 | <dd class="description">Request type</dd> | |
1246 | <dt>version </dt> | |
1247 | <dd class="description">Version number</dd> | |
1248 | </dl> | |
1249 | <h2 class="title"><a name="UNIONS">Unions</a></h2> | |
1250 | <h3 class="union"><a name="cups_snmp_value_u">cups_snmp_value_u</a></h3> | |
1251 | <p class="description">Object value</p> | |
1252 | <p class="code">union cups_snmp_value_u {<br> | |
1253 | int boolean;<br> | |
1254 | unsigned counter;<br> | |
1255 | unsigned gauge;<br> | |
1256 | struct <a href="#cups_snmp_hexstring_s">cups_snmp_hexstring_s</a> hex_string;<br> | |
1257 | int integer;<br> | |
1258 | int oid[CUPS_SNMP_MAX_OID];<br> | |
1259 | char string[CUPS_SNMP_MAX_STRING];<br> | |
1260 | unsigned timeticks;<br> | |
1261 | };</p> | |
1262 | <h4 class="members">Members</h4> | |
1263 | <dl> | |
1264 | <dt>boolean </dt> | |
1265 | <dd class="description">Boolean value</dd> | |
1266 | <dt>counter </dt> | |
1267 | <dd class="description">Counter value</dd> | |
1268 | <dt>gauge </dt> | |
1269 | <dd class="description">Gauge value</dd> | |
1270 | <dt>hex_string </dt> | |
1271 | <dd class="description">Hex string value</dd> | |
1272 | <dt>integer </dt> | |
1273 | <dd class="description">Integer value</dd> | |
1274 | <dt>oid[CUPS_SNMP_MAX_OID] </dt> | |
1275 | <dd class="description">OID value</dd> | |
1276 | <dt>string[CUPS_SNMP_MAX_STRING] </dt> | |
1277 | <dd class="description">String value</dd> | |
1278 | <dt>timeticks </dt> | |
1279 | <dd class="description">Timeticks value</dd> | |
1280 | </dl> | |
5a738aea | 1281 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
ac884b6a MS |
1282 | <h3 class="enumeration"><a name="cups_asn1_e">cups_asn1_e</a></h3> |
1283 | <p class="description">ASN1 request/object types</p> | |
1284 | <h4 class="constants">Constants</h4> | |
1285 | <dl> | |
1286 | <dt>CUPS_ASN1_BIT_STRING </dt> | |
1287 | <dd class="description">BIT STRING</dd> | |
1288 | <dt>CUPS_ASN1_BOOLEAN </dt> | |
1289 | <dd class="description">BOOLEAN</dd> | |
1290 | <dt>CUPS_ASN1_COUNTER </dt> | |
1291 | <dd class="description">32-bit unsigned aka Counter32</dd> | |
1292 | <dt>CUPS_ASN1_END_OF_CONTENTS </dt> | |
1293 | <dd class="description">End-of-contents</dd> | |
1294 | <dt>CUPS_ASN1_GAUGE </dt> | |
1295 | <dd class="description">32-bit unsigned aka Gauge32</dd> | |
1296 | <dt>CUPS_ASN1_GET_NEXT_REQUEST </dt> | |
1297 | <dd class="description">GetNextRequest-PDU</dd> | |
1298 | <dt>CUPS_ASN1_GET_REQUEST </dt> | |
1299 | <dd class="description">GetRequest-PDU</dd> | |
1300 | <dt>CUPS_ASN1_GET_RESPONSE </dt> | |
1301 | <dd class="description">GetResponse-PDU</dd> | |
1302 | <dt>CUPS_ASN1_HEX_STRING </dt> | |
1303 | <dd class="description">Binary string aka Hex-STRING</dd> | |
1304 | <dt>CUPS_ASN1_INTEGER </dt> | |
1305 | <dd class="description">INTEGER or ENUMERATION</dd> | |
1306 | <dt>CUPS_ASN1_NULL_VALUE </dt> | |
1307 | <dd class="description">NULL VALUE</dd> | |
1308 | <dt>CUPS_ASN1_OCTET_STRING </dt> | |
1309 | <dd class="description">OCTET STRING</dd> | |
1310 | <dt>CUPS_ASN1_OID </dt> | |
1311 | <dd class="description">OBJECT IDENTIFIER</dd> | |
1312 | <dt>CUPS_ASN1_SEQUENCE </dt> | |
1313 | <dd class="description">SEQUENCE</dd> | |
1314 | <dt>CUPS_ASN1_TIMETICKS </dt> | |
1315 | <dd class="description">32-bit unsigned aka Timeticks32</dd> | |
1316 | </dl> | |
5a738aea MS |
1317 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> |
1318 | <p class="description">Backend exit codes</p> | |
1319 | <h4 class="constants">Constants</h4> | |
1320 | <dl> | |
1321 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1322 | <dd class="description">Job failed, authentication required</dd> | |
1323 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1324 | <dd class="description">Job failed, cancel job</dd> | |
1325 | <dt>CUPS_BACKEND_FAILED </dt> | |
1326 | <dd class="description">Job failed, use error-policy</dd> | |
1327 | <dt>CUPS_BACKEND_HOLD </dt> | |
1328 | <dd class="description">Job failed, hold job</dd> | |
1329 | <dt>CUPS_BACKEND_OK </dt> | |
1330 | <dd class="description">Job completed successfully</dd> | |
1331 | <dt>CUPS_BACKEND_STOP </dt> | |
1332 | <dd class="description">Job failed, stop queue</dd> | |
1333 | </dl> | |
1334 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
1335 | <p class="description">Bidirectional capabilities</p> | |
1336 | <h4 class="constants">Constants</h4> | |
1337 | <dl> | |
1338 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1339 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1340 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1341 | <dd class="description">Bidirectional I/O is supported</dd> | |
1342 | </dl> | |
1343 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1344 | <p class="description">Request command codes</p> | |
1345 | <h4 class="constants">Constants</h4> | |
1346 | <dl> | |
1347 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1348 | <dd class="description">Drain all pending output</dd> | |
1349 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1350 | <dd class="description">Return bidirectional capabilities</dd> | |
1351 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> | |
1352 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1353 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1354 | <dd class="description">Return the device state</dd> | |
1355 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> | |
1356 | <dd class="description">Do a soft reset</dd> | |
1357 | </dl> | |
1358 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> | |
1359 | <p class="description">Printer state bits</p> | |
1360 | <h4 class="constants">Constants</h4> | |
1361 | <dl> | |
1362 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1363 | <dd class="description">Device is busy</dd> | |
1364 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1365 | <dd class="description">Other error condition</dd> | |
1366 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1367 | <dd class="description">Toner/ink out condition</dd> | |
1368 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1369 | <dd class="description">Toner/ink low condition</dd> | |
1370 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1371 | <dd class="description">Paper out condition</dd> | |
1372 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1373 | <dd class="description">Paper low condition</dd> | |
1374 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
1375 | <dd class="description">Device is off-line</dd> | |
1376 | <dt>CUPS_SC_STATE_ONLINE </dt> | |
1377 | <dd class="description">Device is on-line</dd> | |
1378 | </dl> | |
1379 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1380 | <p class="description">Response status codes</p> | |
1381 | <h4 class="constants">Constants</h4> | |
1382 | <dl> | |
1383 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1384 | <dd class="description">The command/response message was invalid</dd> | |
1385 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1386 | <dd class="description">An I/O error occurred</dd> | |
1387 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1388 | <dd class="description">No status</dd> | |
1389 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1390 | <dd class="description">Command not implemented</dd> | |
1391 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1392 | <dd class="description">The device did not respond</dd> | |
1393 | <dt>CUPS_SC_STATUS_OK </dt> | |
1394 | <dd class="description">Operation succeeded</dd> | |
1395 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1396 | <dd class="description">The backend did not respond</dd> | |
1397 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1398 | <dd class="description">Response too big</dd> | |
1399 | </dl> | |
1400 | </div> | |
ef416fc2 | 1401 | </body> |
1402 | </html> |