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