]>
Commit | Line | Data |
---|---|---|
abacc52b MS |
1 | --- |
2 | title: CUPS Programming Manual | |
3 | author: Michael R Sweet | |
9c44e2cb | 4 | copyright: Copyright © 2007-2017 by Apple Inc. All Rights Reserved. |
abacc52b MS |
5 | version: 2.2.4 |
6 | ... | |
7 | ||
798d6e29 MS |
8 | > Note: This document is under active development and is incomplete, with a goal |
9 | > completing it prior to releasing CUPS 2.2.4. Please | |
10 | > [file issues on Github](https://github.com/apple/cups/issues) | |
11 | > to provide any feedback. | |
12 | ||
13 | ||
abacc52b MS |
14 | # Introduction |
15 | ||
16 | CUPS provides the "cups" library to talk to the different parts of CUPS and with | |
17 | Internet Printing Protocol (IPP) printers. The "cups" library functions are | |
18 | accessed by including the `<cups/cups.h>` header. | |
19 | ||
20 | CUPS is based on the Internet Printing Protocol ("IPP"), which allows clients | |
21 | (applications) to communicate with a server (the scheduler, printers, etc.) to | |
22 | get a list of destinations, send print jobs, and so forth. You identify which | |
23 | server you want to communicate with using a pointer to the opaque structure | |
24 | `http_t`. The `CUPS_HTTP_DEFAULT` constant can be used when you want to talk to | |
25 | the CUPS scheduler. | |
26 | ||
27 | ||
28 | ## Guidelines | |
29 | ||
30 | When writing software that uses the "cups" library: | |
31 | ||
32 | - Do not use undocumented or deprecated APIs, | |
33 | - Do not rely on pre-configured printers, | |
34 | - Do not assume that printers support specific features or formats, and | |
35 | - Do not rely on implementation details (PPDs, etc.) | |
36 | ||
37 | CUPS is designed to insulate users and developers from the implementation | |
38 | details of printers and file formats. The goal is to allow an application to | |
39 | supply a print file in a standard format with the user intent ("print four | |
40 | copies, two-sided on A4 media, and staple each copy") and have the printing | |
41 | system manage the printer communication and format conversion needed. | |
42 | ||
43 | Similarly, printer and job management applications can use standard query | |
44 | operations to obtain the status information in a common, generic form and use | |
45 | standard management operations to control the state of those printers and jobs. | |
46 | ||
47 | ||
48 | ## Terms Used in This Document | |
49 | ||
50 | A *Destination* is a printer or print queue that accepts print jobs. A | |
51 | *Print Job* is one or more documents that are processed by a destination | |
52 | using options supplied when creating the job. A *Document* is a file (JPEG | |
53 | image, PDF file, etc.) suitable for printing. An *Option* controls some aspect | |
54 | of printing, such as the media used. *Media* is the sheets or roll that is | |
55 | printed on. An *Attribute* is an option encoded for an Internet Printing | |
56 | Protocol (IPP) request. | |
57 | ||
58 | ||
59 | ## Compiling Programs That Use the CUPS API | |
60 | ||
61 | The CUPS libraries can be used from any C, C++, or Objective C program. | |
62 | The method of compiling against the libraries varies depending on the | |
63 | operating system and installation of CUPS. The following sections show how | |
64 | to compile a simple program (shown below) in two common environments. | |
65 | ||
66 | The following simple program lists the available destinations: | |
67 | ||
68 | #include <stdio.h> | |
69 | #include <cups/cups.h> | |
70 | ||
71 | int print_dest(void *user_data, unsigned flags, cups_dest_t *dest) | |
72 | { | |
73 | if (dest->instance) | |
74 | printf("%s/%s\n", dest->name, dest->instance); | |
75 | else | |
76 | puts(dest->name); | |
77 | ||
78 | return (1); | |
79 | } | |
80 | ||
81 | int main(void) | |
82 | { | |
83 | cupsEnumDests(CUPS_DEST_FLAGS_NONE, 1000, NULL, 0, 0, print_dest, NULL); | |
84 | ||
85 | return (0); | |
86 | } | |
87 | ||
88 | ||
89 | ### Compiling with Xcode | |
90 | ||
91 | In Xcode, choose *New Project...* from the *File* menu (or press SHIFT+CMD+N), | |
92 | then select the *Command Line Tool* under the macOS Application project type. | |
93 | Click *Next* and enter a name for the project, for example "firstcups". Click | |
94 | *Next* and choose a project directory. The click *Next* to create the project. | |
95 | ||
96 | In the project window, click on the *Build Phases* group and expand the | |
97 | *Link Binary with Libraries* section. Click *+*, type "libcups" to show the | |
98 | library, and then double-click on `libcups.tbd`. | |
99 | ||
100 | Finally, click on the `main.c` file in the sidebar and copy the example program | |
101 | to the file. Build and run (CMD+R) to see the list of destinations. | |
102 | ||
103 | ||
104 | ### Compiling with GCC | |
105 | ||
106 | From the command-line, create a file called `sample.c` using your favorite | |
107 | editor, copy the example to this file, and save. Then run the following command | |
108 | to compile it with GCC and run it: | |
109 | ||
110 | gcc -o simple `cups-config --cflags` simple.c `cups-config --libs` | |
111 | ./simple | |
112 | ||
113 | The `cups-config` command provides the compiler flags (`cups-config --cflags`) | |
114 | and libraries (`cups-config --libs`) needed for the local system. | |
115 | ||
116 | ||
117 | # Working with Destinations | |
118 | ||
798d6e29 | 119 | Destinations, which in CUPS represent individual printers or classes |
9c44e2cb MS |
120 | (collections or pools) of printers, are represented by the `cups_dest_t` |
121 | structure which includes the name \(`name`), instance \(`instance`, saved | |
122 | options/settings), whether the destination is the default for the user | |
123 | \(`is_default`), and the options and basic information associated with that | |
124 | destination \(`num_options` and `options`). | |
abacc52b | 125 | |
798d6e29 MS |
126 | Historically destinations have been manually maintained by the administrator of |
127 | a system or network, but CUPS also supports dynamic discovery of destinations on | |
128 | the current network. | |
abacc52b | 129 | |
abacc52b | 130 | |
798d6e29 | 131 | ## Finding Available Destinations |
abacc52b | 132 | |
798d6e29 MS |
133 | The `cupsEnumDests` function finds all of the available destinations: |
134 | ||
135 | int | |
136 | cupsEnumDests(unsigned flags, int msec, int *cancel, | |
137 | cups_ptype_t type, cups_ptype_t mask, | |
138 | cups_dest_cb_t cb, void *user_data) | |
139 | ||
140 | The `flags` argument specifies enumeration options, which at present must be | |
141 | `CUPS_DEST_FLAGS_NONE`. | |
142 | ||
143 | The `msec` argument specifies the maximum amount of time that should be used for | |
144 | enumeration in milliseconds - interactive applications should keep this value to | |
145 | 5000 or less when run on the main thread. | |
146 | ||
147 | The `cancel` argument points to an integer variable that, when set to a non-zero | |
148 | value, will cause enumeration to stop as soon as possible. It can be `NULL` if | |
149 | not needed. | |
150 | ||
151 | The `type` and `mask` arguments are bitfields that allow the caller to filter | |
152 | the destinations based on categories and/or capabilities. The destination's | |
153 | "printer-type" value is masked by the `mask` value and compared to the `type` | |
154 | value when filtering. For example, to only enumerate destinations that are | |
155 | hosted on the local system, pass `CUPS_PRINTER_LOCAL` for the `type` argument | |
f50db552 MS |
156 | and `CUPS_PRINTER_DISCOVERED` for the `mask` argument. The following constants |
157 | can be used for filtering: | |
798d6e29 MS |
158 | |
159 | - `CUPS_PRINTER_CLASS`: A collection of destinations. | |
160 | - `CUPS_PRINTER_FAX`: A facsimile device. | |
161 | - `CUPS_PRINTER_LOCAL`: A local printer or class. This constant has the value 0 | |
162 | (no bits set) and is only used for the `type` argument and is paired with the | |
f50db552 MS |
163 | `CUPS_PRINTER_REMOTE` or `CUPS_PRINTER_DISCOVERED` constant passed in the |
164 | `mask` argument. | |
165 | - `CUPS_PRINTER_REMOTE`: A remote (shared) printer or class. | |
166 | - `CUPS_PRINTER_DISCOVERED`: An available network printer or class. | |
798d6e29 MS |
167 | - `CUPS_PRINTER_BW`: Can do B&W printing. |
168 | - `CUPS_PRINTER_COLOR`: Can do color printing. | |
169 | - `CUPS_PRINTER_DUPLEX`: Can do two-sided printing. | |
170 | - `CUPS_PRINTER_STAPLE`: Can staple output. | |
171 | - `CUPS_PRINTER_COLLATE`: Can quickly collate copies. | |
172 | - `CUPS_PRINTER_PUNCH`: Can punch output. | |
173 | - `CUPS_PRINTER_COVER`: Can cover output. | |
174 | - `CUPS_PRINTER_BIND`: Can bind output. | |
175 | - `CUPS_PRINTER_SORT`: Can sort output (mailboxes, etc.) | |
176 | - `CUPS_PRINTER_SMALL`: Can print on Letter/Legal/A4-size media. | |
177 | - `CUPS_PRINTER_MEDIUM`: Can print on Tabloid/B/C/A3/A2-size media. | |
178 | - `CUPS_PRINTER_LARGE`: Can print on D/E/A1/A0-size media. | |
179 | - `CUPS_PRINTER_VARIABLE`: Can print on rolls and custom-size media. | |
180 | ||
181 | The `cb` argument specifies a function to call for every destination that is | |
182 | found: | |
183 | ||
184 | typedef int (*cups_dest_cb_t)(void *user_data, | |
185 | unsigned flags, | |
186 | cups_dest_t *dest); | |
187 | ||
188 | The callback function receives a copy of the `user_data` argument along with a | |
189 | bitfield \(`flags`) and the destination that was found. The `flags` argument | |
190 | can have any of the following constant (bit) values set: | |
191 | ||
192 | - `CUPS_DEST_FLAGS_MORE`: There are more destinations coming. | |
193 | - `CUPS_DEST_FLAGS_REMOVED`: The destination has gone away and should be removed | |
194 | from the list of destinations a user can select. | |
195 | - `CUPS_DEST_FLAGS_ERROR`: An error occurred. The reason for the error can be | |
196 | found by calling the `cupsLastError` and/or `cupsLastErrorString` functions. | |
197 | ||
198 | The callback function returns 0 to stop enumeration or 1 to continue. | |
199 | ||
500fca27 MS |
200 | > Note that the callback function will likely be called multiple times for the |
201 | > same destination, so it is up to the caller to suppress any duplicate | |
202 | > destinations. | |
203 | ||
798d6e29 MS |
204 | The following example shows how to use `cupsEnumDests` to get a filtered array |
205 | of destinations: | |
206 | ||
207 | typedef struct | |
208 | { | |
209 | int num_dests; | |
210 | cups_dest_t *dests; | |
211 | } my_user_data_t; | |
abacc52b | 212 | |
798d6e29 MS |
213 | int |
214 | my_dest_cb(my_user_data_t *user_data, unsigned flags, | |
215 | cups_dest_t *dest) | |
216 | { | |
217 | if (flags & CUPS_DEST_FLAGS_REMOVED) | |
218 | { | |
219 | /* | |
220 | * Remove destination from array... | |
221 | */ | |
222 | ||
223 | user_data->num_dests = | |
224 | cupsRemoveDest(dest->name, dest->instance, | |
225 | user_data->num_dests, | |
226 | &(user_data->dests)); | |
227 | } | |
228 | else | |
229 | { | |
230 | /* | |
231 | * Add destination to array... | |
232 | */ | |
abacc52b | 233 | |
798d6e29 MS |
234 | user_data->num_dests = |
235 | cupsCopyDest(dest, user_data->num_dests, | |
236 | &(user_data->dests)); | |
237 | } | |
abacc52b | 238 | |
798d6e29 MS |
239 | return (1); |
240 | } | |
abacc52b | 241 | |
798d6e29 MS |
242 | int |
243 | my_get_dests(cups_ptype_t type, cups_ptype_t mask, | |
244 | cups_dest_t **dests) | |
245 | { | |
246 | my_user_data_t user_data = { 0, NULL }; | |
abacc52b | 247 | |
798d6e29 MS |
248 | if (!cupsEnumDests(CUPS_DEST_FLAGS_NONE, 1000, NULL, type, |
249 | mask, (cups_dest_cb_t)my_dest_cb, | |
250 | &user_data)) | |
251 | { | |
252 | /* | |
253 | * An error occurred, free all of the destinations and | |
254 | * return... | |
255 | */ | |
abacc52b | 256 | |
798d6e29 | 257 | cupsFreeDests(user_data.num_dests, user_dasta.dests); |
abacc52b | 258 | |
798d6e29 | 259 | *dests = NULL; |
abacc52b | 260 | |
798d6e29 MS |
261 | return (0); |
262 | } | |
abacc52b | 263 | |
798d6e29 MS |
264 | /* |
265 | * Return the destination array... | |
266 | */ | |
abacc52b | 267 | |
798d6e29 | 268 | *dests = user_data.dests; |
abacc52b | 269 | |
798d6e29 MS |
270 | return (user_data.num_dests); |
271 | } | |
abacc52b | 272 | |
abacc52b | 273 | |
798d6e29 MS |
274 | ## Basic Destination Information |
275 | ||
276 | The `num_options` and `options` members of the `cups_dest_t` structure provide | |
277 | basic attributes about the destination in addition to the user default options | |
278 | and values for that destination. The following names are predefined for various | |
279 | destination attributes: | |
280 | ||
281 | - "auth-info-required": The type of authentication required for printing to this | |
282 | destination: "none", "username,password", "domain,username,password", or | |
283 | "negotiate" (Kerberos). | |
284 | - "printer-info": The human-readable description of the destination such as "My | |
285 | Laser Printer". | |
286 | - "printer-is-accepting-jobs": "true" if the destination is accepting new jobs, | |
287 | "false" otherwise. | |
288 | - "printer-is-shared": "true" if the destination is being shared with other | |
289 | computers, "false" otherwise. | |
290 | - "printer-location": The human-readable location of the destination such as | |
291 | "Lab 4". | |
292 | - "printer-make-and-model": The human-readable make and model of the destination | |
293 | such as "ExampleCorp LaserPrinter 4000 Series". | |
294 | - "printer-state": "3" if the destination is idle, "4" if the destination is | |
295 | printing a job, and "5" if the destination is stopped. | |
296 | - "printer-state-change-time": The UNIX time when the destination entered the | |
297 | current state. | |
298 | - "printer-state-reasons": Additional comma-delimited state keywords for the | |
299 | destination such as "media-tray-empty-error" and "toner-low-warning". | |
300 | - "printer-type": The `cups_ptype_t` value associated with the destination. | |
53af7f21 MS |
301 | - "printer-uri-supported": The URI associated with the destination; if not set, |
302 | this destination was discovered but is not yet setup as a local printer. | |
798d6e29 MS |
303 | |
304 | Use the `cupsGetOption` function to retrieve the value. For example, the | |
305 | following code gets the make and model of a destination: | |
306 | ||
307 | const char *model = cupsGetOption("printer-make-and-model", | |
308 | dest->num_options, | |
309 | dest->options); | |
310 | ||
53af7f21 | 311 | |
798d6e29 MS |
312 | ## Detailed Destination Information |
313 | ||
314 | Once a destination has been chosen, the `cupsCopyDestInfo` function can be used | |
315 | to gather detailed information about the destination: | |
316 | ||
317 | cups_dinfo_t * | |
318 | cupsCopyDestInfo(http_t *http, cups_dest_t *dest); | |
319 | ||
320 | The `http` argument specifies a connection to the CUPS scheduler and is | |
321 | typically the constant `CUPS_HTTP_DEFAULT`. The `dest` argument specifies the | |
322 | destination to query. | |
323 | ||
324 | The `cups_dinfo_t` structure that is returned contains a snapshot of the | |
325 | supported options and their supported, ready, and default values. It also can | |
326 | report constraints between different options and values, and recommend changes | |
327 | to resolve those constraints. | |
abacc52b | 328 | |
53af7f21 | 329 | |
798d6e29 | 330 | ### Getting Supported Options and Values |
abacc52b | 331 | |
798d6e29 MS |
332 | The `cupsCheckDestSupported` function can be used to test whether a particular |
333 | option or option and value is supported: | |
334 | ||
335 | int | |
336 | cupsCheckDestSupported(http_t *http, cups_dest_t *dest, | |
337 | cups_dinfo_t *info, | |
338 | const char *option, | |
339 | const char *value); | |
340 | ||
341 | The `option` argument specifies the name of the option to check. The following | |
342 | constants can be used to check the various standard options: | |
343 | ||
344 | - `CUPS_COPIES`: Controls the number of copies that are produced. | |
345 | - `CUPS_FINISHINGS`: A comma-delimited list of integer constants that control | |
346 | the finishing processes that are applied to the job, including stapling, | |
347 | punching, and folding. | |
348 | - `CUPS_MEDIA`: Controls the media size that is used, typically one of the | |
349 | following: `CUPS_MEDIA_3X5`, `CUPS_MEDIA_4X6`, `CUPS_MEDIA_5X7`, | |
350 | `CUPS_MEDIA_8X10`, `CUPS_MEDIA_A3`, `CUPS_MEDIA_A4`, `CUPS_MEDIA_A5`, | |
351 | `CUPS_MEDIA_A6`, `CUPS_MEDIA_ENV10`, `CUPS_MEDIA_ENVDL`, `CUPS_MEDIA_LEGAL`, | |
352 | `CUPS_MEDIA_LETTER`, `CUPS_MEDIA_PHOTO_L`, `CUPS_MEDIA_SUPERBA3`, or | |
353 | `CUPS_MEDIA_TABLOID`. | |
354 | - `CUPS_MEDIA_SOURCE`: Controls where the media is pulled from, typically either | |
355 | `CUPS_MEDIA_SOURCE_AUTO` or `CUPS_MEDIA_SOURCE_MANUAL`. | |
356 | - `CUPS_MEDIA_TYPE`: Controls the type of media that is used, typically one of | |
357 | the following: `CUPS_MEDIA_TYPE_AUTO`, `CUPS_MEDIA_TYPE_ENVELOPE`, | |
358 | `CUPS_MEDIA_TYPE_LABELS`, `CUPS_MEDIA_TYPE_LETTERHEAD`, | |
359 | `CUPS_MEDIA_TYPE_PHOTO`, `CUPS_MEDIA_TYPE_PHOTO_GLOSSY`, | |
360 | `CUPS_MEDIA_TYPE_PHOTO_MATTE`, `CUPS_MEDIA_TYPE_PLAIN`, or | |
361 | `CUPS_MEDIA_TYPE_TRANSPARENCY`. | |
362 | - `CUPS_NUMBER_UP`: Controls the number of document pages that are placed on | |
363 | each media side. | |
364 | - `CUPS_ORIENTATION`: Controls the orientation of document pages placed on the | |
365 | media: `CUPS_ORIENTATION_PORTRAIT` or `CUPS_ORIENTATION_LANDSCAPE`. | |
366 | - `CUPS_PRINT_COLOR_MODE`: Controls whether the output is in color | |
367 | \(`CUPS_PRINT_COLOR_MODE_COLOR`), grayscale | |
368 | \(`CUPS_PRINT_COLOR_MODE_MONOCHROME`), or either | |
369 | \(`CUPS_PRINT_COLOR_MODE_AUTO`). | |
370 | - `CUPS_PRINT_QUALITY`: Controls the generate quality of the output: | |
371 | `CUPS_PRINT_QUALITY_DRAFT`, `CUPS_PRINT_QUALITY_NORMAL`, or | |
372 | `CUPS_PRINT_QUALITY_HIGH`. | |
373 | - `CUPS_SIDES`: Controls whether prints are placed on one or both sides of the | |
374 | media: `CUPS_SIDES_ONE_SIDED`, `CUPS_SIDES_TWO_SIDED_PORTRAIT`, or | |
375 | `CUPS_SIDES_TWO_SIDED_LANDSCAPE`. | |
376 | ||
377 | If the `value` argument is `NULL`, the `cupsCheckDestSupported` function returns | |
378 | whether the option is supported by the destination. Otherwise, the function | |
379 | returns whether the specified value of the option is supported. | |
380 | ||
381 | The `cupsFindDestSupported` function returns the IPP attribute containing the | |
382 | supported values for a given option: | |
383 | ||
384 | ipp_attribute_t * | |
385 | cupsFindDestSupported(http_t *http, cups_dest_t *dest, | |
386 | cups_dinfo_t *dinfo, | |
387 | const char *option); | |
388 | ||
389 | For example, the following code prints the supported finishing processes for a | |
390 | destination, if any, to the standard output: | |
391 | ||
392 | cups_dinfo_t *info = cupsCopyDestInfo(CUPS_HTTP_DEFAULT, | |
393 | dest); | |
394 | ||
395 | if (cupsCheckDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
396 | CUPS_FINISHINGS, NULL)) | |
397 | { | |
398 | ipp_attribute_t *finishings = | |
399 | cupsFindDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
400 | CUPS_FINISHINGS); | |
401 | int i, count = ippGetCount(finishings); | |
402 | ||
403 | puts("finishings supported:"); | |
404 | for (i = 0; i < count; i ++) | |
405 | printf(" %d\n", ippGetInteger(finishings, i)); | |
406 | } | |
407 | else | |
408 | puts("finishings not supported."); | |
abacc52b | 409 | |
798d6e29 MS |
410 | The "job-creation-attributes" option can be queried to get a list of supported |
411 | options. For example, the following code prints the list of supported options | |
412 | to the standard output: | |
abacc52b | 413 | |
798d6e29 MS |
414 | ipp_attribute_t *attrs = |
415 | cupsFindDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
416 | "job-creation-attributes"); | |
417 | int i, count = ippGetCount(attrs); | |
abacc52b | 418 | |
798d6e29 MS |
419 | for (i = 0; i < count; i ++) |
420 | puts(ippGetString(attrs, i, NULL)); | |
abacc52b MS |
421 | |
422 | ||
798d6e29 | 423 | ### Getting Default Values |
abacc52b | 424 | |
798d6e29 MS |
425 | There are two sets of default values - user defaults that are available via the |
426 | `num_options` and `options` members of the `cups_dest_t` structure, and | |
427 | destination defaults that available via the `cups_dinfo_t` structure and the | |
428 | `cupsFindDestDefault` function which returns the IPP attribute containing the | |
429 | default value(s) for a given option: | |
abacc52b | 430 | |
798d6e29 MS |
431 | ipp_attribute_t * |
432 | cupsFindDestDefault(http_t *http, cups_dest_t *dest, | |
433 | cups_dinfo_t *dinfo, | |
434 | const char *option); | |
abacc52b | 435 | |
798d6e29 MS |
436 | The user defaults from `cupsGetOption` should always take preference over the |
437 | destination defaults. For example, the following code prints the default | |
438 | finishings value(s) to the standard output: | |
abacc52b | 439 | |
798d6e29 MS |
440 | const char *def_value = |
441 | cupsGetOption(CUPS_FINISHINGS, dest->num_options, | |
442 | dest->options); | |
443 | ipp_attribute_t *def_attr = | |
444 | cupsFindDestDefault(CUPS_HTTP_DEFAULT, dest, info, | |
445 | CUPS_FINISHINGS); | |
abacc52b | 446 | |
798d6e29 MS |
447 | if (def_value != NULL) |
448 | { | |
449 | printf("Default finishings: %s\n", def_value); | |
450 | } | |
451 | else | |
452 | { | |
453 | int i, count = ippGetCount(def_attr); | |
abacc52b | 454 | |
798d6e29 MS |
455 | printf("Default finishings: %d", |
456 | ippGetInteger(def_attr, 0)); | |
457 | for (i = 1; i < count; i ++) | |
458 | printf(",%d", ippGetInteger(def_attr, i)); | |
459 | putchar('\n'); | |
460 | } | |
abacc52b MS |
461 | |
462 | ||
798d6e29 | 463 | ### Getting Ready (Loaded) Values |
abacc52b | 464 | |
798d6e29 MS |
465 | The finishings and media options also support queries for the ready, or loaded, |
466 | values. For example, a printer may have punch and staple finishers installed | |
467 | but be out of staples - the supported values will list both punch and staple | |
468 | finishing processes but the ready values will only list the punch processes. | |
469 | Similarly, a printer may support hundreds of different sizes of media but only | |
470 | have a single size loaded at any given time - the ready values are limited to | |
471 | the media that is actually in the printer. | |
abacc52b | 472 | |
798d6e29 MS |
473 | The `cupsFindDestReady` function finds the IPP attribute containing the ready |
474 | values for a given option: | |
abacc52b | 475 | |
798d6e29 MS |
476 | ipp_attribute_t * |
477 | cupsFindDestReady(http_t *http, cups_dest_t *dest, | |
478 | cups_dinfo_t *dinfo, const char *option); | |
abacc52b | 479 | |
798d6e29 | 480 | For example, the following code lists the ready finishing processes: |
abacc52b | 481 | |
798d6e29 MS |
482 | ipp_attribute_t *ready_finishings = |
483 | cupsFindDestReady(CUPS_HTTP_DEFAULT, dest, info, | |
484 | CUPS_FINISHINGS); | |
abacc52b | 485 | |
798d6e29 MS |
486 | if (ready_finishings != NULL) |
487 | { | |
488 | int i, count = ippGetCount(ready_finishings); | |
abacc52b | 489 | |
798d6e29 MS |
490 | puts("finishings ready:"); |
491 | for (i = 0; i < count; i ++) | |
492 | printf(" %d\n", ippGetInteger(ready_finishings, i)); | |
493 | } | |
494 | else | |
495 | puts("no finishings are ready."); | |
abacc52b | 496 | |
abacc52b | 497 | |
798d6e29 | 498 | ### Media Size Options |
abacc52b | 499 | |
798d6e29 MS |
500 | CUPS provides functions for querying the dimensions and margins for each of the |
501 | supported media size options. The `cups_size_t` structure is used to describe a | |
502 | media size: | |
abacc52b | 503 | |
798d6e29 MS |
504 | typedef struct cups_size_s |
505 | { | |
506 | char media[128]; | |
507 | int width, length; | |
508 | int bottom, left, right, top; | |
509 | } cups_size_t; | |
510 | ||
511 | The `width` and `length` members specify the dimensions of the media in | |
512 | hundredths of millimeters (1/2540th of an inch). The `bottom`, `left`, `right`, | |
513 | and `top` members specify the margins of the printable area, also in hundredths | |
514 | of millimeters. | |
515 | ||
516 | The `cupsGetDestMediaByName` and `cupsGetDestMediaBySize` functions lookup the | |
517 | media size information using a standard media size name or dimensions in | |
518 | hundredths of millimeters: | |
519 | ||
520 | int | |
521 | cupsGetDestMediaByName(http_t *http, cups_dest_t *dest, | |
522 | cups_dinfo_t *dinfo, | |
523 | const char *media, | |
524 | unsigned flags, cups_size_t *size); | |
525 | ||
526 | int | |
527 | cupsGetDestMediaBySize(http_t *http, cups_dest_t *dest, | |
528 | cups_dinfo_t *dinfo, | |
529 | int width, int length, | |
530 | unsigned flags, cups_size_t *size); | |
531 | ||
532 | The `media`, `width`, and `length` arguments specify the size to lookup. The | |
533 | `flags` argument specifies a bitfield controlling various lookup options: | |
534 | ||
535 | - `CUPS_MEDIA_FLAGS_DEFAULT`: Find the closest size supported by the printer. | |
536 | - `CUPS_MEDIA_FLAGS_BORDERLESS`: Find a borderless size. | |
537 | - `CUPS_MEDIA_FLAGS_DUPLEX`: Find a size compatible with two-sided printing. | |
538 | - `CUPS_MEDIA_FLAGS_EXACT`: Find an exact match for the size. | |
539 | - `CUPS_MEDIA_FLAGS_READY`: If the printer supports media sensing or | |
540 | configuration of the media in each tray/source, find the size amongst the | |
541 | "ready" media. | |
542 | ||
543 | If a matching size is found for the destination, the size information is stored | |
544 | in the structure pointed to by the `size` argument and 1 is returned. Otherwise | |
545 | 0 is returned. | |
546 | ||
547 | For example, the following code prints the margins for two-sided printing on US | |
548 | Letter media: | |
549 | ||
550 | cups_size_t size; | |
551 | ||
552 | if (cupsGetDestMediaByName(CUPS_HTTP_DEFAULT, dest, info, | |
553 | CUPS_MEDIA_LETTER, | |
554 | CUPS_MEDIA_FLAGS_DUPLEX, &size)) | |
abacc52b | 555 | { |
798d6e29 MS |
556 | puts("Margins for duplex US Letter:"); |
557 | printf(" Bottom: %.2fin\n", size.bottom / 2540.0); | |
558 | printf(" Left: %.2fin\n", size.left / 2540.0); | |
559 | printf(" Right: %.2fin\n", size.right / 2540.0); | |
560 | printf(" Top: %.2fin\n", size.top / 2540.0); | |
abacc52b | 561 | } |
798d6e29 MS |
562 | else |
563 | puts("Margins for duplex US Letter are not available."); | |
abacc52b | 564 | |
798d6e29 MS |
565 | You can also enumerate all of the sizes that match a given `flags` value using |
566 | the `cupsGetDestMediaByIndex` and `cupsGetDestMediaCount` functions: | |
abacc52b | 567 | |
798d6e29 MS |
568 | int |
569 | cupsGetDestMediaByIndex(http_t *http, cups_dest_t *dest, | |
570 | cups_dinfo_t *dinfo, int n, | |
571 | unsigned flags, cups_size_t *size); | |
abacc52b | 572 | |
798d6e29 MS |
573 | int |
574 | cupsGetDestMediaCount(http_t *http, cups_dest_t *dest, | |
575 | cups_dinfo_t *dinfo, unsigned flags); | |
abacc52b | 576 | |
798d6e29 MS |
577 | For example, the following code prints the list of ready media and corresponding |
578 | margins: | |
abacc52b | 579 | |
798d6e29 MS |
580 | cups_size_t size; |
581 | int i; | |
582 | int count = cupsGetDestMediaCount(CUPS_HTTP_DEFAULT, | |
583 | dest, info, | |
584 | CUPS_MEDIA_FLAGS_READY); | |
abacc52b | 585 | |
798d6e29 MS |
586 | for (i = 0; i < count; i ++) |
587 | { | |
588 | if (cupsGetDestMediaByIndex(CUPS_HTTP_DEFAULT, dest, info, | |
589 | i, CUPS_MEDIA_FLAGS_READY, | |
590 | &size)) | |
591 | { | |
592 | printf("%s:\n", size.name); | |
593 | printf(" Width: %.2fin\n", size.width / 2540.0); | |
594 | printf(" Length: %.2fin\n", size.length / 2540.0); | |
595 | printf(" Bottom: %.2fin\n", size.bottom / 2540.0); | |
596 | printf(" Left: %.2fin\n", size.left / 2540.0); | |
597 | printf(" Right: %.2fin\n", size.right / 2540.0); | |
598 | printf(" Top: %.2fin\n", size.top / 2540.0); | |
599 | } | |
600 | } | |
abacc52b | 601 | |
798d6e29 | 602 | Finally, the `cupsGetDestMediaDefault` function returns the default media size: |
abacc52b | 603 | |
798d6e29 MS |
604 | int |
605 | cupsGetDestMediaDefault(http_t *http, cups_dest_t *dest, | |
606 | cups_dinfo_t *dinfo, unsigned flags, | |
607 | cups_size_t *size); | |
abacc52b | 608 | |
abacc52b | 609 | |
798d6e29 | 610 | ### Localizing Options and Values |
abacc52b | 611 | |
6ad44eeb MS |
612 | CUPS provides three functions to get localized, human-readable strings in the |
613 | user's current locale for options and values: `cupsLocalizeDestMedia`, | |
614 | `cupsLocalizeDestOption`, and `cupsLocalizeDestValue`: | |
abacc52b | 615 | |
798d6e29 MS |
616 | const char * |
617 | cupsLocalizeDestMedia(http_t *http, cups_dest_t *dest, | |
618 | cups_dinfo_t *info, unsigned flags, | |
619 | cups_size_t *size); | |
abacc52b | 620 | |
798d6e29 MS |
621 | const char * |
622 | cupsLocalizeDestOption(http_t *http, cups_dest_t *dest, | |
623 | cups_dinfo_t *info, | |
624 | const char *option); | |
abacc52b | 625 | |
798d6e29 MS |
626 | const char * |
627 | cupsLocalizeDestValue(http_t *http, cups_dest_t *dest, | |
628 | cups_dinfo_t *info, | |
629 | const char *option, const char *value); | |
abacc52b | 630 | |
abacc52b | 631 | |
798d6e29 | 632 | ## Submitting a Print Job |
abacc52b | 633 | |
798d6e29 MS |
634 | Once you are ready to submit a print job, you create a job using the |
635 | `cupsCreateDestJob` function: | |
636 | ||
637 | ipp_status_t | |
638 | cupsCreateDestJob(http_t *http, cups_dest_t *dest, | |
639 | cups_dinfo_t *info, int *job_id, | |
640 | const char *title, int num_options, | |
641 | cups_option_t *options); | |
642 | ||
643 | The `title` argument specifies a name for the print job such as "My Document". | |
644 | The `num_options` and `options` arguments specify the options for the print | |
645 | job which are allocated using the `cupsAddOption` function. | |
646 | ||
647 | When successful, the job's numeric identifier is stored in the integer pointed | |
648 | to by the `job_id` argument and `IPP_STATUS_OK` is returned. Otherwise, an IPP | |
649 | error status is returned. | |
650 | ||
651 | For example, the following code creates a new job that will print 42 copies of a | |
652 | two-sided US Letter document: | |
653 | ||
654 | int job_id = 0; | |
655 | int num_options = 0; | |
656 | cups_option_t *options = NULL; | |
657 | ||
658 | num_options = cupsAddOption(CUPS_COPIES, "42", | |
659 | num_options, &options); | |
660 | num_options = cupsAddOption(CUPS_MEDIA, CUPS_MEDIA_LETTER, | |
661 | num_options, &options); | |
662 | num_options = cupsAddOption(CUPS_SIDES, | |
663 | CUPS_SIDES_TWO_SIDED_PORTRAIT, | |
664 | num_options, &options); | |
665 | ||
666 | if (cupsCreateDestJob(CUPS_HTTP_DEFAULT, dest, info, | |
667 | &job_id, "My Document", num_options, | |
668 | options) == IPP_STATUS_OK) | |
669 | printf("Created job: %d\n", job_id); | |
670 | else | |
671 | printf("Unable to create job: %s\n", | |
672 | cupsLastErrorString()); | |
673 | ||
674 | Once the job is created, you submit documents for the job using the | |
675 | `cupsStartDestDocument`, `cupsWriteRequestData`, and `cupsFinishDestDocument` | |
676 | functions: | |
677 | ||
678 | http_status_t | |
679 | cupsStartDestDocument(http_t *http, cups_dest_t *dest, | |
680 | cups_dinfo_t *info, int job_id, | |
681 | const char *docname, | |
682 | const char *format, | |
683 | int num_options, | |
684 | cups_option_t *options, | |
685 | int last_document); | |
686 | ||
687 | http_status_t | |
688 | cupsWriteRequestData(http_t *http, const char *buffer, | |
689 | size_t length); | |
690 | ||
691 | ipp_status_t | |
692 | cupsFinishDestDocument(http_t *http, cups_dest_t *dest, | |
693 | cups_dinfo_t *info); | |
694 | ||
695 | The `docname` argument specifies the name of the document, typically the | |
696 | original filename. The `format` argument specifies the MIME media type of the | |
697 | document, including the following constants: | |
698 | ||
699 | - `CUPS_FORMAT_JPEG`: "image/jpeg" | |
700 | - `CUPS_FORMAT_PDF`: "application/pdf" | |
701 | - `CUPS_FORMAT_POSTSCRIPT`: "application/postscript" | |
702 | - `CUPS_FORMAT_TEXT`: "text/plain" | |
703 | ||
704 | The `num_options` and `options` arguments specify per-document print options, | |
705 | which at present must be 0 and `NULL`. The `last_document` argument specifies | |
706 | whether this is the last document in the job. | |
707 | ||
708 | For example, the following code submits a PDF file to the job that was just | |
709 | created: | |
710 | ||
711 | FILE *fp = fopen("filename.pdf", "rb"); | |
712 | size_t bytes; | |
713 | char buffer[65536]; | |
714 | ||
715 | if (cupsStartDestDocument(CUPS_HTTP_DEFAULT, dest, info, | |
716 | job_id, "filename.pdf", 0, NULL, | |
717 | 1) == HTTP_STATUS_CONTINUE) | |
abacc52b | 718 | { |
798d6e29 MS |
719 | while ((bytes = fread(buffer, 1, sizeof(buffer), fp)) > 0) |
720 | if (cupsWriteRequestData(CUPS_HTTP_DEFAULT, buffer, | |
721 | bytes) != HTTP_STATUS_CONTINUE) | |
722 | break; | |
723 | ||
724 | if (cupsFinishDestDocument(CUPS_HTTP_DEFAULT, dest, | |
725 | info) == IPP_STATUS_OK) | |
726 | puts("Document send succeeded."); | |
727 | else | |
728 | printf("Document send failed: %s\n", | |
729 | cupsLastErrorString()); | |
abacc52b | 730 | } |
798d6e29 MS |
731 | |
732 | fclose(fp); | |
65bebeac MS |
733 | |
734 | ||
735 | # Sending IPP Requests | |
736 | ||
b0fb2d75 MS |
737 | CUPS provides a rich API for sending IPP requests to the scheduler or printers, |
738 | typically from management or utility applications whose primary purpose is not | |
739 | to send print jobs. | |
740 | ||
741 | ||
65bebeac MS |
742 | ## Connecting to the Scheduler or Printer |
743 | ||
b0fb2d75 MS |
744 | The connection to the scheduler or printer is represented by the HTTP connection |
745 | type `http_t`. The `cupsConnectDest` function connects to the scheduler or | |
746 | printer associated with the destination: | |
747 | ||
748 | http_t * | |
749 | cupsConnectDest(cups_dest_t *dest, unsigned flags, int msec, | |
750 | int *cancel, char *resource, | |
751 | size_t resourcesize, cups_dest_cb_t cb, | |
752 | void *user_data); | |
753 | ||
754 | The `dest` argument specifies the destination to connect to. | |
755 | ||
756 | The `flags` argument specifies whether you want to connect to the scheduler | |
757 | (`CUPS_DEST_FLAGS_NONE`) or device/printer (`CUPS_DEST_FLAGS_DEVICE`) associated | |
758 | with the destination. | |
759 | ||
760 | The `msec` argument specifies how long you are willing to wait for the | |
761 | connection to be established in milliseconds. Specify a value of `-1` to wait | |
762 | indefinitely. | |
763 | ||
764 | The `cancel` argument specifies the address of an integer variable that can be | |
765 | set to a non-zero value to cancel the connection. Specify a value of `NULL` | |
766 | to not provide a cancel variable. | |
767 | ||
768 | The `resource` and `resourcesize` arguments specify the address and size of a | |
769 | character string array to hold the path to use when sending an IPP request. | |
770 | ||
771 | The `cb` and `user_data` arguments specify a destination callback function that | |
772 | returns 1 to continue connecting or 0 to stop. The destination callback work | |
773 | the same way as the one used for the `cupsEnumDests` function. | |
65bebeac | 774 | |
b0fb2d75 MS |
775 | On success, a HTTP connection is returned that can be used to send IPP requests |
776 | and get IPP responses. | |
777 | ||
778 | For example, the following code connects to the printer associated with a | |
779 | destination with a 30 second timeout: | |
780 | ||
781 | char resource[256]; | |
782 | http_t *http = cupsConnectDest(dest, CUPS_DEST_FLAGS_DEVICE, | |
783 | 30000, NULL, resource, | |
784 | sizeof(resource), NULL, NULL); | |
65bebeac MS |
785 | |
786 | ||
787 | ## Creating an IPP Request | |
788 | ||
b0fb2d75 MS |
789 | IPP requests are represented by the IPP message type `ipp_t` and each IPP |
790 | attribute in the request is representing using the type `ipp_attribute_t`. Each | |
791 | IPP request includes an operation code (`IPP_OP_CREATE_JOB`, | |
792 | `IPP_OP_GET_PRINTER_ATTRIBUTES`, etc.) and a 32-bit integer identifier. | |
793 | ||
794 | The `ippNewRequest` function creates a new IPP request: | |
795 | ||
796 | ipp_t * | |
797 | ippNewRequest(ipp_op_t op); | |
798 | ||
799 | The `op` argument specifies the IPP operation code for the request. For | |
800 | example, the following code creates an IPP Get-Printer-Attributes request: | |
801 | ||
802 | ipp_t *request = ippNewRequest(IPP_OP_GET_PRINTER_ATTRIBUTES); | |
803 | ||
804 | The request identifier is automatically set to a unique value for the current | |
805 | process. | |
806 | ||
807 | Each IPP request starts with two IPP attributes, "attributes-charset" and | |
808 | "attributes-natural-language", followed by IPP attribute(s) that specify the | |
809 | target of the operation. The `ippNewRequest` automatically adds the correct | |
810 | "attributes-charset" and "attributes-natural-language" attributes, but you must | |
811 | add the target attribute(s). For example, the following code adds the | |
812 | "printer-uri" attribute to the IPP Get-Printer-Attributes request to specify | |
813 | which printer is being queried: | |
814 | ||
815 | const char *printer_uri = cupsGetOption("device-uri", | |
816 | dest->num_options, | |
817 | dest->options); | |
818 | ||
819 | ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI, | |
820 | "printer-uri", NULL, printer_uri); | |
821 | ||
822 | > Note: If we wanted to query the scheduler instead of the device, we would look | |
823 | > up the "printer-uri-supported" option instead of the "device-uri" value. | |
824 | ||
825 | The `ippAddString` function adds the "printer-uri" attribute the the IPP | |
826 | request. The `IPP_TAG_OPERATION` argument specifies that the attribute is part | |
827 | of the operation. The `IPP_TAG_URI` argument specifies that the value is a | |
828 | Universal Resource Identifier (URI) string. The `NULL` argument specifies there | |
829 | is no language (English, French, Japanese, etc.) associated with the string, and | |
830 | the `printer_uri` argument specifies the string value. | |
831 | ||
832 | The IPP Get-Printer-Attributes request also supports an IPP attribute called | |
833 | "requested-attributes" that lists the attributes and values you are interested | |
834 | in. For example, the following code requests the printer state attributes: | |
835 | ||
836 | static const char * const requested_attributes[] = | |
837 | { | |
838 | "printer-state", | |
839 | "printer-state-message", | |
840 | "printer-state-reasons" | |
841 | }; | |
842 | ||
843 | ippAddStrings(request, IPP_TAG_OPERATION, IPP_TAG_KEYWORD, | |
844 | "requested-attributes", 3, NULL, | |
845 | requested_attributes); | |
846 | ||
847 | The `ippAddStrings` function adds an attribute with one or more strings, in this | |
848 | case three. The `IPP_TAG_KEYWORD` argument specifies that the strings are | |
849 | keyword values, which are used for attribute names. All strings use the same | |
850 | language (`NULL`), and the attribute will contain the three strings in the | |
851 | array `requested_attributes`. | |
852 | ||
853 | CUPS provides many functions to adding attributes of different types: | |
854 | ||
855 | - `ippAddBoolean` adds a boolean (`IPP_TAG_BOOLEAN`) attribute with one value. | |
856 | - `ippAddInteger` adds an enum (`IPP_TAG_ENUM`) or integer (`IPP_TAG_INTEGER`) | |
857 | attribute with one value. | |
858 | - `ippAddIntegers` adds an enum or integer attribute with one or more values. | |
859 | - `ippAddOctetString` adds an octetString attribute with one value. | |
860 | - `ippAddOutOfBand` adds a admin-defined (`IPP_TAG_ADMINDEFINE`), default | |
861 | (`IPP_TAG_DEFAULT`), delete-attribute (`IPP_TAG_DELETEATTR`), no-value | |
862 | (`IPP_TAG_NOVALUE`), not-settable (`IPP_TAG_NOTSETTABLE`), unknown | |
863 | (`IPP_TAG_UNKNOWN`), or unsupported (`IPP_TAG_UNSUPPORTED_VALUE`) out-of-band | |
864 | attribute. | |
865 | - `ippAddRange` adds a rangeOfInteger attribute with one range. | |
866 | - `ippAddRanges` adds a rangeOfInteger attribute with one or more ranges. | |
867 | - `ippAddResolution` adds a resolution attribute with one resolution. | |
868 | - `ippAddResolutions` adds a resolution attribute with one or more resolutions. | |
869 | - `ippAddString` adds a charset (`IPP_TAG_CHARSET`), keyword (`IPP_TAG_KEYWORD`), | |
870 | mimeMediaType (`IPP_TAG_MIMETYPE`), name (`IPP_TAG_NAME` and | |
871 | `IPP_TAG_NAMELANG`), naturalLanguage (`IPP_TAG_NATURAL_LANGUAGE`), text | |
872 | (`IPP_TAG_TEXT` and `IPP_TAG_TEXTLANG`), uri (`IPP_TAG_URI`), or uriScheme | |
873 | (`IPP_TAG_URISCHEME`) attribute with one value. | |
874 | - `ippAddStrings` adds a charset, keyword, mimeMediaType, name, naturalLanguage, | |
875 | text, uri, or uriScheme attribute with one or more values. | |
876 | ||
877 | ||
65bebeac MS |
878 | ## Sending the IPP Request |
879 | ||
b0fb2d75 MS |
880 | Once you have created the IPP request, you can send it using the |
881 | `cupsDoRequest` function. For example, the following code sends the IPP | |
882 | Get-Printer-Attributes request to the destination and saves the response: | |
883 | ||
884 | ipp_t *response = cupsDoRequest(http, request, resource); | |
885 | ||
886 | For requests like Send-Document that include a file, the `cupsDoFileRequest` | |
887 | function should be used: | |
888 | ||
889 | ipp_t *response = cupsDoFileRequest(http, request, resource, | |
890 | filename); | |
891 | ||
892 | Both `cupsDoRequest` and `cupsDoFileRequest` free the IPP request. If a valid | |
893 | IPP response is received, it is stored in a new IPP message (`ipp_t`) and | |
894 | returned to the caller. Otherwise `NULL` is returned. | |
895 | ||
896 | The status from the most recent request can be queried using the `cupsLastError` | |
897 | function, for example: | |
898 | ||
899 | if (cupsLastError() >= IPP_STATUS_ERROR_BAD_REQUEST) | |
900 | { | |
901 | /* request failed */ | |
902 | } | |
903 | ||
904 | A human-readable error message is also available using the `cupsLastErrorString` | |
905 | function: | |
906 | ||
907 | if (cupsLastError() >= IPP_STATUS_ERROR_BAD_REQUEST) | |
908 | { | |
909 | /* request failed */ | |
910 | printf("Request failed: %s\n", cupsLastErrorString()); | |
911 | } | |
912 | ||
913 | ||
914 | ## Processing the IPP Response | |
915 | ||
916 | Each response to an IPP request is also an IPP message (`ipp_t`) with its own | |
917 | IPP attributes (`ipp_attribute_t`) that includes a status code (`IPP_STATUS_OK`, | |
918 | `IPP_STATUS_ERROR_BAD_REQUEST`, etc.) and the corresponding 32-bit integer | |
919 | identifier from the request. | |
920 | ||
921 | For example, the following code finds the printer state attributes and prints | |
922 | their values: | |
923 | ||
924 | ipp_attribute_t *attr; | |
925 | ||
926 | if ((attr = ippFindAttribute(response, "printer-state", | |
927 | IPP_TAG_ENUM)) != NULL) | |
928 | { | |
929 | printf("printer-state=%s\n", | |
930 | ippTagString("printer-state", ippGetInteger(attr, 0))); | |
931 | } | |
932 | else | |
933 | puts("printer-state=unknown"); | |
934 | ||
935 | if ((attr = ippFindAttribute(response, "printer-state-message", | |
936 | IPP_TAG_TEXT)) != NULL) | |
937 | { | |
938 | printf("printer-state-message=\"%s\"\n", | |
939 | ippGetString(attr, 0, NULL))); | |
940 | } | |
941 | ||
942 | if ((attr = ippFindAttribute(response, "printer-state-reasons", | |
943 | IPP_TAG_KEYWORD)) != NULL) | |
944 | { | |
945 | int i, count = ippGetCount(attr); | |
946 | ||
947 | puts("printer-state-reasons="); | |
948 | for (i = 0; i < count; i ++) | |
949 | printf(" %s\n", ippGetString(attr, i, NULL))); | |
950 | } | |
951 | ||
952 | The `ippGetCount` function returns the number of values in an attribute. | |
953 | ||
954 | The `ippGetInteger` and `ippGetString` functions return a single integer or | |
955 | string value from an attribute. | |
956 | ||
957 | The `ippTagString` function converts a enum value to its keyword (string) | |
958 | equivalent. | |
959 | ||
960 | Once you are done using the IPP response message, free it using the `ippDelete` | |
961 | function: | |
962 | ||
963 | ippDelete(response); | |
964 | ||
65bebeac MS |
965 | |
966 | ## Authentication | |
b0fb2d75 MS |
967 | |
968 | CUPS normally handles authentication through the console. GUI applications | |
969 | should set a password callback using the `cupsSetPasswordCB2` function: | |
970 | ||
971 | void | |
972 | cupsSetPasswordCB2(cups_password_cb2_t cb, void *user_data); | |
973 | ||
974 | The password callback will be called when needed and is responsible for setting | |
975 | the current user name using `cupsSetUser` and returning a string: | |
976 | ||
977 | const char * | |
978 | cups_password_cb2(const char *prompt, http_t *http, | |
979 | const char *method, const char *resource, | |
980 | void *user_data); | |
981 | ||
982 | The `prompt` argument is a string from CUPS that should be displayed to the | |
983 | user. | |
984 | ||
985 | The `http` argument is the connection hosting the request that is being | |
986 | authenticated. The password callback can call the `httpGetField` and | |
987 | `httpGetSubField` functions to look for additional details concerning the | |
988 | authentication challenge. | |
989 | ||
990 | The `method` argument specifies the HTTP method used for the request and is | |
991 | typically "POST". | |
992 | ||
993 | The `resource` argument specifies the path used for the request. | |
994 | ||
995 | The `user_data` argument provides the user data pointer from the | |
996 | `cupsSetPasswordCB2` call. |