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<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
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<HTML
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><HEAD
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><TITLE
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>Support Functions and Macros</TITLE
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><meta name="MSSmartTagsPreventParsing" content="TRUE">
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<META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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"><LINK
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REL="HOME"
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TITLE="eCos Reference Manual"
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HREF="ecos-ref.html"><LINK
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REL="UP"
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TITLE="Embedded HTTP Server"
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HREF="net-httpd-chapter.html"><LINK
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REL="PREVIOUS"
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TITLE="Server Configuration"
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HREF="net-httpd-configuration.html"><LINK
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REL="NEXT"
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TITLE="System Monitor"
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HREF="net-httpd-monitor.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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SUMMARY="Header navigation table"
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CELLPADDING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>eCos Reference Manual</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="net-httpd-configuration.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 48. Embedded HTTP Server</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="net-httpd-monitor.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="NET-HTTPD-HTML">Support Functions and Macros</H1
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><P
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>The emphasis of this server is on dynamically generated content,
88
rather than fetching it from a filesystem. To do this the handler
89
functions make calls to <TT
90
CLASS="FUNCTION"
91
>fprintf()</TT
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> and
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<TT
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CLASS="FUNCTION"
95
>fputs()</TT
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>. Such handler functions would end up a
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mass of print calls, with the actual structure of the HTML page hidden
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in the format strings and arguments, making maintenance and debugging
99
very difficult. Such an approach would also result in the definition
100
of many, often only slightly different, format strings, leading to
101
unnecessary bloat.</P
102
><P
103
>In an effort to expose the structure of the HTML in the structure of
104
the C code, and to maximize the sharing of string constants, the
105
<TT
106
CLASS="FILENAME"
107
>cyg/httpd/httpd.h</TT
108
> header file defines a set of
109
helper functions and macros. Most of these are wrappers for predefined
110
print calls on the <TT
111
CLASS="PARAMETER"
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><I
113
>client</I
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></TT
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> stream passed to the
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hander function. For examples of their use, see the System Monitor
117
example.</P
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><DIV
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CLASS="NOTE"
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><BLOCKQUOTE
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CLASS="NOTE"
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><P
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><B
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>Note: </B
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>All arguments to macros are pointers to strings, unless otherwise
126
stated. In general, wherever a function or macro has an
127
<TT
128
CLASS="PARAMETER"
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><I
130
>attr</I
131
></TT
132
> or <TT
133
CLASS="PARAMETER"
134
><I
135
>__attr</I
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></TT
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>
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parameter, then the contents of this string will be inserted into the
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tag being defined as HTML attributes. If it is a NULL or empty string
140
it will be ignored.</P
141
></BLOCKQUOTE
142
></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="AEN15305">HTTP Support</H2
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
155
><PRE
156
CLASS="PROGRAMLISTING"
157
>void cyg_http_start( FILE *client, char *content_type, int content_length );
158
void cyg_http_finish( FILE *client );
159
#define html_begin(__client)
160
#define html_end( __client )</PRE
161
></TD
162
></TR
163
></TABLE
164
><P
165
>The function <TT
166
CLASS="FUNCTION"
167
>cyg_http_start()</TT
168
> generates a simple
169
HTTP response header containing the value of
170
<TT
171
CLASS="LITERAL"
172
>CYGDAT_HTTPD_SERVER_ID</TT
173
> in the &quot;Server&quot; field, and the
174
values of <TT
175
CLASS="PARAMETER"
176
><I
177
>content_type</I
178
></TT
179
> and
180
<TT
181
CLASS="PARAMETER"
182
><I
183
>content_length</I
184
></TT
185
> in the &quot;Content-type&quot;
186
and &quot;Content-length&quot; field respectively. The function
187
<TT
188
CLASS="FUNCTION"
189
>cyg_http_finish()</TT
190
> just adds an extra newline to
191
the end of the output and then flushes it to force the data out to the
192
client.</P
193
><P
194
>The macro <TT
195
CLASS="LITERAL"
196
>html_begin()</TT
197
> generates an HTTP header
198
with a &quot;text/html&quot; content type followed by an opening
199
&quot;&lt;html&gt;&quot; tag. <TT
200
CLASS="LITERAL"
201
>html_end()</TT
202
> generates
203
a closing &quot;&lt;/html&gt;&quot; tag and calls
204
<TT
205
CLASS="FUNCTION"
206
>cyg_http_finish()</TT
207
>.</P
208
></DIV
209
><DIV
210
CLASS="SECT2"
211
><H2
212
CLASS="SECT2"
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><A
214
NAME="AEN15318">General HTML Support</H2
215
><TABLE
216
BORDER="5"
217
BGCOLOR="#E0E0F0"
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WIDTH="70%"
219
><TR
220
><TD
221
><PRE
222
CLASS="PROGRAMLISTING"
223
>void cyg_html_tag_begin( FILE *client, char *tag, char *attr );
224
void cyg_html_tag_end( FILE *client, char *tag );
225
#define html_tag_begin( __client, __tag, __attr )
226
#define html_tag_end( __client, __tag )
227
#define html_head( __client, __title, __meta )
228
#define html_body_begin( __client, __attr )
229
#define html_body_end( __client )
230
#define html_heading( __client, __level, __heading )
231
#define html_para_begin( __client, __attr )
232
#define html_url( __client, __text, __link )
233
#define html_image( __client, __source, __alt, __attr )</PRE
234
></TD
235
></TR
236
></TABLE
237
><P
238
>The function <TT
239
CLASS="FUNCTION"
240
>cyg_html_tag_begin()</TT
241
> generates an
242
opening tag with the given name. The function
243
<TT
244
CLASS="FUNCTION"
245
>cyg_html_tag_end()</TT
246
> generates a closing tag with
247
the given name. The macros <TT
248
CLASS="LITERAL"
249
>html_tag_begin()</TT
250
> and
251
<TT
252
CLASS="LITERAL"
253
>html_tag_end</TT
254
> are just wrappers for these functions.</P
255
><P
256
>The macro <TT
257
CLASS="LITERAL"
258
>html_head()</TT
259
> generates an HTML header
260
section with <TT
261
CLASS="PARAMETER"
262
><I
263
>__title</I
264
></TT
265
> as the title. The
266
<TT
267
CLASS="PARAMETER"
268
><I
269
>__meta</I
270
></TT
271
> argument defines any meta tags that will
272
be inserted into the header. <TT
273
CLASS="LITERAL"
274
>html_body_begin()</TT
275
> and
276
<TT
277
CLASS="LITERAL"
278
>html_body_end</TT
279
> generate HTML body begin and end
280
tags.</P
281
><P
282
><TT
283
CLASS="LITERAL"
284
>html_heading()</TT
285
> generates a complete HTML header
286
where <TT
287
CLASS="PARAMETER"
288
><I
289
>__level</I
290
></TT
291
> is a numerical level, between 1
292
and 6, and <TT
293
CLASS="PARAMETER"
294
><I
295
>__heading</I
296
></TT
297
> is the heading
298
text. <TT
299
CLASS="LITERAL"
300
>html_para_begin()</TT
301
> generates a paragraph
302
break.</P
303
><P
304
><TT
305
CLASS="LITERAL"
306
>html_url()</TT
307
> inserts a URL where
308
<TT
309
CLASS="PARAMETER"
310
><I
311
>__text</I
312
></TT
313
> is the displayed text and
314
<TT
315
CLASS="PARAMETER"
316
><I
317
>__link</I
318
></TT
319
> is the URL of the linked
320
page. <TT
321
CLASS="LITERAL"
322
>html_image()</TT
323
> inserts an image tag where
324
<TT
325
CLASS="PARAMETER"
326
><I
327
>__source</I
328
></TT
329
> is the URL of the image to be
330
included and <TT
331
CLASS="PARAMETER"
332
><I
333
>__alt</I
334
></TT
335
> is the alternative text for
336
when the image is not displayed.</P
337
></DIV
338
><DIV
339
CLASS="SECT2"
340
><H2
341
CLASS="SECT2"
342
><A
343
NAME="AEN15344">Table Support</H2
344
><TABLE
345
BORDER="5"
346
BGCOLOR="#E0E0F0"
347
WIDTH="70%"
348
><TR
349
><TD
350
><PRE
351
CLASS="PROGRAMLISTING"
352
>#define html_table_begin( __client, __attr )
353
#define html_table_end( __client )
354
#define html_table_header( __client, __content, __attr )
355
#define html_table_row_begin( __client, __attr )
356
#define html_table_row_end( __client )
357
#define html_table_data_begin( __client, __attr )
358
#define html_table_data_end( __client )               </PRE
359
></TD
360
></TR
361
></TABLE
362
><P
363
><TT
364
CLASS="LITERAL"
365
>html_table_begin()</TT
366
> starts a table and
367
<TT
368
CLASS="LITERAL"
369
>html_table_end()</TT
370
> end
371
it. <TT
372
CLASS="LITERAL"
373
>html_table_header()</TT
374
> generates a simple table
375
column header containg the string <TT
376
CLASS="PARAMETER"
377
><I
378
>__content</I
379
></TT
380
>. </P
381
><P
382
><TT
383
CLASS="LITERAL"
384
>html_table_row_begin()</TT
385
> and
386
<TT
387
CLASS="LITERAL"
388
>html_table_row_end()</TT
389
> begin and end a table row,
390
and similarly <TT
391
CLASS="LITERAL"
392
>html_table_data_begin()</TT
393
> and
394
<TT
395
CLASS="LITERAL"
396
>html_table_data_end()</TT
397
> begin and end a table
398
entry. </P
399
></DIV
400
><DIV
401
CLASS="SECT2"
402
><H2
403
CLASS="SECT2"
404
><A
405
NAME="AEN15357">Forms Support</H2
406
><TABLE
407
BORDER="5"
408
BGCOLOR="#E0E0F0"
409
WIDTH="70%"
410
><TR
411
><TD
412
><PRE
413
CLASS="PROGRAMLISTING"
414
>#define html_form_begin( __client, __url, __attr )
415
#define html_form_end( __client )
416
#define html_form_input( __client, __type, __name, __value, __attr )
417
#define html_form_input_radio( __client, __name, __value, __checked )
418
#define html_form_input_checkbox( __client, __name, __value, __checked )
419
#define html_form_input_hidden( __client, __name, __value )
420
#define html_form_select_begin( __client, __name, __attr )
421
#define html_form_option( __client, __value, __label, __selected )
422
#define html_form_select_end( __client )
423
void cyg_formdata_parse( char *data, char *list[], int size );
424
char *cyg_formlist_find( char *list[], char *name );</PRE
425
></TD
426
></TR
427
></TABLE
428
><P
429
><TT
430
CLASS="LITERAL"
431
>html_form_begin()</TT
432
> begins a form, the
433
<TT
434
CLASS="PARAMETER"
435
><I
436
>__url</I
437
></TT
438
> argument is the value for the
439
<TT
440
CLASS="LITERAL"
441
>action</TT
442
>
443
attribute. <TT
444
CLASS="LITERAL"
445
>html_form_end()</TT
446
> ends the form.</P
447
><P
448
><TT
449
CLASS="LITERAL"
450
>html_form_input()</TT
451
> defines a general form input
452
element with the given type, name and
453
value. <TT
454
CLASS="LITERAL"
455
>html_form_input_radio</TT
456
> creates a radio button
457
with the given name and value; the <TT
458
CLASS="PARAMETER"
459
><I
460
>__checked</I
461
></TT
462
>
463
argument is a boolean expression that is used to determine whether the
464
<TT
465
CLASS="LITERAL"
466
>checked</TT
467
> attribute is added to the tag. Similarly
468
<TT
469
CLASS="LITERAL"
470
>html_form_input_checkbox()</TT
471
> defines a checkbox
472
element. <TT
473
CLASS="LITERAL"
474
>html_form_input_hidden()</TT
475
> defines a hidden
476
form element with the given name and value.</P
477
><P
478
><TT
479
CLASS="LITERAL"
480
>html_form_select_begin()</TT
481
> begins a multiple choice
482
menu with the given name. <TT
483
CLASS="LITERAL"
484
>html_form_select_end()</TT
485
>
486
end it. <TT
487
CLASS="LITERAL"
488
>html_form_option()</TT
489
> defines a menu entry
490
with the given value and label; the <TT
491
CLASS="PARAMETER"
492
><I
493
>__selected</I
494
></TT
495
>
496
argument is a boolean expression controlling whether the
497
<TT
498
CLASS="LITERAL"
499
>selected</TT
500
> attribute is added to the tag.</P
501
><P
502
><TT
503
CLASS="FUNCTION"
504
>cyg_formdata_parse()</TT
505
> converts a form response
506
string into an <TT
507
CLASS="LITERAL"
508
>NULL</TT
509
>-terminated array of
510
&quot;name=value&quot; entries. The <TT
511
CLASS="PARAMETER"
512
><I
513
>data</I
514
></TT
515
>
516
argument is the string as passed to the handler function; note that
517
this string is not copied and will be updated in place to form the
518
list entries.  <TT
519
CLASS="PARAMETER"
520
><I
521
>list</I
522
></TT
523
> is a pointer to an array of
524
character pointers, and is <TT
525
CLASS="PARAMETER"
526
><I
527
>size</I
528
></TT
529
> elements long.
530
<TT
531
CLASS="FUNCTION"
532
>cyg_formlist_find()</TT
533
> searches a list generated by
534
<TT
535
CLASS="FUNCTION"
536
>cyg_formdata_parse()</TT
537
> and returns a pointer to the
538
value part of the string whose name part matches
539
<TT
540
CLASS="PARAMETER"
541
><I
542
>name</I
543
></TT
544
>; if there is no match it will return
545
<TT
546
CLASS="LITERAL"
547
>NULL</TT
548
>.</P
549
></DIV
550
><DIV
551
CLASS="SECT2"
552
><H2
553
CLASS="SECT2"
554
><A
555
NAME="AEN15388">Predefined Handlers</H2
556
><TABLE
557
BORDER="5"
558
BGCOLOR="#E0E0F0"
559
WIDTH="70%"
560
><TR
561
><TD
562
><PRE
563
CLASS="PROGRAMLISTING"
564
>&#13;int cyg_httpd_send_html( FILE *client, char *filename, char *request, void *arg );
565
 
566
typedef struct
567
{
568
    char        *content_type;
569
    cyg_uint32  content_length;
570
    cyg_uint8   *data;
571
} cyg_httpd_data;
572
#define CYG_HTTPD_DATA( __name, __type, __length, __data )
573
 
574
int cyg_httpd_send_data( FILE *client, char *filename, char *request, void *arg );&#13;</PRE
575
></TD
576
></TR
577
></TABLE
578
><P
579
>The HTTP server defines a couple of predefined handers to make it
580
easier to deliver simple, static content.</P
581
><P
582
><TT
583
CLASS="FUNCTION"
584
>cyg_httpd_send_html()</TT
585
> takes a
586
<TT
587
CLASS="LITERAL"
588
>NULL</TT
589
>-terminated string as the argument and sends it
590
to the client with an HTTP header indicating that it is HTML. The
591
following is an example of its use:</P
592
><TABLE
593
BORDER="5"
594
BGCOLOR="#E0E0F0"
595
WIDTH="70%"
596
><TR
597
><TD
598
><PRE
599
CLASS="PROGRAMLISTING"
600
>&#13;char cyg_html_message[] = "&lt;head&gt;&lt;title&gt;Welcome&lt;/title&gt;&lt;/head&gt;\n"
601
                          "&lt;body&gt;&lt;h2&gt;Welcome to my Web Page&lt;/h2&gt;&lt;/body&gt;\n"
602
 
603
CYG_HTTPD_TABLE_ENTRY( cyg_html_message_entry,
604
                       "/message.html",
605
                       cyg_httpd_send_html,
606
                       cyg_html_message );&#13;</PRE
607
></TD
608
></TR
609
></TABLE
610
><P
611
><TT
612
CLASS="FUNCTION"
613
>cyg_httpd_send_data()</TT
614
> Sends arbitrary data to the
615
client. The argument is a pointer to a <SPAN
616
CLASS="TYPE"
617
>cyg_httpd_data</SPAN
618
>
619
structure that defines the content type and length of the data, and a
620
pointer to the data itself. The <TT
621
CLASS="LITERAL"
622
>CYG_HTTPD_DATA()</TT
623
>
624
macro automates the definition of the structure. Here is a typical
625
example of its use:</P
626
><TABLE
627
BORDER="5"
628
BGCOLOR="#E0E0F0"
629
WIDTH="70%"
630
><TR
631
><TD
632
><PRE
633
CLASS="PROGRAMLISTING"
634
>&#13;static cyg_uint8 ecos_logo_gif[] = {
635
    ...
636
};
637
 
638
CYG_HTTPD_DATA( cyg_monitor_ecos_logo_data,
639
                "image/gif",
640
                sizeof(ecos_logo_gif),
641
                ecos_logo_gif );
642
 
643
CYG_HTTPD_TABLE_ENTRY( cyg_monitor_ecos_logo,
644
                       "/monitor/ecos.gif",
645
                       cyg_httpd_send_data,
646
                       &amp;cyg_monitor_ecos_logo_data );&#13;</PRE
647
></TD
648
></TR
649
></TABLE
650
></DIV
651
></DIV
652
><DIV
653
CLASS="NAVFOOTER"
654
><HR
655
ALIGN="LEFT"
656
WIDTH="100%"><TABLE
657
SUMMARY="Footer navigation table"
658
WIDTH="100%"
659
BORDER="0"
660
CELLPADDING="0"
661
CELLSPACING="0"
662
><TR
663
><TD
664
WIDTH="33%"
665
ALIGN="left"
666
VALIGN="top"
667
><A
668
HREF="net-httpd-configuration.html"
669
ACCESSKEY="P"
670
>Prev</A
671
></TD
672
><TD
673
WIDTH="34%"
674
ALIGN="center"
675
VALIGN="top"
676
><A
677
HREF="ecos-ref.html"
678
ACCESSKEY="H"
679
>Home</A
680
></TD
681
><TD
682
WIDTH="33%"
683
ALIGN="right"
684
VALIGN="top"
685
><A
686
HREF="net-httpd-monitor.html"
687
ACCESSKEY="N"
688
>Next</A
689
></TD
690
></TR
691
><TR
692
><TD
693
WIDTH="33%"
694
ALIGN="left"
695
VALIGN="top"
696
>Server Configuration</TD
697
><TD
698
WIDTH="34%"
699
ALIGN="center"
700
VALIGN="top"
701
><A
702
HREF="net-httpd-chapter.html"
703
ACCESSKEY="U"
704
>Up</A
705
></TD
706
><TD
707
WIDTH="33%"
708
ALIGN="right"
709
VALIGN="top"
710
>System Monitor</TD
711
></TR
712
></TABLE
713
></DIV
714
></BODY
715
></HTML
716
>

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