aboutsummaryrefslogtreecommitdiffstats
path: root/src/input_curl.c
blob: f863865224e96c3349d80bd6abd4caa44b3044d0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
/* the Music Player Daemon (MPD)
 * Copyright (C) 2008 Max Kellermann <max@duempel.org>
 * This project's homepage is: http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "input_curl.h"
#include "input_stream.h"
#include "config.h"
#include "tag.h"
#include "icy_metadata.h"

#include <assert.h>
#include <sys/select.h>
#include <string.h>
#include <errno.h>

#include <curl/curl.h>
#include <glib.h>

/** rewinding is possible after up to 64 kB */
static const off_t max_rewind_size = 64 * 1024;

/**
 * Buffers created by input_curl_writefunction().
 */
struct buffer {
	/** size of the payload */
	size_t size;

	/** how much has been consumed yet? */
	size_t consumed;

	/** the payload */
	unsigned char data[sizeof(long)];
};

struct input_curl {
	/* some buffers which were passed to libcurl, which we have
	   too free */
	char *url, *range;
	struct curl_slist *request_headers;

	/** the curl handles */
	CURL *easy;
	CURLM *multi;

	/** list of buffers, where input_curl_writefunction() appends
	    to, and input_curl_read() reads from them */
	GQueue *buffers;

	/** has something been added to the buffers list? */
	bool buffered;

	/** did libcurl tell us the we're at the end of the response body? */
	bool eof;

	/** limited list of old buffers, for rewinding */
	GQueue *rewind;

	/** error message provided by libcurl */
	char error[CURL_ERROR_SIZE];

	/** parser for icy-metadata */
	struct icy_metadata icy_metadata;

	/** the stream name from the icy-name response header */
	char *meta_name;

	/** the tag object ready to be requested via
	    input_stream_tag() */
	struct tag *tag;
};

/** libcurl should accept "ICY 200 OK" */
static struct curl_slist *http_200_aliases;

void input_curl_global_init(void)
{
	CURLcode code = curl_global_init(CURL_GLOBAL_ALL);
	if (code != CURLE_OK)
		g_warning("curl_global_init() failed: %s\n",
			  curl_easy_strerror(code));

	http_200_aliases = curl_slist_append(http_200_aliases, "ICY 200 OK");
}

void input_curl_global_finish(void)
{
	curl_slist_free_all(http_200_aliases);

	curl_global_cleanup();
}

static void
buffer_free_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
{
	struct buffer *buffer = data;

	assert(buffer->consumed <= buffer->size);

	g_free(data);
}

/**
 * Frees the current "libcurl easy" handle, and everything associated
 * with it.
 */
static void
input_curl_easy_free(struct input_curl *c)
{
	if (c->easy != NULL) {
		curl_multi_remove_handle(c->multi, c->easy);
		curl_easy_cleanup(c->easy);
		c->easy = NULL;
	}

	curl_slist_free_all(c->request_headers);
	c->request_headers = NULL;

	g_free(c->range);
	c->range = NULL;

	g_queue_foreach(c->buffers, buffer_free_callback, NULL);
	g_queue_clear(c->buffers);

	if (c->rewind != NULL) {
		g_queue_foreach(c->rewind, buffer_free_callback, NULL);
		g_queue_clear(c->rewind);
	}
}

/**
 * Frees this stream (but not the input_stream struct itself).
 */
static void
input_curl_free(struct input_stream *is)
{
	struct input_curl *c = is->data;

	if (c->tag != NULL)
		tag_free(c->tag);
	g_free(c->meta_name);

	input_curl_easy_free(c);

	if (c->multi != NULL)
		curl_multi_cleanup(c->multi);

	g_queue_free(c->buffers);
	if (c->rewind != NULL)
		g_queue_free(c->rewind);

	g_free(c->url);
	g_free(c);
}

static struct tag *
input_curl_tag(struct input_stream *is)
{
	struct input_curl *c = is->data;
	struct tag *tag = c->tag;

	c->tag = NULL;
	return tag;
}

static bool
input_curl_multi_info_read(struct input_stream *is)
{
	struct input_curl *c = is->data;
	CURLMsg *msg;
	int msgs_in_queue;

	while ((msg = curl_multi_info_read(c->multi,
					   &msgs_in_queue)) != NULL) {
		if (msg->msg == CURLMSG_DONE) {
			c->eof = true;

			if (msg->data.result != CURLE_OK) {
				g_warning("curl failed: %s\n", c->error);
				is->error = -1;
				return false;
			}
		}
	}

	return true;
}

/**
 * Wait for the libcurl socket.
 *
 * @return -1 on error, 0 if no data is available yet, 1 if data is
 * available
 */
static int
input_curl_select(struct input_curl *c)
{
	fd_set rfds, wfds, efds;
	int max_fd, ret;
	CURLMcode mcode;
	/* XXX hard coded timeout value.. */
	struct timeval timeout = {
		.tv_sec = 1,
		.tv_usec = 0,
	};

	FD_ZERO(&rfds);
	FD_ZERO(&wfds);
	FD_ZERO(&efds);

	mcode = curl_multi_fdset(c->multi, &rfds, &wfds, &efds, &max_fd);
	if (mcode != CURLM_OK) {
		g_warning("curl_multi_fdset() failed: %s\n",
			  curl_multi_strerror(mcode));
		return -1;
	}

	assert(max_fd >= 0);

	ret = select(max_fd + 1, &rfds, &wfds, &efds, &timeout);
	if (ret < 0)
		g_warning("select() failed: %s\n", strerror(errno));

	return ret;
}

/**
 * Mark a part of the buffer object as consumed.
 */
static struct buffer *
consume_buffer(struct buffer *buffer, size_t length, GQueue *rewind_buffers)
{
	assert(buffer != NULL);
	assert(buffer->consumed < buffer->size);

	buffer->consumed += length;
	if (buffer->consumed < buffer->size)
		return buffer;

	assert(buffer->consumed == buffer->size);

	if (rewind_buffers != NULL)
		/* append this buffer to the rewind buffer list */
		g_queue_push_tail(rewind_buffers, buffer);
	else
		g_free(buffer);

	return NULL;
}

static size_t
read_from_buffer(struct icy_metadata *icy_metadata, GQueue *buffers,
		 void *dest0, size_t length,
		 GQueue *rewind_buffers)
{
	struct buffer *buffer = g_queue_pop_head(buffers);
	uint8_t *dest = dest0;
	size_t nbytes = 0;

	assert(buffer->size > 0);
	assert(buffer->consumed < buffer->size);

	if (length > buffer->size - buffer->consumed)
		length = buffer->size - buffer->consumed;

	while (true) {
		size_t chunk;

		chunk = icy_data(icy_metadata, length);
		if (chunk > 0) {
			memcpy(dest, buffer->data + buffer->consumed,
			       chunk);
			buffer = consume_buffer(buffer, chunk, rewind_buffers);

			nbytes += chunk;
			dest += chunk;
			length -= chunk;

			if (length == 0)
				break;

			assert(buffer != NULL);
		}

		chunk = icy_meta(icy_metadata, buffer->data + buffer->consumed,
				 length);
		if (chunk > 0) {
			buffer = consume_buffer(buffer, chunk, rewind_buffers);

			length -= chunk;

			if (length == 0)
				break;

			assert(buffer != NULL);
		}
	}

	if (buffer != NULL)
		g_queue_push_head(buffers, buffer);

	return nbytes;
}

static void
copy_icy_tag(struct input_curl *c)
{
	struct tag *tag = icy_tag(&c->icy_metadata);

	if (tag == NULL)
		return;

	if (c->tag != NULL)
		tag_free(c->tag);

	if (c->meta_name != NULL && !tag_has_type(tag, TAG_ITEM_NAME))
		tag_add_item(tag, TAG_ITEM_NAME, c->meta_name);

	c->tag = tag;
}

static size_t
input_curl_read(struct input_stream *is, void *ptr, size_t size)
{
	struct input_curl *c = is->data;
	CURLMcode mcode = CURLM_CALL_MULTI_PERFORM;
	GQueue *rewind_buffers;
	size_t nbytes = 0;
	char *dest = ptr;

#ifndef NDEBUG
	if (c->rewind != NULL &&
	    (!g_queue_is_empty(c->rewind) || is->offset == 0)) {
		off_t offset = 0;
		struct buffer *buffer;

		for (GList *list = g_queue_peek_head_link(c->rewind);
		     list != NULL; list = g_list_next(list)) {
			buffer = list->data;
			offset += buffer->consumed;
			assert(offset <= is->offset);
		}

		buffer = g_queue_peek_head(c->buffers);
		if (buffer != NULL)
			offset += buffer->consumed;

		assert(offset == is->offset);
	}
#endif

	/* fill the buffer */

	while (!c->eof && g_queue_is_empty(c->buffers)) {
		int running_handles;
		bool bret;

		if (mcode != CURLM_CALL_MULTI_PERFORM) {
			/* if we're still here, there is no input yet
			   - wait for input */
			int ret = input_curl_select(c);
			if (ret <= 0)
				/* no data yet or error */
				return 0;
		}

		mcode = curl_multi_perform(c->multi, &running_handles);
		if (mcode != CURLM_OK && mcode != CURLM_CALL_MULTI_PERFORM) {
			g_warning("curl_multi_perform() failed: %s\n",
				  curl_multi_strerror(mcode));
			c->eof = true;
			return 0;
		}

		bret = input_curl_multi_info_read(is);
		if (!bret)
			return 0;
	}

	/* send buffer contents */

	if (c->rewind != NULL &&
	    (!g_queue_is_empty(c->rewind) || is->offset == 0))
		/* at the beginning or already writing the rewind
		   buffer list */
		rewind_buffers = c->rewind;
	else
		/* we don't need the rewind buffers anymore */
		rewind_buffers = NULL;

	while (size > 0 && !g_queue_is_empty(c->buffers)) {
		size_t copy = read_from_buffer(&c->icy_metadata, c->buffers,
					       dest + nbytes, size,
					       rewind_buffers);

		nbytes += copy;
		size -= copy;
	}

	if (icy_defined(&c->icy_metadata))
		copy_icy_tag(c);

	is->offset += (off_t)nbytes;

#ifndef NDEBUG
	if (rewind_buffers != NULL) {
		off_t offset = 0;
		struct buffer *buffer;

		for (GList *list = g_queue_peek_head_link(c->rewind);
		     list != NULL; list = g_list_next(list)) {
			buffer = list->data;
			offset += buffer->consumed;
			assert(offset <= is->offset);
		}

		buffer = g_queue_peek_head(c->buffers);
		if (buffer != NULL)
			offset += buffer->consumed;

		assert(offset == is->offset);
	}
#endif

	if (rewind_buffers != NULL && is->offset > max_rewind_size) {
		/* drop the rewind buffer, it has grown too large */

		g_queue_foreach(c->rewind, buffer_free_callback, NULL);
		g_queue_clear(c->rewind);
	}

	return nbytes;
}

static void
input_curl_close(struct input_stream *is)
{
	input_curl_free(is);
}

static bool
input_curl_eof(G_GNUC_UNUSED struct input_stream *is)
{
	struct input_curl *c = is->data;

	return c->eof && g_queue_is_empty(c->buffers);
}

static int
input_curl_buffer(struct input_stream *is)
{
	struct input_curl *c = is->data;
	CURLMcode mcode;
	int running_handles;
	bool ret;

	c->buffered = false;

	do {
		mcode = curl_multi_perform(c->multi, &running_handles);
	} while (mcode == CURLM_CALL_MULTI_PERFORM &&
		 g_queue_is_empty(c->buffers));

	if (mcode != CURLM_OK && mcode != CURLM_CALL_MULTI_PERFORM) {
		g_warning("curl_multi_perform() failed: %s\n",
			  curl_multi_strerror(mcode));
		c->eof = true;
		return -1;
	}

	ret = input_curl_multi_info_read(is);
	if (!ret)
		return -1;

	return c->buffered;
}

/** called by curl when new data is available */
static size_t
input_curl_headerfunction(void *ptr, size_t size, size_t nmemb, void *stream)
{
	struct input_stream *is = stream;
	struct input_curl *c = is->data;
	const char *header = ptr, *end, *value;
	char name[64];

	size *= nmemb;
	end = header + size;

	value = memchr(header, ':', size);
	if (value == NULL || (size_t)(value - header) >= sizeof(name))
		return size;

	memcpy(name, header, value - header);
	name[value - header] = 0;

	/* skip the colon */

	++value;

	/* strip the value */

	while (value < end && g_ascii_isspace(*value))
		++value;

	while (end > value && g_ascii_isspace(end[-1]))
		--end;

	if (strcasecmp(name, "accept-ranges") == 0) {
		/* a stream with icy-metadata is not seekable */
		if (!icy_defined(&c->icy_metadata))
			is->seekable = true;
	} else if (strcasecmp(name, "content-length") == 0) {
		char buffer[64];

		if ((size_t)(end - header) >= sizeof(buffer))
			return size;

		memcpy(buffer, value, end - value);
		buffer[end - value] = 0;

		is->size = is->offset + g_ascii_strtoull(buffer, NULL, 10);
	} else if (strcasecmp(name, "content-type") == 0) {
		g_free(is->mime);
		is->mime = g_strndup(value, end - value);
	} else if (strcasecmp(name, "icy-name") == 0 ||
		   strcasecmp(name, "ice-name") == 0 ||
		   strcasecmp(name, "x-audiocast-name") == 0) {
		g_free(c->meta_name);
		c->meta_name = g_strndup(value, end - value);

		if (c->tag != NULL)
			tag_free(c->tag);

		c->tag = tag_new();
		tag_add_item(c->tag, TAG_ITEM_NAME, c->meta_name);
	} else if (strcasecmp(name, "icy-metaint") == 0) {
		char buffer[64];
		size_t icy_metaint;

		if ((size_t)(end - header) >= sizeof(buffer) ||
		    icy_defined(&c->icy_metadata))
			return size;

		memcpy(buffer, value, end - value);
		buffer[end - value] = 0;

		icy_metaint = g_ascii_strtoull(buffer, NULL, 10);
		g_debug("icy-metaint=%zu", icy_metaint);

		if (icy_metaint > 0) {
			icy_start(&c->icy_metadata, icy_metaint);

			/* a stream with icy-metadata is not
			   seekable */
			is->seekable = false;

			if (c->rewind != NULL) {
				/* rewinding with icy-metadata is too
				   hairy for me .. */
				assert(g_queue_is_empty(c->rewind));

				g_queue_free(c->rewind);
				c->rewind = NULL;
			}
		}
	}

	return size;
}

/** called by curl when new data is available */
static size_t
input_curl_writefunction(void *ptr, size_t size, size_t nmemb, void *stream)
{
	struct input_stream *is = stream;
	struct input_curl *c = is->data;
	struct buffer *buffer;

	size *= nmemb;
	if (size == 0)
		return 0;

	buffer = g_malloc(sizeof(*buffer) - sizeof(buffer->data) + size);
	buffer->size = size;
	buffer->consumed = 0;
	memcpy(buffer->data, ptr, size);
	g_queue_push_tail(c->buffers, buffer);

	c->buffered = true;
	is->ready = true;

	return size;
}

static bool
input_curl_easy_init(struct input_stream *is)
{
	struct input_curl *c = is->data;
	CURLcode code;
	CURLMcode mcode;

	c->eof = false;

	c->easy = curl_easy_init();
	if (c->easy == NULL) {
		g_warning("curl_easy_init() failed\n");
		return false;
	}

	mcode = curl_multi_add_handle(c->multi, c->easy);
	if (mcode != CURLM_OK)
		return false;

	curl_easy_setopt(c->easy, CURLOPT_USERAGENT,
			 "Music Player Daemon " VERSION);
	curl_easy_setopt(c->easy, CURLOPT_HEADERFUNCTION,
			 input_curl_headerfunction);
	curl_easy_setopt(c->easy, CURLOPT_WRITEHEADER, is);
	curl_easy_setopt(c->easy, CURLOPT_WRITEFUNCTION,
			 input_curl_writefunction);
	curl_easy_setopt(c->easy, CURLOPT_WRITEDATA, is);
	curl_easy_setopt(c->easy, CURLOPT_HTTP200ALIASES, http_200_aliases);
	curl_easy_setopt(c->easy, CURLOPT_FOLLOWLOCATION, 1);
	curl_easy_setopt(c->easy, CURLOPT_MAXREDIRS, 5);
	curl_easy_setopt(c->easy, CURLOPT_FAILONERROR, true);
	curl_easy_setopt(c->easy, CURLOPT_ERRORBUFFER, c->error);

	code = curl_easy_setopt(c->easy, CURLOPT_URL, c->url);
	if (code != CURLE_OK)
		return false;

	c->request_headers = NULL;
	c->request_headers = curl_slist_append(c->request_headers,
					       "Icy-Metadata: 1");
	curl_easy_setopt(c->easy, CURLOPT_HTTPHEADER, c->request_headers);

	return true;
}

static bool
input_curl_send_request(struct input_curl *c)
{
	CURLMcode mcode;
	int running_handles;

	do {
		mcode = curl_multi_perform(c->multi, &running_handles);
	} while (mcode == CURLM_CALL_MULTI_PERFORM);

	if (mcode != CURLM_OK) {
		g_warning("curl_multi_perform() failed: %s\n",
			  curl_multi_strerror(mcode));
		return false;
	}

	return true;
}

static bool
input_curl_can_rewind(struct input_stream *is)
{
	struct input_curl *c = is->data;
	struct buffer *buffer;

	if (c->rewind == NULL)
		return false;

	if (!g_queue_is_empty(c->rewind))
		/* the rewind buffer hasn't been wiped yet */
		return true;

	if (g_queue_is_empty(c->buffers))
		/* there are no buffers at all - cheap rewind not
		   possible */
		return false;

	/* rewind is possible if this is the very first buffer of the
	   resource */
	buffer = (struct buffer*)g_queue_peek_head(c->buffers);
	return (off_t)buffer->consumed == is->offset;
}

static void
input_curl_rewind(struct input_stream *is)
{
	struct input_curl *c = is->data;
#ifndef NDEBUG
	off_t offset = 0;
#endif

	assert(c->rewind != NULL);

	/* rewind the current buffer */

	if (!g_queue_is_empty(c->buffers)) {
		struct buffer *buffer =
			(struct buffer*)g_queue_peek_head(c->buffers);
#ifndef NDEBUG
		offset += buffer->consumed;
#endif
		buffer->consumed = 0;
	}

	/* reset and move all rewind buffers back to the regular buffer list */

	while (!g_queue_is_empty(c->rewind)) {
		struct buffer *buffer =
			(struct buffer*)g_queue_pop_tail(c->rewind);
#ifndef NDEBUG
		offset += buffer->consumed;
#endif
		buffer->consumed = 0;
		g_queue_push_head(c->buffers, buffer);
	}

	assert(offset == is->offset);

	is->offset = 0;

	/* rewind the icy_metadata object */

	icy_reset(&c->icy_metadata);
}

static bool
input_curl_seek(struct input_stream *is, off_t offset, int whence)
{
	struct input_curl *c = is->data;
	bool ret;

	if (whence == SEEK_SET && offset == 0) {
		if (is->offset == 0)
			/* no-op */
			return true;

		if (input_curl_can_rewind(is)) {
			/* we have enough rewind buffers left */
			input_curl_rewind(is);
			return true;
		}
	}

	if (!is->seekable)
		return false;

	/* calculate the absolute offset */

	switch (whence) {
	case SEEK_SET:
		break;

	case SEEK_CUR:
		offset += is->offset;
		break;

	case SEEK_END:
		if (is->size < 0)
			/* stream size is not known */
			return false;

		offset += is->size;
		break;

	default:
		return false;
	}

	if (offset < 0)
		return false;

	/* check if we can fast-forward the buffer */

	while (offset > is->offset && !g_queue_is_empty(c->buffers)) {
		GQueue *rewind_buffers;
		struct buffer *buffer;
		size_t length;

		if (c->rewind != NULL &&
		    (!g_queue_is_empty(c->rewind) || is->offset == 0))
			/* at the beginning or already writing the rewind
			   buffer list */
			rewind_buffers = c->rewind;
		else
			/* we don't need the rewind buffers anymore */
			rewind_buffers = NULL;

		buffer = (struct buffer *)g_queue_pop_head(c->buffers);

		length = buffer->size - buffer->consumed;
		if (offset - is->offset < (off_t)length)
			length = offset - is->offset;

		buffer = consume_buffer(buffer, length, rewind_buffers);
		if (buffer != NULL)
			g_queue_push_head(c->buffers, buffer);

		is->offset += length;
	}

	if (offset == is->offset)
		return true;

	/* close the old connection and open a new one */

	input_curl_easy_free(c);

	is->offset = offset;
	if (is->offset == is->size) {
		/* seek to EOF: simulate empty result; avoid
		   triggering a "416 Requested Range Not Satisfiable"
		   response */
		c->eof = true;
		return true;
	}

	ret = input_curl_easy_init(is);
	if (!ret)
		return false;

	/* send the "Range" header */

	if (is->offset > 0) {
		c->range = g_strdup_printf("%lld-", (long long)is->offset);
		curl_easy_setopt(c->easy, CURLOPT_RANGE, c->range);
	}

	ret = input_curl_send_request(c);
	if (!ret)
		return false;

	return input_curl_multi_info_read(is);
}

static bool
input_curl_open(struct input_stream *is, const char *url)
{
	struct input_curl *c;
	bool ret;

	if (strncmp(url, "http://", 7) != 0)
		return false;

	c = g_new0(struct input_curl, 1);
	c->url = g_strdup(url);
	c->buffers = g_queue_new();
	c->rewind = g_queue_new();

	is->data = c;

	c->multi = curl_multi_init();
	if (c->multi == NULL) {
		g_warning("curl_multi_init() failed\n");

		input_curl_free(is);
		return false;
	}

	icy_clear(&c->icy_metadata);
	c->tag = NULL;

	ret = input_curl_easy_init(is);
	if (!ret) {
		input_curl_free(is);
		return false;
	}

	ret = input_curl_send_request(c);
	if (!ret) {
		input_curl_free(is);
		return false;
	}

	return true;
}

const struct input_plugin input_plugin_curl = {
	.open = input_curl_open,
	.close = input_curl_close,
	.tag = input_curl_tag,
	.buffer = input_curl_buffer,
	.read = input_curl_read,
	.eof = input_curl_eof,
	.seek = input_curl_seek,
};