aboutsummaryrefslogtreecommitdiff
path: root/lib/select.c
blob: 14dc6e1348a2c469f49978622e039496d06ec635 (plain)
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
/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif

#if !defined(HAVE_SELECT) && !defined(HAVE_POLL_FINE)
#error "We can't compile without select() or poll() support."
#endif

#if defined(__BEOS__) && !defined(__HAIKU__)
/* BeOS has FD_SET defined in socket.h */
#include <socket.h>
#endif

#ifdef MSDOS
#include <dos.h>  /* delay() */
#endif

#ifdef __VXWORKS__
#include <strings.h>  /* bzero() in FD_SET */
#endif

#include <curl/curl.h>

#include "urldata.h"
#include "connect.h"
#include "select.h"
#include "warnless.h"

/* Convenience local macros */
#define ELAPSED_MS()  (int)curlx_tvdiff(curlx_tvnow(), initial_tv)

int Curl_ack_eintr = 0;
#define ERROR_NOT_EINTR(error) (Curl_ack_eintr || error != EINTR)

/*
 * Internal function used for waiting a specific amount of ms
 * in Curl_socket_check() and Curl_poll() when no file descriptor
 * is provided to wait on, just being used to delay execution.
 * WinSock select() and poll() timeout mechanisms need a valid
 * socket descriptor in a not null file descriptor set to work.
 * Waiting indefinitely with this function is not allowed, a
 * zero or negative timeout value will return immediately.
 * Timeout resolution, accuracy, as well as maximum supported
 * value is system dependent, neither factor is a citical issue
 * for the intended use of this function in the library.
 *
 * Return values:
 *   -1 = system call error, invalid timeout value, or interrupted
 *    0 = specified timeout has elapsed
 */
int Curl_wait_ms(int timeout_ms)
{
#if !defined(MSDOS) && !defined(USE_WINSOCK)
#ifndef HAVE_POLL_FINE
  struct timeval pending_tv;
#endif
  struct timeval initial_tv;
  int pending_ms;
  int error;
#endif
  int r = 0;

  if(!timeout_ms)
    return 0;
  if(timeout_ms < 0) {
    SET_SOCKERRNO(EINVAL);
    return -1;
  }
#if defined(MSDOS)
  delay(timeout_ms);
#elif defined(USE_WINSOCK)
  Sleep(timeout_ms);
#else
  pending_ms = timeout_ms;
  initial_tv = curlx_tvnow();
  do {
#if defined(HAVE_POLL_FINE)
    r = poll(NULL, 0, pending_ms);
#else
    pending_tv.tv_sec = pending_ms / 1000;
    pending_tv.tv_usec = (pending_ms % 1000) * 1000;
    r = select(0, NULL, NULL, NULL, &pending_tv);
#endif /* HAVE_POLL_FINE */
    if(r != -1)
      break;
    error = SOCKERRNO;
    if(error && ERROR_NOT_EINTR(error))
      break;
    pending_ms = timeout_ms - ELAPSED_MS();
    if(pending_ms <= 0) {
      r = 0;  /* Simulate a "call timed out" case */
      break;
    }
  } while(r == -1);
#endif /* USE_WINSOCK */
  if(r)
    r = -1;
  return r;
}

/*
 * Wait for read or write events on a set of file descriptors. It uses poll()
 * when a fine poll() is available, in order to avoid limits with FD_SETSIZE,
 * otherwise select() is used.  An error is returned if select() is being used
 * and a file descriptor is too large for FD_SETSIZE.
 *
 * A negative timeout value makes this function wait indefinitely,
 * unless no valid file descriptor is given, when this happens the
 * negative timeout is ignored and the function times out immediately.
 *
 * Return values:
 *   -1 = system call error or fd >= FD_SETSIZE
 *    0 = timeout
 *    [bitmask] = action as described below
 *
 * CURL_CSELECT_IN - first socket is readable
 * CURL_CSELECT_IN2 - second socket is readable
 * CURL_CSELECT_OUT - write socket is writable
 * CURL_CSELECT_ERR - an error condition occurred
 */
int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
                      curl_socket_t readfd1,
                      curl_socket_t writefd, /* socket to write to */
                      time_t timeout_ms)     /* milliseconds to wait */
{
#ifdef HAVE_POLL_FINE
  struct pollfd pfd[3];
  int num;
#else
  struct timeval pending_tv;
  struct timeval *ptimeout;
  fd_set fds_read;
  fd_set fds_write;
  fd_set fds_err;
  curl_socket_t maxfd;
#endif
  struct timeval initial_tv = {0, 0};
  int pending_ms = 0;
  int error;
  int r;
  int ret;

#if SIZEOF_LONG != SIZEOF_INT
  /* wrap-around precaution */
  if(timeout_ms >= INT_MAX)
    timeout_ms = INT_MAX;
#endif

  if((readfd0 == CURL_SOCKET_BAD) && (readfd1 == CURL_SOCKET_BAD) &&
     (writefd == CURL_SOCKET_BAD)) {
    /* no sockets, just wait */
    r = Curl_wait_ms((int)timeout_ms);
    return r;
  }

  /* Avoid initial timestamp, avoid curlx_tvnow() call, when elapsed
     time in this function does not need to be measured. This happens
     when function is called with a zero timeout or a negative timeout
     value indicating a blocking call should be performed. */

  if(timeout_ms > 0) {
    pending_ms = (int)timeout_ms;
    initial_tv = curlx_tvnow();
  }

#ifdef HAVE_POLL_FINE

  num = 0;
  if(readfd0 != CURL_SOCKET_BAD) {
    pfd[num].fd = readfd0;
    pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI;
    pfd[num].revents = 0;
    num++;
  }
  if(readfd1 != CURL_SOCKET_BAD) {
    pfd[num].fd = readfd1;
    pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI;
    pfd[num].revents = 0;
    num++;
  }
  if(writefd != CURL_SOCKET_BAD) {
    pfd[num].fd = writefd;
    pfd[num].events = POLLWRNORM|POLLOUT;
    pfd[num].revents = 0;
    num++;
  }

  do {
    if(timeout_ms < 0)
      pending_ms = -1;
    else if(!timeout_ms)
      pending_ms = 0;
    r = poll(pfd, num, pending_ms);
    if(r != -1)
      break;
    error = SOCKERRNO;
    if(error && ERROR_NOT_EINTR(error))
      break;
    if(timeout_ms > 0) {
      pending_ms = (int)(timeout_ms - ELAPSED_MS());
      if(pending_ms <= 0) {
        r = 0;  /* Simulate a "call timed out" case */
        break;
      }
    }
  } while(r == -1);

  if(r < 0)
    return -1;
  if(r == 0)
    return 0;

  ret = 0;
  num = 0;
  if(readfd0 != CURL_SOCKET_BAD) {
    if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP))
      ret |= CURL_CSELECT_IN;
    if(pfd[num].revents & (POLLRDBAND|POLLPRI|POLLNVAL))
      ret |= CURL_CSELECT_ERR;
    num++;
  }
  if(readfd1 != CURL_SOCKET_BAD) {
    if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP))
      ret |= CURL_CSELECT_IN2;
    if(pfd[num].revents & (POLLRDBAND|POLLPRI|POLLNVAL))
      ret |= CURL_CSELECT_ERR;
    num++;
  }
  if(writefd != CURL_SOCKET_BAD) {
    if(pfd[num].revents & (POLLWRNORM|POLLOUT))
      ret |= CURL_CSELECT_OUT;
    if(pfd[num].revents & (POLLERR|POLLHUP|POLLNVAL))
      ret |= CURL_CSELECT_ERR;
  }

  return ret;

#else  /* HAVE_POLL_FINE */

  FD_ZERO(&fds_err);
  maxfd = (curl_socket_t)-1;

  FD_ZERO(&fds_read);
  if(readfd0 != CURL_SOCKET_BAD) {
    VERIFY_SOCK(readfd0);
    FD_SET(readfd0, &fds_read);
    FD_SET(readfd0, &fds_err);
    maxfd = readfd0;
  }
  if(readfd1 != CURL_SOCKET_BAD) {
    VERIFY_SOCK(readfd1);
    FD_SET(readfd1, &fds_read);
    FD_SET(readfd1, &fds_err);
    if(readfd1 > maxfd)
      maxfd = readfd1;
  }

  FD_ZERO(&fds_write);
  if(writefd != CURL_SOCKET_BAD) {
    VERIFY_SOCK(writefd);
    FD_SET(writefd, &fds_write);
    FD_SET(writefd, &fds_err);
    if(writefd > maxfd)
      maxfd = writefd;
  }

  ptimeout = (timeout_ms < 0) ? NULL : &pending_tv;

  do {
    if(timeout_ms > 0) {
      pending_tv.tv_sec = pending_ms / 1000;
      pending_tv.tv_usec = (pending_ms % 1000) * 1000;
    }
    else if(!timeout_ms) {
      pending_tv.tv_sec = 0;
      pending_tv.tv_usec = 0;
    }

    /* WinSock select() must not be called with an fd_set that contains zero
       fd flags, or it will return WSAEINVAL.  But, it also can't be called
       with no fd_sets at all!  From the documentation:

         Any two of the parameters, readfds, writefds, or exceptfds, can be
         given as null. At least one must be non-null, and any non-null
         descriptor set must contain at least one handle to a socket.

       We know that we have at least one bit set in at least two fd_sets in
       this case, but we may have no bits set in either fds_read or fd_write,
       so check for that and handle it.  Luckily, with WinSock, we can _also_
       ask how many bits are set on an fd_set.

       It is unclear why WinSock doesn't just handle this for us instead of
       calling this an error.

       Note also that WinSock ignores the first argument, so we don't worry
       about the fact that maxfd is computed incorrectly with WinSock (since
       curl_socket_t is unsigned in such cases and thus -1 is the largest
       value).
    */
#ifdef USE_WINSOCK
    r = select((int)maxfd + 1,
               fds_read.fd_count ? &fds_read : NULL,
               fds_write.fd_count ? &fds_write : NULL,
               &fds_err, ptimeout);
#else
    r = select((int)maxfd + 1, &fds_read, &fds_write, &fds_err, ptimeout);
#endif

    if(r != -1)
      break;
    error = SOCKERRNO;
    if(error && ERROR_NOT_EINTR(error))
      break;
    if(timeout_ms > 0) {
      pending_ms = (int)(timeout_ms - ELAPSED_MS());
      if(pending_ms <= 0) {
        r = 0;  /* Simulate a "call timed out" case */
        break;
      }
    }
  } while(r == -1);

  if(r < 0)
    return -1;
  if(r == 0)
    return 0;

  ret = 0;
  if(readfd0 != CURL_SOCKET_BAD) {
    if(FD_ISSET(readfd0, &fds_read))
      ret |= CURL_CSELECT_IN;
    if(FD_ISSET(readfd0, &fds_err))
      ret |= CURL_CSELECT_ERR;
  }
  if(readfd1 != CURL_SOCKET_BAD) {
    if(FD_ISSET(readfd1, &fds_read))
      ret |= CURL_CSELECT_IN2;
    if(FD_ISSET(readfd1, &fds_err))
      ret |= CURL_CSELECT_ERR;
  }
  if(writefd != CURL_SOCKET_BAD) {
    if(FD_ISSET(writefd, &fds_write))
      ret |= CURL_CSELECT_OUT;
    if(FD_ISSET(writefd, &fds_err))
      ret |= CURL_CSELECT_ERR;
  }

  return ret;

#endif  /* HAVE_POLL_FINE */

}

/*
 * This is a wrapper around poll().  If poll() does not exist, then
 * select() is used instead.  An error is returned if select() is
 * being used and a file descriptor is too large for FD_SETSIZE.
 * A negative timeout value makes this function wait indefinitely,
 * unless no valid file descriptor is given, when this happens the
 * negative timeout is ignored and the function times out immediately.
 *
 * Return values:
 *   -1 = system call error or fd >= FD_SETSIZE
 *    0 = timeout
 *    N = number of structures with non zero revent fields
 */
int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
{
#ifndef HAVE_POLL_FINE
  struct timeval pending_tv;
  struct timeval *ptimeout;
  fd_set fds_read;
  fd_set fds_write;
  fd_set fds_err;
  curl_socket_t maxfd;
#endif
  struct timeval initial_tv = {0, 0};
  bool fds_none = TRUE;
  unsigned int i;
  int pending_ms = 0;
  int error;
  int r;

  if(ufds) {
    for(i = 0; i < nfds; i++) {
      if(ufds[i].fd != CURL_SOCKET_BAD) {
        fds_none = FALSE;
        break;
      }
    }
  }
  if(fds_none) {
    r = Curl_wait_ms(timeout_ms);
    return r;
  }

  /* Avoid initial timestamp, avoid curlx_tvnow() call, when elapsed
     time in this function does not need to be measured. This happens
     when function is called with a zero timeout or a negative timeout
     value indicating a blocking call should be performed. */

  if(timeout_ms > 0) {
    pending_ms = timeout_ms;
    initial_tv = curlx_tvnow();
  }

#ifdef HAVE_POLL_FINE

  do {
    if(timeout_ms < 0)
      pending_ms = -1;
    else if(!timeout_ms)
      pending_ms = 0;
    r = poll(ufds, nfds, pending_ms);
    if(r != -1)
      break;
    error = SOCKERRNO;
    if(error && ERROR_NOT_EINTR(error))
      break;
    if(timeout_ms > 0) {
      pending_ms = (int)(timeout_ms - ELAPSED_MS());
      if(pending_ms <= 0) {
        r = 0;  /* Simulate a "call timed out" case */
        break;
      }
    }
  } while(r == -1);

  if(r < 0)
    return -1;
  if(r == 0)
    return 0;

  for(i = 0; i < nfds; i++) {
    if(ufds[i].fd == CURL_SOCKET_BAD)
      continue;
    if(ufds[i].revents & POLLHUP)
      ufds[i].revents |= POLLIN;
    if(ufds[i].revents & POLLERR)
      ufds[i].revents |= (POLLIN|POLLOUT);
  }

#else  /* HAVE_POLL_FINE */

  FD_ZERO(&fds_read);
  FD_ZERO(&fds_write);
  FD_ZERO(&fds_err);
  maxfd = (curl_socket_t)-1;

  for(i = 0; i < nfds; i++) {
    ufds[i].revents = 0;
    if(ufds[i].fd == CURL_SOCKET_BAD)
      continue;
    VERIFY_SOCK(ufds[i].fd);
    if(ufds[i].events & (POLLIN|POLLOUT|POLLPRI|
                          POLLRDNORM|POLLWRNORM|POLLRDBAND)) {
      if(ufds[i].fd > maxfd)
        maxfd = ufds[i].fd;
      if(ufds[i].events & (POLLRDNORM|POLLIN))
        FD_SET(ufds[i].fd, &fds_read);
      if(ufds[i].events & (POLLWRNORM|POLLOUT))
        FD_SET(ufds[i].fd, &fds_write);
      if(ufds[i].events & (POLLRDBAND|POLLPRI))
        FD_SET(ufds[i].fd, &fds_err);
    }
  }

#ifdef USE_WINSOCK
  /* WinSock select() can't handle zero events.  See the comment about this in
     Curl_check_socket(). */
  if(fds_read.fd_count == 0 && fds_write.fd_count == 0
     && fds_err.fd_count == 0) {
    r = Curl_wait_ms(timeout_ms);
    return r;
  }
#endif

  ptimeout = (timeout_ms < 0) ? NULL : &pending_tv;

  do {
    if(timeout_ms > 0) {
      pending_tv.tv_sec = pending_ms / 1000;
      pending_tv.tv_usec = (pending_ms % 1000) * 1000;
    }
    else if(!timeout_ms) {
      pending_tv.tv_sec = 0;
      pending_tv.tv_usec = 0;
    }

#ifdef USE_WINSOCK
    r = select((int)maxfd + 1,
               /* WinSock select() can't handle fd_sets with zero bits set, so
                  don't give it such arguments.  See the comment about this in
                  Curl_check_socket().
               */
               fds_read.fd_count ? &fds_read : NULL,
               fds_write.fd_count ? &fds_write : NULL,
               fds_err.fd_count ? &fds_err : NULL, ptimeout);
#else
    r = select((int)maxfd + 1, &fds_read, &fds_write, &fds_err, ptimeout);
#endif
    if(r != -1)
      break;
    error = SOCKERRNO;
    if(error && ERROR_NOT_EINTR(error))
      break;
    if(timeout_ms > 0) {
      pending_ms = timeout_ms - ELAPSED_MS();
      if(pending_ms <= 0) {
        r = 0;  /* Simulate a "call timed out" case */
        break;
      }
    }
  } while(r == -1);

  if(r < 0)
    return -1;
  if(r == 0)
    return 0;

  r = 0;
  for(i = 0; i < nfds; i++) {
    ufds[i].revents = 0;
    if(ufds[i].fd == CURL_SOCKET_BAD)
      continue;
    if(FD_ISSET(ufds[i].fd, &fds_read))
      ufds[i].revents |= POLLIN;
    if(FD_ISSET(ufds[i].fd, &fds_write))
      ufds[i].revents |= POLLOUT;
    if(FD_ISSET(ufds[i].fd, &fds_err))
      ufds[i].revents |= POLLPRI;
    if(ufds[i].revents != 0)
      r++;
  }

#endif  /* HAVE_POLL_FINE */

  return r;
}

#ifdef TPF
/*
 * This is a replacement for select() on the TPF platform.
 * It is used whenever libcurl calls select().
 * The call below to tpf_process_signals() is required because
 * TPF's select calls are not signal interruptible.
 *
 * Return values are the same as select's.
 */
int tpf_select_libcurl(int maxfds, fd_set* reads, fd_set* writes,
                       fd_set* excepts, struct timeval* tv)
{
   int rc;

   rc = tpf_select_bsd(maxfds, reads, writes, excepts, tv);
   tpf_process_signals();
   return rc;
}
#endif /* TPF */