net/base/nss_memio.c

   1 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 // Written in NSPR style to also be suitable for adding to the NSS demo suite
   5
   6 /* memio is a simple NSPR I/O layer that lets you decouple NSS from
   7  * the real network.  It's rather like openssl's memory bio,
   8  * and is useful when your app absolutely, positively doesn't
   9  * want to let NSS do its own networking.
  10  */
  11
  12 #include <stdlib.h>
  13 #include <string.h>
  14
  15 #include <prerror.h>
  16 #include <prinit.h>
  17 #include <prlog.h>
  18
  19 #include "nss_memio.h"
  20
  21 /*--------------- private memio types -----------------------*/
  22
  23 /*----------------------------------------------------------------------
  24  Simple private circular buffer class.  Size cannot be changed once allocated.
  25 ----------------------------------------------------------------------*/
  26
  27 struct memio_buffer {
  28     int head;     /* where to take next byte out of buf */
  29     int tail;     /* where to put next byte into buf */
  30     int bufsize;  /* number of bytes allocated to buf */
  31     /* TODO(port): error handling is pessimistic right now.
  32      * Once an error is set, the socket is considered broken
  33      * (PR_WOULD_BLOCK_ERROR not included).
  34      */
  35     PRErrorCode last_err;
  36     char *buf;
  37 };
  38
  39
  40 /* The 'secret' field of a PRFileDesc created by memio_CreateIOLayer points
  41  * to one of these.
  42  * In the public header, we use struct memio_Private as a typesafe alias
  43  * for this.  This causes a few ugly typecasts in the private file, but
  44  * seems safer.
  45  */
  46 struct PRFilePrivate {
  47     /* read requests are satisfied from this buffer */
  48     struct memio_buffer readbuf;
  49
  50     /* write requests are satisfied from this buffer */
  51     struct memio_buffer writebuf;
  52
  53     /* SSL needs to know socket peer's name */
  54     PRNetAddr peername;
  55
  56     /* if set, empty I/O returns EOF instead of EWOULDBLOCK */
  57     int eof;
  58
  59     /* if set, the number of bytes requested from readbuf that were not
  60      * fulfilled (due to readbuf being empty) */
  61     int read_requested;
  62 };
  63
  64 /*--------------- private memio_buffer functions ---------------------*/
  65
  66 /* Forward declarations.  */
  67
  68 /* Allocate a memio_buffer of given size. */
  69 static void memio_buffer_new(struct memio_buffer *mb, int size);
  70
  71 /* Deallocate a memio_buffer allocated by memio_buffer_new. */
  72 static void memio_buffer_destroy(struct memio_buffer *mb);
  73
  74 /* How many bytes can be read out of the buffer without wrapping */
  75 static int memio_buffer_used_contiguous(const struct memio_buffer *mb);
  76
  77 /* How many bytes exist after the wrap? */
  78 static int memio_buffer_wrapped_bytes(const struct memio_buffer *mb);
  79
  80 /* How many bytes can be written into the buffer without wrapping */
  81 static int memio_buffer_unused_contiguous(const struct memio_buffer *mb);
  82
  83 /* Write n bytes into the buffer.  Returns number of bytes written. */
  84 static int memio_buffer_put(struct memio_buffer *mb, const char *buf, int n);
  85
  86 /* Read n bytes from the buffer.  Returns number of bytes read. */
  87 static int memio_buffer_get(struct memio_buffer *mb, char *buf, int n);
  88
  89 /* Allocate a memio_buffer of given size. */
  90 static void memio_buffer_new(struct memio_buffer *mb, int size)
  91 {
  92     mb->head = 0;
  93     mb->tail = 0;
  94     mb->bufsize = size;
  95     mb->buf = malloc(size);
  96 }
  97
  98 /* Deallocate a memio_buffer allocated by memio_buffer_new. */
  99 static void memio_buffer_destroy(struct memio_buffer *mb)
 100 {
 101     free(mb->buf);
 102     mb->buf = NULL;
 103     mb->head = 0;
 104     mb->tail = 0;
 105 }
 106
 107 /* How many bytes can be read out of the buffer without wrapping */
 108 static int memio_buffer_used_contiguous(const struct memio_buffer *mb)
 109 {
 110     return (((mb->tail >= mb->head) ? mb->tail : mb->bufsize) - mb->head);
 111 }
 112
 113 /* How many bytes exist after the wrap? */
 114 static int memio_buffer_wrapped_bytes(const struct memio_buffer *mb)
 115 {
 116     return (mb->tail >= mb->head) ? 0 : mb->tail;
 117 }
 118
 119 /* How many bytes can be written into the buffer without wrapping */
 120 static int memio_buffer_unused_contiguous(const struct memio_buffer *mb)
 121 {
 122     if (mb->head > mb->tail) return mb->head - mb->tail - 1;
 123     return mb->bufsize - mb->tail - (mb->head == 0);
 124 }
 125
 126 /* Write n bytes into the buffer.  Returns number of bytes written. */
 127 static int memio_buffer_put(struct memio_buffer *mb, const char *buf, int n)
 128 {
 129     int len;
 130     int transferred = 0;
 131
 132     /* Handle part before wrap */
 133     len = PR_MIN(n, memio_buffer_unused_contiguous(mb));
 134     if (len > 0) {
 135         /* Buffer not full */
 136         memcpy(&mb->buf[mb->tail], buf, len);
 137         mb->tail += len;
 138         if (mb->tail == mb->bufsize)
 139             mb->tail = 0;
 140         n -= len;
 141         buf += len;
 142         transferred += len;
 143
 144         /* Handle part after wrap */
 145         len = PR_MIN(n, memio_buffer_unused_contiguous(mb));
 146         if (len > 0) {
 147             /* Output buffer still not full, input buffer still not empty */
 148             memcpy(&mb->buf[mb->tail], buf, len);
 149             mb->tail += len;
 150             if (mb->tail == mb->bufsize)
 151                 mb->tail = 0;
 152             transferred += len;
 153         }
 154     }
 155
 156     return transferred;
 157 }
 158
 159
 160 /* Read n bytes from the buffer.  Returns number of bytes read. */
 161 static int memio_buffer_get(struct memio_buffer *mb, char *buf, int n)
 162 {
 163     int len;
 164     int transferred = 0;
 165
 166     /* Handle part before wrap */
 167     len = PR_MIN(n, memio_buffer_used_contiguous(mb));
 168     if (len) {
 169         memcpy(buf, &mb->buf[mb->head], len);
 170         mb->head += len;
 171         if (mb->head == mb->bufsize)
 172             mb->head = 0;
 173         n -= len;
 174         buf += len;
 175         transferred += len;
 176
 177         /* Handle part after wrap */
 178         len = PR_MIN(n, memio_buffer_used_contiguous(mb));
 179         if (len) {
 180             memcpy(buf, &mb->buf[mb->head], len);
 181             mb->head += len;
 182             if (mb->head == mb->bufsize)
 183                 mb->head = 0;
 184             transferred += len;
 185         }
 186     }
 187
 188     return transferred;
 189 }
 190
 191 /*--------------- private memio functions -----------------------*/
 192
 193 static PRStatus PR_CALLBACK memio_Close(PRFileDesc *fd)
 194 {
 195     struct PRFilePrivate *secret = fd->secret;
 196     memio_buffer_destroy(&secret->readbuf);
 197     memio_buffer_destroy(&secret->writebuf);
 198     free(secret);
 199     fd->dtor(fd);
 200     return PR_SUCCESS;
 201 }
 202
 203 static PRStatus PR_CALLBACK memio_Shutdown(PRFileDesc *fd, PRIntn how)
 204 {
 205     /* TODO: pass shutdown status to app somehow */
 206     return PR_SUCCESS;
 207 }
 208
 209 /* If there was a network error in the past taking bytes
 210  * out of the buffer, return it to the next call that
 211  * tries to read from an empty buffer.
 212  */
 213 static int PR_CALLBACK memio_Recv(PRFileDesc *fd, void *buf, PRInt32 len,
 214                                   PRIntn flags, PRIntervalTime timeout)
 215 {
 216     struct PRFilePrivate *secret;
 217     struct memio_buffer *mb;
 218     int rv;
 219
 220     if (flags) {
 221         PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0);
 222         return -1;
 223     }
 224
 225     secret = fd->secret;
 226     mb = &secret->readbuf;
 227     PR_ASSERT(mb->bufsize);
 228     rv = memio_buffer_get(mb, buf, len);
 229     if (rv == 0 && !secret->eof) {
 230         secret->read_requested = len;
 231         /* If there is no more data in the buffer, report any pending errors
 232          * that were previously observed. Note that both the readbuf and the
 233          * writebuf are checked for errors, since the application may have
 234          * encountered a socket error while writing that would otherwise not
 235          * be reported until the application attempted to write again - which
 236          * it may never do.
 237          */
 238         if (mb->last_err)
 239             PR_SetError(mb->last_err, 0);
 240         else if (secret->writebuf.last_err)
 241             PR_SetError(secret->writebuf.last_err, 0);
 242         else
 243             PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
 244         return -1;
 245     }
 246
 247     secret->read_requested = 0;
 248     return rv;
 249 }
 250
 251 static int PR_CALLBACK memio_Read(PRFileDesc *fd, void *buf, PRInt32 len)
 252 {
 253     /* pull bytes from buffer */
 254     return memio_Recv(fd, buf, len, 0, PR_INTERVAL_NO_TIMEOUT);
 255 }
 256
 257 static int PR_CALLBACK memio_Send(PRFileDesc *fd, const void *buf, PRInt32 len,
 258                                   PRIntn flags, PRIntervalTime timeout)
 259 {
 260     struct PRFilePrivate *secret;
 261     struct memio_buffer *mb;
 262     int rv;
 263
 264     secret = fd->secret;
 265     mb = &secret->writebuf;
 266     PR_ASSERT(mb->bufsize);
 267
 268     /* Note that the read error state is not reported, because it cannot be
 269      * reported until all buffered data has been read. If there is an error
 270      * with the next layer, attempting to call Send again will report the
 271      * error appropriately.
 272      */
 273     if (mb->last_err) {
 274         PR_SetError(mb->last_err, 0);
 275         return -1;
 276     }
 277     rv = memio_buffer_put(mb, buf, len);
 278     if (rv == 0) {
 279         PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
 280         return -1;
 281     }
 282     return rv;
 283 }
 284
 285 static int PR_CALLBACK memio_Write(PRFileDesc *fd, const void *buf, PRInt32 len)
 286 {
 287     /* append bytes to buffer */
 288     return memio_Send(fd, buf, len, 0, PR_INTERVAL_NO_TIMEOUT);
 289 }
 290
 291 static PRStatus PR_CALLBACK memio_GetPeerName(PRFileDesc *fd, PRNetAddr *addr)
 292 {
 293     /* TODO: fail if memio_SetPeerName has not been called */
 294     struct PRFilePrivate *secret = fd->secret;
 295     *addr = secret->peername;
 296     return PR_SUCCESS;
 297 }
 298
 299 static PRStatus memio_GetSocketOption(PRFileDesc *fd, PRSocketOptionData *data)
 300 {
 301     /*
 302      * Even in the original version for real tcp sockets,
 303      * PR_SockOpt_Nonblocking is a special case that does not
 304      * translate to a getsockopt() call
 305      */
 306     if (PR_SockOpt_Nonblocking == data->option) {
 307         data->value.non_blocking = PR_TRUE;
 308         return PR_SUCCESS;
 309     }
 310     PR_SetError(PR_OPERATION_NOT_SUPPORTED_ERROR, 0);
 311     return PR_FAILURE;
 312 }
 313
 314 /*--------------- private memio data -----------------------*/
 315
 316 /*
 317  * Implement just the bare minimum number of methods needed to make ssl happy.
 318  *
 319  * Oddly, PR_Recv calls ssl_Recv calls ssl_SocketIsBlocking calls
 320  * PR_GetSocketOption, so we have to provide an implementation of
 321  * PR_GetSocketOption that just says "I'm nonblocking".
 322  */
 323
 324 static struct PRIOMethods  memio_layer_methods = {
 325     PR_DESC_LAYERED,
 326     memio_Close,
 327     memio_Read,
 328     memio_Write,
 329     NULL,
 330     NULL,
 331     NULL,
 332     NULL,
 333     NULL,
 334     NULL,
 335     NULL,
 336     NULL,
 337     NULL,
 338     NULL,
 339     NULL,
 340     NULL,
 341     memio_Shutdown,
 342     memio_Recv,
 343     memio_Send,
 344     NULL,
 345     NULL,
 346     NULL,
 347     NULL,
 348     NULL,
 349     NULL,
 350     memio_GetPeerName,
 351     NULL,
 352     NULL,
 353     memio_GetSocketOption,
 354     NULL,
 355     NULL,
 356     NULL,
 357     NULL,
 358     NULL,
 359     NULL,
 360     NULL,
 361 };
 362
 363 static PRDescIdentity memio_identity = PR_INVALID_IO_LAYER;
 364
 365 static PRStatus memio_InitializeLayerName(void)
 366 {
 367     memio_identity = PR_GetUniqueIdentity("memio");
 368     return PR_SUCCESS;
 369 }
 370
 371 /*--------------- public memio functions -----------------------*/
 372
 373 PRFileDesc *memio_CreateIOLayer(int readbufsize, int writebufsize)
 374 {
 375     PRFileDesc *fd;
 376     struct PRFilePrivate *secret;
 377     static PRCallOnceType once;
 378
 379     PR_CallOnce(&once, memio_InitializeLayerName);
 380
 381     fd = PR_CreateIOLayerStub(memio_identity, &memio_layer_methods);
 382     secret = malloc(sizeof(struct PRFilePrivate));
 383     memset(secret, 0, sizeof(*secret));
 384
 385     memio_buffer_new(&secret->readbuf, readbufsize);
 386     memio_buffer_new(&secret->writebuf, writebufsize);
 387     fd->secret = secret;
 388     return fd;
 389 }
 390
 391 void memio_SetPeerName(PRFileDesc *fd, const PRNetAddr *peername)
 392 {
 393     PRFileDesc *memiofd = PR_GetIdentitiesLayer(fd, memio_identity);
 394     struct PRFilePrivate *secret = memiofd->secret;
 395     secret->peername = *peername;
 396 }
 397
 398 memio_Private *memio_GetSecret(PRFileDesc *fd)
 399 {
 400     PRFileDesc *memiofd = PR_GetIdentitiesLayer(fd, memio_identity);
 401     struct PRFilePrivate *secret =  memiofd->secret;
 402     return (memio_Private *)secret;
 403 }
 404
 405 int memio_GetReadRequest(memio_Private *secret)
 406 {
 407     return ((PRFilePrivate *)secret)->read_requested;
 408 }
 409
 410 int memio_GetReadParams(memio_Private *secret, char **buf)
 411 {
 412     struct memio_buffer* mb = &((PRFilePrivate *)secret)->readbuf;
 413     PR_ASSERT(mb->bufsize);
 414
 415     *buf = &mb->buf[mb->tail];
 416     return memio_buffer_unused_contiguous(mb);
 417 }
 418
 419 int memio_GetReadableBufferSize(memio_Private *secret)
 420 {
 421     struct memio_buffer* mb = &((PRFilePrivate *)secret)->readbuf;
 422     PR_ASSERT(mb->bufsize);
 423
 424     return memio_buffer_used_contiguous(mb);
 425 }
 426
 427 void memio_PutReadResult(memio_Private *secret, int bytes_read)
 428 {
 429     struct memio_buffer* mb = &((PRFilePrivate *)secret)->readbuf;
 430     PR_ASSERT(mb->bufsize);
 431
 432     if (bytes_read > 0) {
 433         mb->tail += bytes_read;
 434         if (mb->tail == mb->bufsize)
 435             mb->tail = 0;
 436     } else if (bytes_read == 0) {
 437         /* Record EOF condition and report to caller when buffer runs dry */
 438         ((PRFilePrivate *)secret)->eof = PR_TRUE;
 439     } else /* if (bytes_read < 0) */ {
 440         mb->last_err = bytes_read;
 441     }
 442 }
 443
 444 void memio_GetWriteParams(memio_Private *secret,
 445                           const char **buf1, unsigned int *len1,
 446                           const char **buf2, unsigned int *len2)
 447 {
 448     struct memio_buffer* mb = &((PRFilePrivate *)secret)->writebuf;
 449     PR_ASSERT(mb->bufsize);
 450
 451     *buf1 = &mb->buf[mb->head];
 452     *len1 = memio_buffer_used_contiguous(mb);
 453     *buf2 = mb->buf;
 454     *len2 = memio_buffer_wrapped_bytes(mb);
 455 }
 456
 457 void memio_PutWriteResult(memio_Private *secret, int bytes_written)
 458 {
 459     struct memio_buffer* mb = &((PRFilePrivate *)secret)->writebuf;
 460     PR_ASSERT(mb->bufsize);
 461
 462     if (bytes_written > 0) {
 463         mb->head += bytes_written;
 464         if (mb->head >= mb->bufsize)
 465             mb->head -= mb->bufsize;
 466     } else if (bytes_written < 0) {
 467         mb->last_err = bytes_written;
 468     }
 469 }
 470
 471 /*--------------- private memio_buffer self-test -----------------*/
 472
 473 /* Even a trivial unit test is very helpful when doing circular buffers. */
 474 /*#define TRIVIAL_SELF_TEST*/
 475 #ifdef TRIVIAL_SELF_TEST
 476 #include <stdio.h>
 477
 478 #define TEST_BUFLEN 7
 479
 480 #define CHECKEQ(a, b) { \
 481     if ((a) != (b)) { \
 482         printf("%d != %d, Test failed line %d\n", a, b, __LINE__); \
 483         exit(1); \
 484     } \
 485 }
 486
 487 int main()
 488 {
 489     struct memio_buffer mb;
 490     char buf[100];
 491     int i;
 492
 493     memio_buffer_new(&mb, TEST_BUFLEN);
 494
 495     CHECKEQ(memio_buffer_unused_contiguous(&mb), TEST_BUFLEN-1);
 496     CHECKEQ(memio_buffer_used_contiguous(&mb), 0);
 497
 498     CHECKEQ(memio_buffer_put(&mb, "howdy", 5), 5);
 499
 500     CHECKEQ(memio_buffer_unused_contiguous(&mb), TEST_BUFLEN-1-5);
 501     CHECKEQ(memio_buffer_used_contiguous(&mb), 5);
 502     CHECKEQ(memio_buffer_wrapped_bytes(&mb), 0);
 503
 504     CHECKEQ(memio_buffer_put(&mb, "!", 1), 1);
 505
 506     CHECKEQ(memio_buffer_unused_contiguous(&mb), 0);
 507     CHECKEQ(memio_buffer_used_contiguous(&mb), 6);
 508     CHECKEQ(memio_buffer_wrapped_bytes(&mb), 0);
 509
 510     CHECKEQ(memio_buffer_get(&mb, buf, 6), 6);
 511     CHECKEQ(memcmp(buf, "howdy!", 6), 0);
 512
 513     CHECKEQ(memio_buffer_unused_contiguous(&mb), 1);
 514     CHECKEQ(memio_buffer_used_contiguous(&mb), 0);
 515
 516     CHECKEQ(memio_buffer_put(&mb, "01234", 5), 5);
 517
 518     CHECKEQ(memio_buffer_used_contiguous(&mb), 1);
 519     CHECKEQ(memio_buffer_wrapped_bytes(&mb), 4);
 520     CHECKEQ(memio_buffer_unused_contiguous(&mb), TEST_BUFLEN-1-5);
 521
 522     CHECKEQ(memio_buffer_put(&mb, "5", 1), 1);
 523
 524     CHECKEQ(memio_buffer_unused_contiguous(&mb), 0);
 525     CHECKEQ(memio_buffer_used_contiguous(&mb), 1);
 526
 527     /* TODO: add more cases */
 528
 529     printf("Test passed\n");
 530     exit(0);
 531 }
 532
 533 #endif