net/base/nss_memio.h

   1 // Copyright (c) 2011 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 #ifndef __MEMIO_H
   7 #define __MEMIO_H
   8
   9 #include <stddef.h>
  10
  11 #ifdef __cplusplus
  12 extern "C" {
  13 #endif
  14
  15 #include "prio.h"
  16
  17 /* Opaque structure.  Really just a more typesafe alias for PRFilePrivate. */
  18 struct memio_Private;
  19 typedef struct memio_Private memio_Private;
  20
  21 /*----------------------------------------------------------------------
  22  NSPR I/O layer that terminates in a pair of circular buffers
  23  rather than talking to the real network.
  24  To use this with NSS:
  25  1) call memio_CreateIOLayer to create a fake NSPR socket
  26  2) call SSL_ImportFD to ssl-ify the socket
  27  3) Do your own networking calls to set up a TCP connection
  28  4) call memio_SetPeerName to tell NSS about the other end of the connection
  29  5) While at the same time doing plaintext nonblocking NSPR I/O as
  30     usual to the nspr file descriptor returned by SSL_ImportFD,
  31     your app must shuttle encrypted data between
  32     the real network and memio's network buffers.
  33     memio_GetReadParams/memio_PutReadResult
  34     are the hooks you need to pump data into memio's input buffer,
  35     and memio_GetWriteParams/memio_PutWriteResult
  36     are the hooks you need to pump data out of memio's output buffer.
  37 ----------------------------------------------------------------------*/
  38
  39 /* Create the I/O layer and its two circular buffers. */
  40 PRFileDesc *memio_CreateIOLayer(int readbufsize, int writebufsize);
  41
  42 /* Must call before trying to make an ssl connection */
  43 void memio_SetPeerName(PRFileDesc *fd, const PRNetAddr *peername);
  44
  45 /* Return a private pointer needed by the following
  46  * four functions.  (We could have passed a PRFileDesc to
  47  * them, but that would be slower.  Better for the caller
  48  * to grab the pointer once and cache it.
  49  * This may be a premature optimization.)
  50  */
  51 memio_Private *memio_GetSecret(PRFileDesc *fd);
  52
  53 /* Ask memio how many bytes were requested by a higher layer if the
  54  * last attempt to read data resulted in PR_WOULD_BLOCK_ERROR, due to the
  55  * transport buffer being empty. If the last attempt to read data from the
  56  * memio did not result in PR_WOULD_BLOCK_ERROR, returns 0.
  57  */
  58 int memio_GetReadRequest(memio_Private *secret);
  59
  60 /* Ask memio where to put bytes from the network, and how many it can handle.
  61  * Returns bytes available to write, or 0 if none available.
  62  * Puts current buffer position into *buf.
  63  */
  64 int memio_GetReadParams(memio_Private *secret, char **buf);
  65
  66 /* Ask memio how many bytes are contained in the internal buffer.
  67  * Returns bytes available to read, or 0 if none available.
  68  */
  69 int memio_GetReadableBufferSize(memio_Private *secret);
  70
  71 /* Tell memio how many bytes were read from the network.
  72  * If bytes_read is 0, causes EOF to be reported to
  73  * NSS after it reads the last byte from the circular buffer.
  74  * If bytes_read is < 0, it is treated as an NSPR error code.
  75  * See nspr/pr/src/md/unix/unix_errors.c for how to
  76  * map from Unix errors to NSPR error codes.
  77  * On EWOULDBLOCK or the equivalent, don't call this function.
  78  */
  79 void memio_PutReadResult(memio_Private *secret, int bytes_read);
  80
  81 /* Ask memio what data it has to send to the network.
  82  * If there was previous a write error, the NSPR error code is returned.
  83  * Otherwise, it returns 0 and provides up to two buffers of data by
  84  * writing the positions and lengths into |buf1|, |len1| and |buf2|, |len2|.
  85  */
  86 int memio_GetWriteParams(memio_Private *secret,
  87                          const char **buf1, unsigned int *len1,
  88                          const char **buf2, unsigned int *len2);
  89
  90 /* Tell memio how many bytes were sent to the network.
  91  * If bytes_written is < 0, it is treated as an NSPR error code.
  92  * See nspr/pr/src/md/unix/unix_errors.c for how to
  93  * map from Unix errors to NSPR error codes.
  94  * On EWOULDBLOCK or the equivalent, don't call this function.
  95  */
  96 void memio_PutWriteResult(memio_Private *secret, int bytes_written);
  97
  98 #ifdef __cplusplus
  99 }
 100 #endif
 101
 102 #endif