text: // Copyright (c) 2008 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  // Written in NSPR style to also be suitable for adding to the NSS demo suite
  
  #ifndef __MEMIO_H
  #define __MEMIO_H
  
  #ifdef __cplusplus
  extern "C" {
  #endif 
  
  #include "prio.h"
  
  /* Opaque structure.  Really just a more typesafe alias for PRFilePrivate. */
  struct memio_Private;
  typedef struct memio_Private memio_Private;
  
  /*----------------------------------------------------------------------
   NSPR I/O layer that terminates in a pair of circular buffers
   rather than talking to the real network.
   To use this with NSS:
   1) call memio_CreateIOLayer to create a fake NSPR socket
   2) call SSL_ImportFD to ssl-ify the socket
   3) Do your own networking calls to set up a TCP connection
   4) call memio_SetPeerName to tell NSS about the other end of the connection
   5) While at the same time doing plaintext nonblocking NSPR I/O as
      usual to the nspr file descriptor returned by SSL_ImportFD,
      your app must shuttle encrypted data between
      the real network and memio's network buffers.  
      memio_GetReadParams/memio_PutReadResult
      are the hooks you need to pump data into memio's input buffer,
      and memio_GetWriteParams/memio_PutWriteResult
      are the hooks you need to pump data out of memio's output buffer.
  ----------------------------------------------------------------------*/
  
  /* Create the I/O layer and its two circular buffers. */
  PRFileDesc *memio_CreateIOLayer(int bufsize);
  
  /* Must call before trying to make an ssl connection */
  void memio_SetPeerName(PRFileDesc *fd, const PRNetAddr *peername);
  
  /* Return a private pointer needed by the following
   * four functions.  (We could have passed a PRFileDesc to
   * them, but that would be slower.  Better for the caller
   * to grab the pointer once and cache it.
   * This may be a premature optimization.)
   */
  memio_Private *memio_GetSecret(PRFileDesc *fd);
  
  /* Ask memio where to put bytes from the network, and how many it can handle.
   * Returns bytes available to write, or 0 if none available.
   * Puts current buffer position into *buf.
   */
  int memio_GetReadParams(memio_Private *secret, char **buf);
  
  /* Tell memio how many bytes were read from the network.
   * If bytes_read is 0, causes EOF to be reported to 
   * NSS after it reads the last byte from the circular buffer.
   * If bytes_read is < 0, it is treated as an NSPR error code.
   * See nspr/pr/src/md/unix/unix_errors.c for how to
   * map from Unix errors to NSPR error codes.
   * On EWOULDBLOCK or the equivalent, don't call this function.
   */
  void memio_PutReadResult(memio_Private *secret, int bytes_read);
  
  /* Ask memio what data it has to send to the network.
   * Returns buffer space available to read into, or 0 if none available.
   * Puts current buffer position into *buf.
   */
  int memio_GetWriteParams(memio_Private *secret, const char **buf);
  
  /* Tell memio how many bytes were sent to the network.
   * If bytes_written is < 0, it is treated as an NSPR error code.
   * See nspr/pr/src/md/unix/unix_errors.c for how to
   * map from Unix errors to NSPR error codes.
   * On EWOULDBLOCK or the equivalent, don't call this function.
   */
  void memio_PutWriteResult(memio_Private *secret, int bytes_written);
  
  
  #ifdef __cplusplus
  }
  #endif 
  
  #endif
  