bss_bio.c

mediastreamer2是开源的网络传输媒体流的库

/* crypto/bio/bss_bio.c  -*- Mode: C; c-file-style: "eay" -*- */
/* ====================================================================
 * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    [e-mail].
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * ([e-mail]).  This product includes software written by Tim
 * Hudson ([e-mail]).
 *
 */

/* Special method for a BIO where the other endpoint is also a BIO
 * of this kind, handled by the same thread (i.e. the "peer" is actually
 * ourselves, wearing a different hat).
 * Such "BIO pairs" are mainly for using the SSL library with I/O interfaces
 * for which no specific BIO method is available.
 * See ssl/ssltest.c for some hints on how this can be used. */

/* BIO_DEBUG implies BIO_PAIR_DEBUG */
#ifdef BIO_DEBUG
# ifndef BIO_PAIR_DEBUG
#  define BIO_PAIR_DEBUG
# endif
#endif

/* disable assert() unless BIO_PAIR_DEBUG has been defined */
#ifndef BIO_PAIR_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif

#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/crypto.h>

#include "e_os.h"

/* VxWorks defines SSIZE_MAX with an empty value causing compile errors */
#if defined(OPENSSL_SYS_VXWORKS)
# undef SSIZE_MAX
#endif
#ifndef SSIZE_MAX
# define SSIZE_MAX INT_MAX
#endif

static int bio_new(BIO *bio);
static int bio_free(BIO *bio);
static int bio_read(BIO *bio, char *buf, int size);
static int bio_write(BIO *bio, const char *buf, int num);
static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr);
static int bio_puts(BIO *bio, const char *str);

static int bio_make_pair(BIO *bio1, BIO *bio2);
static void bio_destroy_pair(BIO *bio);

static BIO_METHOD methods_biop =
{
	BIO_TYPE_BIO,
	"BIO pair",
	bio_write,
	bio_read,
	bio_puts,
	NULL /* no bio_gets */,
	bio_ctrl,
	bio_new,
	bio_free,
	NULL /* no bio_callback_ctrl */
};

BIO_METHOD *BIO_s_bio(void)
	{
	return &methods_biop;
	}

struct bio_bio_st
{
	BIO *peer;     /* NULL if buf == NULL.
	                * If peer != NULL, then peer->ptr is also a bio_bio_st,
	                * and its "peer" member points back to us.
	                * peer != NULL iff init != 0 in the BIO. */
	
	/* This is for what we write (i.e. reading uses peer's struct): */
	int closed;     /* valid iff peer != NULL */
	size_t len;     /* valid iff buf != NULL; 0 if peer == NULL */
	size_t offset;  /* valid iff buf != NULL; 0 if len == 0 */
	size_t size;
	char *buf;      /* "size" elements (if != NULL) */

	size_t request; /* valid iff peer != NULL; 0 if len != 0,
	                 * otherwise set by peer to number of bytes
	                 * it (unsuccessfully) tried to read,
	                 * never more than buffer space (size-len) warrants. */
};

static int bio_new(BIO *bio)
	{
	struct bio_bio_st *b;
	
	b = OPENSSL_malloc(sizeof *b);
	if (b == NULL)
		return 0;

	b->peer = NULL;
	b->size = 17*1024; /* enough for one TLS record (just a default) */
	b->buf = NULL;

	bio->ptr = b;
	return 1;
	}


static int bio_free(BIO *bio)
	{
	struct bio_bio_st *b;

	if (bio == NULL)
		return 0;
	b = bio->ptr;

	assert(b != NULL);

	if (b->peer)
		bio_destroy_pair(bio);
	
	if (b->buf != NULL)
		{
		OPENSSL_free(b->buf);
		}

	OPENSSL_free(b);

	return 1;
	}



static int bio_read(BIO *bio, char *buf, int size_)
	{
	size_t size = size_;
	size_t rest;
	struct bio_bio_st *b, *peer_b;

	BIO_clear_retry_flags(bio);

	if (!bio->init)
		return 0;

	b = bio->ptr;
	assert(b != NULL);
	assert(b->peer != NULL);
	peer_b = b->peer->ptr;
	assert(peer_b != NULL);
	assert(peer_b->buf != NULL);

	peer_b->request = 0; /* will be set in "retry_read" situation */

	if (buf == NULL || size == 0)
		return 0;

	if (peer_b->len == 0)
		{
		if (peer_b->closed)
			return 0; /* writer has closed, and no data is left */
		else
			{
			BIO_set_retry_read(bio); /* buffer is empty */
			if (size <= peer_b->size)
				peer_b->request = size;
			else
				/* don't ask for more than the peer can
				 * deliver in one write */
				peer_b->request = peer_b->size;
			return -1;
			}
		}

	/* we can read */
	if (peer_b->len < size)
		size = peer_b->len;

	/* now read "size" bytes */
	
	rest = size;
	
	assert(rest > 0);
	do /* one or two iterations */
		{
		size_t chunk;
		
		assert(rest <= peer_b->len);
		if (peer_b->offset + rest <= peer_b->size)
			chunk = rest;
		else
			/* wrap around ring buffer */
			chunk = peer_b->size - peer_b->offset;
		assert(peer_b->offset + chunk <= peer_b->size);
		
		memcpy(buf, peer_b->buf + peer_b->offset, chunk);
		
		peer_b->len -= chunk;
		if (peer_b->len)
			{
			peer_b->offset += chunk;
			assert(peer_b->offset <= peer_b->size);
			if (peer_b->offset == peer_b->size)
				peer_b->offset = 0;
			buf += chunk;
			}
		else
			{
			/* buffer now empty, no need to advance "buf" */
			assert(chunk == rest);
			peer_b->offset = 0;
			}
		rest -= chunk;
		}
	while (rest);
	
	return size;
	}

/* non-copying interface: provide pointer to available data in buffer
 *    bio_nread0:  return number of available bytes
 *    bio_nread:   also advance index
 * (example usage:  bio_nread0(), read from buffer, bio_nread()
 *  or just         bio_nread(), read from buffer)
 */
/* WARNING: The non-copying interface is largely untested as of yet
 * and may contain bugs. */
static ssize_t bio_nread0(BIO *bio, char **buf)
	{
	struct bio_bio_st *b, *peer_b;
	ssize_t num;
	
	BIO_clear_retry_flags(bio);

	if (!bio->init)
		return 0;
	
	b = bio->ptr;
	assert(b != NULL);
	assert(b->peer != NULL);
	peer_b = b->peer->ptr;
	assert(peer_b != NULL);
	assert(peer_b->buf != NULL);
	
	peer_b->request = 0;
	
	if (peer_b->len == 0)
		{
		char dummy;
		
		/* avoid code duplication -- nothing available for reading */
		return bio_read(bio, &dummy, 1); /* returns 0 or -1 */
		}

	num = peer_b->len;
	if (peer_b->size < peer_b->offset + num)
		/* no ring buffer wrap-around for non-copying interface */
		num = peer_b->size - peer_b->offset;
	assert(num > 0);

	if (buf != NULL)
		*buf = peer_b->buf + peer_b->offset;
	return num;
	}

static ssize_t bio_nread(BIO *bio, char **buf, size_t num_)
	{
	struct bio_bio_st *b, *peer_b;
	ssize_t num, available;

	if (num_ > SSIZE_MAX)
		num = SSIZE_MAX;
	else
		num = (ssize_t)num_;

	available = bio_nread0(bio, buf);
	if (num > available)
		num = available;
	if (num <= 0)
		return num;

	b = bio->ptr;
	peer_b = b->peer->ptr;

	peer_b->len -= num;
	if (peer_b->len) 
		{
		peer_b->offset += num;
		assert(peer_b->offset <= peer_b->size);
		if (peer_b->offset == peer_b->size)
			peer_b->offset = 0;
		}
	else
		peer_b->offset = 0;

	return num;
	}


static int bio_write(BIO *bio, const char *buf, int num_)
	{
	size_t num = num_;
	size_t rest;
	struct bio_bio_st *b;

	BIO_clear_retry_flags(bio);

	if (!bio->init || buf == NULL || num == 0)
		return 0;

	b = bio->ptr;		
	assert(b != NULL);
	assert(b->peer != NULL);
	assert(b->buf != NULL);

	b->request = 0;
	if (b->closed)
		{
		/* we already closed */
		BIOerr(BIO_F_BIO_WRITE, BIO_R_BROKEN_PIPE);
		return -1;
		}

	assert(b->len <= b->size);

	if (b->len == b->size)
		{
		BIO_set_retry_write(bio); /* buffer is full */
		return -1;
		}

	/* we can write */
	if (num > b->size - b->len)
		num = b->size - b->len;
	
	/* now write "num" bytes */

	rest = num;
	
	assert(rest > 0);
	do /* one or two iterations */
		{
		size_t write_offset;
		size_t chunk;

		assert(b->len + rest <= b->size);

		write_offset = b->offset + b->len;
		if (write_offset >= b->size)
			write_offset -= b->size;
		/* b->buf[write_offset] is the first byte we can write to. */

		if (write_offset + rest <= b->size)
			chunk = rest;
		else
			/* wrap around ring buffer */
			chunk = b->size - write_offset;
		
		memcpy(b->buf + write_offset, buf, chunk);
		
		b->len += chunk;

		assert(b->len <= b->size);
		
		rest -= chunk;
		buf += chunk;
		}
	while (rest);

	return num;
	}

/* non-copying interface: provide pointer to region to write to
 *   bio_nwrite0:  check how much space is available
 *   bio_nwrite:   also increase length
 * (example usage:  bio_nwrite0(), write to buffer, bio_nwrite()
 *  or just         bio_nwrite(), write to buffer)
 */
static ssize_t bio_nwrite0(BIO *bio, char **buf)
	{
	struct bio_bio_st *b;
	size_t num;
	size_t write_offset;

	BIO_clear_retry_flags(bio);

	if (!bio->init)
		return 0;

	b = bio->ptr;		
	assert(b != NULL);
	assert(b->peer != NULL);
	assert(b->buf != NULL);

	b->request = 0;
	if (b->closed)
		{
		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);
		return -1;
		}

	assert(b->len <= b->size);

	if (b->len == b->size)
		{
		BIO_set_retry_write(bio);
		return -1;
		}

	num = b->size - b->len;
	write_offset = b->offset + b->len;