/* $OpenBSD: bss_bio.c,v 1.25 2022/01/07 09:02:17 tb Exp $ */
/* ====================================================================
 * 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
 *    openssl-core@openssl.org.
 *
 * 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
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

/* 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 <sys/types.h>

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

#include "bio_local.h"

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 const BIO_METHOD methods_biop = {
	.type = BIO_TYPE_BIO,
	.name = "BIO pair",
	.bwrite = bio_write,
	.bread = bio_read,
	.bputs = bio_puts,
	.ctrl = bio_ctrl,
	.create = bio_new,
	.destroy = bio_free
};

const 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 = 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);

	free(b->buf);
	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 */
		BIOerror(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) {
		BIOerror(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;
	if (write_offset >= b->size)
		write_offset -= b->size;
	if (write_offset + num > b->size)
		/* no ring buffer wrap-around for non-copying interface
		 * (to fulfil the promise by BIO_ctrl_get_write_guarantee,
		 * BIO_nwrite may have to be called twice) */
		num = b->size - write_offset;

	if (buf != NULL)
		*buf = b->buf + write_offset;
	assert(write_offset + num <= b->size);

	return num;
}

static ssize_t
bio_nwrite(BIO *bio, char **buf, size_t num_)
{
	struct bio_bio_st *b;
	ssize_t num, space;

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

	space = bio_nwrite0(bio, buf);
	if (num > space)
		num = space;
	if (num <= 0)
		return num;
	b = bio->ptr;
	assert(b != NULL);
	b->len += num;
	assert(b->len <= b->size);

	return num;
}


static long
bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
{
	long ret;
	struct bio_bio_st *b = bio->ptr;

	assert(b != NULL);

	switch (cmd) {
		/* specific CTRL codes */

	case BIO_C_SET_WRITE_BUF_SIZE:
		if (b->peer) {
			BIOerror(BIO_R_IN_USE);
			ret = 0;
		} else if (num == 0) {
			BIOerror(BIO_R_INVALID_ARGUMENT);
			ret = 0;
		} else {
			size_t new_size = num;

			if (b->size != new_size) {
				free(b->buf);
				b->buf = NULL;
				b->size = new_size;
			}
			ret = 1;
		}
		break;

	case BIO_C_GET_WRITE_BUF_SIZE:
		ret = (long) b->size;
		break;

	case BIO_C_MAKE_BIO_PAIR:
		{
			BIO *other_bio = ptr;

			if (bio_make_pair(bio, other_bio))
				ret = 1;
			else
				ret = 0;
		}
		break;

	case BIO_C_DESTROY_BIO_PAIR:
		/* Affects both BIOs in the pair -- call just once!
		 * Or let BIO_free(bio1); BIO_free(bio2); do the job. */
		bio_destroy_pair(bio);
		ret = 1;
		break;

	case BIO_C_GET_WRITE_GUARANTEE:
		/* How many bytes can the caller feed to the next write
		 * without having to keep any? */
		if (b->peer == NULL || b->closed)
			ret = 0;
		else
			ret = (long) b->size - b->len;
		break;

	case BIO_C_GET_READ_REQUEST:
		/* If the peer unsuccessfully tried to read, how many bytes
		 * were requested?  (As with BIO_CTRL_PENDING, that number
		 * can usually be treated as boolean.) */
		ret = (long) b->request;
		break;

	case BIO_C_RESET_READ_REQUEST:
		/* Reset request.  (Can be useful after read attempts
		 * at the other side that are meant to be non-blocking,
		 * e.g. when probing SSL_read to see if any data is
		 * available.) */
		b->request = 0;
		ret = 1;
		break;

	case BIO_C_SHUTDOWN_WR:
		/* similar to shutdown(..., SHUT_WR) */
		b->closed = 1;
		ret = 1;
		break;

	case BIO_C_NREAD0:
		/* prepare for non-copying read */
		ret = (long) bio_nread0(bio, ptr);
		break;

	case BIO_C_NREAD:
		/* non-copying read */
		ret = (long) bio_nread(bio, ptr, (size_t) num);
		break;

	case BIO_C_NWRITE0:
		/* prepare for non-copying write */
		ret = (long) bio_nwrite0(bio, ptr);
		break;

	case BIO_C_NWRITE:
		/* non-copying write */
		ret = (long) bio_nwrite(bio, ptr, (size_t) num);
		break;


		/* standard CTRL codes follow */

	case BIO_CTRL_RESET:
		if (b->buf != NULL) {
			b->len = 0;
			b->offset = 0;
		}
		ret = 0;
		break;


	case BIO_CTRL_GET_CLOSE:
		ret = bio->shutdown;
		break;

	case BIO_CTRL_SET_CLOSE:
		bio->shutdown = (int) num;
		ret = 1;
		break;

	case BIO_CTRL_PENDING:
		if (b->peer != NULL) {
			struct bio_bio_st *peer_b = b->peer->ptr;

			ret = (long) peer_b->len;
		} else
			ret = 0;
		break;

	case BIO_CTRL_WPENDING:
		if (b->buf != NULL)
			ret = (long) b->len;
		else
			ret = 0;
		break;

	case BIO_CTRL_DUP:
		/* See BIO_dup_chain for circumstances we have to expect. */
		{
			BIO *other_bio = ptr;
			struct bio_bio_st *other_b;

			assert(other_bio != NULL);
			other_b = other_bio->ptr;
			assert(other_b != NULL);

			assert(other_b->buf == NULL); /* other_bio is always fresh */

			other_b->size = b->size;
		}

		ret = 1;
		break;

	case BIO_CTRL_FLUSH:
		ret = 1;
		break;

	case BIO_CTRL_EOF:
		{
			BIO *other_bio = ptr;

			if (other_bio) {
				struct bio_bio_st *other_b = other_bio->ptr;

				assert(other_b != NULL);
				ret = other_b->len == 0 && other_b->closed;
			} else
				ret = 1;
		}
		break;

	default:
		ret = 0;
	}
	return ret;
}

static int
bio_puts(BIO *bio, const char *str)
{
	return bio_write(bio, str, strlen(str));
}


static int
bio_make_pair(BIO *bio1, BIO *bio2)
{
	struct bio_bio_st *b1, *b2;

	assert(bio1 != NULL);
	assert(bio2 != NULL);

	b1 = bio1->ptr;
	b2 = bio2->ptr;

	if (b1->peer != NULL || b2->peer != NULL) {
		BIOerror(BIO_R_IN_USE);
		return 0;
	}

	if (b1->buf == NULL) {
		b1->buf = malloc(b1->size);
		if (b1->buf == NULL) {
			BIOerror(ERR_R_MALLOC_FAILURE);
			return 0;
		}
		b1->len = 0;
		b1->offset = 0;
	}

	if (b2->buf == NULL) {
		b2->buf = malloc(b2->size);
		if (b2->buf == NULL) {
			BIOerror(ERR_R_MALLOC_FAILURE);
			return 0;
		}
		b2->len = 0;
		b2->offset = 0;
	}

	b1->peer = bio2;
	b1->closed = 0;
	b1->request = 0;
	b2->peer = bio1;
	b2->closed = 0;
	b2->request = 0;

	bio1->init = 1;
	bio2->init = 1;

	return 1;
}

static void
bio_destroy_pair(BIO *bio)
{
	struct bio_bio_st *b = bio->ptr;

	if (b != NULL) {
		BIO *peer_bio = b->peer;

		if (peer_bio != NULL) {
			struct bio_bio_st *peer_b = peer_bio->ptr;

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

			peer_b->peer = NULL;
			peer_bio->init = 0;
			assert(peer_b->buf != NULL);
			peer_b->len = 0;
			peer_b->offset = 0;

			b->peer = NULL;
			bio->init = 0;
			assert(b->buf != NULL);
			b->len = 0;
			b->offset = 0;
		}
	}
}


/* Exported convenience functions */
int
BIO_new_bio_pair(BIO **bio1_p, size_t writebuf1, BIO **bio2_p, size_t writebuf2)
{
	BIO *bio1 = NULL, *bio2 = NULL;
	long r;
	int ret = 0;

	bio1 = BIO_new(BIO_s_bio());
	if (bio1 == NULL)
		goto err;
	bio2 = BIO_new(BIO_s_bio());
	if (bio2 == NULL)
		goto err;

	if (writebuf1) {
		r = BIO_set_write_buf_size(bio1, writebuf1);
		if (!r)
			goto err;
	}
	if (writebuf2) {
		r = BIO_set_write_buf_size(bio2, writebuf2);
		if (!r)
			goto err;
	}

	r = BIO_make_bio_pair(bio1, bio2);
	if (!r)
		goto err;
	ret = 1;

	err:
	if (ret == 0) {
		if (bio1) {
			BIO_free(bio1);
			bio1 = NULL;
		}
		if (bio2) {
			BIO_free(bio2);
			bio2 = NULL;
		}
	}

	*bio1_p = bio1;
	*bio2_p = bio2;
	return ret;
}

size_t
BIO_ctrl_get_write_guarantee(BIO *bio)
{
	return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);
}

size_t
BIO_ctrl_get_read_request(BIO *bio)
{
	return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
}

int
BIO_ctrl_reset_read_request(BIO *bio)
{
	return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);
}


/* BIO_nread0/nread/nwrite0/nwrite are available only for BIO pairs for now
 * (conceivably some other BIOs could allow non-copying reads and writes too.)
 */
int
BIO_nread0(BIO *bio, char **buf)
{
	long ret;

	if (!bio->init) {
		BIOerror(BIO_R_UNINITIALIZED);
		return -2;
	}

	ret = BIO_ctrl(bio, BIO_C_NREAD0, 0, buf);
	if (ret > INT_MAX)
		return INT_MAX;
	else
		return (int) ret;
}

int
BIO_nread(BIO *bio, char **buf, int num)
{
	int ret;

	if (!bio->init) {
		BIOerror(BIO_R_UNINITIALIZED);
		return -2;
	}

	ret = (int) BIO_ctrl(bio, BIO_C_NREAD, num, buf);
	if (ret > 0)
		bio->num_read += ret;
	return ret;
}

int
BIO_nwrite0(BIO *bio, char **buf)
{
	long ret;

	if (!bio->init) {
		BIOerror(BIO_R_UNINITIALIZED);
		return -2;
	}

	ret = BIO_ctrl(bio, BIO_C_NWRITE0, 0, buf);
	if (ret > INT_MAX)
		return INT_MAX;
	else
		return (int) ret;
}

int
BIO_nwrite(BIO *bio, char **buf, int num)
{
	int ret;

	if (!bio->init) {
		BIOerror(BIO_R_UNINITIALIZED);
		return -2;
	}

	ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);
	if (ret > 0)
		bio->num_write += ret;
	return ret;
}
