/* $OpenBSD: bss_bio.c,v 1.30 2025/05/10 05:54:38 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/crypto.h>

#include "bio_local.h"
#include "err_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;
}
LCRYPTO_ALIAS(BIO_s_bio);

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;
}

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;
}

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;

        /* 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;
}
LCRYPTO_ALIAS(BIO_new_bio_pair);

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

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

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