/*

 * Copyright 1999-2021 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/*

 * 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.

 */

#include "e_os.h"

#include <assert.h>

#include <limits.h>

#include <stdlib.h>

#include <string.h>

#include "bio_local.h"

#include <openssl/err.h>

#include <openssl/crypto.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 = {

    BIO_TYPE_BIO,

    "BIO pair",

    bwrite_conv,

    bio_write,

    bread_conv,

    bio_read,

    bio_puts,

    NULL /* no bio_gets */ ,

    bio_ctrl,

    bio_new,

    bio_free,

    NULL                        /* no bio_callback_ctrl */

};

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 = OPENSSL_zalloc(sizeof(*b));

    if (b == NULL)

        return 0;

    /* enough for one TLS record (just a default) */

    b->size = 17 * 1024;

    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);

    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 ossl_ssize_t bio_nread0(BIO *bio, char **buf)

{

    struct bio_bio_st *b, *peer_b;

    ossl_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 ossl_ssize_t bio_nread(BIO *bio, char **buf, size_t num_)

{

    struct bio_bio_st *b, *peer_b;

    ossl_ssize_t num, available;

    if (num_ > OSSL_SSIZE_MAX)

        num = OSSL_SSIZE_MAX;

    else

        num = (ossl_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 */

        ERR_raise(ERR_LIB_BIO, 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 ossl_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) {

        ERR_raise(ERR_LIB_BIO, 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 ossl_ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)

{

    struct bio_bio_st *b;

    ossl_ssize_t num, space;

    if (num_ > OSSL_SSIZE_MAX)

        num = OSSL_SSIZE_MAX;

    else

        num = (ossl_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) {

            ERR_raise(ERR_LIB_BIO, BIO_R_IN_USE);

            ret = 0;

        } else if (num == 0) {

            ERR_raise(ERR_LIB_BIO, BIO_R_INVALID_ARGUMENT);

            ret = 0;

        } else {

            size_t new_size = num;

            if (b->size != new_size) {

                OPENSSL_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:

        if (b->peer != NULL) {

            struct bio_bio_st *peer_b = b->peer->ptr;

            if (peer_b->len == 0 && peer_b->closed)

                ret = 1;

            else

                ret = 0;

        } 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) {

        ERR_raise(ERR_LIB_BIO, BIO_R_IN_USE);

        return 0;

    }

    if (b1->buf == NULL) {

        b1->buf = OPENSSL_malloc(b1->size);

        if (b1->buf == NULL) {

            ERR_raise(ERR_LIB_BIO, ERR_R_MALLOC_FAILURE);

            return 0;

        }

        b1->len = 0;

        b1->offset = 0;

    }

    if (b2->buf == NULL) {

        b2->buf = OPENSSL_malloc(b2->size);

        if (b2->buf == NULL) {

            ERR_raise(ERR_LIB_BIO, 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) {

        BIO_free(bio1);

        bio1 = NULL;

        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) {

        ERR_raise(ERR_LIB_BIO, 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) {

        ERR_raise(ERR_LIB_BIO, 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) {

        ERR_raise(ERR_LIB_BIO, 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) {

        ERR_raise(ERR_LIB_BIO, BIO_R_UNINITIALIZED);

        return -2;

    }

    ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);

    if (ret > 0)

        bio->num_write += ret;

    return ret;

}