/* $OpenBSD: bio_enc.c,v 1.26 2022/01/14 08:40:57 tb Exp $ */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * 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 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 acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS 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 AUTHOR OR 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.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

#include <errno.h>

#include <stdio.h>

#include <string.h>

#include <openssl/buffer.h>

#include <openssl/evp.h>

#include "bio_local.h"

#include "evp_locl.h"

static int enc_write(BIO *h, const char *buf, int num);

static int enc_read(BIO *h, char *buf, int size);

/*static int enc_puts(BIO *h, const char *str); */

/*static int enc_gets(BIO *h, char *str, int size); */

static long enc_ctrl(BIO *h, int cmd, long arg1, void *arg2);

static int enc_new(BIO *h);

static int enc_free(BIO *data);

static long enc_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fps);

#define ENC_BLOCK_SIZE  (1024*4)

#define BUF_OFFSET  (EVP_MAX_BLOCK_LENGTH*2)

typedef struct enc_struct {

  int buf_len;

  int buf_off;

  int cont;   /* <= 0 when finished */

  int finished;

  int ok;     /* bad decrypt */

  EVP_CIPHER_CTX cipher;

  /* buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate

   * can return up to a block more data than is presented to it

   */

  char buf[ENC_BLOCK_SIZE + BUF_OFFSET + 2];

} BIO_ENC_CTX;

static const BIO_METHOD methods_enc = {

  .type = BIO_TYPE_CIPHER,

  .name = "cipher",

  .bwrite = enc_write,

  .bread = enc_read,

  .ctrl = enc_ctrl,

  .create = enc_new,

  .destroy = enc_free,

  .callback_ctrl = enc_callback_ctrl

};

const BIO_METHOD *

BIO_f_cipher(void)

{

  return (&methods_enc);

}

static int

enc_new(BIO *bi)

{

  BIO_ENC_CTX *ctx;

  ctx = malloc(sizeof(BIO_ENC_CTX));

  if (ctx == NULL)

    return (0);

  EVP_CIPHER_CTX_init(&ctx->cipher);

  ctx->buf_len = 0;

  ctx->buf_off = 0;

  ctx->cont = 1;

  ctx->finished = 0;

  ctx->ok = 1;

  bi->init = 0;

  bi->ptr = (char *)ctx;

  bi->flags = 0;

  return (1);

}

static int

enc_free(BIO *a)

{

  BIO_ENC_CTX *b;

  if (a == NULL)

    return (0);

  b = (BIO_ENC_CTX *)a->ptr;

  EVP_CIPHER_CTX_cleanup(&(b->cipher));

  freezero(a->ptr, sizeof(BIO_ENC_CTX));

  a->ptr = NULL;

  a->init = 0;

  a->flags = 0;

  return (1);

}

static int

enc_read(BIO *b, char *out, int outl)

{

  int ret = 0, i;

  BIO_ENC_CTX *ctx;

  if (out == NULL)

    return (0);

  ctx = (BIO_ENC_CTX *)b->ptr;

  if ((ctx == NULL) || (b->next_bio == NULL))

    return (0);

  /* First check if there are bytes decoded/encoded */

  if (ctx->buf_len > 0) {

    i = ctx->buf_len - ctx->buf_off;

    if (i > outl)

      i = outl;

    memcpy(out, &(ctx->buf[ctx->buf_off]), i);

    ret = i;

    out += i;

    outl -= i;

    ctx->buf_off += i;

    if (ctx->buf_len == ctx->buf_off) {

      ctx->buf_len = 0;

      ctx->buf_off = 0;

    }

  }

  /* At this point, we have room of outl bytes and an empty

   * buffer, so we should read in some more. */

  while (outl > 0) {

    if (ctx->cont <= 0)

      break;

    /* read in at IV offset, read the EVP_Cipher

     * documentation about why */

    i = BIO_read(b->next_bio, &(ctx->buf[BUF_OFFSET]), ENC_BLOCK_SIZE);

    if (i <= 0) {

      /* Should be continue next time we are called? */

      if (!BIO_should_retry(b->next_bio)) {

        ctx->cont = i;

        i = EVP_CipherFinal_ex(&(ctx->cipher),

            (unsigned char *)ctx->buf,

            &(ctx->buf_len));

        ctx->ok = i;

        ctx->buf_off = 0;

      } else {

        ret = (ret == 0) ? i : ret;

        break;

      }

    } else {

      EVP_CipherUpdate(&(ctx->cipher),

          (unsigned char *)ctx->buf, &ctx->buf_len,

          (unsigned char *)&(ctx->buf[BUF_OFFSET]), i);

      ctx->cont = 1;

      /* Note: it is possible for EVP_CipherUpdate to

       * decrypt zero bytes because this is or looks like

       * the final block: if this happens we should retry

       * and either read more data or decrypt the final

       * block

       */

      if (ctx->buf_len == 0)

        continue;

    }

    if (ctx->buf_len <= outl)

      i = ctx->buf_len;

    else

      i = outl;

    if (i <= 0)

      break;

    memcpy(out, ctx->buf, i);

    ret += i;

    ctx->buf_off = i;

    outl -= i;

    out += i;

  }

  BIO_clear_retry_flags(b);

  BIO_copy_next_retry(b);

  return ((ret == 0) ? ctx->cont : ret);

}

static int

enc_write(BIO *b, const char *in, int inl)

{

  int ret = 0, n, i;

  BIO_ENC_CTX *ctx;

  ctx = (BIO_ENC_CTX *)b->ptr;

  ret = inl;

  BIO_clear_retry_flags(b);

  n = ctx->buf_len - ctx->buf_off;

  while (n > 0) {

    i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);

    if (i <= 0) {

      BIO_copy_next_retry(b);

      return (i);

    }

    ctx->buf_off += i;

    n -= i;

  }

  /* at this point all pending data has been written */

  if ((in == NULL) || (inl <= 0))

    return (0);

  ctx->buf_off = 0;

  while (inl > 0) {

    n = (inl > ENC_BLOCK_SIZE) ? ENC_BLOCK_SIZE : inl;

    EVP_CipherUpdate(&(ctx->cipher),

        (unsigned char *)ctx->buf, &ctx->buf_len,

        (unsigned char *)in, n);

    inl -= n;

    in += n;

    ctx->buf_off = 0;

    n = ctx->buf_len;

    while (n > 0) {

      i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);

      if (i <= 0) {

        BIO_copy_next_retry(b);

        return (ret == inl) ? i : ret - inl;

      }

      n -= i;

      ctx->buf_off += i;

    }

    ctx->buf_len = 0;

    ctx->buf_off = 0;

  }

  BIO_copy_next_retry(b);

  return (ret);

}

static long

enc_ctrl(BIO *b, int cmd, long num, void *ptr)

{

  BIO *dbio;

  BIO_ENC_CTX *ctx, *dctx;

  long ret = 1;

  int i;

  EVP_CIPHER_CTX **c_ctx;

  ctx = (BIO_ENC_CTX *)b->ptr;

  switch (cmd) {

  case BIO_CTRL_RESET:

    ctx->ok = 1;

    ctx->finished = 0;

    EVP_CipherInit_ex(&(ctx->cipher), NULL, NULL, NULL, NULL,

        ctx->cipher.encrypt);

    ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  case BIO_CTRL_EOF: /* More to read */

    if (ctx->cont <= 0)

      ret = 1;

    else

      ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  case BIO_CTRL_WPENDING:

    ret = ctx->buf_len - ctx->buf_off;

    if (ret <= 0)

      ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  case BIO_CTRL_PENDING: /* More to read in buffer */

    ret = ctx->buf_len - ctx->buf_off;

    if (ret <= 0)

      ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  case BIO_CTRL_FLUSH:

    /* do a final write */

again:

    while (ctx->buf_len != ctx->buf_off) {

      i = enc_write(b, NULL, 0);

      if (i < 0)

        return i;

    }

    if (!ctx->finished) {

      ctx->finished = 1;

      ctx->buf_off = 0;

      ret = EVP_CipherFinal_ex(&(ctx->cipher),

          (unsigned char *)ctx->buf,

          &(ctx->buf_len));

      ctx->ok = (int)ret;

      if (ret <= 0)

        break;

      /* push out the bytes */

      goto again;

    }

    /* Finally flush the underlying BIO */

    ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  case BIO_C_GET_CIPHER_STATUS:

    ret = (long)ctx->ok;

    break;

  case BIO_C_DO_STATE_MACHINE:

    BIO_clear_retry_flags(b);

    ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    BIO_copy_next_retry(b);

    break;

  case BIO_C_GET_CIPHER_CTX:

    c_ctx = (EVP_CIPHER_CTX **)ptr;

    (*c_ctx) = &(ctx->cipher);

    b->init = 1;

    break;

  case BIO_CTRL_DUP:

    dbio = (BIO *)ptr;

    dctx = (BIO_ENC_CTX *)dbio->ptr;

    EVP_CIPHER_CTX_init(&dctx->cipher);

    ret = EVP_CIPHER_CTX_copy(&dctx->cipher, &ctx->cipher);

    if (ret)

      dbio->init = 1;

    break;

  default:

    ret = BIO_ctrl(b->next_bio, cmd, num, ptr);

    break;

  }

  return (ret);

}

static long

enc_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)

{

  long ret = 1;

  if (b->next_bio == NULL)

    return (0);

  switch (cmd) {

  default:

    ret = BIO_callback_ctrl(b->next_bio, cmd, fp);

    break;

  }

  return (ret);

}

int

BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,

    const unsigned char *i, int e)

{

  BIO_ENC_CTX *ctx;

  long (*cb)(BIO *, int, const char *, int, long, long);

  if (b == NULL)

    return 0;

  if ((ctx = BIO_get_data(b)) == NULL)

    return 0;

  if ((cb = BIO_get_callback(b)) != NULL) {

    if (cb(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 0L)

        <= 0)

      return 0;

  }

  BIO_set_init(b, 1);

  if (!EVP_CipherInit_ex(&(ctx->cipher), c, NULL, k, i, e))

    return 0;

  if (cb != NULL)

    return cb(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 1L);

  return 1;

}