/* $OpenBSD: bio_enc.c,v 1.33 2024/04/12 11:10:34 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 <stdlib.h>
#include <string.h>

#include <openssl/buffer.h>
#include <openssl/evp.h>

#include "bio_local.h"
#include "evp_local.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_ctx;
        /* 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;
}
LCRYPTO_ALIAS(BIO_f_cipher);

static void
bio_enc_ctx_free(BIO_ENC_CTX *ctx)
{
        if (ctx == NULL)
                return;

        EVP_CIPHER_CTX_free(ctx->cipher_ctx);
        freezero(ctx, sizeof(*ctx));
}

static int
enc_new(BIO *bio)
{
        BIO_ENC_CTX *ctx;
        int ret = 0;

        if ((ctx = calloc(1, sizeof(BIO_ENC_CTX))) == NULL)
                goto err;
        if ((ctx->cipher_ctx = EVP_CIPHER_CTX_new()) == NULL)
                goto err;

        ctx->cont = 1;
        ctx->ok = 1;

        bio->ptr = ctx;
        ctx = NULL;

        ret = 1;

 err:
        bio_enc_ctx_free(ctx);

        return ret;
}

static int
enc_free(BIO *bio)
{
        if (bio == NULL)
                return 0;

        bio_enc_ctx_free(bio->ptr);
        explicit_bzero(bio, sizeof(*bio));

        return 1;
}

static int
enc_read(BIO *bio, char *out, int outl)
{
        BIO_ENC_CTX *ctx;
        int ret = 0, i;

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

        if (ctx == NULL || bio->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(bio->next_bio, &ctx->buf[BUF_OFFSET],
                    ENC_BLOCK_SIZE);

                if (i <= 0) {
                        /* Should be continue next time we are called? */
                        if (!BIO_should_retry(bio->next_bio)) {
                                ctx->cont = i;
                                i = EVP_CipherFinal_ex(ctx->cipher_ctx,
                                    (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_ctx,
                            (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(bio);
        BIO_copy_next_retry(bio);
        return ret == 0 ? ctx->cont : ret;
}

static int
enc_write(BIO *bio, const char *in, int inl)
{
        BIO_ENC_CTX *ctx;
        int ret = 0, n, i;

        ctx = bio->ptr;
        ret = inl;

        BIO_clear_retry_flags(bio);
        n = ctx->buf_len - ctx->buf_off;
        while (n > 0) {
                i = BIO_write(bio->next_bio, &(ctx->buf[ctx->buf_off]), n);
                if (i <= 0) {
                        BIO_copy_next_retry(bio);
                        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_ctx,
                    (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(bio->next_bio, &ctx->buf[ctx->buf_off], n);
                        if (i <= 0) {
                                BIO_copy_next_retry(bio);
                                return ret == inl ? i : ret - inl;
                        }
                        n -= i;
                        ctx->buf_off += i;
                }
                ctx->buf_len = 0;
                ctx->buf_off = 0;
        }
        BIO_copy_next_retry(bio);

        return ret;
}

static long
enc_ctrl(BIO *bio, int cmd, long num, void *ptr)
{
        BIO *dbio;
        BIO_ENC_CTX *ctx, *dctx;
        EVP_CIPHER_CTX **c_ctx;
        int i;
        long ret = 1;

        ctx = bio->ptr;

        switch (cmd) {
        case BIO_CTRL_RESET:
                ctx->ok = 1;
                ctx->finished = 0;
                EVP_CipherInit_ex(ctx->cipher_ctx, NULL, NULL, NULL, NULL,
                    ctx->cipher_ctx->encrypt);
                ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_EOF:      /* More to read */
                if (ctx->cont <= 0)
                        ret = 1;
                else
                        ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_WPENDING:
                ret = ctx->buf_len - ctx->buf_off;
                if (ret <= 0)
                        ret = BIO_ctrl(bio->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(bio->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(bio, NULL, 0);
                        if (i < 0)
                                return i;
                }

                if (!ctx->finished) {
                        ctx->finished = 1;
                        ctx->buf_off = 0;
                        ret = EVP_CipherFinal_ex(ctx->cipher_ctx,
                            (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(bio->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(bio);
                ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
                BIO_copy_next_retry(bio);
                break;
        case BIO_C_GET_CIPHER_CTX:
                c_ctx = ptr;
                *c_ctx = ctx->cipher_ctx;
                bio->init = 1;
                break;
        case BIO_CTRL_DUP:
                dbio = ptr;
                dctx = dbio->ptr;
                ret = EVP_CIPHER_CTX_copy(dctx->cipher_ctx, ctx->cipher_ctx);
                if (ret)
                        dbio->init = 1;
                break;
        default:
                ret = BIO_ctrl(bio->next_bio, cmd, num, ptr);
                break;
        }

        return ret;
}

static long
enc_callback_ctrl(BIO *bio, int cmd, BIO_info_cb *fp)
{
        long ret = 1;

        if (bio->next_bio == NULL)
                return 0;

        switch (cmd) {
        default:
                ret = BIO_callback_ctrl(bio->next_bio, cmd, fp);
                break;
        }

        return ret;
}

int
BIO_set_cipher(BIO *bio, 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 (bio == NULL)
                return 0;

        if ((ctx = BIO_get_data(bio)) == NULL)
                return 0;

        if ((cb = BIO_get_callback(bio)) != NULL) {
                if (cb(bio, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 0L) <= 0)
                        return 0;
        }

        BIO_set_init(bio, 1);

        if (!EVP_CipherInit_ex(ctx->cipher_ctx, c, NULL, k, i, e))
                return 0;

        if (cb != NULL)
                return cb(bio, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 1L);

        return 1;
}
LCRYPTO_ALIAS(BIO_set_cipher);