/*

 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (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

 */

#include <stdio.h>

#include <errno.h>

#include "internal/cryptlib.h"

#include <openssl/buffer.h>

#include <openssl/evp.h>

#include "internal/bio.h"

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

static int enc_read(BIO *h, char *buf, 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 ENC_MIN_CHUNK   (256)

#define BUF_OFFSET      (ENC_MIN_CHUNK + EVP_MAX_BLOCK_LENGTH)

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;

    unsigned char *read_start, *read_end;

    /*

     * buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return

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

     */

    unsigned char buf[BUF_OFFSET + ENC_BLOCK_SIZE];

} BIO_ENC_CTX;

static const BIO_METHOD methods_enc = {

    BIO_TYPE_CIPHER,

    "cipher",

    /* TODO: Convert to new style write function */

    bwrite_conv,

    enc_write,

    /* TODO: Convert to new style read function */

    bread_conv,

    enc_read,

    NULL,                       /* enc_puts, */

    NULL,                       /* enc_gets, */

    enc_ctrl,

    enc_new,

    enc_free,

    enc_callback_ctrl,

};

const BIO_METHOD *BIO_f_cipher(void)

{

    return &methods_enc;

}

static int enc_new(BIO *bi)

{

    BIO_ENC_CTX *ctx;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL) {

        EVPerr(EVP_F_ENC_NEW, ERR_R_MALLOC_FAILURE);

        return 0;

    }

    ctx->cipher = EVP_CIPHER_CTX_new();

    if (ctx->cipher == NULL) {

        OPENSSL_free(ctx);

        return 0;

    }

    ctx->cont = 1;

    ctx->ok = 1;

    ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);

    BIO_set_data(bi, ctx);

    BIO_set_init(bi, 1);

    return 1;

}

static int enc_free(BIO *a)

{

    BIO_ENC_CTX *b;

    if (a == NULL)

        return 0;

    b = BIO_get_data(a);

    if (b == NULL)

        return 0;

    EVP_CIPHER_CTX_free(b->cipher);

    OPENSSL_clear_free(b, sizeof(BIO_ENC_CTX));

    BIO_set_data(a, NULL);

    BIO_set_init(a, 0);

    return 1;

}

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

{

    int ret = 0, i, blocksize;

    BIO_ENC_CTX *ctx;

    BIO *next;

    if (out == NULL)

        return 0;

    ctx = BIO_get_data(b);

    next = BIO_next(b);

    if ((ctx == NULL) || (next == 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;

        }

    }

    blocksize = EVP_CIPHER_CTX_block_size(ctx->cipher);

    if (blocksize == 1)

        blocksize = 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;

        if (ctx->read_start == ctx->read_end) { /* time to read more data */

            ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);

            i = BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE);

            if (i > 0)

                ctx->read_end += i;

        } else {

            i = ctx->read_end - ctx->read_start;

        }

        if (i <= 0) {

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

            if (!BIO_should_retry(next)) {

                ctx->cont = i;

                i = EVP_CipherFinal_ex(ctx->cipher,

                                       ctx->buf, &(ctx->buf_len));

                ctx->ok = i;

                ctx->buf_off = 0;

            } else {

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

                break;

            }

        } else {

            if (outl > ENC_MIN_CHUNK) {

                /*

                 * Depending on flags block cipher decrypt can write

                 * one extra block and then back off, i.e. output buffer

                 * has to accommodate extra block...

                 */

                int j = outl - blocksize, buf_len;

                if (!EVP_CipherUpdate(ctx->cipher,

                                      (unsigned char *)out, &buf_len,

                                      ctx->read_start, i > j ? j : i)) {

                    BIO_clear_retry_flags(b);

                    return 0;

                }

                ret += buf_len;

                out += buf_len;

                outl -= buf_len;

                if ((i -= j) <= 0) {

                    ctx->read_start = ctx->read_end;

                    continue;

                }

                ctx->read_start += j;

            }

            if (i > ENC_MIN_CHUNK)

                i = ENC_MIN_CHUNK;

            if (!EVP_CipherUpdate(ctx->cipher,

                                  ctx->buf, &ctx->buf_len,

                                  ctx->read_start, i)) {

                BIO_clear_retry_flags(b);

                ctx->ok = 0;

                return 0;

            }

            ctx->read_start += 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;

    BIO *next;

    ctx = BIO_get_data(b);

    next = BIO_next(b);

    if ((ctx == NULL) || (next == NULL))

        return 0;

    ret = inl;

    BIO_clear_retry_flags(b);

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

    while (n > 0) {

        i = BIO_write(next, &(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;

        if (!EVP_CipherUpdate(ctx->cipher,

                              ctx->buf, &ctx->buf_len,

                              (const unsigned char *)in, n)) {

            BIO_clear_retry_flags(b);

            ctx->ok = 0;

            return 0;

        }

        inl -= n;

        in += n;

        ctx->buf_off = 0;

        n = ctx->buf_len;

        while (n > 0) {

            i = BIO_write(next, &(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;

    BIO *next;

    ctx = BIO_get_data(b);

    next = BIO_next(b);

    if (ctx == NULL)

        return 0;

    switch (cmd) {

    case BIO_CTRL_RESET:

        ctx->ok = 1;

        ctx->finished = 0;

        if (!EVP_CipherInit_ex(ctx->cipher, NULL, NULL, NULL, NULL,

                               EVP_CIPHER_CTX_encrypting(ctx->cipher)))

            return 0;

        ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_EOF:         /* More to read */

        if (ctx->cont <= 0)

            ret = 1;

        else

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_WPENDING:

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

        if (ret <= 0)

            ret = BIO_ctrl(next, 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(next, 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(next, 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(next, 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;

        BIO_set_init(b, 1);

        break;

    case BIO_CTRL_DUP:

        dbio = (BIO *)ptr;

        dctx = BIO_get_data(dbio);

        dctx->cipher = EVP_CIPHER_CTX_new();

        if (dctx->cipher == NULL)

            return 0;

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

        if (ret)

            BIO_set_init(dbio, 1);

        break;

    default:

        ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    }

    return ret;

}

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

{

    long ret = 1;

    BIO *next = BIO_next(b);

    if (next == NULL)

        return 0;

    switch (cmd) {

    default:

        ret = BIO_callback_ctrl(next, 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 (*callback) (struct bio_st *, int, const char *, int, long, long);

    ctx = BIO_get_data(b);

    if (ctx == NULL)

        return 0;

    callback = BIO_get_callback(b);

    if ((callback != NULL) &&

            (callback(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 (callback != NULL)

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

    return 1;

}