bio_enc.c

/* crypto/evp/bio_enc.c */
/* 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 <stdio.h>
#include <errno.h>
#include "cryptlib.h"
#include <openssl/buffer.h>
#include <openssl/evp.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 BIO_METHOD methods_enc = {
    BIO_TYPE_CIPHER, "cipher",
    enc_write,
    enc_read,
    NULL,                       /* enc_puts, */
    NULL,                       /* enc_gets, */
    enc_ctrl,
    enc_new,
    enc_free,
    enc_callback_ctrl,
};

BIO_METHOD *BIO_f_cipher(void)
{
    return (&methods_enc);
}

static int enc_new(BIO *bi)
{
    BIO_ENC_CTX *ctx;

    ctx = OPENSSL_malloc(sizeof(*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));
    OPENSSL_clear_free(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 {
            if (!EVP_CipherUpdate(&(ctx->cipher),
                                  (unsigned char *)ctx->buf, &ctx->buf_len,
                                  (unsigned char *)&(ctx->buf[BUF_OFFSET]),
                                  i)) {
                BIO_clear_retry_flags(b);
                return 0;
            }
            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;
        if (!EVP_CipherUpdate(&(ctx->cipher),
                              (unsigned char *)ctx->buf, &ctx->buf_len,
                              (unsigned char *)in, n)) {
            BIO_clear_retry_flags(b);
            return 0;
        }
        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;
        if (!EVP_CipherInit_ex(&(ctx->cipher), NULL, NULL, NULL, NULL,
                               ctx->cipher.encrypt))
            return 0;
        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);
}

/*-
void BIO_set_cipher_ctx(b,c)
BIO *b;
EVP_CIPHER_ctx *c;
        {
        if (b == NULL) return;

        if ((b->callback != NULL) &&
                (b->callback(b,BIO_CB_CTRL,(char *)c,BIO_CTRL_SET,e,0L) <= 0))
                return;

        b->init=1;
        ctx=(BIO_ENC_CTX *)b->ptr;
        memcpy(ctx->cipher,c,sizeof(EVP_CIPHER_CTX));

        if (b->callback != NULL)
                b->callback(b,BIO_CB_CTRL,(char *)c,BIO_CTRL_SET,e,1L);
        }
*/

int BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,
                   const unsigned char *i, int e)
{
    BIO_ENC_CTX *ctx;

    if (b == NULL)
        return 0;

    if ((b->callback != NULL) &&
        (b->callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 0L) <=
         0))
        return 0;

    b->init = 1;
    ctx = (BIO_ENC_CTX *)b->ptr;
    if (!EVP_CipherInit_ex(&(ctx->cipher), c, NULL, k, i, e))
        return 0;

    if (b->callback != NULL)
        return b->callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e,
                           1L);
    return 1;
}