/*

  zip_source_winzip_aes_decode.c -- Winzip AES decryption routines

  Copyright (C) 2009-2024 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.

  The authors can be contacted at <info@libzip.org>

  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 above 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. The names of the authors may not be used to endorse or promote

  products derived from this software without specific prior

  written permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.

*/

#include <stdlib.h>

#include <string.h>

#include "zipint.h"

#include "zip_crypto.h"

struct winzip_aes {

    char *password;

    zip_uint16_t encryption_method;

    zip_uint64_t data_length;

    zip_uint64_t current_position;

    zip_winzip_aes_t *aes_ctx;

    bool hmac_verify_failed;

    bool hmac_verified;

    zip_error_t error;

};

static int decrypt_header(zip_source_t *src, struct winzip_aes *ctx);

static void winzip_aes_free(struct winzip_aes *);

static zip_int64_t winzip_aes_decrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd);

static struct winzip_aes *winzip_aes_new(zip_uint16_t encryption_method, const char *password, zip_error_t *error);

zip_source_t *zip_source_winzip_aes_decode(zip_t *za, zip_source_t *src, zip_uint16_t encryption_method, int flags, const char *password) {

    zip_source_t *s2;

    zip_stat_t st;

    zip_uint64_t aux_length;

    struct winzip_aes *ctx;

    if ((encryption_method != ZIP_EM_AES_128 && encryption_method != ZIP_EM_AES_192 && encryption_method != ZIP_EM_AES_256) || password == NULL || src == NULL) {

        zip_error_set(&za->error, ZIP_ER_INVAL, 0);

        return NULL;

    }

    if (flags & ZIP_CODEC_ENCODE) {

        zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);

        return NULL;

    }

    if (zip_source_stat(src, &st) != 0) {

        zip_error_set_from_source(&za->error, src);

        return NULL;

    }

    aux_length = WINZIP_AES_PASSWORD_VERIFY_LENGTH + SALT_LENGTH(encryption_method) + HMAC_LENGTH;

    if ((st.valid & ZIP_STAT_COMP_SIZE) == 0 || st.comp_size < aux_length) {

        zip_error_set(&za->error, ZIP_ER_OPNOTSUPP, 0);

        return NULL;

    }

    if ((ctx = winzip_aes_new(encryption_method, password, &za->error)) == NULL) {

        return NULL;

    }

    ctx->data_length = st.comp_size - aux_length;

    if ((s2 = zip_source_layered(za, src, winzip_aes_decrypt, ctx)) == NULL) {

        winzip_aes_free(ctx);

        return NULL;

    }

    return s2;

}

static int decrypt_header(zip_source_t *src, struct winzip_aes *ctx) {

    zip_uint8_t header[WINZIP_AES_MAX_HEADER_LENGTH];

    zip_uint8_t password_verification[WINZIP_AES_PASSWORD_VERIFY_LENGTH];

    unsigned int headerlen;

    zip_int64_t n;

    headerlen = WINZIP_AES_PASSWORD_VERIFY_LENGTH + SALT_LENGTH(ctx->encryption_method);

    if ((n = zip_source_read(src, header, headerlen)) < 0) {

        zip_error_set_from_source(&ctx->error, src);

        return -1;

    }

    if (n != headerlen) {

        zip_error_set(&ctx->error, ZIP_ER_EOF, 0);

        return -1;

    }

    if ((ctx->aes_ctx = _zip_winzip_aes_new((zip_uint8_t *)ctx->password, strlen(ctx->password), header, ctx->encryption_method, password_verification, &ctx->error)) == NULL) {

        return -1;

    }

    if (memcmp(password_verification, header + SALT_LENGTH(ctx->encryption_method), WINZIP_AES_PASSWORD_VERIFY_LENGTH) != 0) {

        _zip_winzip_aes_free(ctx->aes_ctx);

        ctx->aes_ctx = NULL;

        zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);

        return -1;

    }

    return 0;

}

static void verify_hmac(zip_source_t *src, struct winzip_aes *ctx) {

    unsigned char computed[ZIP_CRYPTO_SHA1_LENGTH], from_file[HMAC_LENGTH];

    if (ctx->hmac_verified) {

        return;

    }

    ctx->hmac_verified = true;

    if (zip_source_read(src, from_file, HMAC_LENGTH) < HMAC_LENGTH) {

        zip_error_set_from_source(&ctx->error, src);

        ctx->hmac_verify_failed = true;

        return;

    }

    if (!_zip_winzip_aes_finish(ctx->aes_ctx, computed)) {

        zip_error_set(&ctx->error, ZIP_ER_INTERNAL, 0);

        ctx->hmac_verify_failed = true;

        return;

    }

    _zip_winzip_aes_free(ctx->aes_ctx);

    ctx->aes_ctx = NULL;

    if (memcmp(from_file, computed, HMAC_LENGTH) != 0) {

        zip_error_set(&ctx->error, ZIP_ER_CRC, 0);

        ctx->hmac_verify_failed = true;

        return;

    }

    return;

}

static zip_int64_t winzip_aes_decrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd) {

    struct winzip_aes *ctx;

    zip_int64_t n;

    ctx = (struct winzip_aes *)ud;

    switch (cmd) {

    case ZIP_SOURCE_AT_EOF:

        return ctx->current_position == ctx->data_length;

    case ZIP_SOURCE_OPEN:

        ctx->hmac_verify_failed = false;

        ctx->hmac_verified = false;

        if (decrypt_header(src, ctx) < 0) {

            return -1;

        }

        ctx->current_position = 0;

        return 0;

    case ZIP_SOURCE_READ:

        len = ZIP_MIN(len, ctx->data_length - ctx->current_position);

        if (len > 0) {

            if ((n = zip_source_read(src, data, len)) < 0) {

                zip_error_set_from_source(&ctx->error, src);

                return -1;

            }

            if (n == 0) {

                zip_error_set(&ctx->error, ZIP_ER_EOF, 0);

                return -1;

            }

            ctx->current_position += (zip_uint64_t)n;

            if (!_zip_winzip_aes_decrypt(ctx->aes_ctx, (zip_uint8_t *)data, (zip_uint64_t)n)) {

                zip_error_set(&ctx->error, ZIP_ER_INTERNAL, 0);

                return -1;

            }

        }

        else {

            n = 0;

        }

        if (ctx->current_position == ctx->data_length) {

            verify_hmac(src, ctx);

        }

        if (n > 0) {

            return n;

        }

        else {

            return ctx->hmac_verify_failed ? -1 : 0;

        }

    case ZIP_SOURCE_CLOSE:

        /* For empty files, we should verify the HMAC even if no data has been read. */

        if (ctx->current_position == ctx->data_length) {

            verify_hmac(src, ctx);

        }

        return ctx->hmac_verify_failed ? -1 : 0;

    case ZIP_SOURCE_STAT: {

        zip_stat_t *st;

        st = (zip_stat_t *)data;

        st->encryption_method = ZIP_EM_NONE;

        st->valid |= ZIP_STAT_ENCRYPTION_METHOD;

        if (st->valid & ZIP_STAT_COMP_SIZE) {

            if (st->comp_size < WINZIP_AES_PASSWORD_VERIFY_LENGTH + SALT_LENGTH(ctx->encryption_method) + HMAC_LENGTH) {

                zip_error_set(&ctx->error, ZIP_ER_DATA_LENGTH, 0);

                return -1;

            }

            st->comp_size -= WINZIP_AES_PASSWORD_VERIFY_LENGTH + SALT_LENGTH(ctx->encryption_method) + HMAC_LENGTH;

        }

        return 0;

    }

    case ZIP_SOURCE_SUPPORTS:

        return zip_source_make_command_bitmap(ZIP_SOURCE_AT_EOF, ZIP_SOURCE_OPEN, ZIP_SOURCE_READ, ZIP_SOURCE_CLOSE, ZIP_SOURCE_STAT, ZIP_SOURCE_ERROR, ZIP_SOURCE_FREE, ZIP_SOURCE_SUPPORTS_REOPEN, -1);

    case ZIP_SOURCE_ERROR:

        return zip_error_to_data(&ctx->error, data, len);

    case ZIP_SOURCE_FREE:

        winzip_aes_free(ctx);

        return 0;

    default:

        return zip_source_pass_to_lower_layer(src, data, len, cmd);

    }

}

static void winzip_aes_free(struct winzip_aes *ctx) {

    if (ctx == NULL) {

        return;

    }

    _zip_crypto_clear(ctx->password, strlen(ctx->password));

    free(ctx->password);

    zip_error_fini(&ctx->error);

    _zip_winzip_aes_free(ctx->aes_ctx);

    free(ctx);

}

static struct winzip_aes *winzip_aes_new(zip_uint16_t encryption_method, const char *password, zip_error_t *error) {

    struct winzip_aes *ctx;

    if ((ctx = (struct winzip_aes *)malloc(sizeof(*ctx))) == NULL) {

        zip_error_set(error, ZIP_ER_MEMORY, 0);

        return NULL;

    }

    if ((ctx->password = strdup(password)) == NULL) {

        zip_error_set(error, ZIP_ER_MEMORY, 0);

        free(ctx);

        return NULL;

    }

    ctx->encryption_method = encryption_method;

    ctx->aes_ctx = NULL;

    ctx->hmac_verify_failed = false;

    ctx->hmac_verified = false;

    zip_error_init(&ctx->error);

    return ctx;

}