/* Copyright (C) 2021 Open Information Security Foundation

 *

 * You can copy, redistribute or modify this Program under the terms of

 * the GNU General Public License version 2 as published by the Free

 * Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * version 2 along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

use std::os::raw::c_uchar;

use libc::c_ulong;

#[repr(C)]

#[allow(non_camel_case_types)]

pub enum Base64ReturnCode {

    SC_BASE64_OK = 0,

    SC_BASE64_INVALID_ARG,

    SC_BASE64_OVERFLOW,

}

/// Base64 encode a buffer.

///

/// This method exposes the Rust base64 encoder to C and should not be called from

/// Rust code.

///

/// The output parameter must be an allocated buffer of at least the size returned

/// from Base64EncodeBufferSize for the input_len, and this length must be provided

/// in the output_len variable.

#[no_mangle]

pub unsafe extern "C" fn Base64Encode(

    input: *const u8, input_len: c_ulong, output: *mut c_uchar, output_len: *mut c_ulong,

) -> Base64ReturnCode {

    if input.is_null() || output.is_null() || output_len.is_null() {

        return Base64ReturnCode::SC_BASE64_INVALID_ARG;

    }

    let input = std::slice::from_raw_parts(input, input_len as usize);

    let encoded = base64::encode(input);

    if encoded.len() + 1 > *output_len as usize {

        return Base64ReturnCode::SC_BASE64_OVERFLOW;

    }

    let output = std::slice::from_raw_parts_mut(&mut *output, *output_len as usize);

    output[0..encoded.len()].copy_from_slice(encoded.as_bytes());

    output[encoded.len()] = 0;

    *output_len = encoded.len() as c_ulong;

    Base64ReturnCode::SC_BASE64_OK

}

/// Ratio of output bytes to input bytes for Base64 Encoding is 4:3, hence the

/// required output bytes are 4 * ceil(input_len / 3) and an additional byte for

/// storing the NULL pointer.

#[no_mangle]

pub extern "C" fn Base64EncodeBufferSize(len: c_ulong) -> c_ulong {

    (4 * ((len) + 2) / 3) + 1

}