/*
 * Copyright 2013 Jack Lloyd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use libc::{c_uchar, c_int, c_uint};
use crypto::hash;

#[allow(dead_code)]
#[allow(non_camel_case_types)]
#[repr(C)]
pub struct HMAC_CTX {
    md: *mut hash::EVP_MD,
    md_ctx: hash::EVP_MD_CTX,
    i_ctx: hash::EVP_MD_CTX,
    o_ctx: hash::EVP_MD_CTX,
    key_length: c_uint,
    key: [c_uchar, ..128]
}

#[link(name = "crypto")]
extern {
    fn HMAC_CTX_init(ctx: *mut HMAC_CTX);
    fn HMAC_Init_ex(ctx: *mut HMAC_CTX, key: *const u8, keylen: c_int, md: *const hash::EVP_MD, imple: *const ENGINE);
    fn HMAC_Update(ctx: *mut HMAC_CTX, input: *const u8, len: c_uint);
    fn HMAC_Final(ctx: *mut HMAC_CTX, output: *mut u8, len: *mut c_uint);
}

#[allow(non_camel_case_types)]
#[repr(C)]
struct ENGINE;

pub struct HMAC {
    ctx: HMAC_CTX,
    len: uint,
}

#[allow(non_snake_case)]
pub fn HMAC(ht: hash::HashType, key: &[u8]) -> HMAC {
    unsafe {
        let (evp, mdlen) = hash::evpmd(ht);

        let mut ctx : HMAC_CTX = ::std::mem::uninitialized();

        HMAC_CTX_init(&mut ctx);
        HMAC_Init_ex(&mut ctx,
                     key.as_ptr(),
                     key.len() as c_int,
                     evp, 0 as *const _);

        HMAC { ctx: ctx, len: mdlen }
    }
}

impl HMAC {
    pub fn update(&mut self, data: &[u8]) {
        unsafe {
            HMAC_Update(&mut self.ctx, data.as_ptr(), data.len() as c_uint)
        }
    }

    pub fn final(&mut self) -> Vec<u8> {
        unsafe {
            let mut res = Vec::from_elem(self.len, 0u8);
            let mut outlen = 0;
            HMAC_Final(&mut self.ctx, res.as_mut_ptr(), &mut outlen);
            assert!(self.len == outlen as uint)
            res
        }
    }
}

#[cfg(test)]
mod tests {
    use serialize::hex::FromHex;
    use crypto::hash::{HashType, MD5, SHA1, SHA224, SHA256, SHA384, SHA512};
    use super::HMAC;

    #[test]
    fn test_hmac_md5() {
        // test vectors from RFC 2202
        let tests: [(Vec<u8>, Vec<u8>, Vec<u8>), ..7] = [
            (Vec::from_elem(16, 0x0b_u8), Vec::from_slice(b"Hi There"),
             "9294727a3638bb1c13f48ef8158bfc9d".from_hex().unwrap()),
            (Vec::from_slice(b"Jefe"),
             Vec::from_slice(b"what do ya want for nothing?"),
             "750c783e6ab0b503eaa86e310a5db738".from_hex().unwrap()),
            (Vec::from_elem(16, 0xaa_u8), Vec::from_elem(50, 0xdd_u8),
             "56be34521d144c88dbb8c733f0e8b3f6".from_hex().unwrap()),
            ("0102030405060708090a0b0c0d0e0f10111213141516171819".from_hex().unwrap(),
             Vec::from_elem(50, 0xcd_u8),
             "697eaf0aca3a3aea3a75164746ffaa79".from_hex().unwrap()),
            (Vec::from_elem(16, 0x0c_u8),
             Vec::from_slice(b"Test With Truncation"),
             "56461ef2342edc00f9bab995690efd4c".from_hex().unwrap()),
            (Vec::from_elem(80, 0xaa_u8),
             Vec::from_slice(b"Test Using Larger Than Block-Size Key - Hash Key First"),
             "6b1ab7fe4bd7bf8f0b62e6ce61b9d0cd".from_hex().unwrap()),
            (Vec::from_elem(80, 0xaa_u8),
             Vec::from_slice(b"Test Using Larger Than Block-Size Key \
                               and Larger Than One Block-Size Data"),
             "6f630fad67cda0ee1fb1f562db3aa53e".from_hex().unwrap())
        ];

        for &(ref key, ref data, ref res) in tests.iter() {
            let mut hmac = HMAC(MD5, key.as_slice());
            hmac.update(data.as_slice());
            assert_eq!(hmac.final(), *res);
        }
    }

    #[test]
    fn test_hmac_sha1() {
        // test vectors from RFC 2202
        let tests: [(Vec<u8>, Vec<u8>, Vec<u8>), ..7] = [
            (Vec::from_elem(20, 0x0b_u8), Vec::from_slice(b"Hi There"),
             "b617318655057264e28bc0b6fb378c8ef146be00".from_hex().unwrap()),
            (Vec::from_slice(b"Jefe"),
             Vec::from_slice(b"what do ya want for nothing?"),
             "effcdf6ae5eb2fa2d27416d5f184df9c259a7c79".from_hex().unwrap()),
            (Vec::from_elem(20, 0xaa_u8), Vec::from_elem(50, 0xdd_u8),
             "125d7342b9ac11cd91a39af48aa17b4f63f175d3".from_hex().unwrap()),
            ("0102030405060708090a0b0c0d0e0f10111213141516171819".from_hex().unwrap(),
             Vec::from_elem(50, 0xcd_u8),
             "4c9007f4026250c6bc8414f9bf50c86c2d7235da".from_hex().unwrap()),
            (Vec::from_elem(20, 0x0c_u8),
             Vec::from_slice(b"Test With Truncation"),
             "4c1a03424b55e07fe7f27be1d58bb9324a9a5a04".from_hex().unwrap()),
            (Vec::from_elem(80, 0xaa_u8),
             Vec::from_slice(b"Test Using Larger Than Block-Size Key - Hash Key First"),
             "aa4ae5e15272d00e95705637ce8a3b55ed402112".from_hex().unwrap()),
            (Vec::from_elem(80, 0xaa_u8),
             Vec::from_slice(b"Test Using Larger Than Block-Size Key \
                               and Larger Than One Block-Size Data"),
             "e8e99d0f45237d786d6bbaa7965c7808bbff1a91".from_hex().unwrap())
        ];

        for &(ref key, ref data, ref res) in tests.iter() {
            let mut hmac = HMAC(SHA1, key.as_slice());
            hmac.update(data.as_slice());
            assert_eq!(hmac.final(), *res);
        }
    }

    fn test_sha2(ty: HashType, results: &[Vec<u8>]) {
        // test vectors from RFC 4231
        let tests: [(Vec<u8>, Vec<u8>), ..6] = [
            (Vec::from_elem(20, 0x0b_u8), Vec::from_slice(b"Hi There")),
            (Vec::from_slice(b"Jefe"),
             Vec::from_slice(b"what do ya want for nothing?")),
            (Vec::from_elem(20, 0xaa_u8), Vec::from_elem(50, 0xdd_u8)),
            ("0102030405060708090a0b0c0d0e0f10111213141516171819".from_hex().unwrap(),
             Vec::from_elem(50, 0xcd_u8)),
            (Vec::from_elem(131, 0xaa_u8),
             Vec::from_slice(b"Test Using Larger Than Block-Size Key - Hash Key First")),
            (Vec::from_elem(131, 0xaa_u8),
             Vec::from_slice(b"This is a test using a larger than block-size key and a \
                               larger than block-size data. The key needs to be hashed \
                               before being used by the HMAC algorithm."))
        ];

        for (&(ref key, ref data), res) in tests.iter().zip(results.iter()) {
            let mut hmac = HMAC(ty, key.as_slice());
            hmac.update(data.as_slice());
            assert_eq!(hmac.final(), *res);
        }
    }

    #[test]
    fn test_hmac_sha224() {
        let results = [
            "896fb1128abbdf196832107cd49df33f47b4b1169912ba4f53684b22".from_hex().unwrap(),
            "a30e01098bc6dbbf45690f3a7e9e6d0f8bbea2a39e6148008fd05e44".from_hex().unwrap(),
            "7fb3cb3588c6c1f6ffa9694d7d6ad2649365b0c1f65d69d1ec8333ea".from_hex().unwrap(),
            "6c11506874013cac6a2abc1bb382627cec6a90d86efc012de7afec5a".from_hex().unwrap(),
            "95e9a0db962095adaebe9b2d6f0dbce2d499f112f2d2b7273fa6870e".from_hex().unwrap(),
            "3a854166ac5d9f023f54d517d0b39dbd946770db9c2b95c9f6f565d1".from_hex().unwrap()
        ];
        test_sha2(SHA224, results);
    }

    #[test]
    fn test_hmac_sha256() {
        let results = [
            "b0344c61d8db38535ca8afceaf0bf12b881dc200c9833da726e9376c2e32cff7".from_hex().unwrap(),
            "5bdcc146bf60754e6a042426089575c75a003f089d2739839dec58b964ec3843".from_hex().unwrap(),
            "773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565fe".from_hex().unwrap(),
            "82558a389a443c0ea4cc819899f2083a85f0faa3e578f8077a2e3ff46729665b".from_hex().unwrap(),
            "60e431591ee0b67f0d8a26aacbf5b77f8e0bc6213728c5140546040f0ee37f54".from_hex().unwrap(),
            "9b09ffa71b942fcb27635fbcd5b0e944bfdc63644f0713938a7f51535c3a35e2".from_hex().unwrap()
        ];
        test_sha2(SHA256, results);
    }

    #[test]
    fn test_hmac_sha384() {
        let results = [
            "afd03944d84895626b0825f4ab46907f\
             15f9dadbe4101ec682aa034c7cebc59c\
             faea9ea9076ede7f4af152e8b2fa9cb6".from_hex().unwrap(),
            "af45d2e376484031617f78d2b58a6b1b\
             9c7ef464f5a01b47e42ec3736322445e\
             8e2240ca5e69e2c78b3239ecfab21649".from_hex().unwrap(),
            "88062608d3e6ad8a0aa2ace014c8a86f\
             0aa635d947ac9febe83ef4e55966144b\
             2a5ab39dc13814b94e3ab6e101a34f27".from_hex().unwrap(),
            "3e8a69b7783c25851933ab6290af6ca7\
             7a9981480850009cc5577c6e1f573b4e\
             6801dd23c4a7d679ccf8a386c674cffb".from_hex().unwrap(),
            "4ece084485813e9088d2c63a041bc5b4\
             4f9ef1012a2b588f3cd11f05033ac4c6\
             0c2ef6ab4030fe8296248df163f44952".from_hex().unwrap(),
            "6617178e941f020d351e2f254e8fd32c\
             602420feb0b8fb9adccebb82461e99c5\
             a678cc31e799176d3860e6110c46523e".from_hex().unwrap()
        ];
        test_sha2(SHA384, results);
    }

    #[test]
    fn test_hmac_sha512() {
        let results = [
            "87aa7cdea5ef619d4ff0b4241a1d6cb0\
             2379f4e2ce4ec2787ad0b30545e17cde\
             daa833b7d6b8a702038b274eaea3f4e4\
             be9d914eeb61f1702e696c203a126854".from_hex().unwrap(),
            "164b7a7bfcf819e2e395fbe73b56e0a3\
             87bd64222e831fd610270cd7ea250554\
             9758bf75c05a994a6d034f65f8f0e6fd\
             caeab1a34d4a6b4b636e070a38bce737".from_hex().unwrap(),
            "fa73b0089d56a284efb0f0756c890be9\
             b1b5dbdd8ee81a3655f83e33b2279d39\
             bf3e848279a722c806b485a47e67c807\
             b946a337bee8942674278859e13292fb".from_hex().unwrap(),
            "b0ba465637458c6990e5a8c5f61d4af7\
             e576d97ff94b872de76f8050361ee3db\
             a91ca5c11aa25eb4d679275cc5788063\
             a5f19741120c4f2de2adebeb10a298dd".from_hex().unwrap(),
            "80b24263c7c1a3ebb71493c1dd7be8b4\
             9b46d1f41b4aeec1121b013783f8f352\
             6b56d037e05f2598bd0fd2215d6a1e52\
             95e64f73f63f0aec8b915a985d786598".from_hex().unwrap(),
            "e37b6a775dc87dbaa4dfa9f96e5e3ffd\
             debd71f8867289865df5a32d20cdc944\
             b6022cac3c4982b10d5eeb55c3e4de15\
             134676fb6de0446065c97440fa8c6a58".from_hex().unwrap()
        ];
        test_sha2(SHA512, results);
    }
}