// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use bytes::Bytes;
use crate::crypto_utils;
use crate::integrity::{self, hmac_sha1::HmacSha1};
use crate::keywrap;
use crate::suite_selector;
use crate::Error;
use failure::{self, ensure};
use std::fmt;

macro_rules! return_none_if_unknown_algo {
    ($e:expr) => {
        if !$e.has_known_algorithm() {
            return None;
        }
    };
}

// IEEE Std 802.11-2016, 9.4.2.25.3, Table 9-133
// 0 - Reserved.
pub const EAP: u8 = 1;
pub const PSK: u8 = 2;
pub const FT_EAP: u8 = 3;
pub const FT_PSK: u8 = 4;
pub const EAP_SHA256: u8 = 5;
pub const PSK_SHA256: u8 = 6;
pub const TDLS: u8 = 7;
pub const SAE: u8 = 8;
pub const FT_SAE: u8 = 9;
pub const AP_PEERKEY: u8 = 10;
pub const EAP_SUITEB: u8 = 11;
pub const EAP_SUITEB_SHA384: u8 = 12;
pub const FT_EAP_SHA384: u8 = 13;
// 14-255 - Reserved.

#[derive(PartialOrd, PartialEq, Clone)]
pub struct Akm {
    pub oui: Bytes,
    pub suite_type: u8,
}

impl Akm {
    /// Only AKMs specified in IEEE 802.11-2016, 9.4.2.25.4, Table 9-133 have known algorithms.
    pub fn has_known_algorithm(&self) -> bool {
        if self.is_reserved() || self.is_vendor_specific() {
            false
        } else {
            self.suite_type != 7 && self.suite_type != 10
        }
    }

    pub fn is_vendor_specific(&self) -> bool {
        // IEEE 802.11-2016, 9.4.2.25.4, Table 9-133
        !&self.oui[..].eq(&suite_selector::OUI)
    }

    pub fn is_reserved(&self) -> bool {
        // IEEE 802.11-2016, 9.4.2.25.4, Table 9-133
        (self.suite_type == 0 || self.suite_type >= 14) && !self.is_vendor_specific()
    }

    pub fn mic_bytes(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...11 => Some(16),
            12 | 13 => Some(24),
            _ => None,
        }
    }

    pub fn kck_bytes(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...11 => Some(16),
            12 | 13 => Some(24),
            _ => None,
        }
    }

    pub fn kek_bytes(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...11 => Some(16),
            12 | 13 => Some(32),
            _ => None,
        }
    }

    pub fn pmk_bytes(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.1.3
        match self.suite_type {
            1...11 | 13 => Some(32),
            12 => Some(48),
            _ => None,
        }
    }

    #[deprecated(note="use `kck_bytes` instead")]
    pub fn kck_bits(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...11 => Some(128),
            12 | 13 => Some(192),
            _ => None,
        }
    }

    #[deprecated(note="use `kek_bytes` instead")]
    pub fn kek_bits(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...11 => Some(128),
            12 | 13 => Some(256),
            _ => None,
        }
    }

    #[deprecated(note="use `pmk_bytes` instead")]
    pub fn pmk_bits(&self) -> Option<u16> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.1.3
        match self.suite_type {
            1...11 | 13 => Some(256),
            12 => Some(384),
            _ => None,
        }
    }

    pub fn integrity_algorithm(&self) -> Option<Box<integrity::Algorithm>> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1 | 2 => Some(Box::new(HmacSha1::new())),
            // TODO(hahnr): Add remaining integrity algorithms.
            3...13 => None,
            _ => None,
        }
    }

    pub fn keywrap_algorithm(&self) -> Option<Box<keywrap::Algorithm>> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.3, Table 12-8
        match self.suite_type {
            1...13 => Some(Box::new(keywrap::aes::NistAes)),
            _ => None,
        }
    }

    pub fn prf(
        &self,
        k: &[u8],
        a: &str,
        b: &[u8],
        bits: usize,
    ) -> Option<Result<Vec<u8>, failure::Error>> {
        return_none_if_unknown_algo!(self);

        // IEEE 802.11-2016, 12.7.1.2
        match self.suite_type {
            1...4 | 8 | 9 => Some(crypto_utils::prf(k, a, b, bits)),
            _ => None,
        }
    }
}

impl suite_selector::Factory for Akm {
    type Suite = Akm;

    fn new(oui: Bytes, suite_type: u8) -> Result<Self::Suite, failure::Error> {
        ensure!(oui.len() == 3, Error::InvalidOuiLength(oui.len()));
        Ok(Akm { oui, suite_type })
    }
}

impl fmt::Debug for Akm {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "{:02X}-{:02X}-{:02X}:{}",
            self.oui[0], self.oui[1], self.oui[2], self.suite_type
        )
    }
}