1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155

use snafu::{ensure, ResultExt};
use std::{marker::PhantomData, str::FromStr};

use ethabi::{Function, Param, ParamType, Token};
use evm_state::ExitSucceed;
use once_cell::sync::Lazy;
use primitive_types::H160;

use super::abi_parse::ParseTokens;
use super::errors::*;
use super::{PrecompileContext, PrecompileOk, Result};
use crate::scope::evm::gweis_to_lamports;
use solana_sdk::pubkey::Pubkey;

pub trait NativeFunction<Inputs> {
    fn call(&self, inputs: Inputs, cx: PrecompileContext<'_>) -> Result<PrecompileOk>;
}

impl<F, Inputs> NativeFunction<Inputs> for F
where
    F: Fn(Inputs, PrecompileContext<'_>) -> Result<PrecompileOk>,
{
    fn call(&self, inputs: Inputs, cx: PrecompileContext<'_>) -> Result<PrecompileOk> {
        (*self)(inputs, cx)
    }
}

#[derive(Clone)]
pub struct NativeContract<F, I> {
    // TODO: Replace by real function hash calculation
    function_hash: [u8; 4],
    pub abi: Function,
    implementation: F,
    pd: PhantomData<I>,
}

impl<F, I> NativeContract<F, I>
where
    F: NativeFunction<I>,
    I: ParseTokens,
{
    pub fn new(function_hash: [u8; 4], abi: Function, implementation: F) -> Self {
        Self {
            function_hash,
            abi,
            implementation,
            pd: PhantomData,
        }
    }

    fn check_args(&self, tokens: &[Token]) -> Result<()> {
        ensure!(
            tokens.len() == self.abi.inputs.len(),
            ParamsCountMismatch {
                expected: self.abi.inputs.len(),
                got: tokens.len()
            }
        );
        Ok(())
    }

    pub fn parse_abi(&self, function_abi_input: &[u8]) -> Result<I> {
        ensure!(
            function_abi_input.len() >= 4,
            InputToShort {
                input_len: function_abi_input.len()
            }
        );
        let (hash, input) = function_abi_input.split_at(4);

        ensure!(
            hash == self.function_hash,
            MismatchFunctionHash {
                expected: hex::encode(&self.function_hash),
                got: hex::encode(hash)
            }
        );

        self.abi
            .decode_input(input)
            .with_context(|| FailedToParse {
                name: self.abi.name.clone(),
            })
            .and_then(|tokens| self.check_args(&tokens).map(|_| tokens))
            .and_then(I::parse)
    }

    pub fn eval(&self, function_abi_input: &[u8], cx: PrecompileContext) -> Result<PrecompileOk> {
        let params = self.parse_abi(function_abi_input)?;

        self.implementation.call(params, cx)
    }
}

//
// NativeContracts declaration below
//

// TODO: Implement some procedural macro to render this in more
pub static ETH_TO_VLX_ADDR: Lazy<H160> = Lazy::new(|| {
    H160::from_str(concat!(
        "56454c41532d434841494e", // 'VELAS-CHAIN'
        "0000000000",             // just spaces
        "53574150",               // 'SWAP'
    ))
    .expect("Serialization of static data should be determenistic and never fail.")
});

type EthToVlxImp = fn(Pubkey, PrecompileContext) -> Result<PrecompileOk>;

pub static ETH_TO_VLX_CODE: Lazy<NativeContract<EthToVlxImp, Pubkey>> = Lazy::new(|| {
    let abi = Function {
        name: String::from("transferToNative"),
        inputs: vec![Param {
            name: String::from("native_recipient"),
            kind: ParamType::FixedBytes(32),
        }],
        outputs: vec![],
        constant: false,
    };

    // TOOD: Modify gas left.
    fn implementation(pubkey: Pubkey, cx: PrecompileContext) -> Result<PrecompileOk> {
        // EVM should ensure that user has enough tokens, before calling this precompile.

        let user = if let Some(account) = cx.accounts.find_user(&pubkey) {
            account
        } else {
            return AccountNotFound { public_key: pubkey }.fail();
        };

        // TODO: return change back
        let (lamports, _change) = gweis_to_lamports(cx.evm_context.apparent_value);

        let mut evm_account = cx
            .accounts
            .evm
            .try_account_ref_mut()
            .with_context(|| NativeChainInstructionError {})?;

        let mut user_account = user
            .try_account_ref_mut()
            .with_context(|| NativeChainInstructionError {})?;

        if lamports > evm_account.lamports {
            return InsufficientFunds { lamports }.fail();
        }

        evm_account.lamports -= lamports;
        user_account.lamports += lamports;
        Ok(PrecompileOk::new(ExitSucceed::Returned, vec![], 0))
    }

    NativeContract::new([0xb1, 0xd6, 0x92, 0x7a], abi, implementation)
});