120 lines
4.2 KiB
Rust
120 lines
4.2 KiB
Rust
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
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// This file is part of OpenEthereum.
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// OpenEthereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// OpenEthereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with OpenEthereum. If not, see <http://www.gnu.org/licenses/>.
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//! Utility functions.
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//!
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//! Contains small functions used by the AuRa engine that are not strictly limited to that scope.
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use std::fmt;
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use client::{traits::EngineClient, BlockChainClient};
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use ethabi::{self, FunctionOutputDecoder};
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use ethabi_contract::use_contract;
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use ethereum_types::{Address, U256};
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use log::{debug, error};
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use types::{header::Header, ids::BlockId};
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/// A contract bound to a client and block number.
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///
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/// A bound contract is a combination of a `Client` reference, a `BlockId` and a contract `Address`.
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/// These three parts are enough to call a contract's function; return values are automatically
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/// decoded.
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pub struct BoundContract<'a> {
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client: &'a dyn EngineClient,
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block_id: BlockId,
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contract_addr: Address,
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}
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/// Contract call failed error.
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#[derive(Debug)]
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pub enum CallError {
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/// The call itself failed.
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CallFailed(String),
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/// Decoding the return value failed or the decoded value was a failure.
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DecodeFailed(ethabi::Error),
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/// The passed in client reference could not be upgraded to a `BlockchainClient`.
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NotFullClient,
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}
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impl<'a> fmt::Debug for BoundContract<'a> {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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fmt.debug_struct("BoundContract")
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.field("client", &(self.client as *const dyn EngineClient))
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.field("block_id", &self.block_id)
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.field("contract_addr", &self.contract_addr)
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.finish()
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}
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}
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impl<'a> BoundContract<'a> {
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/// Create a new `BoundContract`.
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pub fn new(
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client: &dyn EngineClient,
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block_id: BlockId,
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contract_addr: Address,
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) -> BoundContract {
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BoundContract {
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client,
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block_id,
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contract_addr,
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}
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}
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/// Perform a function call to an Ethereum machine that doesn't create a transaction or change the state.
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///
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/// Runs a constant function call on `client`. The `call` value can be serialized by calling any
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/// api function generated by the `use_contract!` macro. This does not create any transactions, it only produces a
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/// result based on the state at the current block: It is constant in the sense that it does not alter the EVM
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/// state.
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pub fn call_const<D>(&self, call: (ethabi::Bytes, D)) -> Result<D::Output, CallError>
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where
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D: ethabi::FunctionOutputDecoder,
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{
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let (data, output_decoder) = call;
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let call_return = self
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.client
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.as_full_client()
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.ok_or(CallError::NotFullClient)?
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.call_contract(self.block_id, self.contract_addr, data)
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.map_err(CallError::CallFailed)?;
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// Decode the result and return it.
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output_decoder
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.decode(call_return.as_slice())
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.map_err(CallError::DecodeFailed)
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}
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}
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use_contract!(contract, "res/contracts/block_gas_limit.json");
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pub fn block_gas_limit(
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full_client: &dyn BlockChainClient,
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header: &Header,
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address: Address,
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) -> Option<U256> {
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let (data, decoder) = contract::functions::block_gas_limit::call();
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let value = full_client.call_contract(BlockId::Hash(*header.parent_hash()), address, data).map_err(|err| {
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error!(target: "block_gas_limit", "Contract call failed. Not changing the block gas limit. {:?}", err);
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}).ok()?;
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if value.is_empty() {
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debug!(target: "block_gas_limit", "Contract call returned nothing. Not changing the block gas limit.");
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None
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} else {
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decoder.decode(&value).ok()
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}
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}
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