openethereum/ethcore/light/src/provider.rs

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// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity 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
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! A provider for the LES protocol. This is typically a full node, who can
//! give as much data as necessary to its peers.
use ethcore::blockchain_info::BlockChainInfo;
use ethcore::client::{BlockChainClient, ProvingBlockChainClient};
use ethcore::transaction::SignedTransaction;
use ethcore::ids::BlockId;
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use util::{Bytes, H256};
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use request;
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/// Defines the operations that a provider for `LES` must fulfill.
///
/// These are defined at [1], but may be subject to change.
/// Requests which can't be fulfilled should return either an empty RLP list
/// or empty vector where appropriate.
///
/// [1]: https://github.com/ethcore/parity/wiki/Light-Ethereum-Subprotocol-(LES)
#[cfg_attr(feature = "ipc", ipc(client_ident="LightProviderClient"))]
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pub trait Provider: Send + Sync {
/// Provide current blockchain info.
fn chain_info(&self) -> BlockChainInfo;
/// Find the depth of a common ancestor between two blocks.
/// If either block is unknown or an ancestor can't be found
/// then return `None`.
fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64>;
/// Earliest block where state queries are available.
/// If `None`, no state queries are servable.
fn earliest_state(&self) -> Option<u64>;
/// Provide a list of headers starting at the requested block,
/// possibly in reverse and skipping `skip` at a time.
///
/// The returned vector may have any length in the range [0, `max`], but the
/// results within must adhere to the `skip` and `reverse` parameters.
fn block_headers(&self, req: request::Headers) -> Vec<Bytes>;
/// Provide as many as possible of the requested blocks (minus the headers) encoded
/// in RLP format.
fn block_bodies(&self, req: request::Bodies) -> Vec<Bytes>;
/// Provide the receipts as many as possible of the requested blocks.
/// Returns a vector of RLP-encoded lists of receipts.
fn receipts(&self, req: request::Receipts) -> Vec<Bytes>;
/// Provide a set of merkle proofs, as requested. Each request is a
/// block hash and request parameters.
///
/// Returns a vector of RLP-encoded lists satisfying the requests.
fn proofs(&self, req: request::StateProofs) -> Vec<Bytes>;
/// Provide contract code for the specified (block_hash, account_hash) pairs.
/// Each item in the resulting vector is either the raw bytecode or empty.
fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes>;
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/// Provide header proofs from the Canonical Hash Tries as well as the headers
/// they correspond to -- each element in the returned vector is a 2-tuple.
/// The first element is a block header and the second a merkle proof of
/// the header in a requested CHT.
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fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes>;
/// Provide pending transactions.
fn pending_transactions(&self) -> Vec<SignedTransaction>;
}
// Implementation of a light client data provider for a client.
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impl<T: ProvingBlockChainClient + ?Sized> Provider for T {
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fn chain_info(&self) -> BlockChainInfo {
BlockChainClient::chain_info(self)
}
fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64> {
self.tree_route(a, b).map(|route| route.index as u64)
}
fn earliest_state(&self) -> Option<u64> {
Some(self.pruning_info().earliest_state)
}
fn block_headers(&self, req: request::Headers) -> Vec<Bytes> {
use request::HashOrNumber;
use ethcore::views::HeaderView;
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let best_num = self.chain_info().best_block_number;
let start_num = match req.start {
HashOrNumber::Number(start_num) => start_num,
HashOrNumber::Hash(hash) => match self.block_header(BlockId::Hash(hash)) {
None => {
trace!(target: "les_provider", "Unknown block hash {} requested", hash);
return Vec::new();
}
Some(header) => {
let num = HeaderView::new(&header).number();
if req.max == 1 || self.block_hash(BlockId::Number(num)) != Some(hash) {
// Non-canonical header or single header requested.
return vec![header];
}
num
}
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}
};
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(0u64..req.max as u64)
.map(|x: u64| x.saturating_mul(req.skip + 1))
.take_while(|x| if req.reverse { x < &start_num } else { best_num - start_num >= *x })
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.map(|x| if req.reverse { start_num - x } else { start_num + x })
.map(|x| self.block_header(BlockId::Number(x)))
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.take_while(|x| x.is_some())
.flat_map(|x| x)
.collect()
}
fn block_bodies(&self, req: request::Bodies) -> Vec<Bytes> {
req.block_hashes.into_iter()
.map(|hash| self.block_body(BlockId::Hash(hash)))
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.map(|body| body.unwrap_or_else(|| ::rlp::EMPTY_LIST_RLP.to_vec()))
.collect()
}
fn receipts(&self, req: request::Receipts) -> Vec<Bytes> {
req.block_hashes.into_iter()
.map(|hash| self.block_receipts(&hash))
.map(|receipts| receipts.unwrap_or_else(|| ::rlp::EMPTY_LIST_RLP.to_vec()))
.collect()
}
fn proofs(&self, req: request::StateProofs) -> Vec<Bytes> {
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use rlp::{RlpStream, Stream};
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let mut results = Vec::with_capacity(req.requests.len());
for request in req.requests {
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let proof = match request.key2 {
Some(key2) => self.prove_storage(request.key1, key2, request.from_level, BlockId::Hash(request.block)),
None => self.prove_account(request.key1, request.from_level, BlockId::Hash(request.block)),
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};
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let mut stream = RlpStream::new_list(proof.len());
for node in proof {
stream.append_raw(&node, 1);
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}
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results.push(stream.out());
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}
results
}
fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes> {
req.code_requests.into_iter()
.map(|req| {
self.code_by_hash(req.account_key, BlockId::Hash(req.block_hash))
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})
.collect()
}
fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes> {
req.requests.into_iter().map(|_| ::rlp::EMPTY_LIST_RLP.to_vec()).collect()
}
fn pending_transactions(&self) -> Vec<SignedTransaction> {
BlockChainClient::pending_transactions(self)
}
}