openethereum/ethcore/light/src/provider.rs

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// Copyright 2015-2017 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 std::sync::Arc;
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use ethcore::blockchain_info::BlockChainInfo;
use ethcore::client::{BlockChainClient, ProvingBlockChainClient};
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use ethcore::transaction::PendingTransaction;
use ethcore::ids::BlockId;
use ethcore::encoded;
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use util::{RwLock, H256};
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use cht::{self, BlockInfo};
use client::{LightChainClient, AsLightClient};
use transaction_queue::TransactionQueue;
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use request;
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/// Defines the operations that a provider for the light subprotocol must fulfill.
#[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.
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fn block_headers(&self, req: request::CompleteHeadersRequest) -> Option<request::HeadersResponse> {
use request::HashOrNumber;
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if req.max == 0 { return None }
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 => {
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trace!(target: "pip_provider", "Unknown block hash {} requested", hash);
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return None;
}
Some(header) => {
let num = header.number();
let canon_hash = self.block_header(BlockId::Number(num))
.map(|h| h.hash());
if req.max == 1 || canon_hash != Some(hash) {
// Non-canonical header or single header requested.
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return Some(::request::HeadersResponse {
headers: vec![header],
})
}
num
}
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}
};
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let headers: Vec<_> = (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.saturating_sub(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)
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.collect();
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if headers.is_empty() {
None
} else {
Some(::request::HeadersResponse { headers: headers })
}
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}
/// Get a block header by id.
fn block_header(&self, id: BlockId) -> Option<encoded::Header>;
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/// Fulfill a block body request.
fn block_body(&self, req: request::CompleteBodyRequest) -> Option<request::BodyResponse>;
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/// Fulfill a request for block receipts.
fn block_receipts(&self, req: request::CompleteReceiptsRequest) -> Option<request::ReceiptsResponse>;
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/// Get an account proof.
fn account_proof(&self, req: request::CompleteAccountRequest) -> Option<request::AccountResponse>;
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/// Get a storage proof.
fn storage_proof(&self, req: request::CompleteStorageRequest) -> Option<request::StorageResponse>;
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/// Provide contract code for the specified (block_hash, code_hash) pair.
fn contract_code(&self, req: request::CompleteCodeRequest) -> Option<request::CodeResponse>;
/// Provide a header proof from a given Canonical Hash Trie as well as the
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/// corresponding header.
fn header_proof(&self, req: request::CompleteHeaderProofRequest) -> Option<request::HeaderProofResponse>;
/// Provide pending transactions.
fn ready_transactions(&self) -> Vec<PendingTransaction>;
/// Provide a proof-of-execution for the given transaction proof request.
/// Returns a vector of all state items necessary to execute the transaction.
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fn transaction_proof(&self, req: request::CompleteExecutionRequest) -> Option<request::ExecutionResponse>;
}
// Implementation of a light client data provider for a client.
impl<T: ProvingBlockChainClient + ?Sized> Provider for T {
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_header(&self, id: BlockId) -> Option<encoded::Header> {
BlockChainClient::block_header(self, id)
}
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fn block_body(&self, req: request::CompleteBodyRequest) -> Option<request::BodyResponse> {
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BlockChainClient::block_body(self, BlockId::Hash(req.hash))
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.map(|body| ::request::BodyResponse { body: body })
}
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fn block_receipts(&self, req: request::CompleteReceiptsRequest) -> Option<request::ReceiptsResponse> {
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BlockChainClient::block_receipts(self, &req.hash)
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.map(|x| ::request::ReceiptsResponse { receipts: ::rlp::decode_list(&x) })
}
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fn account_proof(&self, req: request::CompleteAccountRequest) -> Option<request::AccountResponse> {
self.prove_account(req.address_hash, BlockId::Hash(req.block_hash)).map(|(proof, acc)| {
::request::AccountResponse {
proof: proof,
nonce: acc.nonce,
balance: acc.balance,
code_hash: acc.code_hash,
storage_root: acc.storage_root,
}
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})
}
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fn storage_proof(&self, req: request::CompleteStorageRequest) -> Option<request::StorageResponse> {
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self.prove_storage(req.address_hash, req.key_hash, BlockId::Hash(req.block_hash)).map(|(proof, item) | {
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::request::StorageResponse {
proof: proof,
value: item,
}
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})
}
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fn contract_code(&self, req: request::CompleteCodeRequest) -> Option<request::CodeResponse> {
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self.state_data(&req.code_hash)
.map(|code| ::request::CodeResponse { code: code })
}
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fn header_proof(&self, req: request::CompleteHeaderProofRequest) -> Option<request::HeaderProofResponse> {
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let cht_number = match cht::block_to_cht_number(req.num) {
Some(cht_num) => cht_num,
None => {
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debug!(target: "pip_provider", "Requested CHT proof with invalid block number");
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return None;
}
};
let mut needed = None;
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// build the CHT, caching the requested header as we pass through it.
let cht = {
let block_info = |id| {
let hdr = self.block_header(id);
let td = self.block_total_difficulty(id);
match (hdr, td) {
(Some(hdr), Some(td)) => {
let info = BlockInfo {
hash: hdr.hash(),
parent_hash: hdr.parent_hash(),
total_difficulty: td,
};
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if hdr.number() == req.num {
needed = Some((hdr, td));
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}
Some(info)
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}
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_ => None,
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}
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};
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match cht::build(cht_number, block_info) {
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Some(cht) => cht,
None => return None, // incomplete CHT.
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}
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};
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let (needed_hdr, needed_td) = needed.expect("`needed` always set in loop, number checked before; qed");
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// prove our result.
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match cht.prove(req.num, 0) {
Ok(Some(proof)) => Some(::request::HeaderProofResponse {
proof: proof,
hash: needed_hdr.hash(),
td: needed_td,
}),
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Ok(None) => None,
Err(e) => {
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debug!(target: "pip_provider", "Error looking up number in freshly-created CHT: {}", e);
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None
}
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}
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}
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fn transaction_proof(&self, req: request::CompleteExecutionRequest) -> Option<request::ExecutionResponse> {
use ethcore::transaction::Transaction;
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let id = BlockId::Hash(req.block_hash);
let nonce = match self.nonce(&req.from, id.clone()) {
Some(nonce) => nonce,
None => return None,
};
let transaction = Transaction {
nonce: nonce,
gas: req.gas,
gas_price: req.gas_price,
action: req.action,
value: req.value,
data: req.data,
}.fake_sign(req.from);
self.prove_transaction(transaction, id)
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.map(|proof| ::request::ExecutionResponse { items: proof })
}
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fn ready_transactions(&self) -> Vec<PendingTransaction> {
BlockChainClient::ready_transactions(self)
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}
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}
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/// The light client "provider" implementation. This wraps a `LightClient` and
/// a light transaction queue.
pub struct LightProvider<L> {
client: Arc<L>,
txqueue: Arc<RwLock<TransactionQueue>>,
}
impl<L> LightProvider<L> {
/// Create a new `LightProvider` from the given client and transaction queue.
pub fn new(client: Arc<L>, txqueue: Arc<RwLock<TransactionQueue>>) -> Self {
LightProvider {
client: client,
txqueue: txqueue,
}
}
}
// TODO: draw from cache (shared between this and the RPC layer)
impl<L: AsLightClient + Send + Sync> Provider for LightProvider<L> {
fn chain_info(&self) -> BlockChainInfo {
self.client.as_light_client().chain_info()
}
fn reorg_depth(&self, _a: &H256, _b: &H256) -> Option<u64> {
None
}
fn earliest_state(&self) -> Option<u64> {
None
}
fn block_header(&self, id: BlockId) -> Option<encoded::Header> {
self.client.as_light_client().block_header(id)
}
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fn block_body(&self, _req: request::CompleteBodyRequest) -> Option<request::BodyResponse> {
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None
}
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fn block_receipts(&self, _req: request::CompleteReceiptsRequest) -> Option<request::ReceiptsResponse> {
None
}
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fn account_proof(&self, _req: request::CompleteAccountRequest) -> Option<request::AccountResponse> {
None
}
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fn storage_proof(&self, _req: request::CompleteStorageRequest) -> Option<request::StorageResponse> {
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None
}
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fn contract_code(&self, _req: request::CompleteCodeRequest) -> Option<request::CodeResponse> {
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None
}
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fn header_proof(&self, _req: request::CompleteHeaderProofRequest) -> Option<request::HeaderProofResponse> {
None
}
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fn transaction_proof(&self, _req: request::CompleteExecutionRequest) -> Option<request::ExecutionResponse> {
None
}
fn ready_transactions(&self) -> Vec<PendingTransaction> {
let chain_info = self.chain_info();
self.txqueue.read().ready_transactions(chain_info.best_block_number, chain_info.best_block_timestamp)
}
}
impl<L: AsLightClient> AsLightClient for LightProvider<L> {
type Client = L::Client;
fn as_light_client(&self) -> &L::Client {
self.client.as_light_client()
}
}
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#[cfg(test)]
mod tests {
use ethcore::client::{EachBlockWith, TestBlockChainClient};
use super::Provider;
#[test]
fn cht_proof() {
let client = TestBlockChainClient::new();
client.add_blocks(2000, EachBlockWith::Nothing);
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let req = ::request::CompleteHeaderProofRequest {
num: 1500,
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};
assert!(client.header_proof(req.clone()).is_none());
client.add_blocks(48, EachBlockWith::Nothing);
assert!(client.header_proof(req.clone()).is_some());
}
}