diff --git a/ethcore/light/src/cht.rs b/ethcore/light/src/cht.rs index 2f6659353..1fcb7b26a 100644 --- a/ethcore/light/src/cht.rs +++ b/ethcore/light/src/cht.rs @@ -23,7 +23,7 @@ use ethcore::ids::BlockId; use util::{Bytes, H256, U256, HashDB, MemoryDB}; use util::trie::{self, TrieMut, TrieDBMut, Trie, TrieDB, Recorder}; -use rlp::{Stream, RlpStream}; +use rlp::{Stream, RlpStream, UntrustedRlp, View}; // encode a key. macro_rules! key { @@ -136,6 +136,30 @@ pub fn compute_root(cht_num: u64, iterable: I) -> Option } } +/// Check a proof for a CHT. +/// Given a set of a trie nodes, a number to query, and a trie root, +/// verify the given trie branch and extract the canonical hash and total difficulty. +// TODO: better support for partially-checked queries. +pub fn check_proof(proof: &[Bytes], num: u64, root: H256) -> Option<(H256, U256)> { + let mut db = MemoryDB::new(); + + for node in proof { db.insert(&node[..]); } + let res = match TrieDB::new(&db, &root) { + Err(_) => return None, + Ok(trie) => trie.get_with(&key!(num), |val: &[u8]| { + let rlp = UntrustedRlp::new(val); + rlp.val_at::(0) + .and_then(|h| rlp.val_at::(1).map(|td| (h, td))) + .ok() + }) + }; + + match res { + Ok(Some(Some((hash, td)))) => Some((hash, td)), + _ => None, + } +} + /// Convert a block number to a CHT number. /// Returns `None` for `block_num` == 0, `Some` otherwise. pub fn block_to_cht_number(block_num: u64) -> Option { diff --git a/ethcore/light/src/on_demand/mod.rs b/ethcore/light/src/on_demand/mod.rs index 73a9f7e2c..10be00dd7 100644 --- a/ethcore/light/src/on_demand/mod.rs +++ b/ethcore/light/src/on_demand/mod.rs @@ -29,7 +29,7 @@ use futures::sync::oneshot; use network::PeerId; use net::{Handler, Status, Capabilities, Announcement, EventContext, BasicContext, ReqId}; -use util::{Bytes, RwLock}; +use util::{Bytes, RwLock, U256}; use types::les_request::{self as les_request, Request as LesRequest}; pub mod request; @@ -79,7 +79,7 @@ struct Peer { // Attempted request info and sender to put received value. enum Pending { - HeaderByNumber(request::HeaderByNumber, Sender), // num + CHT root + HeaderByNumber(request::HeaderByNumber, Sender<(encoded::Header, U256)>), // num + CHT root HeaderByHash(request::HeaderByHash, Sender), Block(request::Body, Sender), BlockReceipts(request::BlockReceipts, Sender>), @@ -105,14 +105,15 @@ impl Default for OnDemand { impl OnDemand { /// Request a header by block number and CHT root hash. - pub fn header_by_number(&self, ctx: &BasicContext, req: request::HeaderByNumber) -> Response { + /// Returns the header and the total difficulty. + pub fn header_by_number(&self, ctx: &BasicContext, req: request::HeaderByNumber) -> Response<(encoded::Header, U256)> { let (sender, receiver) = oneshot::channel(); self.dispatch_header_by_number(ctx, req, sender); Response(receiver) } // dispatch the request, completing the request if no peers available. - fn dispatch_header_by_number(&self, ctx: &BasicContext, req: request::HeaderByNumber, sender: Sender) { + fn dispatch_header_by_number(&self, ctx: &BasicContext, req: request::HeaderByNumber, sender: Sender<(encoded::Header, U256)>) { let num = req.num; let cht_num = match ::cht::block_to_cht_number(req.num) { Some(cht_num) => cht_num, diff --git a/ethcore/light/src/on_demand/request.rs b/ethcore/light/src/on_demand/request.rs index 025a92af6..90d6801c8 100644 --- a/ethcore/light/src/on_demand/request.rs +++ b/ethcore/light/src/on_demand/request.rs @@ -21,7 +21,7 @@ use ethcore::encoded; use ethcore::receipt::Receipt; use rlp::{RlpStream, Stream, UntrustedRlp, View}; -use util::{Address, Bytes, HashDB, H256}; +use util::{Address, Bytes, HashDB, H256, U256}; use util::memorydb::MemoryDB; use util::sha3::Hashable; use util::trie::{Trie, TrieDB, TrieError}; @@ -66,24 +66,16 @@ pub struct HeaderByNumber { impl HeaderByNumber { /// Check a response with a header and cht proof. - pub fn check_response(&self, header: &[u8], proof: &[Bytes]) -> Result { - use util::trie::{Trie, TrieDB}; - - // check the proof - let mut db = MemoryDB::new(); - - for node in proof { db.insert(&node[..]); } - let key = ::rlp::encode(&self.num); - - let expected_hash: H256 = match TrieDB::new(&db, &self.cht_root).and_then(|t| t.get(&*key))? { - Some(val) => ::rlp::decode(&val), - None => return Err(Error::BadProof) + pub fn check_response(&self, header: &[u8], proof: &[Bytes]) -> Result<(encoded::Header, U256), Error> { + let (expected_hash, td) = match ::cht::check_proof(proof, self.num, self.cht_root) { + Some((expected_hash, td)) => (expected_hash, td), + None => return Err(Error::BadProof), }; // and compare the hash to the found header. let found_hash = header.sha3(); match expected_hash == found_hash { - true => Ok(encoded::Header::new(header.to_vec())), + true => Ok((encoded::Header::new(header.to_vec()), td)), false => Err(Error::WrongHash(expected_hash, found_hash)), } } @@ -191,51 +183,44 @@ impl Account { mod tests { use super::*; use util::{MemoryDB, Address, H256, FixedHash}; - use util::trie::{Trie, TrieMut, TrieDB, SecTrieDB, TrieDBMut, SecTrieDBMut}; + use util::trie::{Trie, TrieMut, SecTrieDB, SecTrieDBMut}; use util::trie::recorder::Recorder; + use ethcore::client::{BlockChainClient, TestBlockChainClient, EachBlockWith}; use ethcore::header::Header; use ethcore::encoded; use ethcore::receipt::Receipt; #[test] fn check_header_by_number() { - let mut root = H256::default(); - let mut db = MemoryDB::new(); - let mut header = Header::new(); - header.set_number(10_000); - header.set_extra_data(b"test_header".to_vec()); + use ::cht; - { - let mut trie = TrieDBMut::new(&mut db, &mut root); - for i in (0..2048u64).map(|x| x + 8192) { - let hash = if i == 10_000 { - header.hash() - } else { - H256::random() - }; - trie.insert(&*::rlp::encode(&i), &*::rlp::encode(&hash)).unwrap(); - } - } + let test_client = TestBlockChainClient::new(); + test_client.add_blocks(10500, EachBlockWith::Nothing); - let proof = { - let trie = TrieDB::new(&db, &root).unwrap(); - let key = ::rlp::encode(&10_000u64); - let mut recorder = Recorder::new(); + let cht = { + let fetcher = |id| { + let hdr = test_client.block_header(id).unwrap(); + let td = test_client.block_total_difficulty(id).unwrap(); + Some(cht::BlockInfo { + hash: hdr.hash(), + parent_hash: hdr.parent_hash(), + total_difficulty: td, + }) + }; - trie.get_with(&*key, &mut recorder).unwrap().unwrap(); - - recorder.drain().into_iter().map(|r| r.data).collect::>() + cht::build(cht::block_to_cht_number(10_000).unwrap(), fetcher).unwrap() }; + let proof = cht.prove(10_000, 0).unwrap().unwrap(); let req = HeaderByNumber { num: 10_000, - cht_root: root, + cht_root: cht.root(), }; - let raw_header = ::rlp::encode(&header); + let raw_header = test_client.block_header(::ethcore::ids::BlockId::Number(10_000)).unwrap(); - assert!(req.check_response(&*raw_header, &proof[..]).is_ok()); + assert!(req.check_response(&raw_header.into_inner(), &proof[..]).is_ok()); } #[test]