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don't keep headers in memory to avoid DoS

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This commit is contained in:
Robert Habermeier 2017-03-21 20:23:58 +01:00
parent d013a13be6
commit 21771aa1a6
1 changed files with 118 additions and 35 deletions
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153
ethcore/light/src/client/header_chain.rs
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@ -24,7 +24,7 @@
//! - It stores only headers (and a pruned subset of them)
//! - To allow for flexibility in the database layout once that's incorporated.
use std::collections::{BTreeMap, HashMap};
use std::collections::BTreeMap;
use std::sync::Arc;
use cht;
@ -35,7 +35,7 @@ use ethcore::encoded;
use ethcore::header::Header;
use ethcore::ids::BlockId;
use rlp::{Encodable, Decodable, Decoder, DecoderError, RlpStream, View};
use rlp::{Encodable, Decodable, Decoder, DecoderError, RlpStream, Rlp, View};
use util::{H256, U256, HeapSizeOf, RwLock};
use util::kvdb::{DBTransaction, KeyValueDB};
@ -46,8 +46,8 @@ use smallvec::SmallVec;
/// relevant to any blocks we've got in memory.
const HISTORY: u64 = 2048;
/// The best block key. Maps to a `u64` best block number.
const BEST_KEY: &'static [u8] = &*b"best_block_key";
/// The best block key. Maps to an RLP list: [best_era, last_era]
const CURRENT_KEY: &'static [u8] = &*b"best_and_latest";
/// Information about a block.
#[derive(Debug, Clone)]
@ -131,7 +131,6 @@ fn era_key(number: u64) -> String {
pub struct HeaderChain {
genesis_header: encoded::Header, // special-case the genesis.
candidates: RwLock<BTreeMap<u64, Entry>>,
headers: RwLock<HashMap<H256, encoded::Header>>,
best_block: RwLock<BlockDescriptor>,
db: Arc<KeyValueDB>,
col: Option<u32>,
@ -142,30 +141,33 @@ impl HeaderChain {
pub fn new(db: Arc<KeyValueDB>, col: Option<u32>, genesis: &[u8]) -> Result<Self, String> {
use ethcore::views::HeaderView;
let chain = if let Some(best_number) = db.get(col, BEST_KEY)?.map(|x| ::rlp::decode(&x)) {
let mut cur_number = best_number;
let chain = if let Some(current) = db.get(col, CURRENT_KEY)? {
let (best_number, highest_number) = {
let rlp = Rlp::new(&current);
(rlp.val_at(0), rlp.val_at(1))
};
let mut cur_number = highest_number;
let mut candidates = BTreeMap::new();
let mut headers = HashMap::new();
// load all era entries and referenced headers within them.
while let Some(entry) = db.get(col, era_key(cur_number).as_bytes())? {
let entry: Entry = ::rlp::decode(&entry);
for candidate in &entry.candidates {
match db.get(col, &*candidate.hash)? {
Some(hdr) => headers.insert(candidate.hash, encoded::Header::new(hdr.to_vec())),
None => return Err(format!("Database missing referenced header: {}", candidate.hash)),
};
}
trace!(target: "chain", "loaded header chain entry for era {} with {} candidates",
cur_number, entry.candidates.len());
candidates.insert(cur_number, entry);
cur_number -= 1;
}
// fill best block block descriptor.
if candidates.is_empty() { return Err(format!("Database corrupt: best block referenced but no data.")) }
let best_block = {
let era = candidates.get(&best_number)
.expect("candidates non-empty; filled in loop starting at best_number; qed");
let era = match candidates.get(&best_number) {
Some(era) => era,
None => return Err(format!("Database corrupt: highest block referenced but no data.")),
};
let best = &era.candidates[0];
BlockDescriptor {
hash: best.hash,
@ -178,7 +180,6 @@ impl HeaderChain {
genesis_header: encoded::Header::new(genesis.to_owned()),
best_block: RwLock::new(best_block),
candidates: RwLock::new(candidates),
headers: RwLock::new(headers),
db: db,
col: col,
}
@ -192,7 +193,6 @@ impl HeaderChain {
total_difficulty: g_view.difficulty(),
}),
candidates: RwLock::new(BTreeMap::new()),
headers: RwLock::new(HashMap::new()),
db: db,
col: col,
}
@ -225,7 +225,7 @@ impl HeaderChain {
let total_difficulty = parent_td + *header.difficulty();
// insert headers and candidates entries.
// insert headers and candidates entries and write era to disk.
{
let cur_era = candidates.entry(number)
.or_insert_with(|| Entry { candidates: SmallVec::new(), canonical_hash: hash });
@ -234,15 +234,32 @@ impl HeaderChain {
parent_hash: parent_hash,
total_difficulty: total_difficulty,
});
// fix ordering of era before writing.
if total_difficulty > cur_era.candidates[0].total_difficulty {
let cur_pos = cur_era.candidates.len() - 1;
cur_era.candidates.swap(cur_pos, 0);
cur_era.canonical_hash = hash;
}
transaction.put(self.col, era_key(number).as_bytes(), &::rlp::encode(&*cur_era))
}
let raw = ::rlp::encode(&header);
transaction.put(self.col, &hash[..], &*raw);
self.headers.write().insert(hash, encoded::Header::new(raw.to_vec()));
let (best_num, is_new_best) = {
let cur_best = self.best_block.read();
if cur_best.total_difficulty < total_difficulty {
(number, true)
} else {
(cur_best.number, false)
}
};
// reorganize ancestors so canonical entries are first in their
// respective candidates vectors.
if self.best_block.read().total_difficulty < total_difficulty {
if is_new_best {
let mut canon_hash = hash;
for (&height, entry) in candidates.iter_mut().rev().skip_while(|&(height, _)| *height > number) {
if height != number && entry.canonical_hash == canon_hash { break; }
@ -262,9 +279,11 @@ impl HeaderChain {
// resetting to the last block of a given CHT should be possible.
canon_hash = entry.candidates[0].parent_hash;
// write altered era to disk.
let rlp_era = ::rlp::encode(&*entry);
transaction.put(self.col, era_key(height).as_bytes(), &rlp_era);
// write altered era to disk
if height != number {
let rlp_era = ::rlp::encode(&*entry);
transaction.put(self.col, era_key(height).as_bytes(), &rlp_era);
}
}
trace!(target: "chain", "New best block: ({}, {}), TD {}", number, hash, total_difficulty);
@ -273,7 +292,6 @@ impl HeaderChain {
number: number,
total_difficulty: total_difficulty,
};
transaction.put(self.col, BEST_KEY, &*::rlp::encode(&number));
// produce next CHT root if it's time.
let earliest_era = *candidates.keys().next().expect("at least one era just created; qed");
@ -281,8 +299,6 @@ impl HeaderChain {
let cht_num = cht::block_to_cht_number(earliest_era)
.expect("fails only for number == 0; genesis never imported; qed");
let mut headers = self.headers.write();
let cht_root = {
let mut i = earliest_era;
@ -296,7 +312,6 @@ impl HeaderChain {
i += 1;
for ancient in &era_entry.candidates {
headers.remove(&ancient.hash);
transaction.delete(self.col, &ancient.hash);
}
@ -313,20 +328,37 @@ impl HeaderChain {
}
}
// write the best and latest eras to the database.
{
let latest_num = *candidates.iter().rev().next().expect("at least one era just inserted; qed").0;
let mut stream = RlpStream::new_list(2);
stream.append(&best_num).append(&latest_num);
transaction.put(self.col, CURRENT_KEY, &stream.out())
}
Ok(())
}
/// Get a block header. In the case of query by number, only canonical blocks
/// will be returned.
pub fn block_header(&self, id: BlockId) -> Option<encoded::Header> {
let load_from_db = |hash: H256| {
match self.db.get(self.col, &hash) {
Ok(val) => val.map(|x| x.to_vec()).map(encoded::Header::new),
Err(e) => {
warn!(target: "chain", "Failed to read from database: {}", e);
None
}
}
};
match id {
BlockId::Earliest | BlockId::Number(0) => Some(self.genesis_header.clone()),
BlockId::Hash(hash) => self.headers.read().get(&hash).cloned(),
BlockId::Hash(hash) => load_from_db(hash),
BlockId::Number(num) => {
if self.best_block.read().number < num { return None }
self.candidates.read().get(&num).map(|entry| entry.canonical_hash)
.and_then(|hash| self.headers.read().get(&hash).cloned())
.and_then(load_from_db)
}
BlockId::Latest | BlockId::Pending => {
let hash = {
@ -338,7 +370,7 @@ impl HeaderChain {
best.hash
};
self.headers.read().get(&hash).cloned()
load_from_db(hash)
}
}
}
@ -401,7 +433,7 @@ impl HeaderChain {
/// Get block status.
pub fn status(&self, hash: &H256) -> BlockStatus {
match self.headers.read().contains_key(hash) {
match self.db.get(self.col, &*hash).ok().map_or(false, |x| x.is_some()) {
true => BlockStatus::InChain,
false => BlockStatus::Unknown,
}
@ -410,8 +442,7 @@ impl HeaderChain {
impl HeapSizeOf for HeaderChain {
fn heap_size_of_children(&self) -> usize {
self.candidates.read().heap_size_of_children() +
self.headers.read().heap_size_of_children()
self.candidates.read().heap_size_of_children()
}
}
@ -603,4 +634,56 @@ mod tests {
assert!(chain.cht_root(3).is_none());
assert_eq!(chain.block_header(BlockId::Latest).unwrap().number(), 9999);
}
#[test]
fn restore_higher_non_canonical() {
let spec = Spec::new_test();
let genesis_header = spec.genesis_header();
let db = make_db();
{
let chain = HeaderChain::new(db.clone(), None, &::rlp::encode(&genesis_header)).unwrap();
let mut parent_hash = genesis_header.hash();
let mut rolling_timestamp = genesis_header.timestamp();
// push 100 low-difficulty blocks.
for i in 1..101 {
let mut header = Header::new();
header.set_parent_hash(parent_hash);
header.set_number(i);
header.set_timestamp(rolling_timestamp);
header.set_difficulty(*genesis_header.difficulty() * i.into());
parent_hash = header.hash();
let mut tx = db.transaction();
chain.insert(&mut tx, header).unwrap();
db.write(tx).unwrap();
rolling_timestamp += 10;
}
// push fewer high-difficulty blocks.
for i in 1..11 {
let mut header = Header::new();
header.set_parent_hash(parent_hash);
header.set_number(i);
header.set_timestamp(rolling_timestamp);
header.set_difficulty(*genesis_header.difficulty() * i.into() * 1000.into());
parent_hash = header.hash();
let mut tx = db.transaction();
chain.insert(&mut tx, header).unwrap();
db.write(tx).unwrap();
rolling_timestamp += 10;
}
assert_eq!(chain.block_header(BlockId::Latest).unwrap().number(), 10);
}
// after restoration, non-canonical eras should still be loaded.
let chain = HeaderChain::new(db.clone(), None, &::rlp::encode(&genesis_header)).unwrap();
assert_eq!(chain.block_header(BlockId::Latest).unwrap().number(), 10);
assert!(chain.candidates.read().get(&100).is_some())
}
}