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checking proofs in safe contract

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This commit is contained in:
Robert Habermeier 2017-07-28 19:38:52 +02:00
parent e84f308264
commit 2bd5c3dba7
4 changed files with 124 additions and 75 deletions
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2
ethcore/src/client/client.rs
View File

@ -765,7 +765,7 @@ impl Client {
res.map(|(output, proof)| (output, proof.into_iter().map(|x| x.into_vec()).collect()))
};
match (with_state)(&call) {
match with_state.generate_proof(&call) {
Ok(proof) => proof,
Err(e) => {
warn!(target: "client", "Failed to generate transition proof for block {}: {}", hash, e);

14
ethcore/src/engines/mod.rs
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@ -120,12 +120,22 @@ pub type Headers<'a> = Fn(H256) -> Option<Header> + 'a;
/// Type alias for a function we can query pending transitions by block hash through.
pub type PendingTransitionStore<'a> = Fn(H256) -> Option<PendingTransition> + 'a;
/// Proof dependent on state.
pub trait StateDependentProof {
/// Generate a proof, given the state.
fn generate_proof(&self, caller: &Call) -> Result<Vec<u8>, String>;
/// Check a proof generated elsewhere (potentially by a peer).
// `engine` needed to check state proofs, while really this should
// just be state machine params.
fn check_proof(&self, engine: &Engine, proof: &[u8]) -> Result<(), String>;
}
/// Proof generated on epoch change.
pub enum Proof {
/// Known proof (exctracted from signal)
Known(Vec<u8>),
/// Extract proof from caller.
WithState(Box<Fn(&Call) -> Result<Vec<u8>, String>>),
/// State dependent proof.
WithState(Box<StateDependentProof>),
}
/// Generated epoch verifier.

45
ethcore/src/engines/tendermint/mod.rs
View File

@ -577,18 +577,35 @@ impl Engine for Tendermint {
Ok(())
}
/// Verify validators and gas limit.
/// Verify gas limit.
fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
if header.number() == 0 {
return Err(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() }).into());
}
let gas_limit_divisor = self.gas_limit_bound_divisor;
let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
self.validators.report_malicious(header.author(), header.number(), header.number(), Default::default());
return Err(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() }).into());
}
Ok(())
}
fn verify_block_external(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
if let Ok(proposal) = ConsensusMessage::new_proposal(header) {
let proposer = proposal.verify()?;
if !self.is_authority(&proposer) {
return Err(EngineError::NotAuthorized(proposer).into());
}
self.check_view_proposer(header.parent_hash(), proposal.vote_step.height, proposal.vote_step.view, &proposer)?;
self.check_view_proposer(
header.parent_hash(),
proposal.vote_step.height,
proposal.vote_step.view,
&proposer
).map_err(Into::into)
} else {
let vote_step = VoteStep::new(header.number() as usize, consensus_view(header)?, Step::Precommit);
let precommit_hash = message_hash(vote_step.clone(), header.bare_hash());
@ -614,18 +631,8 @@ impl Engine for Tendermint {
}
}
self.check_above_threshold(origins.len())?
self.check_above_threshold(origins.len()).map_err(Into::into)
}
let gas_limit_divisor = self.gas_limit_bound_divisor;
let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
self.validators.report_malicious(header.author(), header.number(), header.number(), Default::default());
return Err(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() }).into());
}
Ok(())
}
fn signals_epoch_end(&self, header: &Header, block: Option<&[u8]>, receipts: Option<&[::receipt::Receipt]>)
@ -892,14 +899,14 @@ mod tests {
let seal = proposal_seal(&tap, &header, 0);
header.set_seal(seal);
// Good proposer.
assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
assert!(engine.verify_block_external(&header, None).is_ok());
let validator = insert_and_unlock(&tap, "0");
header.set_author(validator);
let seal = proposal_seal(&tap, &header, 0);
header.set_seal(seal);
// Bad proposer.
match engine.verify_block_family(&header, &parent_header, None) {
match engine.verify_block_external(&header, None) {
Err(Error::Engine(EngineError::NotProposer(_))) => {},
_ => panic!(),
}
@ -909,7 +916,7 @@ mod tests {
let seal = proposal_seal(&tap, &header, 0);
header.set_seal(seal);
// Not authority.
match engine.verify_block_family(&header, &parent_header, None) {
match engine.verify_block_external(&header, None) {
Err(Error::Engine(EngineError::NotAuthorized(_))) => {},
_ => panic!(),
};
@ -939,7 +946,7 @@ mod tests {
header.set_seal(seal.clone());
// One good signature is not enough.
match engine.verify_block_family(&header, &parent_header, None) {
match engine.verify_block_external(&header, None) {
Err(Error::Engine(EngineError::BadSealFieldSize(_))) => {},
_ => panic!(),
}
@ -950,7 +957,7 @@ mod tests {
seal[2] = ::rlp::encode_list(&vec![H520::from(signature1.clone()), H520::from(signature0.clone())]).into_vec();
header.set_seal(seal.clone());
assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
assert!(engine.verify_block_external(&header, None).is_ok());
let bad_voter = insert_and_unlock(&tap, "101");
let bad_signature = tap.sign(bad_voter, None, vote_info.sha3()).unwrap();
@ -959,7 +966,7 @@ mod tests {
header.set_seal(seal);
// One good and one bad signature.
match engine.verify_block_family(&header, &parent_header, None) {
match engine.verify_block_external(&header, None) {
Err(Error::Engine(EngineError::NotAuthorized(_))) => {},
_ => panic!(),
};

138
ethcore/src/engines/validator_set/safe_contract.rs
View File

@ -44,6 +44,29 @@ lazy_static! {
static ref EVENT_NAME_HASH: H256 = EVENT_NAME.sha3();
}
// state-dependent proofs for the safe contract:
// only "first" proofs are such.
struct StateProof {
header: Header,
provider: Provider,
}
impl ::engines::StateDependentProof for StateProof {
fn generate_proof(&self, caller: &Call) -> Result<Vec<u8>, String> {
prove_initial(&self.provider, &self.header, caller)
}
fn check_proof(&self, engine: &Engine, proof: &[u8]) -> Result<(), String> {
let (header, state_items) = decode_first_proof(&UntrustedRlp::new(proof))
.map_err(|e| format!("proof incorrectly encoded: {}", e))?;
if header != self.header {
return Err("wrong header in proof".into());
}
check_first_proof(engine, &self.provider, header, &state_items).map(|_| ())
}
}
/// The validator contract should have the following interface:
pub struct ValidatorSafeContract {
pub address: Address,
@ -63,6 +86,59 @@ fn encode_first_proof(header: &Header, state_items: &[Vec<u8>]) -> Bytes {
stream.out()
}
// check a first proof: fetch the validator set at the given block.
fn check_first_proof(engine: &Engine, provider: &Provider, old_header: Header, state_items: &[DBValue])
-> Result<Vec<Address>, String>
{
use transaction::{Action, Transaction};
// TODO: match client contract_call_tx more cleanly without duplication.
const PROVIDED_GAS: u64 = 50_000_000;
let env_info = ::evm::env_info::EnvInfo {
number: old_header.number(),
author: *old_header.author(),
difficulty: *old_header.difficulty(),
gas_limit: PROVIDED_GAS.into(),
timestamp: old_header.timestamp(),
last_hashes: {
// this will break if we don't inclue all 256 last hashes.
let mut last_hashes: Vec<_> = (0..256).map(|_| H256::default()).collect();
last_hashes[255] = *old_header.parent_hash();
Arc::new(last_hashes)
},
gas_used: 0.into(),
};
// check state proof using given engine.
let number = old_header.number();
provider.get_validators(move |a, d| {
let from = Address::default();
let tx = Transaction {
nonce: engine.account_start_nonce(number),
action: Action::Call(a),
gas: PROVIDED_GAS.into(),
gas_price: U256::default(),
value: U256::default(),
data: d,
}.fake_sign(from);
let res = ::state::check_proof(
state_items,
*old_header.state_root(),
&tx,
engine,
&env_info,
);
match res {
::state::ProvedExecution::BadProof => Err("Bad proof".into()),
::state::ProvedExecution::Failed(e) => Err(format!("Failed call: {}", e)),
::state::ProvedExecution::Complete(e) => Ok(e.output),
}
}).wait()
}
fn decode_first_proof(rlp: &UntrustedRlp) -> Result<(Header, Vec<DBValue>), ::error::Error> {
let header = rlp.val_at(0)?;
let state_items = rlp.at(1)?.iter().map(|x| {
@ -100,8 +176,7 @@ fn prove_initial(provider: &Provider, header: &Header, caller: &Call) -> Result<
Ok(result)
};
provider.get_validators(caller)
.wait()
provider.get_validators(caller).wait()
};
res.map(|validators| {
@ -255,9 +330,11 @@ impl ValidatorSet for ValidatorSafeContract {
// transition to the first block of a contract requires finality but has no log event.
if first {
debug!(target: "engine", "signalling transition to fresh contract.");
let (provider, header) = (self.provider.clone(), header.clone());
let with_caller: Box<Fn(&Call) -> _> = Box::new(move |caller| prove_initial(&provider, &header, caller));
return ::engines::EpochChange::Yes(::engines::Proof::WithState(with_caller))
let state_proof = Box::new(StateProof {
header: header.clone(),
provider: self.provider.clone(),
});
return ::engines::EpochChange::Yes(::engines::Proof::WithState(state_proof as Box<_>));
}
// otherwise, we're checking for logs.
@ -286,61 +363,16 @@ impl ValidatorSet for ValidatorSafeContract {
fn epoch_set(&self, first: bool, engine: &Engine, _number: ::header::BlockNumber, proof: &[u8])
-> Result<(SimpleList, Option<H256>), ::error::Error>
{
use transaction::{Action, Transaction};
let rlp = UntrustedRlp::new(proof);
if first {
trace!(target: "engine", "Recovering initial epoch set");
// TODO: match client contract_call_tx more cleanly without duplication.
const PROVIDED_GAS: u64 = 50_000_000;
let (old_header, state_items) = decode_first_proof(&rlp)?;
let old_hash = old_header.hash();
let env_info = ::evm::env_info::EnvInfo {
number: old_header.number(),
author: *old_header.author(),
difficulty: *old_header.difficulty(),
gas_limit: PROVIDED_GAS.into(),
timestamp: old_header.timestamp(),
last_hashes: {
// this will break if we don't inclue all 256 last hashes.
let mut last_hashes: Vec<_> = (0..256).map(|_| H256::default()).collect();
last_hashes[255] = *old_header.parent_hash();
Arc::new(last_hashes)
},
gas_used: 0.into(),
};
// check state proof using given engine.
let number = old_header.number();
let addresses = self.provider.get_validators(move |a, d| {
let from = Address::default();
let tx = Transaction {
nonce: engine.account_start_nonce(number),
action: Action::Call(a),
gas: PROVIDED_GAS.into(),
gas_price: U256::default(),
value: U256::default(),
data: d,
}.fake_sign(from);
let res = ::state::check_proof(
&state_items,
*old_header.state_root(),
&tx,
engine,
&env_info,
);
match res {
::state::ProvedExecution::BadProof => Err("Bad proof".into()),
::state::ProvedExecution::Failed(e) => Err(format!("Failed call: {}", e)),
::state::ProvedExecution::Complete(e) => Ok(e.output),
}
}).wait().map_err(::engines::EngineError::InsufficientProof)?;
let old_hash = old_header.hash();
let addresses = check_first_proof(engine, &self.provider, old_header, &state_items)
.map_err(::engines::EngineError::InsufficientProof)?;
trace!(target: "engine", "extracted epoch set at #{}: {} addresses",
number, addresses.len());