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EIP198 and built-in activation (#4926) 

* EIP198 and built-in activation

* address review
This commit is contained in:
Robert Habermeier 2017-03-21 17:36:38 +01:00 committed by Nikolay Volf
parent 3687a7c717
commit 797a3e1cd9
8 changed files with 303 additions and 35 deletions
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1
Cargo.lock generated
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@ -406,6 +406,7 @@ dependencies = [
"linked-hash-map 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
"lru-cache 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
"num 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)",
"num_cpus 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
"rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
"rlp 0.1.0",

1
ethcore/Cargo.toml
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@ -44,6 +44,7 @@ ethcore-stratum = { path = "../stratum" }
ethcore-bloom-journal = { path = "../util/bloom" }
hardware-wallet = { path = "../hw" }
stats = { path = "../util/stats" }
num = "0.1"
[dependencies.hyper]
git = "https://github.com/ethcore/hyper"

1
ethcore/res/ethereum/foundation.json
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@ -189,6 +189,7 @@
"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
"0000000000000000000000000000000000000005": { "builtin": { "name": "modexp", "activate_at": "0x7fffffffffffff", "pricing": { "modexp": { "divisor": 20 } } } },
"3282791d6fd713f1e94f4bfd565eaa78b3a0599d": {
"balance": "1337000000000000000000"
},

272
ethcore/src/builtin.rs
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@ -14,11 +14,16 @@
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
use std::cmp::{max, min};
use std::io::{self, Read};
use byteorder::{ByteOrder, BigEndian};
use crypto::sha2::Sha256 as Sha256Digest;
use crypto::ripemd160::Ripemd160 as Ripemd160Digest;
use crypto::digest::Digest;
use std::cmp::min;
use util::{U256, H256, Hashable, BytesRef};
use num::{BigUint, Zero, One};
use util::{U256, H256, Uint, Hashable, BytesRef};
use ethkey::{Signature, recover as ec_recover};
use ethjson;
@ -30,8 +35,8 @@ pub trait Impl: Send + Sync {
/// A gas pricing scheme for built-in contracts.
pub trait Pricer: Send + Sync {
/// The gas cost of running this built-in for the given size of input data.
fn cost(&self, in_size: usize) -> U256;
/// The gas cost of running this built-in for the given input data.
fn cost(&self, input: &[u8]) -> U256;
}
/// A linear pricing model. This computes a price using a base cost and a cost per-word.
@ -40,40 +45,94 @@ struct Linear {
word: usize,
}
/// A special pricing model for modular exponentiation.
struct Modexp {
divisor: usize,
}
impl Pricer for Linear {
fn cost(&self, in_size: usize) -> U256 {
U256::from(self.base) + U256::from(self.word) * U256::from((in_size + 31) / 32)
fn cost(&self, input: &[u8]) -> U256 {
U256::from(self.base) + U256::from(self.word) * U256::from((input.len() + 31) / 32)
}
}
/// Pricing scheme and execution definition for a built-in contract.
impl Pricer for Modexp {
fn cost(&self, input: &[u8]) -> U256 {
let mut reader = input.chain(io::repeat(0));
let mut buf = [0; 32];
// read lengths as U256 here for accurate gas calculation.
let mut read_len = || {
reader.read_exact(&mut buf[..]).expect("reading from zero-extended memory cannot fail; qed");
U256::from(H256::from_slice(&buf[..]))
};
let base_len = read_len();
let exp_len = read_len();
let mod_len = read_len();
// floor(max(length_of_MODULUS, length_of_BASE) ** 2 * max(length_of_EXPONENT, 1) / GQUADDIVISOR)
// TODO: is saturating the best behavior here?
let m = max(mod_len, base_len);
match m.overflowing_mul(m) {
(_, true) => U256::max_value(),
(val, _) => {
match val.overflowing_mul(max(exp_len, U256::one())) {
(_, true) => U256::max_value(),
(val, _) => val / (self.divisor as u64).into()
}
}
}
}
}
/// Pricing scheme, execution definition, and activation block for a built-in contract.
///
/// Call `cost` to compute cost for the given input, `execute` to execute the contract
/// on the given input, and `is_active` to determine whether the contract is active.
///
/// Unless `is_active` is true,
pub struct Builtin {
pricer: Box<Pricer>,
native: Box<Impl>,
activate_at: u64,
}
impl Builtin {
/// Simple forwarder for cost.
pub fn cost(&self, s: usize) -> U256 { self.pricer.cost(s) }
pub fn cost(&self, input: &[u8]) -> U256 { self.pricer.cost(input) }
/// Simple forwarder for execute.
pub fn execute(&self, input: &[u8], output: &mut BytesRef) { self.native.execute(input, output) }
/// Whether the builtin is activated at the given block number.
pub fn is_active(&self, at: u64) -> bool { at >= self.activate_at }
}
impl From<ethjson::spec::Builtin> for Builtin {
fn from(b: ethjson::spec::Builtin) -> Self {
let pricer = match b.pricing {
let pricer: Box<Pricer> = match b.pricing {
ethjson::spec::Pricing::Linear(linear) => {
Box::new(Linear {
base: linear.base,
word: linear.word,
})
}
ethjson::spec::Pricing::Modexp(exp) => {
Box::new(Modexp {
divisor: if exp.divisor == 0 {
warn!("Zero modexp divisor specified. Falling back to default.");
10
} else {
exp.divisor
}
})
}
};
Builtin {
pricer: pricer,
native: ethereum_builtin(&b.name),
activate_at: b.activate_at.map(Into::into).unwrap_or(0),
}
}
}
@ -85,6 +144,7 @@ fn ethereum_builtin(name: &str) -> Box<Impl> {
"ecrecover" => Box::new(EcRecover) as Box<Impl>,
"sha256" => Box::new(Sha256) as Box<Impl>,
"ripemd160" => Box::new(Ripemd160) as Box<Impl>,
"modexp" => Box::new(ModexpImpl) as Box<Impl>,
_ => panic!("invalid builtin name: {}", name),
}
}
@ -95,6 +155,7 @@ fn ethereum_builtin(name: &str) -> Box<Impl> {
// - ec recovery
// - sha256
// - ripemd160
// - modexp (EIP198)
#[derive(Debug)]
struct Identity;
@ -108,6 +169,9 @@ struct Sha256;
#[derive(Debug)]
struct Ripemd160;
#[derive(Debug)]
struct ModexpImpl;
impl Impl for Identity {
fn execute(&self, input: &[u8], output: &mut BytesRef) {
output.write(0, input);
@ -166,9 +230,76 @@ impl Impl for Ripemd160 {
}
}
impl Impl for ModexpImpl {
fn execute(&self, input: &[u8], output: &mut BytesRef) {
let mut reader = input.chain(io::repeat(0));
let mut buf = [0; 32];
// read lengths as usize.
// ignoring the first 24 bytes might technically lead us to fall out of consensus,
// but so would running out of addressable memory!
let mut read_len = |reader: &mut io::Chain<&[u8], io::Repeat>| {
reader.read_exact(&mut buf[..]).expect("reading from zero-extended memory cannot fail; qed");
BigEndian::read_u64(&buf[24..]) as usize
};
let base_len = read_len(&mut reader);
let exp_len = read_len(&mut reader);
let mod_len = read_len(&mut reader);
// read the numbers themselves.
let mut buf = vec![0; max(mod_len, max(base_len, exp_len))];
let mut read_num = |len| {
reader.read_exact(&mut buf[..len]).expect("reading from zero-extended memory cannot fail; qed");
BigUint::from_bytes_be(&buf[..len])
};
let base = read_num(base_len);
let exp = read_num(exp_len);
let modulus = read_num(mod_len);
// calculate modexp: exponentiation by squaring.
fn modexp(mut base: BigUint, mut exp: BigUint, modulus: BigUint) -> BigUint {
match (base == BigUint::zero(), exp == BigUint::zero()) {
(_, true) => return BigUint::one(), // n^0 % m
(true, false) => return BigUint::zero(), // 0^n % m, n>0
(false, false) if modulus <= BigUint::one() => return BigUint::zero(), // a^b % 1 = 0.
_ => {}
}
let mut result = BigUint::one();
base = base % &modulus;
// fast path for base divisible by modulus.
if base == BigUint::zero() { return result }
while exp != BigUint::zero() {
// exp has to be on the right here to avoid move.
if BigUint::one() & &exp == BigUint::one() {
result = (result * &base) % &modulus;
}
exp = exp >> 1;
base = (base.clone() * base) % &modulus;
}
result
}
// write output to given memory, left padded and same length as the modulus.
let bytes = modexp(base, exp, modulus).to_bytes_be();
// always true except in the case of zero-length modulus, which leads to
// output of length and value 1.
if bytes.len() <= mod_len {
let res_start = mod_len - bytes.len();
output.write(res_start, &bytes);
}
}
}
#[cfg(test)]
mod tests {
use super::{Builtin, Linear, ethereum_builtin, Pricer};
use super::{Builtin, Linear, ethereum_builtin, Pricer, Modexp};
use ethjson;
use util::{U256, BytesRef};
@ -295,24 +426,126 @@ mod tests {
assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);*/
}
#[test]
fn modexp() {
use rustc_serialize::hex::FromHex;
let f = Builtin {
pricer: Box::new(Modexp { divisor: 20 }),
native: ethereum_builtin("modexp"),
activate_at: 0,
};
// fermat's little theorem example.
{
let input = FromHex::from_hex("\
0000000000000000000000000000000000000000000000000000000000000001\
0000000000000000000000000000000000000000000000000000000000000020\
0000000000000000000000000000000000000000000000000000000000000020\
03\
fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2e\
fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f"
).unwrap();
let mut output = vec![0u8; 32];
let expected = FromHex::from_hex("0000000000000000000000000000000000000000000000000000000000000001").unwrap();
let expected_cost = 1638;
f.execute(&input[..], &mut BytesRef::Fixed(&mut output[..]));
assert_eq!(output, expected);
assert_eq!(f.cost(&input[..]), expected_cost.into());
}
// second example from EIP: zero base.
{
let input = FromHex::from_hex("\
0000000000000000000000000000000000000000000000000000000000000000\
0000000000000000000000000000000000000000000000000000000000000020\
0000000000000000000000000000000000000000000000000000000000000020\
fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2e\
fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f"
).unwrap();
let mut output = vec![0u8; 32];
let expected = FromHex::from_hex("0000000000000000000000000000000000000000000000000000000000000000").unwrap();
let expected_cost = 1638;
f.execute(&input[..], &mut BytesRef::Fixed(&mut output[..]));
assert_eq!(output, expected);
assert_eq!(f.cost(&input[..]), expected_cost.into());
}
// another example from EIP: zero-padding
{
let input = FromHex::from_hex("\
0000000000000000000000000000000000000000000000000000000000000001\
0000000000000000000000000000000000000000000000000000000000000002\
0000000000000000000000000000000000000000000000000000000000000020\
03\
ffff\
80"
).unwrap();
let mut output = vec![0u8; 32];
let expected = FromHex::from_hex("3b01b01ac41f2d6e917c6d6a221ce793802469026d9ab7578fa2e79e4da6aaab").unwrap();
let expected_cost = 102;
f.execute(&input[..], &mut BytesRef::Fixed(&mut output[..]));
assert_eq!(output, expected);
assert_eq!(f.cost(&input[..]), expected_cost.into());
}
// zero-length modulus.
{
let input = FromHex::from_hex("\
0000000000000000000000000000000000000000000000000000000000000001\
0000000000000000000000000000000000000000000000000000000000000002\
0000000000000000000000000000000000000000000000000000000000000000\
03\
ffff"
).unwrap();
let mut output = vec![];
let expected_cost = 0;
f.execute(&input[..], &mut BytesRef::Flexible(&mut output));
assert_eq!(output.len(), 0); // shouldn't have written any output.
assert_eq!(f.cost(&input[..]), expected_cost.into());
}
}
#[test]
#[should_panic]
fn from_unknown_linear() {
let _ = ethereum_builtin("foo");
}
#[test]
fn is_active() {
let pricer = Box::new(Linear { base: 10, word: 20} );
let b = Builtin {
pricer: pricer as Box<Pricer>,
native: ethereum_builtin("identity"),
activate_at: 100_000,
};
assert!(!b.is_active(99_999));
assert!(b.is_active(100_000));
assert!(b.is_active(100_001));
}
#[test]
fn from_named_linear() {
let pricer = Box::new(Linear { base: 10, word: 20 });
let b = Builtin {
pricer: pricer as Box<Pricer>,
native: ethereum_builtin("identity"),
activate_at: 1,
};
assert_eq!(b.cost(0), U256::from(10));
assert_eq!(b.cost(1), U256::from(30));
assert_eq!(b.cost(32), U256::from(30));
assert_eq!(b.cost(33), U256::from(50));
assert_eq!(b.cost(&[0; 0]), U256::from(10));
assert_eq!(b.cost(&[0; 1]), U256::from(30));
assert_eq!(b.cost(&[0; 32]), U256::from(30));
assert_eq!(b.cost(&[0; 33]), U256::from(50));
let i = [0u8, 1, 2, 3];
let mut o = [255u8; 4];
@ -327,13 +560,14 @@ mod tests {
pricing: ethjson::spec::Pricing::Linear(ethjson::spec::Linear {
base: 10,
word: 20,
})
}),
activate_at: None,
});
assert_eq!(b.cost(0), U256::from(10));
assert_eq!(b.cost(1), U256::from(30));
assert_eq!(b.cost(32), U256::from(30));
assert_eq!(b.cost(33), U256::from(50));
assert_eq!(b.cost(&[0; 0]), U256::from(10));
assert_eq!(b.cost(&[0; 1]), U256::from(30));
assert_eq!(b.cost(&[0; 32]), U256::from(30));
assert_eq!(b.cost(&[0; 33]), U256::from(50));
let i = [0u8, 1, 2, 3];
let mut o = [255u8; 4];

17
ethcore/src/engines/mod.rs
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@ -189,19 +189,14 @@ pub trait Engine : Sync + Send {
/// updating consensus state and potentially issuing a new one.
fn handle_message(&self, _message: &[u8]) -> Result<(), Error> { Err(EngineError::UnexpectedMessage.into()) }
/// Attempt to get a handle to a built-in contract.
/// Only returns references to activated built-ins.
// TODO: builtin contract routing - to do this properly, it will require removing the built-in configuration-reading logic
// from Spec into here and removing the Spec::builtins field.
/// Determine whether a particular address is a builtin contract.
fn is_builtin(&self, a: &Address) -> bool { self.builtins().contains_key(a) }
/// Determine the code execution cost of the builtin contract with address `a`.
/// Panics if `is_builtin(a)` is not true.
fn cost_of_builtin(&self, a: &Address, input: &[u8]) -> U256 {
self.builtins().get(a).expect("queried cost of nonexistent builtin").cost(input.len())
}
/// Execution the builtin contract `a` on `input` and return `output`.
/// Panics if `is_builtin(a)` is not true.
fn execute_builtin(&self, a: &Address, input: &[u8], output: &mut BytesRef) {
self.builtins().get(a).expect("attempted to execute nonexistent builtin").execute(input, output);
fn builtin(&self, a: &Address, block_number: ::header::BlockNumber) -> Option<&Builtin> {
self.builtins()
.get(a)
.and_then(|b| if b.is_active(block_number) { Some(b) } else { None })
}
/// Find out if the block is a proposal block and should not be inserted into the DB.

13
ethcore/src/executive.rs
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@ -261,17 +261,22 @@ impl<'a, B: 'a + StateBackend> Executive<'a, B> {
}
trace!("Executive::call(params={:?}) self.env_info={:?}", params, self.info);
if self.engine.is_builtin(&params.code_address) {
// if destination is builtin, try to execute it
// if destination is builtin, try to execute it
if let Some(builtin) = self.engine.builtin(&params.code_address, self.info.number) {
// Engines aren't supposed to return builtins until activation, but
// prefer to fail rather than silently break consensus.
if !builtin.is_active(self.info.number) {
panic!("Consensus failure: engine implementation prematurely enabled built-in at {}", params.code_address);
}
let default = [];
let data = if let Some(ref d) = params.data { d as &[u8] } else { &default as &[u8] };
let trace_info = tracer.prepare_trace_call(&params);
let cost = self.engine.cost_of_builtin(&params.code_address, data);
let cost = builtin.cost(data);
if cost <= params.gas {
self.engine.execute_builtin(&params.code_address, data, &mut output);
builtin.execute(data, &mut output);
self.state.discard_checkpoint();
// trace only top level calls to builtins to avoid DDoS attacks

1
ethcore/src/lib.rs
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@ -106,6 +106,7 @@ extern crate ethcore_stratum;
extern crate ethabi;
extern crate hardware_wallet;
extern crate stats;
extern crate num;
#[macro_use]
extern crate log;

32
json/src/spec/builtin.rs
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@ -16,6 +16,8 @@
//! Spec builtin deserialization.
use uint::Uint;
/// Linear pricing.
#[derive(Debug, PartialEq, Deserialize, Clone)]
pub struct Linear {
@ -25,12 +27,22 @@ pub struct Linear {
pub word: usize,
}
/// Pricing for modular exponentiation.
#[derive(Debug, PartialEq, Deserialize, Clone)]
pub struct Modexp {
/// Price divisor.
pub divisor: usize,
}
/// Pricing variants.
#[derive(Debug, PartialEq, Deserialize, Clone)]
pub enum Pricing {
/// Linear pricing.
#[serde(rename="linear")]
Linear(Linear),
/// Pricing for modular exponentiation.
#[serde(rename="modexp")]
Modexp(Modexp),
}
/// Spec builtin.
@ -40,12 +52,15 @@ pub struct Builtin {
pub name: String,
/// Builtin pricing.
pub pricing: Pricing,
/// Activation block.
pub activate_at: Option<Uint>,
}
#[cfg(test)]
mod tests {
use serde_json;
use spec::builtin::{Builtin, Pricing, Linear};
use spec::builtin::{Builtin, Pricing, Linear, Modexp};
use uint::Uint;
#[test]
fn builtin_deserialization() {
@ -56,5 +71,20 @@ mod tests {
let deserialized: Builtin = serde_json::from_str(s).unwrap();
assert_eq!(deserialized.name, "ecrecover");
assert_eq!(deserialized.pricing, Pricing::Linear(Linear { base: 3000, word: 0 }));
assert!(deserialized.activate_at.is_none());
}
#[test]
fn activate_at() {
let s = r#"{
"name": "late_start",
"activate_at": 100000,
"pricing": { "modexp": { "divisor": 5 } }
}"#;
let deserialized: Builtin = serde_json::from_str(s).unwrap();
assert_eq!(deserialized.name, "late_start");
assert_eq!(deserialized.pricing, Pricing::Modexp(Modexp { divisor: 5 }));
assert_eq!(deserialized.activate_at, Some(Uint(100000.into())));
}
}