diff --git a/Cargo.lock b/Cargo.lock
index 56a1865dc89..02ac8995de5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -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",
diff --git a/ethcore/Cargo.toml b/ethcore/Cargo.toml
index cdf0135e72f..d1c9d624b1c 100644
--- a/ethcore/Cargo.toml
+++ b/ethcore/Cargo.toml
@@ -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"
diff --git a/ethcore/res/ethereum/foundation.json b/ethcore/res/ethereum/foundation.json
index 7338b2f2b77..77b0d5533fb 100644
--- a/ethcore/res/ethereum/foundation.json
+++ b/ethcore/res/ethereum/foundation.json
@@ -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"
},
diff --git a/ethcore/src/builtin.rs b/ethcore/src/builtin.rs
index ca3b13181e5..9927435dd4b 100644
--- a/ethcore/src/builtin.rs
+++ b/ethcore/src/builtin.rs
@@ -14,11 +14,16 @@
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see .
+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)
+ }
+}
+
+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 and execution definition for a built-in contract.
+/// 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,
native: Box,
+ 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 for Builtin {
fn from(b: ethjson::spec::Builtin) -> Self {
- let pricer = match b.pricing {
+ let pricer: Box = 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 {
"ecrecover" => Box::new(EcRecover) as Box,
"sha256" => Box::new(Sha256) as Box,
"ripemd160" => Box::new(Ripemd160) as Box,
+ "modexp" => Box::new(ModexpImpl) as Box,
_ => panic!("invalid builtin name: {}", name),
}
}
@@ -95,6 +155,7 @@ fn ethereum_builtin(name: &str) -> Box {
// - 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,
+ 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,
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];
diff --git a/ethcore/src/engines/mod.rs b/ethcore/src/engines/mod.rs
index 2cc1ff21f3e..f292a06d8e5 100644
--- a/ethcore/src/engines/mod.rs
+++ b/ethcore/src/engines/mod.rs
@@ -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.
diff --git a/ethcore/src/executive.rs b/ethcore/src/executive.rs
index db1fe6a4ee3..cdae8a85f0d 100644
--- a/ethcore/src/executive.rs
+++ b/ethcore/src/executive.rs
@@ -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(¶ms.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(¶ms.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(¶ms);
- let cost = self.engine.cost_of_builtin(¶ms.code_address, data);
+ let cost = builtin.cost(data);
if cost <= params.gas {
- self.engine.execute_builtin(¶ms.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
diff --git a/ethcore/src/lib.rs b/ethcore/src/lib.rs
index a78e2120f0b..75c8a80e154 100644
--- a/ethcore/src/lib.rs
+++ b/ethcore/src/lib.rs
@@ -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;
diff --git a/json/src/spec/builtin.rs b/json/src/spec/builtin.rs
index 81a066585d7..892bf532edd 100644
--- a/json/src/spec/builtin.rs
+++ b/json/src/spec/builtin.rs
@@ -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,
}
#[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())));
}
}