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