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transaction.rs
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transaction.rs
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//! The `transaction` module provides functionality for creating log transactions.
use bincode::serialize;
use budget::{Budget, Condition};
use chrono::prelude::*;
use hash::Hash;
use payment_plan::{Payment, PaymentPlan, Witness};
use signature::{KeyPair, KeyPairUtil, PublicKey, Signature, SignatureUtil};
pub const SIGNED_DATA_OFFSET: usize = 112;
pub const SIG_OFFSET: usize = 8;
pub const PUB_KEY_OFFSET: usize = 80;
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub enum Plan {
Budget(Budget),
}
// A proxy for the underlying DSL.
impl PaymentPlan for Plan {
fn final_payment(&self) -> Option<Payment> {
match self {
Plan::Budget(budget) => budget.final_payment(),
}
}
fn verify(&self, spendable_tokens: i64) -> bool {
match self {
Plan::Budget(budget) => budget.verify(spendable_tokens),
}
}
fn apply_witness(&mut self, witness: &Witness) {
match self {
Plan::Budget(budget) => budget.apply_witness(witness),
}
}
}
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub struct Contract {
pub tokens: i64,
pub plan: Plan,
}
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub enum Instruction {
NewContract(Contract),
ApplyTimestamp(DateTime<Utc>),
ApplySignature(Signature),
}
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub struct Transaction {
pub sig: Signature,
pub from: PublicKey,
pub instruction: Instruction,
pub last_id: Hash,
pub fee: i64,
}
impl Transaction {
fn new_from_instruction(
from_keypair: &KeyPair,
instruction: Instruction,
last_id: Hash,
fee: i64,
) -> Self {
let from = from_keypair.pubkey();
let mut tx = Transaction {
sig: Signature::default(),
instruction,
last_id,
from,
fee,
};
tx.sign(from_keypair);
tx
}
/// Create and sign a new Transaction. Used for unit-testing.
pub fn new_taxed(
from_keypair: &KeyPair,
to: PublicKey,
tokens: i64,
fee: i64,
last_id: Hash,
) -> Self {
let payment = Payment {
tokens: tokens - fee,
to,
};
let budget = Budget::Pay(payment);
let plan = Plan::Budget(budget);
let instruction = Instruction::NewContract(Contract { plan, tokens });
Self::new_from_instruction(from_keypair, instruction, last_id, fee)
}
/// Create and sign a new Transaction. Used for unit-testing.
pub fn new(from_keypair: &KeyPair, to: PublicKey, tokens: i64, last_id: Hash) -> Self {
Self::new_taxed(from_keypair, to, tokens, 0, last_id)
}
/// Create and sign a new Witness Timestamp. Used for unit-testing.
pub fn new_timestamp(from_keypair: &KeyPair, dt: DateTime<Utc>, last_id: Hash) -> Self {
let instruction = Instruction::ApplyTimestamp(dt);
Self::new_from_instruction(from_keypair, instruction, last_id, 0)
}
/// Create and sign a new Witness Signature. Used for unit-testing.
pub fn new_signature(from_keypair: &KeyPair, tx_sig: Signature, last_id: Hash) -> Self {
let instruction = Instruction::ApplySignature(tx_sig);
Self::new_from_instruction(from_keypair, instruction, last_id, 0)
}
/// Create and sign a postdated Transaction. Used for unit-testing.
pub fn new_on_date(
from_keypair: &KeyPair,
to: PublicKey,
dt: DateTime<Utc>,
tokens: i64,
last_id: Hash,
) -> Self {
let from = from_keypair.pubkey();
let budget = Budget::Race(
(Condition::Timestamp(dt), Payment { tokens, to }),
(Condition::Signature(from), Payment { tokens, to: from }),
);
let plan = Plan::Budget(budget);
let instruction = Instruction::NewContract(Contract { plan, tokens });
Self::new_from_instruction(from_keypair, instruction, last_id, 0)
}
fn get_sign_data(&self) -> Vec<u8> {
let mut data = serialize(&(&self.instruction)).expect("serialize Contract");
let last_id_data = serialize(&(&self.last_id)).expect("serialize last_id");
data.extend_from_slice(&last_id_data);
let fee_data = serialize(&(&self.fee)).expect("serialize last_id");
data.extend_from_slice(&fee_data);
data
}
/// Sign this transaction.
pub fn sign(&mut self, keypair: &KeyPair) {
let sign_data = self.get_sign_data();
self.sig = Signature::clone_from_slice(keypair.sign(&sign_data).as_ref());
}
pub fn verify_sig(&self) -> bool {
warn!("transaction signature verification called");
self.sig.verify(&self.from, &self.get_sign_data())
}
pub fn verify_plan(&self) -> bool {
if let Instruction::NewContract(contract) = &self.instruction {
self.fee >= 0 && self.fee <= contract.tokens
&& contract.plan.verify(contract.tokens - self.fee)
} else {
true
}
}
}
#[cfg(test)]
pub fn test_tx() -> Transaction {
let keypair1 = KeyPair::new();
let pubkey1 = keypair1.pubkey();
let zero = Hash::default();
Transaction::new(&keypair1, pubkey1, 42, zero)
}
#[cfg(test)]
pub fn memfind<A: Eq>(a: &[A], b: &[A]) -> Option<usize> {
assert!(a.len() >= b.len());
let end = a.len() - b.len() + 1;
for i in 0..end {
if a[i..i + b.len()] == b[..] {
return Some(i);
}
}
None
}
#[cfg(test)]
mod tests {
use super::*;
use bincode::{deserialize, serialize};
#[test]
fn test_claim() {
let keypair = KeyPair::new();
let zero = Hash::default();
let tx0 = Transaction::new(&keypair, keypair.pubkey(), 42, zero);
assert!(tx0.verify_plan());
}
#[test]
fn test_transfer() {
let zero = Hash::default();
let keypair0 = KeyPair::new();
let keypair1 = KeyPair::new();
let pubkey1 = keypair1.pubkey();
let tx0 = Transaction::new(&keypair0, pubkey1, 42, zero);
assert!(tx0.verify_plan());
}
#[test]
fn test_transfer_with_fee() {
let zero = Hash::default();
let keypair0 = KeyPair::new();
let pubkey1 = KeyPair::new().pubkey();
assert!(Transaction::new_taxed(&keypair0, pubkey1, 1, 1, zero).verify_plan());
assert!(!Transaction::new_taxed(&keypair0, pubkey1, 1, 2, zero).verify_plan());
assert!(!Transaction::new_taxed(&keypair0, pubkey1, 1, -1, zero).verify_plan());
}
#[test]
fn test_serialize_claim() {
let budget = Budget::Pay(Payment {
tokens: 0,
to: Default::default(),
});
let plan = Plan::Budget(budget);
let instruction = Instruction::NewContract(Contract { plan, tokens: 0 });
let claim0 = Transaction {
instruction,
from: Default::default(),
last_id: Default::default(),
sig: Default::default(),
fee: 0,
};
let buf = serialize(&claim0).unwrap();
let claim1: Transaction = deserialize(&buf).unwrap();
assert_eq!(claim1, claim0);
}
#[test]
fn test_token_attack() {
let zero = Hash::default();
let keypair = KeyPair::new();
let pubkey = keypair.pubkey();
let mut tx = Transaction::new(&keypair, pubkey, 42, zero);
if let Instruction::NewContract(contract) = &mut tx.instruction {
contract.tokens = 1_000_000; // <-- attack, part 1!
if let Plan::Budget(Budget::Pay(ref mut payment)) = contract.plan {
payment.tokens = contract.tokens; // <-- attack, part 2!
}
}
assert!(tx.verify_plan());
assert!(!tx.verify_sig());
}
#[test]
fn test_hijack_attack() {
let keypair0 = KeyPair::new();
let keypair1 = KeyPair::new();
let thief_keypair = KeyPair::new();
let pubkey1 = keypair1.pubkey();
let zero = Hash::default();
let mut tx = Transaction::new(&keypair0, pubkey1, 42, zero);
if let Instruction::NewContract(contract) = &mut tx.instruction {
if let Plan::Budget(Budget::Pay(ref mut payment)) = contract.plan {
payment.to = thief_keypair.pubkey(); // <-- attack!
}
}
assert!(tx.verify_plan());
assert!(!tx.verify_sig());
}
#[test]
fn test_layout() {
let tx = test_tx();
let sign_data = tx.get_sign_data();
let tx_bytes = serialize(&tx).unwrap();
assert_matches!(memfind(&tx_bytes, &sign_data), Some(SIGNED_DATA_OFFSET));
assert_matches!(memfind(&tx_bytes, &tx.sig), Some(SIG_OFFSET));
assert_matches!(memfind(&tx_bytes, &tx.from), Some(PUB_KEY_OFFSET));
}
#[test]
fn test_overspend_attack() {
let keypair0 = KeyPair::new();
let keypair1 = KeyPair::new();
let zero = Hash::default();
let mut tx = Transaction::new(&keypair0, keypair1.pubkey(), 1, zero);
if let Instruction::NewContract(contract) = &mut tx.instruction {
if let Plan::Budget(Budget::Pay(ref mut payment)) = contract.plan {
payment.tokens = 2; // <-- attack!
}
}
assert!(!tx.verify_plan());
// Also, ensure all branchs of the plan spend all tokens
if let Instruction::NewContract(contract) = &mut tx.instruction {
if let Plan::Budget(Budget::Pay(ref mut payment)) = contract.plan {
payment.tokens = 0; // <-- whoops!
}
}
assert!(!tx.verify_plan());
}
}