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//! Predicate representations with required data to be executed during VM runtime
use crate::interpreter::MemoryRange;
use fuel_tx::field;
/// Runtime representation of a predicate
#[derive(Debug, Default, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct RuntimePredicate {
program: MemoryRange,
idx: usize,
}
impl RuntimePredicate {
/// Memory slice with the program representation of the predicate
pub const fn program(&self) -> &MemoryRange {
&self.program
}
/// Index of the transaction input that maps to this predicate
pub const fn idx(&self) -> usize {
self.idx
}
/// Create a new runtime predicate from a transaction, given the input index
///
/// Return `None` if the tx input doesn't map to an input with a predicate
pub fn from_tx<T>(tx: &T, tx_offset: usize, idx: usize) -> Option<Self>
where
T: field::Inputs,
{
let (ofs, len) = tx.inputs_predicate_offset_at(idx)?;
let addr = ofs.saturating_add(tx_offset);
let range = MemoryRange::new(addr, len).expect("Invalid memory range");
Some(Self {
program: range,
idx,
})
}
}
#[cfg(test)]
mod tests {
use alloc::{
vec,
vec::Vec,
};
use core::iter;
use fuel_asm::op;
use fuel_tx::{
field::ScriptGasLimit,
TransactionBuilder,
};
use fuel_types::bytes;
use rand::{
rngs::StdRng,
Rng,
SeedableRng,
};
use crate::{
checked_transaction::CheckPredicateParams,
error::PredicateVerificationFailed,
interpreter::InterpreterParams,
prelude::*,
storage::PredicateStorage,
};
#[test]
fn from_tx_works() {
let rng = &mut StdRng::seed_from_u64(2322u64);
let height = 1.into();
#[rustfmt::skip]
let predicate: Vec<u8> = vec![
op::addi(0x10, 0x00, 0x01),
op::addi(0x10, 0x10, 0x01),
op::ret(0x01),
].into_iter().collect();
let predicate_data = b"If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.".to_vec();
let owner = (*Contract::root_from_code(&predicate)).into();
let a = Input::coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
);
let b = Input::message_coin_predicate(
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
0,
predicate.clone(),
predicate_data.clone(),
);
let c = Input::message_data_predicate(
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
0,
vec![0xff; 10],
predicate.clone(),
predicate_data,
);
let inputs = vec![a, b, c];
for i in inputs {
let tx = TransactionBuilder::script(vec![], vec![])
.add_input(i)
.add_random_fee_input()
.finalize_checked_basic(height);
// assert invalid idx wont panic
let idx = 1;
let tx_offset = TxParameters::DEFAULT.tx_offset();
let runtime = RuntimePredicate::from_tx(tx.as_ref(), tx_offset, idx);
assert!(runtime.is_none());
// fetch the input predicate
let idx = 0;
let runtime = RuntimePredicate::from_tx(tx.as_ref(), tx_offset, idx)
.expect("failed to generate predicate from valid tx");
assert_eq!(idx, runtime.idx());
let mut interpreter = Interpreter::<_, _>::with_storage(
PredicateStorage,
InterpreterParams::default(),
);
assert!(interpreter
.init_predicate(
Context::PredicateVerification {
program: Default::default()
},
tx.transaction().clone(),
*tx.transaction().script_gas_limit()
)
.is_ok());
let pad = bytes::padded_len(&predicate) - predicate.len();
// assert we are testing an edge case
assert_ne!(0, pad);
let padded_predicate: Vec<u8> = predicate
.iter()
.copied()
.chain(iter::repeat(0u8).take(pad))
.collect();
let program = runtime.program();
let program = &interpreter.memory()[program.usizes()];
// assert the program in the vm memory is the same of the input
assert_eq!(program, &padded_predicate);
}
}
/// Verifies the runtime predicate validation rules outlined in the spec are actually
/// validated https://github.com/FuelLabs/fuel-specs/blob/master/src/fuel-vm/index.md#predicate-verification
#[test]
fn inputs_are_validated() {
let rng = &mut StdRng::seed_from_u64(2322u64);
let height = 1.into();
let predicate_data =
b"If you think it's simple, then you have misunderstood the problem."
.to_vec();
macro_rules! predicate_input {
($predicate:expr) => {{
let predicate: Vec<u8> = $predicate.into_iter().collect();
let owner = Input::predicate_owner(&predicate);
[
Input::coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
rng.gen(),
rng.gen(),
15,
predicate.clone(),
predicate_data.clone(),
),
Input::message_coin_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
15,
predicate.clone(),
predicate_data.clone(),
),
Input::message_data_predicate(
rng.gen(),
owner,
rng.gen(),
rng.gen(),
15,
vec![rng.gen(); rng.gen_range(1..100)],
predicate.clone(),
predicate_data.clone(),
),
]
}};
}
let inputs = vec![
(
// A valid predicate
predicate_input!(vec![
op::addi(0x10, 0x00, 0x01),
op::addi(0x10, 0x10, 0x01),
op::ret(0x01),
]),
Ok(()),
),
(
// A valid predicate, but gas amount mismatches
predicate_input!(vec![op::ret(0x01),]),
Err(PredicateVerificationFailed::GasMismatch),
),
(
// Returning an invalid value
predicate_input!(vec![op::ret(0x0)]),
Err(PredicateVerificationFailed::Panic(
PanicReason::PredicateReturnedNonOne,
)),
),
(
// Using a contract instruction
predicate_input!(vec![op::time(0x20, 0x1), op::ret(0x1)]),
Err(PredicateVerificationFailed::PanicInstruction(
PanicInstruction::error(
PanicReason::ContractInstructionNotAllowed,
op::time(0x20, 0x1).into(),
),
)),
),
(
// PC exceeding predicate bounds
predicate_input!(vec![op::ji(0x100), op::ret(0x1)]),
Err(PredicateVerificationFailed::Panic(
PanicReason::MemoryOverflow,
)),
),
];
for (input_group, expected) in inputs {
for input in input_group {
let tx = TransactionBuilder::script(
[op::ret(0x01)].into_iter().collect(),
vec![],
)
.add_input(input)
.gas_price(0)
.add_random_fee_input()
.finalize_checked_basic(height);
let result = Interpreter::<PredicateStorage, Script>::check_predicates(
&tx,
&CheckPredicateParams::default(),
);
assert_eq!(result.map(|_| ()), expected);
}
}
}
}