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use crate::{ScriptError, ScriptGroup};
use ckb_error::Error;
use ckb_hash::new_blake2b;
use ckb_types::{
core::{cell::ResolvedTransaction, Cycle},
prelude::*,
};
// NOTE: we give this special TYPE_ID script a large cycle on purpose. This way
// we can ensure that the special built-in TYPE_ID script here only exists for
// safety, not for saving cycles. In fact if you want to optimize for the cycle
// consumptions, you should implement the TYPE_ID script as a real script, which
// will use far less cycles. This way we can ensure that we won't run into
// situations in similar chains that developers yearn for builtin contracts
// which can have far less gas/cycle consumptions than one implemented in native
// bytecode support by that chain.
pub const TYPE_ID_CYCLES: Cycle = 1_000_000;
pub const ERROR_ARGS: i8 = -1;
pub const ERROR_TOO_MANY_CELLS: i8 = -2;
pub const ERROR_INVALID_INPUT_HASH: i8 = -3;
pub struct TypeIdSystemScript<'a> {
pub rtx: &'a ResolvedTransaction,
pub script_group: &'a ScriptGroup,
pub max_cycles: Cycle,
}
impl<'a> TypeIdSystemScript<'a> {
pub fn verify(&self) -> Result<Cycle, Error> {
if self.max_cycles < TYPE_ID_CYCLES {
return Err(ScriptError::ExceededMaximumCycles.into());
}
// TYPE_ID script should only accept one argument,
// which is the hash of all inputs when creating
// the cell.
if self.script_group.script.args().len() != 32 {
return Err(ScriptError::ValidationFailure(ERROR_ARGS).into());
}
// There could be at most one input cell and one
// output cell with current TYPE_ID script.
if self.script_group.input_indices.len() > 1 || self.script_group.output_indices.len() > 1 {
return Err(ScriptError::ValidationFailure(ERROR_TOO_MANY_CELLS).into());
}
// If there's only one output cell with current
// TYPE_ID script, we are creating such a cell,
// we also need to validate that the first argument matches
// the hash of following items concatenated:
// 1. Transaction hash of the first CellInput's OutPoint
// 2. Cell index of the first CellInput's OutPoint
// 3. Index of the first output cell in current script group.
if self.script_group.input_indices.is_empty() {
let first_cell_input = self
.rtx
.transaction
.inputs()
.get(0)
.ok_or(ScriptError::ValidationFailure(ERROR_ARGS))?;
let first_output_index: u64 = self
.script_group
.output_indices
.get(0)
.map(|output_index| *output_index as u64)
.ok_or(ScriptError::ValidationFailure(ERROR_ARGS))?;
let mut blake2b = new_blake2b();
blake2b.update(first_cell_input.as_slice());
blake2b.update(&first_output_index.to_le_bytes());
let mut ret = [0; 32];
blake2b.finalize(&mut ret);
if ret[..] != self.script_group.script.args().raw_data()[..] {
return Err(ScriptError::ValidationFailure(ERROR_INVALID_INPUT_HASH).into());
}
}
Ok(TYPE_ID_CYCLES)
}
}