1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

use crate::evm_circuit::{
    execution::ExecutionGadget,
    step::ExecutionState,
    table::{FixedTableTag, Lookup},
    util::{
        common_gadget::CommonErrorGadget, constraint_builder::EVMConstraintBuilder, CachedRegion,
        Cell,
    },
    witness::{Block, Call, Chunk, ExecStep, Transaction},
};
use eth_types::Field;
use gadgets::util::Expr;
use halo2_proofs::{circuit::Value, plonk::Error};

/// Gadget for invalid opcodes. It verifies by a fixed lookup for
/// ResponsibleOpcode.
#[derive(Clone, Debug)]
pub(crate) struct ErrorInvalidOpcodeGadget<F> {
    opcode: Cell<F>,
    common_error_gadget: CommonErrorGadget<F>,
}

impl<F: Field> ExecutionGadget<F> for ErrorInvalidOpcodeGadget<F> {
    const NAME: &'static str = "ErrorInvalidOpcode";

    const EXECUTION_STATE: ExecutionState = ExecutionState::ErrorInvalidOpcode;

    fn configure(cb: &mut EVMConstraintBuilder<F>) -> Self {
        let opcode = cb.query_cell();
        cb.add_lookup(
            "Responsible opcode lookup",
            Lookup::Fixed {
                tag: FixedTableTag::ResponsibleOpcode.expr(),
                values: [
                    Self::EXECUTION_STATE.as_u64().expr(),
                    opcode.expr(),
                    0.expr(),
                ],
            },
        );

        let common_error_gadget = CommonErrorGadget::construct(cb, opcode.expr(), 0.expr());

        Self {
            opcode,
            common_error_gadget,
        }
    }

    fn assign_exec_step(
        &self,
        region: &mut CachedRegion<'_, '_, F>,
        offset: usize,
        block: &Block<F>,
        _chunk: &Chunk<F>,
        _: &Transaction,
        call: &Call,
        step: &ExecStep,
    ) -> Result<(), Error> {
        let opcode = F::from(step.opcode().unwrap().as_u64());
        self.opcode.assign(region, offset, Value::known(opcode))?;

        self.common_error_gadget
            .assign(region, offset, block, call, step, 2)?;
        Ok(())
    }
}

#[cfg(test)]
mod test {
    use crate::{evm_circuit::test::rand_bytes, test_util::CircuitTestBuilder};
    use eth_types::{bytecode::Bytecode, Word};
    use lazy_static::lazy_static;
    use mock::{generate_mock_call_bytecode, MockCallBytecodeParams, TestContext};

    lazy_static! {
        static ref TESTING_INVALID_CODES: [Vec<u8>; 6] = [
            // Single invalid opcode
            vec![0x0e],
            vec![0x4f],
            vec![0xa5],
            vec![0xf6],
            vec![0xfe],
            // Multiple invalid opcodes
            vec![0x5c, 0x5e],
        ];
    }

    #[test]
    fn invalid_opcode_root() {
        for invalid_code in TESTING_INVALID_CODES.iter() {
            test_root_ok(invalid_code);
        }
    }

    #[test]
    fn invalid_opcode_internal() {
        for invalid_code in TESTING_INVALID_CODES.iter() {
            test_internal_ok(0x20, 0x00, invalid_code);
        }
    }

    fn test_root_ok(invalid_code: &[u8]) {
        let mut code = Bytecode::default();
        invalid_code.iter().for_each(|b| {
            code.write(*b, true);
        });

        CircuitTestBuilder::new_from_test_ctx(
            TestContext::<2, 1>::simple_ctx_with_bytecode(code).unwrap(),
        )
        .run();
    }

    fn test_internal_ok(call_data_offset: usize, call_data_length: usize, invalid_code: &[u8]) {
        let (addr_a, addr_b) = (mock::MOCK_ACCOUNTS[0], mock::MOCK_ACCOUNTS[1]);

        // Code B gets called by code A, so the call is an internal call.
        let mut code_b = Bytecode::default();
        invalid_code.iter().for_each(|b| {
            code_b.write(*b, true);
        });

        // code A calls code B.
        let code_a = generate_mock_call_bytecode(MockCallBytecodeParams {
            address: addr_b,
            pushdata: rand_bytes(32),
            call_data_length,
            call_data_offset,
            ..MockCallBytecodeParams::default()
        });

        let ctx = TestContext::<3, 1>::new(
            None,
            |accs| {
                accs[0].address(addr_b).code(code_b);
                accs[1].address(addr_a).code(code_a);
                accs[2]
                    .address(mock::MOCK_ACCOUNTS[3])
                    .balance(Word::from(1_u64 << 20));
            },
            |mut txs, accs| {
                txs[0].to(accs[1].address).from(accs[2].address);
            },
            |block, _tx| block,
        )
        .unwrap();

        CircuitTestBuilder::new_from_test_ctx(ctx).run();
    }
}