1use color_eyre::Result;
  2use num_bigint::BigInt;
  3use num_traits::Zero;
  4use std::cell::Cell;
  5use wasmer::{imports, Function, Instance, Memory, MemoryType, Module, Store};
  6
  7use super::{fnv, SafeMemory, Wasm};
  8
  9#[derive(Clone, Debug)]
 10pub struct WitnessCalculator {
 11    pub instance: Wasm,
 12    pub memory: SafeMemory,
 13    pub n64: i32,
 14}
 15
 16impl WitnessCalculator {
 17    pub fn new(path: impl AsRef<std::path::Path>) -> Result<Self> {
 18        let store = Store::default();
 19        let module = Module::from_file(&store, path)?;
 20
 21        // Set up the memory
 22        let memory = Memory::new(&store, MemoryType::new(2000, None, false)).unwrap();
 23        let import_object = imports! {
 24            "env" => {
 25                "memory" => memory.clone(),
 26            },
 27            // Host function callbacks from the WASM
 28            "runtime" => {
 29                "error" => runtime::error(&store),
 30                "logSetSignal" => runtime::log_signal(&store),
 31                "logGetSignal" => runtime::log_signal(&store),
 32                "logFinishComponent" => runtime::log_component(&store),
 33                "logStartComponent" => runtime::log_component(&store),
 34                "log" => runtime::log_component(&store),
 35            }
 36        };
 37        let instance = Wasm::new(Instance::new(&module, &import_object)?);
 38
 39        let n32 = (instance.get_fr_len()? >> 2) - 2;
 40
 41        let mut memory = SafeMemory::new(memory, n32 as usize, BigInt::zero());
 42
 43        let ptr = instance.get_ptr_raw_prime()?;
 44        let prime = memory.read_big(ptr as usize, n32 as usize)?;
 45        let n64 = ((prime.bits() - 1) / 64 + 1) as i32;
 46        memory.prime = prime;
 47
 48        Ok(WitnessCalculator {
 49            instance,
 50            memory,
 51            n64,
 52        })
 53    }
 54
 55    pub fn calculate_witness<I: IntoIterator<Item = (String, Vec<BigInt>)>>(
 56        &mut self,
 57        inputs: I,
 58        sanity_check: bool,
 59    ) -> Result<Vec<BigInt>> {
 60        let old_mem_free_pos = self.memory.free_pos();
 61
 62        self.instance.init(sanity_check)?;
 63
 64        let p_sig_offset = self.memory.alloc_u32();
 65        let p_fr = self.memory.alloc_fr();
 66
 67        // allocate the inputs
 68        for (name, values) in inputs.into_iter() {
 69            let (msb, lsb) = fnv(&name);
 70            self.instance
 71                .get_signal_offset32(p_sig_offset, 0, msb, lsb)?;
 72
 73            let sig_offset = self.memory.read_u32(p_sig_offset as usize) as usize;
 74
 75            for (i, value) in values.into_iter().enumerate() {
 76                self.memory.write_fr(p_fr as usize, &value)?;
 77                self.instance
 78                    .set_signal(0, 0, (sig_offset + i) as i32, p_fr as i32)?;
 79            }
 80        }
 81
 82        let mut w = Vec::new();
 83        let n_vars = self.instance.get_n_vars()?;
 84        for i in 0..n_vars {
 85            let ptr = self.instance.get_ptr_witness(i)? as usize;
 86            let el = self.memory.read_fr(ptr)?;
 87            w.push(el);
 88        }
 89
 90        self.memory.set_free_pos(old_mem_free_pos);
 91
 92        Ok(w)
 93    }
 94
 95    pub fn get_witness_buffer(&self) -> Result<Vec<u8>> {
 96        let ptr = self.instance.get_ptr_witness_buffer()? as usize;
 97
 98        let view = self.memory.memory.view::<u8>();
 99
100        let len = self.instance.get_n_vars()? * self.n64 * 8;
101        let arr = view[ptr..ptr + len as usize]
102            .iter()
103            .map(Cell::get)
104            .collect::<Vec<_>>();
105
106        Ok(arr)
107    }
108}
109
110// callback hooks for debugging
111mod runtime {
112    use super::*;
113
114    pub fn error(store: &Store) -> Function {
115        #[allow(unused)]
116        #[allow(clippy::many_single_char_names)]
117        fn func(a: i32, b: i32, c: i32, d: i32, e: i32, f: i32) {}
118        Function::new_native(&store, func)
119    }
120
121    pub fn log_signal(store: &Store) -> Function {
122        #[allow(unused)]
123        fn func(a: i32, b: i32) {}
124        Function::new_native(&store, func)
125    }
126
127    pub fn log_component(store: &Store) -> Function {
128        #[allow(unused)]
129        fn func(a: i32) {}
130        Function::new_native(&store, func)
131    }
132}
133
134#[cfg(test)]
135mod tests {
136    use super::*;
137    use std::{collections::HashMap, path::PathBuf};
138
139    struct TestCase<'a> {
140        circuit_path: &'a str,
141        inputs_path: &'a str,
142        n_vars: u32,
143        n64: u32,
144        witness: &'a [&'a str],
145    }
146
147    pub fn root_path(p: &str) -> String {
148        let mut path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
149        path.push(p);
150        path.to_string_lossy().to_string()
151    }
152
153    #[test]
154    fn multiplier_1() {
155        run_test(TestCase {
156            circuit_path: root_path("test-vectors/mycircuit.wasm").as_str(),
157            inputs_path: root_path("test-vectors/mycircuit-input1.json").as_str(),
158            n_vars: 4,
159            n64: 4,
160            witness: &["1", "33", "3", "11"],
161        });
162    }
163
164    #[test]
165    fn multiplier_2() {
166        run_test(TestCase {
167            circuit_path: root_path("test-vectors/mycircuit.wasm").as_str(),
168            inputs_path: root_path("test-vectors/mycircuit-input2.json").as_str(),
169            n_vars: 4,
170            n64: 4,
171            witness: &[
172                "1",
173                "21888242871839275222246405745257275088548364400416034343698204186575672693159",
174                "21888242871839275222246405745257275088548364400416034343698204186575796149939",
175                "11",
176            ],
177        });
178    }
179
180    #[test]
181    fn multiplier_3() {
182        run_test(TestCase {
183            circuit_path: root_path("test-vectors/mycircuit.wasm").as_str(),
184            inputs_path: root_path("test-vectors/mycircuit-input3.json").as_str(),
185            n_vars: 4,
186            n64: 4,
187            witness: &[
188                "1",
189                "21888242871839275222246405745257275088548364400416034343698204186575808493616",
190                "10944121435919637611123202872628637544274182200208017171849102093287904246808",
191                "2",
192            ],
193        });
194    }
195
196    #[test]
197    fn safe_multipler() {
198        let witness =
199            std::fs::read_to_string(&root_path("test-vectors/safe-circuit-witness.json")).unwrap();
200        let witness: Vec<String> = serde_json::from_str(&witness).unwrap();
201        let witness = &witness.iter().map(|x| x.as_ref()).collect::<Vec<_>>();
202        run_test(TestCase {
203            circuit_path: root_path("test-vectors/circuit2.wasm").as_str(),
204            inputs_path: root_path("test-vectors/mycircuit-input1.json").as_str(),
205            n_vars: 132, // 128 + 4
206            n64: 4,
207            witness,
208        });
209    }
210
211    #[test]
212    fn smt_verifier() {
213        let witness =
214            std::fs::read_to_string(&root_path("test-vectors/smtverifier10-witness.json")).unwrap();
215        let witness: Vec<String> = serde_json::from_str(&witness).unwrap();
216        let witness = &witness.iter().map(|x| x.as_ref()).collect::<Vec<_>>();
217
218        run_test(TestCase {
219            circuit_path: root_path("test-vectors/smtverifier10.wasm").as_str(),
220            inputs_path: root_path("test-vectors/smtverifier10-input.json").as_str(),
221            n_vars: 4794,
222            n64: 4,
223            witness,
224        });
225    }
226
227    use serde_json::Value;
228    use std::str::FromStr;
229
230    fn value_to_bigint(v: Value) -> BigInt {
231        match v {
232            Value::String(inner) => BigInt::from_str(&inner).unwrap(),
233            Value::Number(inner) => BigInt::from(inner.as_u64().expect("not a u32")),
234            _ => panic!("unsupported type"),
235        }
236    }
237
238    fn run_test(case: TestCase) {
239        let mut wtns = WitnessCalculator::new(case.circuit_path).unwrap();
240        assert_eq!(
241            wtns.memory.prime.to_str_radix(16),
242            "30644E72E131A029B85045B68181585D2833E84879B9709143E1F593F0000001".to_lowercase()
243        );
244        assert_eq!(wtns.instance.get_n_vars().unwrap() as u32, case.n_vars);
245        assert_eq!(wtns.n64 as u32, case.n64);
246
247        let inputs_str = std::fs::read_to_string(case.inputs_path).unwrap();
248        let inputs: std::collections::HashMap<String, serde_json::Value> =
249            serde_json::from_str(&inputs_str).unwrap();
250
251        let inputs = inputs
252            .iter()
253            .map(|(key, value)| {
254                let res = match value {
255                    Value::String(inner) => {
256                        vec![BigInt::from_str(inner).unwrap()]
257                    }
258                    Value::Number(inner) => {
259                        vec![BigInt::from(inner.as_u64().expect("not a u32"))]
260                    }
261                    Value::Array(inner) => inner.iter().cloned().map(value_to_bigint).collect(),
262                    _ => panic!(),
263                };
264
265                (key.clone(), res)
266            })
267            .collect::<HashMap<_, _>>();
268
269        let res = wtns.calculate_witness(inputs, false).unwrap();
270        for (r, w) in res.iter().zip(case.witness) {
271            assert_eq!(r, &BigInt::from_str(w).unwrap());
272        }
273    }
274}