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| 1 | +//! Fuzz target: randomised stream lifecycle sequences (#697). |
| 2 | +//! |
| 3 | +//! # Running |
| 4 | +//! ```bash |
| 5 | +//! cargo install cargo-fuzz |
| 6 | +//! cd contracts/fuzz |
| 7 | +//! cargo fuzz run fuzz_stream_lifecycle |
| 8 | +//! ``` |
| 9 | +//! |
| 10 | +//! # Invariants checked |
| 11 | +//! 1. `claimed_amount` never exceeds `total_amount` for any stream. |
| 12 | +//! 2. `claimable(stream_id, now)` is monotonically non-decreasing in `now` |
| 13 | +//! while the stream is not paused (vesting never runs backwards). |
| 14 | +//! 3. `claimable(stream_id, now)` never exceeds `total_amount - claimed_amount`. |
| 15 | +//! 4. A `claim` for an amount within the reported `claimable` never panics; |
| 16 | +//! a `claim` for an amount strictly greater than `claimable` always fails |
| 17 | +//! (via `try_claim`) rather than transferring more than vested. |
| 18 | +//! 5. Once `canceled`, `claimable` never increases further. |
| 19 | +//! 6. The contract never panics on well-formed inputs within the harness's |
| 20 | +//! generated bounds (arithmetic overflow, storage-key confusion, etc.). |
| 21 | +
|
| 22 | +#![no_main] |
| 23 | + |
| 24 | +extern crate std; |
| 25 | + |
| 26 | +use libfuzzer_sys::fuzz_target; |
| 27 | +use soroban_sdk::testutils::{Address as _, Ledger as _}; |
| 28 | +use soroban_sdk::{token, Address, Env}; |
| 29 | +use stellar_stream::{StellarStreamContract, StellarStreamContractClient}; |
| 30 | + |
| 31 | +/// Number of distinct streams created per fuzz run. Kept small so the |
| 32 | +/// fuzzer can exercise repeated interaction with the same stream quickly. |
| 33 | +const NUM_STREAMS: usize = 3; |
| 34 | + |
| 35 | +fn run(data: &[u8]) { |
| 36 | + if data.len() < 24 { |
| 37 | + return; |
| 38 | + } |
| 39 | + |
| 40 | + let env = Env::default(); |
| 41 | + env.mock_all_auths(); |
| 42 | + |
| 43 | + let contract_id = env.register(StellarStreamContract, ()); |
| 44 | + let client = StellarStreamContractClient::new(&env, &contract_id); |
| 45 | + |
| 46 | + let token_admin = Address::generate(&env); |
| 47 | + let token_id = env |
| 48 | + .register_stellar_asset_contract_v2(token_admin.clone()) |
| 49 | + .address(); |
| 50 | + let token_client = token::Client::new(&env, &token_id); |
| 51 | + let token_admin_client = token::StellarAssetClient::new(&env, &token_id); |
| 52 | + |
| 53 | + let sender = Address::generate(&env); |
| 54 | + let recipient = Address::generate(&env); |
| 55 | + // Mint generously so "insufficient sender balance" never masks the |
| 56 | + // invariants under test — the fuzzer targets stream-accounting bugs, |
| 57 | + // not balance-check bugs (those are covered by the unit test suite). |
| 58 | + token_admin_client.mint(&sender, &i128::MAX); |
| 59 | + |
| 60 | + let mut stream_ids: std::vec::Vec<u64> = std::vec::Vec::new(); |
| 61 | + // Shadow bookkeeping: last observed claimable() per stream, to check |
| 62 | + // monotonicity across time advances. |
| 63 | + let mut last_claimable: std::vec::Vec<i128> = std::vec::Vec::new(); |
| 64 | + let mut canceled: std::vec::Vec<bool> = std::vec::Vec::new(); |
| 65 | + |
| 66 | + let mut i = 0; |
| 67 | + while i + 12 <= data.len() && stream_ids.len() < NUM_STREAMS { |
| 68 | + let total_amount = 1 + (u32::from_le_bytes(data[i..i + 4].try_into().unwrap()) as i128 % 1_000_000); |
| 69 | + let duration = 1 + (u32::from_le_bytes(data[i + 4..i + 8].try_into().unwrap()) as u64 % 100_000); |
| 70 | + let interval = u32::from_le_bytes(data[i + 8..i + 12].try_into().unwrap()) as u64 % 1000; |
| 71 | + i += 12; |
| 72 | + |
| 73 | + let start_time = env.ledger().timestamp(); |
| 74 | + let end_time = start_time + duration; |
| 75 | + |
| 76 | + let id = client.create_stream( |
| 77 | + &sender, |
| 78 | + &recipient, |
| 79 | + &token_id, |
| 80 | + &total_amount, |
| 81 | + &start_time, |
| 82 | + &end_time, |
| 83 | + &interval, |
| 84 | + &None, |
| 85 | + ); |
| 86 | + stream_ids.push(id); |
| 87 | + last_claimable.push(0); |
| 88 | + canceled.push(false); |
| 89 | + } |
| 90 | + |
| 91 | + if stream_ids.is_empty() { |
| 92 | + return; |
| 93 | + } |
| 94 | + |
| 95 | + while i + 6 <= data.len() { |
| 96 | + let op = data[i] % 4; |
| 97 | + let stream_idx = (data[i + 1] as usize) % stream_ids.len(); |
| 98 | + let advance = u32::from_le_bytes([data[i + 2], data[i + 3], data[i + 4], data[i + 5]]) as u64 % 50_000; |
| 99 | + i += 6; |
| 100 | + |
| 101 | + let stream_id = stream_ids[stream_idx]; |
| 102 | + |
| 103 | + match op { |
| 104 | + 0 => { |
| 105 | + // ── advance ledger time ────────────────────────────────── |
| 106 | + env.ledger().with_mut(|li| { |
| 107 | + li.timestamp = li.timestamp.saturating_add(advance); |
| 108 | + }); |
| 109 | + } |
| 110 | + 1 => { |
| 111 | + // ── claimable() monotonicity + bound checks ────────────── |
| 112 | + let now = env.ledger().timestamp(); |
| 113 | + let claimable_now = client.claimable(&stream_id, &now); |
| 114 | + let stream = client.get_stream(&stream_id); |
| 115 | + |
| 116 | + assert!( |
| 117 | + stream.claimed_amount <= stream.total_amount, |
| 118 | + "claimed_amount ({}) exceeded total_amount ({}) for stream {}", |
| 119 | + stream.claimed_amount, |
| 120 | + stream.total_amount, |
| 121 | + stream_id, |
| 122 | + ); |
| 123 | + |
| 124 | + assert!( |
| 125 | + claimable_now <= stream.total_amount - stream.claimed_amount, |
| 126 | + "claimable ({claimable_now}) exceeds remaining unclaimed for stream {stream_id}", |
| 127 | + ); |
| 128 | + |
| 129 | + if !canceled[stream_idx] && !stream.paused { |
| 130 | + assert!( |
| 131 | + claimable_now >= last_claimable[stream_idx], |
| 132 | + "claimable decreased over time for stream {stream_id}: {} -> {claimable_now}", |
| 133 | + last_claimable[stream_idx], |
| 134 | + ); |
| 135 | + } |
| 136 | + last_claimable[stream_idx] = claimable_now; |
| 137 | + } |
| 138 | + 2 => { |
| 139 | + // ── claim exactly the reported claimable amount ────────── |
| 140 | + let now = env.ledger().timestamp(); |
| 141 | + let claimable_now = client.claimable(&stream_id, &now); |
| 142 | + if claimable_now <= 0 { |
| 143 | + continue; |
| 144 | + } |
| 145 | + let prev_recipient_balance = token_client.balance(&recipient); |
| 146 | + let result = client.try_claim(&stream_id, &recipient, &claimable_now); |
| 147 | + if let Ok(Ok(claimed)) = result { |
| 148 | + assert_eq!(claimed, claimable_now, "claim returned a different amount than requested"); |
| 149 | + let new_balance = token_client.balance(&recipient); |
| 150 | + assert_eq!( |
| 151 | + new_balance, |
| 152 | + prev_recipient_balance + claimable_now, |
| 153 | + "recipient balance did not increase by the claimed amount", |
| 154 | + ); |
| 155 | + } |
| 156 | + // An Err result (e.g. ClaimTooFrequent) is a valid outcome — |
| 157 | + // only invariant is that it must not panic the host and must |
| 158 | + // not transfer tokens, which the balance check above already |
| 159 | + // would have caught via prev/new mismatch had it happened. |
| 160 | + } |
| 161 | + 3 => { |
| 162 | + // ── cancel ──────────────────────────────────────────────── |
| 163 | + if !canceled[stream_idx] { |
| 164 | + client.cancel(&stream_id, &sender); |
| 165 | + canceled[stream_idx] = true; |
| 166 | + } |
| 167 | + } |
| 168 | + _ => unreachable!(), |
| 169 | + } |
| 170 | + } |
| 171 | + |
| 172 | + // ── final invariant sweep ───────────────────────────────────────────── |
| 173 | + for &stream_id in &stream_ids { |
| 174 | + let stream = client.get_stream(&stream_id); |
| 175 | + assert!( |
| 176 | + stream.claimed_amount <= stream.total_amount, |
| 177 | + "final check: claimed_amount exceeded total_amount for stream {stream_id}", |
| 178 | + ); |
| 179 | + } |
| 180 | +} |
| 181 | + |
| 182 | +fuzz_target!(|data: &[u8]| { |
| 183 | + run(data); |
| 184 | +}); |
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