Merge rust-bitcoin/rust-bitcoin#3015: Add Arbitrary

3e034d5ede Add Arbitrary dependency (yancy)

Pull request description:

  Adds an example draft showing what is needed to use Arbitrary for coin selection.

  Shot out to how nice Arbitrary is for fuzzing a target by taking unstructured randomness and creating structured rust-bitcoin types for fuzzing.  Is there a way we could add this to rust-bitcoin for structuring the fuzz data needed?

  This is then the example to fuzz test a SRD algo (after applying this PR to rust-bitcoin) using rust-bitcoin types :)

  ```
  #![no_main]

  use arbitrary::Arbitrary;
  use bitcoin::{Amount, FeeRate};
  use bitcoin_coin_selection::{select_coins_srd, WeightedUtxo};
  use libfuzzer_sys::fuzz_target;
  use rand::thread_rng;

  #[derive(Arbitrary, Debug)]
  pub struct Params {
      target: Amount,
      fee_rate: FeeRate,
      weighted_utxos: Vec<WeightedUtxo>,
  }

  fuzz_target!(|params: Params| {
      let Params { target: t, fee_rate: f, weighted_utxos: wu } = params;
      select_coins_srd(t, f, &wu, &mut thread_rng());
  });
  ```

ACKs for top commit:
  tcharding:
    ACK 3e034d5ede
  Kixunil:
    ACK 3e034d5ede
  apoelstra:
    ACK 3e034d5ede successfully ran local tests

Tree-SHA512: accd565815de3b37730d2ff12a24fcfc84e52ad357e5c940b1500a1e0bb17f4ff5fd6e52d31e8e96bb5290ee4fa050cfd2a9bbd6bbae13fc378f43093b64177f

Cargo-minimal.lock

@@ -8,6 +8,12 @@ version = "1.0.57"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08f9b8508dccb7687a1d6c4ce66b2b0ecef467c94667de27d8d7fe1f8d2a9cdc"
 
+[[package]]
+name = "arbitrary"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d5a26814d8dcb93b0e5a0ff3c6d80a8843bafb21b39e8e18a6f05471870e110"
+
 [[package]]
 name = "arrayvec"
 version = "0.7.4"
@@ -49,6 +55,7 @@ dependencies = [
 name = "bitcoin"
 version = "0.32.0-rc1"
 dependencies = [
+ "arbitrary",
  "base58ck",
  "base64",
  "bech32",
@@ -115,6 +122,7 @@ dependencies = [
 name = "bitcoin-units"
 version = "0.1.1"
 dependencies = [
+ "arbitrary",
  "bitcoin-internals",
  "serde",
  "serde_json",

Cargo-recent.lock

@@ -8,6 +8,12 @@ version = "1.0.71"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c7d0618f0e0b7e8ff11427422b64564d5fb0be1940354bfe2e0529b18a9d9b8"
 
+[[package]]
+name = "arbitrary"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d5a26814d8dcb93b0e5a0ff3c6d80a8843bafb21b39e8e18a6f05471870e110"
+
 [[package]]
 name = "arrayvec"
 version = "0.7.4"
@@ -48,6 +54,7 @@ dependencies = [
 name = "bitcoin"
 version = "0.32.0-rc1"
 dependencies = [
+ "arbitrary",
  "base58ck",
  "base64",
  "bech32",
@@ -114,6 +121,7 @@ dependencies = [
 name = "bitcoin-units"
 version = "0.1.1"
 dependencies = [
+ "arbitrary",
  "bitcoin-internals",
  "serde",
  "serde_json",

bitcoin/Cargo.toml

@@ -22,6 +22,7 @@ rand = ["secp256k1/rand"]
 serde = ["dep:serde", "hashes/serde", "internals/serde", "primitives/serde", "secp256k1/serde", "units/serde"]
 secp-lowmemory = ["secp256k1/lowmemory"]
 secp-recovery = ["secp256k1/recovery"]
+arbitrary = ["dep:arbitrary", "units/arbitrary"]
 
 [dependencies]
 base58 = { package = "base58ck", version = "0.1.0", default-features = false, features = ["alloc"] }
@@ -40,6 +41,7 @@ ordered = { version = "0.2.0", optional = true }
 bitcoinconsensus = { version = "0.106.0", default-features = false, optional = true }
 
 serde = { version = "1.0.103", default-features = false, features = [ "derive", "alloc" ], optional = true }
+arbitrary = { version = "1", optional = true }
 
 [dev-dependencies]
 internals = { package = "bitcoin-internals", version = "0.3.0", features = ["test-serde"] }

bitcoin/contrib/test_vars.sh

@@ -5,10 +5,10 @@
 # shellcheck disable=SC2034
 
 # Test all these features with "std" enabled.
-FEATURES_WITH_STD="rand-std serde secp-recovery bitcoinconsensus base64 ordered"
+FEATURES_WITH_STD="rand-std serde secp-recovery bitcoinconsensus base64 ordered arbitrary"
 
 # Test all these features without "std" or "alloc" enabled.
-FEATURES_WITHOUT_STD="rand serde secp-recovery bitcoinconsensus base64 ordered"
+FEATURES_WITHOUT_STD="rand serde secp-recovery bitcoinconsensus base64 ordered arbitrary"
 
 # Run these examples.
 EXAMPLES="ecdsa-psbt:std,bitcoinconsensus sign-tx-segwit-v0:rand-std sign-tx-taproot:rand-std taproot-psbt:bitcoinconsensus,rand-std sighash:std"

bitcoin/src/blockdata/script/owned.rs

@@ -11,6 +11,9 @@ use crate::opcodes::all::*;
 use crate::opcodes::{self, Opcode};
 use crate::prelude::{Box, Vec};
 
+#[cfg(feature = "arbitrary")]
+use arbitrary::{Arbitrary, Unstructured};
+
 /// An owned, growable script.
 ///
 /// `ScriptBuf` is the most common script type that has the ownership over the contents of the
@@ -155,6 +158,14 @@ crate::internal_macros::define_extension_trait! {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+impl<'a> Arbitrary<'a> for ScriptBuf {
+    fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
+        let v = Vec::<u8>::arbitrary(u)?;
+        Ok(ScriptBuf(v))
+    }
+}
+
 crate::internal_macros::define_extension_trait! {
     pub(crate) trait ScriptBufExtPriv impl for ScriptBuf {
         /// Pretends to convert `&mut ScriptBuf` to `&mut Vec<u8>` so that it can be modified.

bitcoin/src/blockdata/transaction.rs

@@ -29,6 +29,9 @@ use crate::sighash::{EcdsaSighashType, TapSighashType};
 use crate::witness::Witness;
 use crate::{Amount, FeeRate, SignedAmount, VarInt};
 
+#[cfg(feature = "arbitrary")]
+use arbitrary::{Arbitrary, Unstructured};
+
 hashes::hash_newtype! {
     /// A bitcoin transaction hash/transaction ID.
     ///
@@ -399,6 +402,16 @@ impl TxOut {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+impl<'a> Arbitrary<'a> for TxOut {
+    fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
+        Ok(TxOut {
+            value: Amount::arbitrary(u)?,
+            script_pubkey: ScriptBuf::arbitrary(u)?,
+        })
+    }
+}
+
 /// Returns the total number of bytes that this script pubkey would contribute to a transaction.
 fn size_from_script_pubkey(script_pubkey: &Script) -> usize {
     let len = script_pubkey.len();

units/Cargo.toml

@@ -21,6 +21,7 @@ alloc = ["internals/alloc"]
 internals = { package = "bitcoin-internals", version = "0.3.0" }
 
 serde = { version = "1.0.103", default-features = false, features = ["derive"], optional = true }
+arbitrary = { version = "1", optional =true }
 
 [dev-dependencies]
 internals = { package = "bitcoin-internals", version = "0.3.0", features = ["test-serde"] }

units/contrib/test_vars.sh

@@ -5,10 +5,10 @@
 # shellcheck disable=SC2034
 
 # Test all these features with "std" enabled.
-FEATURES_WITH_STD="serde"
+FEATURES_WITH_STD="serde arbitrary"
 
 # Test all these features without "std" enabled.
-FEATURES_WITHOUT_STD="alloc serde"
+FEATURES_WITHOUT_STD="alloc serde arbitrary"
 
 # Run these examples.
 EXAMPLES=""

units/src/amount.rs

@@ -16,6 +16,9 @@ use ::serde::{Deserialize, Serialize};
 use internals::error::InputString;
 use internals::write_err;
 
+#[cfg(feature = "arbitrary")]
+use arbitrary::{Arbitrary, Unstructured};
+
 /// A set of denominations in which amounts can be expressed.
 ///
 /// # Accepted Denominations
@@ -1071,6 +1074,14 @@ impl Amount {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+impl<'a> Arbitrary<'a> for Amount {
+    fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
+        let a = u64::arbitrary(u)?;
+        Ok(Amount(a))
+    }
+}
+
 impl default::Default for Amount {
     fn default() -> Self { Amount::ZERO }
 }

units/src/fee_rate.rs

@@ -11,6 +11,9 @@ use serde::{Deserialize, Serialize};
 use crate::amount::Amount;
 use crate::weight::Weight;
 
+#[cfg(feature = "arbitrary")]
+use arbitrary::{Arbitrary, Unstructured};
+
 /// Represents fee rate.
 ///
 /// This is an integer newtype representing fee rate in `sat/kwu`. It provides protection against mixing
@@ -107,6 +110,14 @@ impl FeeRate {
     }
 }
 
+#[cfg(feature = "arbitrary")]
+impl<'a> Arbitrary<'a> for FeeRate {
+    fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
+        let f = u64::arbitrary(u)?;
+        Ok(FeeRate(f))
+    }
+}
+
 /// Alternative will display the unit.
 impl fmt::Display for FeeRate {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {