Merge rust-bitcoin/rust-bitcoin#1021: Enforce segwit v0 script validity when creating address.

6c10d77 Address::from_script() - Check witness v0 program lengths. (Noah)

Pull request description:

  Adds a check in `Address::from_script()` that checks if segwit v0 scripts have a valid length.

  Fix: #995

ACKs for top commit:
  tcharding:
    ACK 6c10d77
  sanket1729:
    ACK 6c10d77. Left a comment can be addressed in separate PR.
  apoelstra:
    ACK 6c10d77

Tree-SHA512: 32aebb13477958b1455c688f668aaa3d3af4db0a7936b9549bcd1d03bd0e16635b8471549d96f1e8d408d6501e8fb515df2eb86b17a08c3152774a5be78ae8b1

Author: apoelstra

src/util/address.rs

@@ -683,6 +683,12 @@ impl Address {
 
     /// Constructs an [`Address`] from an output script (`scriptPubkey`).
     pub fn from_script(script: &script::Script, network: Network) -> Option<Address> {
+        if script.is_witness_program() {
+            if script.witness_version() == Some(WitnessVersion::V0) && !(script.is_v0_p2wpkh() || script.is_v0_p2wsh()) {
+                return None
+            }
+        }
+
         Some(Address {
             payload: Payload::from_script(script)?,
             network,
@@ -1409,4 +1415,13 @@ mod tests {
         let result = address.is_related_to_xonly_pubkey(&xonly_pubkey);
         assert!(result);
     }
+
+    #[test]
+    fn test_fail_address_from_script() {
+        let bad_p2wpkh = hex_script!("0014dbc5b0a8f9d4353b4b54c3db48846bb15abfec");
+        let bad_p2wsh = hex_script!("00202d4fa2eb233d008cc83206fa2f4f2e60199000f5b857a835e3172323385623");
+
+        assert_eq!(Address::from_script(&bad_p2wpkh, Network::Bitcoin), None);
+        assert_eq!(Address::from_script(&bad_p2wsh, Network::Bitcoin), None);
+    }
 }