Add support for parsing Tapscript Miniscripts

Author: sanket1729

src/lib.rs

@@ -172,6 +172,14 @@ impl MiniscriptKey for bitcoin::PublicKey {
     }
 }
 
+impl MiniscriptKey for bitcoin::schnorr::PublicKey {
+    type Hash = hash160::Hash;
+
+    fn to_pubkeyhash(&self) -> Self::Hash {
+        hash160::Hash::hash(&self.serialize())
+    }
+}
+
 impl MiniscriptKey for String {
     type Hash = String;
 
@@ -222,6 +230,20 @@ impl ToPublicKey for bitcoin::PublicKey {
     }
 }
 
+impl ToPublicKey for bitcoin::schnorr::PublicKey {
+    fn to_public_key(&self) -> bitcoin::PublicKey {
+        // This code should never be used.
+        // But is implemented for completeness
+        let mut data: Vec<u8> = vec![0x02];
+        data.extend(self.serialize().iter());
+        bitcoin::PublicKey::from_slice(&data).expect("Cannot fail")
+    }
+
+    fn hash_to_hash160(hash: &hash160::Hash) -> hash160::Hash {
+        *hash
+    }
+}
+
 /// Dummy key which de/serializes to the empty string; useful sometimes for testing
 #[derive(Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Debug)]
 pub struct DummyKey;
@@ -468,7 +490,7 @@ pub enum Error {
     InvalidOpcode(opcodes::All),
     /// Some opcode occurred followed by `OP_VERIFY` when it had
     /// a `VERIFY` version that should have been used instead
-    NonMinimalVerify(miniscript::lex::Token),
+    NonMinimalVerify(String),
     /// Push was illegal in some context
     InvalidPush(Vec<u8>),
     /// rust-bitcoin script error
@@ -541,6 +563,8 @@ pub enum Error {
     ImpossibleSatisfaction,
     /// Bare descriptors don't have any addresses
     BareDescriptorAddr,
+    /// PubKey invalid under current context
+    PubKeyCtxError(String, String),
 }
 
 #[doc(hidden)]
@@ -604,7 +628,7 @@ impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             Error::InvalidOpcode(op) => write!(f, "invalid opcode {}", op),
-            Error::NonMinimalVerify(tok) => write!(f, "{} VERIFY", tok),
+            Error::NonMinimalVerify(ref tok) => write!(f, "{} VERIFY", tok),
             Error::InvalidPush(ref push) => write!(f, "invalid push {:?}", push), // TODO hexify this
             Error::Script(ref e) => fmt::Display::fmt(e, f),
             Error::CmsTooManyKeys(n) => write!(f, "checkmultisig with {} keys", n),
@@ -662,6 +686,9 @@ impl fmt::Display for Error {
             Error::AnalysisError(ref e) => e.fmt(f),
             Error::ImpossibleSatisfaction => write!(f, "Impossible to satisfy Miniscript"),
             Error::BareDescriptorAddr => write!(f, "Bare descriptors don't have address"),
+            Error::PubKeyCtxError(ref pk, ref ctx) => {
+                write!(f, "Pubkey error: {} under {} scriptcontext", pk, ctx)
+            }
         }
     }
 }

src/miniscript/context.rs

@@ -271,6 +271,9 @@ pub trait ScriptContext:
     fn is_tapctx() -> bool {
         return false;
     }
+
+    /// Local helper function to display error messages with context
+    fn to_string() -> String;
 }
 
 /// Legacy ScriptContext
@@ -345,6 +348,10 @@ impl ScriptContext for Legacy {
         // The scriptSig cost is the second element of the tuple
         ms.ext.max_sat_size.map(|x| x.1)
     }
+
+    fn to_string() -> String {
+        String::from("Legacy/p2sh")
+    }
 }
 
 /// Segwitv0 ScriptContext
@@ -434,6 +441,10 @@ impl ScriptContext for Segwitv0 {
         // The witness stack cost is the first element of the tuple
         ms.ext.max_sat_size.map(|x| x.0)
     }
+
+    fn to_string() -> String {
+        String::from("Segwitv0")
+    }
 }
 
 /// Tap ScriptContext
@@ -525,6 +536,10 @@ impl ScriptContext for Tap {
     fn is_tapctx() -> bool {
         true
     }
+
+    fn to_string() -> String {
+        String::from("TapscriptCtx")
+    }
 }
 
 /// Bare ScriptContext
@@ -586,6 +601,10 @@ impl ScriptContext for BareCtx {
         // The witness stack cost is the first element of the tuple
         ms.ext.max_sat_size.map(|x| x.1)
     }
+
+    fn to_string() -> String {
+        String::from("BareCtx")
+    }
 }
 
 /// "No Checks" Context
@@ -631,6 +650,11 @@ impl ScriptContext for NoChecks {
     ) -> Option<usize> {
         panic!("Tried to compute a satisfaction size bound on a no-checks miniscript")
     }
+
+    fn to_string() -> String {
+        // Internally used code
+        String::from("NochecksCtx")
+    }
 }
 
 /// Private Mod to prevent downstream from implementing this public trait