PSBT: adding global types (version, xpub)

src/util/bip32.rs

@@ -390,7 +390,7 @@ pub enum Error {
     InvalidDerivationPathFormat,
     /// Unknown version magic bytes
     UnknownVersion([u8; 4]),
-    /// Encoded extended key data have wrong length
+    /// Encoded extended key data has wrong length
     WrongExtendedKeyLength(usize),
     /// Base58 encoding error
     Base58(base58::Error)
@@ -406,7 +406,7 @@ impl fmt::Display for Error {
             Error::InvalidChildNumberFormat => f.write_str("invalid child number format"),
             Error::InvalidDerivationPathFormat => f.write_str("invalid derivation path format"),
             Error::UnknownVersion(ref bytes) => write!(f, "unknown version magic bytes: {:?}", bytes),
-            Error::WrongExtendedKeyLength(ref len) => write!(f, "encoded extended key data have wrong length {}", len),
+            Error::WrongExtendedKeyLength(ref len) => write!(f, "encoded extended key data has wrong length {}", len),
             Error::Base58(ref err) => write!(f, "base58 encoding error: {}", err),
         }
     }

src/util/psbt/map/global.rs

@@ -14,7 +14,7 @@
 
 use std::collections::BTreeMap;
 use std::collections::btree_map::Entry;
-use std::io::{self, Cursor};
+use std::io::{self, Cursor, Read};
 
 use blockdata::transaction::Transaction;
 use consensus::{encode, Encodable, Decodable};
@@ -22,6 +22,7 @@ use util::psbt::map::Map;
 use util::psbt::raw;
 use util::psbt;
 use util::psbt::Error;
+use util::bip32::{ExtendedPubKey, KeySource, Fingerprint, DerivationPath, ChildNumber};
 
 /// Type: Unsigned Transaction PSBT_GLOBAL_UNSIGNED_TX = 0x00
 const PSBT_GLOBAL_UNSIGNED_TX: u8 = 0x00;
@@ -32,10 +33,15 @@ pub struct Global {
     /// The unsigned transaction, scriptSigs and witnesses for each input must be
     /// empty.
     pub unsigned_tx: Transaction,
+    /// The version number of this PSBT. If omitted, the version number is 0.
+    pub version: u32,
+    /// A global map from extended public keys to the used key fingerprint and
+    /// derivation path as defined by BIP 32
+    pub xpub: BTreeMap<ExtendedPubKey, KeySource>,
     /// Unknown global key-value pairs.
     pub unknown: BTreeMap<raw::Key, Vec<u8>>,
 }
-serde_struct_impl!(Global, unsigned_tx, unknown);
+serde_struct_impl!(Global, unsigned_tx, version, xpub, unknown);
 
 impl Global {
     /// Create a Global from an unsigned transaction, error if not unsigned
@@ -52,6 +58,8 @@ impl Global {
 
         Ok(Global {
             unsigned_tx: tx,
+            xpub: Default::default(),
+            version: 0,
             unknown: Default::default(),
         })
     }
@@ -124,7 +132,9 @@ impl Decodable for Global {
     fn consensus_decode<D: io::Read>(mut d: D) -> Result<Self, encode::Error> {
 
         let mut tx: Option<Transaction> = None;
+        let mut version: Option<u32> = None;
         let mut unknowns: BTreeMap<raw::Key, Vec<u8>> = Default::default();
+        let mut xpub_map: BTreeMap<ExtendedPubKey, (Fingerprint, DerivationPath)> = Default::default();
 
         loop {
             match raw::Pair::consensus_decode(&mut d) {
@@ -158,6 +168,57 @@ impl Decodable for Global {
                                 return Err(Error::InvalidKey(pair.key).into())
                             }
                         }
+                        // Global Xpub
+                        0x01 => {
+                            if !pair.key.key.is_empty() {
+                                let xpub = ExtendedPubKey::decode(&pair.key.key)
+                                    .map_err(|_| {
+                                        encode::Error::ParseFailed("Can't deserialize ExtendedPublicKey from global XPUB key data")
+                                    })?;
+
+                                if pair.value.len() % 4 != 0 {
+                                    return Err(encode::Error::ParseFailed("Incorrect length of global xpub list"))
+                                }
+
+                                let keys_count = pair.value.len() / 4 - 1;
+                                let mut decoder = Cursor::new(pair.value);
+                                let mut fingerprint = [0u8; 4];
+                                decoder.read_exact(&mut fingerprint[..])?;
+                                let mut path = Vec::<ChildNumber>::with_capacity(keys_count);
+                                while let Ok(index) = u32::consensus_decode(&mut decoder) {
+                                    path.push(ChildNumber::from(index))
+                                }
+                                let derivation = DerivationPath::from(path);
+                                // Keys, according to BIP-174, must be unique
+                                if xpub_map.insert(xpub, (Fingerprint::from(&fingerprint[..]), derivation)).is_some() {
+                                    return Err(encode::Error::ParseFailed("Repeated global xpub key"))
+                                }
+                            } else {
+                                return Err(encode::Error::ParseFailed("Xpub global key must contain serialized Xpub data"))
+                            }
+                        }
+                        // Version
+                        0xFB => {
+                            // key has to be empty
+                            if pair.key.key.is_empty() {
+                                // there can only be one version
+                                if version.is_none() {
+                                    let vlen: usize = pair.value.len();
+                                    let mut decoder = Cursor::new(pair.value);
+                                    if vlen != 4 {
+                                        return Err(encode::Error::ParseFailed("Wrong global version value length (must be 4 bytes)"))
+                                    }
+                                    version = Some(Decodable::consensus_decode(&mut decoder)?);
+                                    if decoder.position() != vlen as u64 {
+                                        return Err(encode::Error::ParseFailed("data not consumed entirely when explicitly deserializing"))
+                                    }
+                                } else {
+                                    return Err(Error::DuplicateKey(pair.key).into())
+                                }
+                            } else {
+                                return Err(Error::InvalidKey(pair.key).into())
+                            }
+                        }
                         _ => match unknowns.entry(pair.key) {
                             Entry::Vacant(empty_key) => {empty_key.insert(pair.value);},
                             Entry::Occupied(k) => return Err(Error::DuplicateKey(k.key().clone()).into()),
@@ -171,6 +232,8 @@ impl Decodable for Global {
 
         if let Some(tx) = tx {
             let mut rv: Global = Global::from_unsigned_tx(tx)?;
+            rv.version = version.unwrap_or(0);
+            rv.xpub = xpub_map;
             rv.unknown = unknowns;
             Ok(rv)
         } else {

src/util/psbt/mod.rs

@@ -192,6 +192,8 @@ mod tests {
                     input: vec![],
                     output: vec![],
                 },
+                xpub: Default::default(),
+                version: 0,
                 unknown: BTreeMap::new(),
             },
             inputs: vec![],
@@ -279,6 +281,8 @@ mod tests {
                     },
                 ],
             },
+            xpub: Default::default(),
+            version: 0,
             unknown: Default::default(),
         };
 
@@ -381,6 +385,8 @@ mod tests {
                             },
                         ],
                     },
+                    xpub: Default::default(),
+                    version: 0,
                     unknown: BTreeMap::new(),
                 },
                 inputs: vec![Input {
@@ -604,6 +610,8 @@ mod tests {
                         },
                     ],
                 },
+                version: 0,
+                xpub: Default::default(),
                 unknown: BTreeMap::new(),
             },
             inputs: vec![Input {