Wallet support for address creation

src/wallet/bip32.rs

@@ -123,6 +123,16 @@ impl ExtendedPrivKey {
     })
   }
 
+  /// Creates a privkey from a path
+  pub fn from_path(master: &ExtendedPrivKey, path: &[ChildNumber])
+                   -> Result<ExtendedPrivKey, Error> {
+    let mut sk = *master;
+    for &num in path.iter() {
+      sk = try!(sk.ckd_priv(num));
+    }
+    Ok(sk)
+  }
+
   /// Private->Private child key derivation
   pub fn ckd_priv(&self, i: ChildNumber) -> Result<ExtendedPrivKey, Error> {
     let mut result = [0, ..64];

src/wallet/wallet.rs

@@ -22,16 +22,31 @@ use std::io::extensions::u64_from_be_bytes;
 use collections::hash::sip::hash_with_keys;
 use serialize::{Decoder, Decodable, Encoder, Encodable};
 
+use secp256k1::key::PublicKey;
+
 use blockdata::transaction::{PayToPubkeyHash, TxOut};
 use network::constants::Network;
 use wallet::bip32::{mod, ChildNumber, ExtendedPrivKey, Normal, Hardened};
+use wallet::address::Address;
 
 /// A Wallet error
 pub enum Error {
   /// Tried to lookup an account by name, but none was found
   AccountNotFound,
   /// Tried to add an account when one already exists with that name
-  DuplicateAccount
+  DuplicateAccount,
+  /// An error occured in a BIP32 derivation
+  Bip32Error(bip32::Error)
+}
+
+/// Each account has two chains, as specified in BIP32
+pub enum AccountChain {
+  /// Internal addresses are used within the wallet for change, etc,
+  /// and in principle every generated one will be used.
+  Internal,
+  /// External addresses are shared, and might not be used after generatation,
+  /// complicating recreating the whole wallet from seed.
+  External
 }
 
 /// An account
@@ -39,7 +54,11 @@ pub enum Error {
 pub struct Account {
   name: String,
   internal_path: Vec<ChildNumber>,
-  external_path: Vec<ChildNumber>
+  internal_used: Vec<ChildNumber>,
+  internal_next: u32,
+  external_path: Vec<ChildNumber>,
+  external_used: Vec<ChildNumber>,
+  external_next: u32
 }
 
 impl Default for Account {
@@ -47,7 +66,11 @@ impl Default for Account {
     Account {
       name: String::new(),
       internal_path: vec![Hardened(0), Normal(1)],
-      external_path: vec![Hardened(0), Normal(0)]
+      internal_used: vec![],
+      internal_next: 0,
+      external_path: vec![Hardened(0), Normal(0)],
+      external_used: vec![],
+      external_next: 0
     }
   }
 }
@@ -74,6 +97,9 @@ impl<S: Encoder<E>, E> Encodable<S, E> for Wallet {
   }
 }
 
+impl Account {
+}
+
 impl<D: Decoder<E>, E> Decodable<D, E> for Wallet {
   fn decode(d: &mut D) -> Result<Wallet, E> { 
     d.read_struct("wallet", 2, |d| {
@@ -108,7 +134,7 @@ impl Wallet {
   }
 
   /// Adds an account to a wallet
-  pub fn add_account(&mut self, name: String)
+  pub fn account_insert(&mut self, name: String)
                         -> Result<(), Error> {
     if self.accounts.find(&name).is_some() {
       return Err(DuplicateAccount);
@@ -118,11 +144,69 @@ impl Wallet {
     self.accounts.insert(name.clone(), Account {
       name: name,
       internal_path: vec![Hardened(idx), Normal(1)],
-      external_path: vec![Hardened(idx), Normal(0)]
+      internal_used: vec![],
+      internal_next: 0,
+      external_path: vec![Hardened(idx), Normal(0)],
+      external_used: vec![],
+      external_next: 0
     });
     Ok(())
   }
 
+  /// Locates an account in a wallet
+  pub fn account_find<'a>(&'a self, name: &str)
+                          -> Option<&'a Account> {
+    self.accounts.find_equiv(&name)
+  }
+
+  /// Create a new address
+  pub fn new_address(&mut self,
+                     account: &str,
+                     chain: AccountChain)
+                     -> Result<Address, Error> {
+    let (k1, k2) = self.siphash_key();
+    // TODO: unnecessary allocation, waiting on *_equiv in stdlib
+    let account = self.accounts.find_mut(&account.to_string());
+    let account = match account { Some(a) => a, None => return Err(AccountNotFound) };
+
+    let (mut i, master) = match chain {
+      Internal => (account.internal_next,
+                   try!(ExtendedPrivKey::from_path(
+                          &self.master,
+                          account.internal_path.as_slice()).map_err(Bip32Error))),
+      External => (account.external_next,
+                   try!(ExtendedPrivKey::from_path(
+                          &self.master,
+                          account.external_path.as_slice()).map_err(Bip32Error))),
+    };
+
+    // Scan for next admissible address
+    let mut sk = try!(master.ckd_priv(Normal(i)).map_err(Bip32Error));
+    let mut address = Address::from_key(
+                        master.network,
+                        &PublicKey::from_secret_key(&sk.secret_key, true));
+    while !admissible_address(k1, k2, &address) {
+      i += 1;
+      sk = try!(master.ckd_priv(Normal(i)).map_err(Bip32Error));
+      address = Address::from_key(
+                  master.network,
+                  &PublicKey::from_secret_key(&sk.secret_key, true));
+    }
+
+    match chain {
+      Internal => {
+        account.internal_used.push(Normal(i));
+        account.internal_next = i + 1;
+      }
+      External => {
+        account.external_used.push(Normal(i));
+        account.external_next = i + 1;
+      }
+    }
+
+    Ok(address)
+  }
+
   /// Returns the network of the wallet
   #[inline]
   pub fn network(&self) -> Network {
@@ -142,11 +226,17 @@ impl Wallet {
   pub fn might_be_mine(&self, out: &TxOut) -> bool {
     let (k1, k2) = self.siphash_key();
     match out.classify(self.network()) {
-      PayToPubkeyHash(addr) => hash_with_keys(k1, k2, &addr.as_slice()) & 0xFF == 0,
+      PayToPubkeyHash(addr) => admissible_address(k1, k2, &addr),
       _ => false
     }
   }
 }
 
-
+/// A filter used for creating a small address index. Note that this
+/// function, `might_be_mine` and `siphash_key` are used by wizards-wallet
+/// to create a cheap UTXO index
+#[inline]
+pub fn admissible_address(k1: u64, k2: u64, addr: &Address) -> bool {
+  hash_with_keys(k1, k2, &addr.as_slice()) & 0xFF == 0
+}