add a database migration for new accountdb

ethcore/src/migrations/extras/mod.rs

@@ -2,4 +2,4 @@
 
 mod v6;
 
-pub use self::v6::ToV6;
+pub use self::v6::ToV6;

ethcore/src/migrations/mod.rs

@@ -1,3 +1,4 @@
 //! Database migrations.
 
 pub mod extras;
+pub mod state;

ethcore/src/migrations/state/mod.rs

@@ -0,0 +1,5 @@
+//! State database migrations.
+
+mod v7;
+
+pub use self::v7::ToV7;

ethcore/src/migrations/state/v7.rs

@@ -0,0 +1,31 @@
+use util::hash::{FixedHash, H256};
+use util::migration::Migration;
+use util::sha3::Hashable;
+
+/// This migration migrates the state db to use an accountdb which ensures uniqueness
+/// using an address' hash as opposed to the address itself.
+pub struct ToV7;
+
+impl Migration for ToV7 {
+	fn version(&self) -> u32 {
+		7
+	}
+
+	fn simple_migrate(&self, mut key: Vec<u8>, value: Vec<u8>) -> Option<(Vec<u8>, Vec<u8>)> {
+		let val_hash = value.sha3();
+		assert!(key.len() == 32); // all keys in the state db are hashes.
+		let key_h = H256::from_slice(&key[..]);
+		if key_h != val_hash {
+			// this is a key which has been xor'd with an address.
+			// recover the address
+			let address = key_h ^ val_hash;
+			let address_hash = address.sha3();
+
+			let new_key = address_hash ^ val_hash;
+			key.copy_from_slice(&new_key[..]);
+		}
+		// nothing to do here
+		Some((key, value))
+	}
+}
+