terra/token_bridge: allow newer sequenced vaa metadata

Change-Id: Ie81584abe6671595118082796df57bcea75a8fd3

terra/contracts/token-bridge/src/contract.rs

@@ -41,6 +41,8 @@ use crate::{
         wrapped_asset_address,
         wrapped_asset_address_read,
         wrapped_asset_read,
+        wrapped_asset_seq,
+        wrapped_asset_seq_read,
         Action,
         AssetMeta,
         ConfigInfo,
@@ -273,6 +275,7 @@ fn handle_attest_meta(
     env: Env,
     emitter_chain: u16,
     emitter_address: Vec<u8>,
+    sequence: u64,
     data: &Vec<u8>,
 ) -> StdResult<Response> {
     let meta = AssetMeta::deserialize(data)?;
@@ -294,16 +297,26 @@ fn handle_attest_meta(
     let cfg = config_read(deps.storage).load()?;
     let asset_id = build_asset_id(meta.token_chain, &meta.token_address.as_slice());
 
-    if wrapped_asset_read(deps.storage).load(&asset_id).is_ok() {
-        return Err(StdError::generic_err(
-            "this asset has already been attested",
-        ));
-    }
-
-    wrapped_asset(deps.storage).save(&asset_id, &HumanAddr::from(WRAPPED_ASSET_UPDATING))?;
-
-    Ok(
-        Response::new().add_message(CosmosMsg::Wasm(WasmMsg::Instantiate {
+    // If a CW20 wrapped already exists and this message has a newer sequence ID
+    // we allow updating the metadata. If not, we create a brand new token.
+    let message = if let Ok(contract) = wrapped_asset_read(deps.storage).load(&asset_id) {
+        // Prevent anyone from re-attesting with old VAAs.
+        if sequence <= wrapped_asset_seq_read(deps.storage).load(&asset_id)? {
+            return Err(StdError::generic_err(
+                "this asset has already been attested",
+            ));
+        }
+        CosmosMsg::Wasm(WasmMsg::Execute {
+            contract_addr: contract,
+            msg: to_binary(&WrappedMsg::UpdateMetadata {
+                name: get_string_from_32(&meta.name)?,
+                symbol: get_string_from_32(&meta.symbol)?,
+            })?,
+            funds: vec![],
+        })
+    } else {
+        wrapped_asset(deps.storage).save(&asset_id, &HumanAddr::from(WRAPPED_ASSET_UPDATING))?;
+        CosmosMsg::Wasm(WasmMsg::Instantiate {
             admin: Some(env.contract.address.to_string()),
             code_id: cfg.wrapped_asset_code_id,
             msg: to_binary(&WrappedInit {
@@ -322,8 +335,10 @@ fn handle_attest_meta(
             })?,
             funds: vec![],
             label: String::new(),
-        })),
-    )
+        })
+    };
+    wrapped_asset_seq(deps.storage).save(&asset_id, &sequence)?;
+    Ok(Response::new().add_message(message))
 }
 
 fn handle_create_asset_meta(
@@ -465,6 +480,7 @@ fn submit_vaa(
             env,
             vaa.emitter_chain,
             vaa.emitter_address,
+            vaa.sequence,
             &message.payload,
         ),
         _ => ContractError::InvalidVAAAction.std_err(),

terra/contracts/token-bridge/src/state.rs

@@ -28,6 +28,7 @@ type HumanAddr = String;
 
 pub static CONFIG_KEY: &[u8] = b"config";
 pub static WRAPPED_ASSET_KEY: &[u8] = b"wrapped_asset";
+pub static WRAPPED_ASSET_SEQ_KEY: &[u8] = b"wrapped_seq_asset";
 pub static WRAPPED_ASSET_ADDRESS_KEY: &[u8] = b"wrapped_asset_address";
 pub static BRIDGE_CONTRACTS: &[u8] = b"bridge_contracts";
 pub static BRIDGE_DEPOSITS: &[u8] = b"bridge_deposits";
@@ -76,6 +77,14 @@ pub fn wrapped_asset_read(storage: &dyn Storage) -> ReadonlyBucket<HumanAddr> {
     bucket_read(storage, WRAPPED_ASSET_KEY)
 }
 
+pub fn wrapped_asset_seq(storage: &mut dyn Storage) -> Bucket<u64> {
+    bucket(storage, WRAPPED_ASSET_SEQ_KEY)
+}
+
+pub fn wrapped_asset_seq_read(storage: &mut dyn Storage) -> ReadonlyBucket<u64> {
+    bucket_read(storage, WRAPPED_ASSET_SEQ_KEY)
+}
+
 pub fn wrapped_asset_address(storage: &mut dyn Storage) -> Bucket<Vec<u8>> {
     bucket(storage, WRAPPED_ASSET_ADDRESS_KEY)
 }