fix(rln-relay): handle empty metadata returned by getMetadata proc (#2516)

* fix(rln-relay): silence error on startup when metadata is not found

* chore: fix fetching value from option

* fix: clarity of returned opt

Makefile

@@ -137,7 +137,7 @@ LIBRLN_BUILDDIR := $(CURDIR)/vendor/zerokit
 ifeq ($(RLN_V2),true)
 LIBRLN_VERSION := v0.4.1
 else
-LIBRLN_VERSION := v0.3.4
+LIBRLN_VERSION := v0.3.6
 endif
 
 ifeq ($(OS),Windows_NT)

tests/waku_rln_relay/test_rln_group_manager_onchain.nim

@@ -226,12 +226,13 @@ suite "Onchain group manager":
 
     let metadataSetRes = manager.setMetadata()
     assert metadataSetRes.isOk(), metadataSetRes.error
-    let metadataRes = manager.rlnInstance.getMetadata()
-    assert metadataRes.isOk(), metadataRes.error
-    let metadata = metadataRes.get()
-    require:
-      metadata.chainId == 1337
-      metadata.contractAddress == manager.ethContractAddress
+    let metadataOpt = manager.rlnInstance.getMetadata().valueOr:
+      raiseAssert $error
+    assert metadataOpt.isSome(), "metadata is not set"
+    let metadata = metadataOpt.get()
+    
+    assert metadata.chainId == 1337, "chainId is not equal to 1337"
+    assert metadata.contractAddress == manager.ethContractAddress, "contractAddress is not equal to " & manager.ethContractAddress
     
     await manager.stop()
 
@@ -458,8 +459,11 @@ suite "Onchain group manager":
 
     await fut
 
+    let metadataOpt = manager.rlnInstance.getMetadata().valueOr:
+      raiseAssert $error
+    assert metadataOpt.isSome(), "metadata is not set"
     check:
-      manager.rlnInstance.getMetadata().get().validRoots == manager.validRoots.toSeq()
+      metadataOpt.get().validRoots == manager.validRoots.toSeq()
     await manager.stop()
 
   asyncTest "withdraw: should guard against uninitialized state":

tests/waku_rln_relay/test_waku_rln_relay.nim

@@ -260,18 +260,26 @@ suite "Waku rln relay":
                                   chainId: 1155511,
                                   contractAddress: "0x9c09146844c1326c2dbc41c451766c7138f88155")).isOk()
 
-    let metadataRes = rln.getMetadata()
-
-    require:
-      metadataRes.isOk()
-
-    let metadata = metadataRes.get()
+    let metadataOpt = rln.getMetadata().valueOr:
+      raiseAssert $error
 
+    assert metadataOpt.isSome(), "metadata is not set"
+    let metadata = metadataOpt.get()
     check:
       metadata.lastProcessedBlock == 128
       metadata.chainId == 1155511
       metadata.contractAddress == "0x9c09146844c1326c2dbc41c451766c7138f88155"
 
+  test "getMetadata: empty rln metadata":
+    # create an RLN instance which also includes an empty Merkle tree
+    let rln = createRLNInstanceWrapper().valueOr:
+      raiseAssert $error
+    let metadata = rln.getMetadata().valueOr:
+      raiseAssert $error
+
+    check:
+      metadata.isNone()
+
   test "Merkle tree consistency check between deletion and insertion":
     # create an RLN instance
     let rlnInstance = createRLNInstanceWrapper()

tools/rln_db_inspector/rln_db_inspector.nim

@@ -27,10 +27,15 @@ proc doInspectRlnDb*(conf: WakuNodeConf) =
     quit(1)
 
   # 3. get metadata
-  let metadata = rlnInstance.getMetadata().valueOr:
+  let metadataOpt = rlnInstance.getMetadata().valueOr:
     error "failure while getting RLN metadata", error
     quit(1)
   
+  if metadataOpt.isNone():
+    error "RLN metadata does not exist"
+    quit(1)
+  let metadata = metadataOpt.get()
+
   info "RLN metadata", lastProcessedBlock = metadata.lastProcessedBlock, 
                        chainId = metadata.chainId,
                        contractAddress = metadata.contractAddress,

vendor/zerokit

@@ -1 +1 @@
-Subproject commit b903d8d740e0b8b82057bcc5377ddce05ae5676b
+Subproject commit 7dd019b0a5716e52169f396cecce961021fcac51

waku/waku_rln_relay/group_manager/on_chain/group_manager.nim

@@ -666,11 +666,11 @@ method init*(g: OnchainGroupManager): Future[void] {.async.} =
 
     g.idCredentials = some(keystoreCred.identityCredential)
 
-  let metadataGetRes = g.rlnInstance.getMetadata()
-  if metadataGetRes.isErr():
+  let metadataGetOptRes = g.rlnInstance.getMetadata()
+  if metadataGetOptRes.isErr():
     warn "could not initialize with persisted rln metadata"
-  else:
-    let metadata = metadataGetRes.get()
+  elif metadataGetOptRes.get().isSome():
+    let metadata = metadataGetOptRes.get().get()
     if metadata.chainId != uint64(g.chainId.get()):
       raise newException(ValueError, "persisted data: chain id mismatch")
 

waku/waku_rln_relay/rln/wrappers.nim

@@ -500,7 +500,7 @@ proc setMetadata*(rlnInstance: ptr RLN, metadata: RlnMetadata): RlnRelayResult[v
     return err("could not set the metadata")
   return ok()
 
-proc getMetadata*(rlnInstance: ptr RLN): RlnRelayResult[RlnMetadata] =
+proc getMetadata*(rlnInstance: ptr RLN): RlnRelayResult[Option[RlnMetadata]] =
   ## gets the metadata of the RLN instance
   ## returns an error if the metadata could not be retrieved
   ## returns the metadata if the metadata is retrieved successfully
@@ -514,6 +514,9 @@ proc getMetadata*(rlnInstance: ptr RLN): RlnRelayResult[RlnMetadata] =
     return err("could not get the metadata")
   trace "metadata length", metadataLen = metadata.len
 
+  if metadata.len == 0:
+    return ok(none(RlnMetadata))
+
   let 
     lastProcessedBlockOffset = 0
     chainIdOffset = lastProcessedBlockOffset + 8
@@ -536,7 +539,7 @@ proc getMetadata*(rlnInstance: ptr RLN): RlnRelayResult[RlnMetadata] =
   let validRootsBytes = metadataBytes[validRootsOffset..metadataBytes.high]
   validRoots = MerkleNodeSeq.deserialize(validRootsBytes)
 
-  return ok(RlnMetadata(lastProcessedBlock: lastProcessedBlock,
+  return ok(some(RlnMetadata(lastProcessedBlock: lastProcessedBlock,
                              chainId: chainId,
                              contractAddress: "0x" & contractAddress,
-                        validRoots: validRoots))
+                             validRoots: validRoots)))