fix: Do not allow invalid pubsub topic subscription via relay REST api (#3559)

* Check input pubsub topics for REST /relay/v1/subscriptions endpoint

tests/wakunode_rest/test_rest_relay.nim

@@ -44,6 +44,7 @@ suite "Waku v2 Rest API - Relay":
       assert false, "Failed to mount relay"
 
     var restPort = Port(0)
+
     let restAddress = parseIpAddress("0.0.0.0")
     let restServer = WakuRestServerRef.init(restAddress, restPort).tryGet()
 
@@ -61,8 +62,23 @@ suite "Waku v2 Rest API - Relay":
 
     let shards = @[$shard0, $shard1, $shard2]
 
-    # When
+    let invalidTopic = "/test/2/this/is/a/content/topic/1"
+
+    var containsIncorrect = shards
+    containsIncorrect.add(invalidTopic)
+
+    # When contains incorrect pubsub topics, subscribe shall fail
     let client = newRestHttpClient(initTAddress(restAddress, restPort))
+    let errorResponse = await client.relayPostSubscriptionsV1(containsIncorrect)
+
+    # Then
+    check:
+      errorResponse.status == 400
+      $errorResponse.contentType == $MIMETYPE_TEXT
+      errorResponse.data ==
+        "Invalid pubsub topic(s): @[\"/test/2/this/is/a/content/topic/1\"]"
+
+    # when all pubsub topics are correct, subscribe shall succeed
     let response = await client.relayPostSubscriptionsV1(shards)
 
     # Then

waku/node/waku_node.nim

@@ -129,9 +129,10 @@ proc getShardsGetter(node: WakuNode): GetShards =
     # fetch pubsubTopics subscribed to relay and convert them to shards
     if node.wakuRelay.isNil():
       return @[]
-    let subTopics = node.wakuRelay.subscribedTopics()
-    let relayShards = topicsToRelayShards(subTopics).valueOr:
-      error "could not convert relay topics to shards", error = $error
+    let subscribedTopics = node.wakuRelay.subscribedTopics()
+    let relayShards = topicsToRelayShards(subscribedTopics).valueOr:
+      error "could not convert relay topics to shards",
+        error = $error, topics = subscribedTopics
       return @[]
     if relayShards.isSome():
       let shards = relayShards.get().shardIds

waku/waku_api/rest/relay/handlers.nim

@@ -41,6 +41,15 @@ const ROUTE_RELAY_AUTO_SUBSCRIPTIONSV1* = "/relay/v1/auto/subscriptions"
 const ROUTE_RELAY_AUTO_MESSAGESV1* = "/relay/v1/auto/messages/{contentTopic}"
 const ROUTE_RELAY_AUTO_MESSAGESV1_NO_TOPIC* = "/relay/v1/auto/messages"
 
+proc validatePubSubTopics(topics: seq[PubsubTopic]): Result[void, RestApiResponse] =
+  let badPubSubTopics = topics.filterIt(RelayShard.parseStaticSharding(it).isErr())
+  if badPubSubTopics.len > 0:
+    error "Invalid pubsub topic(s)", PubSubTopics = $badPubSubTopics
+    return
+      err(RestApiResponse.badRequest("Invalid pubsub topic(s): " & $badPubSubTopics))
+
+  return ok()
+
 proc installRelayApiHandlers*(
     router: var RestRouter, node: WakuNode, cache: MessageCache
 ) =
@@ -61,6 +70,9 @@ proc installRelayApiHandlers*(
     let req: seq[PubsubTopic] = decodeRequestBody[seq[PubsubTopic]](contentBody).valueOr:
       return error
 
+    validatePubSubTopics(req).isOkOr:
+      return error
+
     # Only subscribe to topics for which we have no subscribed topic handlers yet
     let newTopics = req.filterIt(not cache.isPubsubSubscribed(it))
 
@@ -87,6 +99,9 @@ proc installRelayApiHandlers*(
     let req: seq[PubsubTopic] = decodeRequestBody[seq[PubsubTopic]](contentBody).valueOr:
       return error
 
+    validatePubSubTopics(req).isOkOr:
+      return error
+
     # Unsubscribe all handlers from requested topics
     for pubsubTopic in req:
       cache.pubsubUnsubscribe(pubsubTopic)