From d1487b31770fdd511bb5d9a539f014ff41d8ea85 Mon Sep 17 00:00:00 2001
From: Wei Tang <accounts@that.world>
Date: Tue, 10 Apr 2018 16:36:14 +0800
Subject: [PATCH] rpc, eth_filter: return error if the filter id does not exist
 (#8341)

---
 rpc/src/v1/helpers/errors.rs   | 8 ++++++++
 rpc/src/v1/impls/eth_filter.rs | 7 ++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/rpc/src/v1/helpers/errors.rs b/rpc/src/v1/helpers/errors.rs
index e86ab630f..6e8836c20 100644
--- a/rpc/src/v1/helpers/errors.rs
+++ b/rpc/src/v1/helpers/errors.rs
@@ -399,6 +399,14 @@ pub fn deprecated<T: Into<Option<String>>>(message: T) -> Error {
 	}
 }
 
+pub fn filter_not_found() -> Error {
+	Error {
+		code: ErrorCode::ServerError(codes::UNSUPPORTED_REQUEST),
+		message: "Filter not found".into(),
+		data: None,
+	}
+}
+
 // on-demand sender cancelled.
 pub fn on_demand_cancel(_cancel: futures::sync::oneshot::Canceled) -> Error {
 	internal("on-demand sender cancelled", "")
diff --git a/rpc/src/v1/impls/eth_filter.rs b/rpc/src/v1/impls/eth_filter.rs
index 6c3d6837e..9e2f2f888 100644
--- a/rpc/src/v1/impls/eth_filter.rs
+++ b/rpc/src/v1/impls/eth_filter.rs
@@ -30,7 +30,7 @@ use jsonrpc_core::futures::{future, Future};
 use jsonrpc_core::futures::future::Either;
 use v1::traits::EthFilter;
 use v1::types::{BlockNumber, Index, Filter, FilterChanges, Log, H256 as RpcH256, U256 as RpcU256};
-use v1::helpers::{PollFilter, PollManager, limit_logs};
+use v1::helpers::{errors, PollFilter, PollManager, limit_logs};
 use v1::impls::eth::pending_logs;
 
 /// Something which provides data that can be filtered over.
@@ -127,7 +127,7 @@ impl<T: Filterable + Send + Sync + 'static> EthFilter for T {
 	fn filter_changes(&self, index: Index) -> BoxFuture<FilterChanges> {
 		let mut polls = self.polls().lock();
 		Box::new(match polls.poll_mut(&index.value()) {
-			None => Either::A(future::ok(FilterChanges::Empty)),
+			None => Either::A(future::err(errors::filter_not_found())),
 			Some(filter) => match *filter {
 				PollFilter::Block(ref mut block_number) => {
 					// +1, cause we want to return hashes including current block hash.
@@ -217,7 +217,8 @@ impl<T: Filterable + Send + Sync + 'static> EthFilter for T {
 			match polls.poll(&index.value()) {
 				Some(&PollFilter::Logs(ref _block_number, ref _previous_log, ref filter)) => filter.clone(),
 				// just empty array
-				_ => return Box::new(future::ok(Vec::new())),
+				Some(_) => return Box::new(future::ok(Vec::new())),
+				None => return Box::new(future::err(errors::filter_not_found())),
 			}
 		};