fix Rpc Ping sequence number (#6408)

* fix Rpc Ping sequence number

* bubble up Outbound Err's and Responses even if the peer disconnected

* send pings via Rpc from main network

* add comment to connected check

* Merge branch 'unstable' into fix-ping-seq-number

beacon_node/lighthouse_network/src/rpc/handler.rs

@@ -4,7 +4,7 @@
 use super::methods::{GoodbyeReason, RPCCodedResponse, RPCResponseErrorCode};
 use super::outbound::OutboundRequestContainer;
 use super::protocol::{InboundOutput, InboundRequest, Protocol, RPCError, RPCProtocol};
-use super::{RPCReceived, RPCResponse, RPCSend, ReqId};
+use super::{RPCReceived, RPCSend, ReqId};
 use crate::rpc::outbound::{OutboundFramed, OutboundRequest};
 use crate::rpc::protocol::InboundFramed;
 use fnv::FnvHashMap;
@@ -14,8 +14,7 @@ use libp2p::swarm::handler::{
     ConnectionEvent, ConnectionHandler, ConnectionHandlerEvent, DialUpgradeError,
     FullyNegotiatedInbound, FullyNegotiatedOutbound, StreamUpgradeError, SubstreamProtocol,
 };
-use libp2p::swarm::{ConnectionId, Stream};
-use libp2p::PeerId;
+use libp2p::swarm::Stream;
 use slog::{crit, debug, trace};
 use smallvec::SmallVec;
 use std::{
@@ -89,12 +88,6 @@ pub struct RPCHandler<Id, E>
 where
     E: EthSpec,
 {
-    /// This `ConnectionId`.
-    id: ConnectionId,
-
-    /// The matching `PeerId` of this connection.
-    peer_id: PeerId,
-
     /// The upgrade for inbound substreams.
     listen_protocol: SubstreamProtocol<RPCProtocol<E>, ()>,
 
@@ -225,16 +218,12 @@ where
     E: EthSpec,
 {
     pub fn new(
-        id: ConnectionId,
-        peer_id: PeerId,
         listen_protocol: SubstreamProtocol<RPCProtocol<E>, ()>,
         fork_context: Arc<ForkContext>,
         log: &slog::Logger,
         resp_timeout: Duration,
     ) -> Self {
         RPCHandler {
-            id,
-            peer_id,
             listen_protocol,
             events_out: SmallVec::new(),
             dial_queue: SmallVec::new(),
@@ -903,15 +892,6 @@ where
             self.shutdown(None);
         }
 
-        // If we received a Ping, we queue a Pong response.
-        if let InboundRequest::Ping(ping) = req {
-            trace!(self.log, "Received Ping, queueing Pong";"connection_id" => %self.id, "peer_id" => %self.peer_id);
-            self.send_response(
-                self.current_inbound_substream_id,
-                RPCCodedResponse::Success(RPCResponse::Pong(ping)),
-            );
-        }
-
         self.events_out.push(HandlerEvent::Ok(RPCReceived::Request(
             self.current_inbound_substream_id,
             req,