Set some noisy, low info logs to "debug" level

psiphon/common/tun/tun.go

@@ -740,10 +740,14 @@ func (server *Server) runClientUpstream(session *session) {
 		}
 
 		if err != nil {
+
+			// Debug since channel I/O errors occur during normal operation.
 			server.config.Logger.WithContextFields(
-				common.LogFields{"error": err}).Warning("read channel packet failed")
+				common.LogFields{"error": err}).Debug("read channel packet failed")
+
 			// Tear down the session. Must be invoked asynchronously.
 			go server.interruptSession(session)
+
 			return
 		}
 
@@ -798,8 +802,9 @@ func (server *Server) runClientDownstream(session *session) {
 		err := session.channel.WriteFramedPackets(packetBuffer)
 		if err != nil {
 
+			// Debug since channel I/O errors occur during normal operation.
 			server.config.Logger.WithContextFields(
-				common.LogFields{"error": err}).Warning("write channel packets failed")
+				common.LogFields{"error": err}).Debug("write channel packets failed")
 
 			session.downstreamPackets.Replace(packetBuffer)
 

psiphon/server/meek.go

@@ -265,7 +265,9 @@ func (server *MeekServer) ServeHTTP(responseWriter http.ResponseWriter, request
 
 	sessionID, session, err := server.getSession(request, meekCookie)
 	if err != nil {
-		log.WithContextFields(LogFields{"error": err}).Warning("session lookup failed")
+		// Debug since session cookie errors commonly occur during
+		// normal operation.
+		log.WithContextFields(LogFields{"error": err}).Debug("session lookup failed")
 		server.terminateConnection(responseWriter, request)
 		return
 	}

psiphon/server/tunnelServer.go

@@ -488,7 +488,7 @@ func (sshServer *sshServer) registerEstablishedClient(client *sshClient) bool {
 	// Call stop() outside the mutex to avoid deadlock.
 	if existingClient != nil {
 		existingClient.stop()
-		log.WithContext().Info(
+		log.WithContext().Debug(
 			"stopped existing client with duplicate session ID")
 	}
 

psiphon/server/udp.go

@@ -107,7 +107,8 @@ func (mux *udpPortForwardMultiplexer) run() {
 		message, err := readUdpgwMessage(mux.sshChannel, buffer)
 		if err != nil {
 			if err != io.EOF {
-				log.WithContextFields(LogFields{"error": err}).Warning("readUdpgwMessage failed")
+				// Debug since I/O errors occur during normal operation
+				log.WithContextFields(LogFields{"error": err}).Debug("readUdpgwMessage failed")
 			}
 			break
 		}
@@ -389,7 +390,10 @@ func readUdpgwMessage(
 
 		_, err := io.ReadFull(reader, buffer[0:2])
 		if err != nil {
-			return nil, common.ContextError(err)
+			if err != io.EOF {
+				err = common.ContextError(err)
+			}
+			return nil, err
 		}
 
 		size := binary.LittleEndian.Uint16(buffer[0:2])
@@ -400,7 +404,10 @@ func readUdpgwMessage(
 
 		_, err = io.ReadFull(reader, buffer[2:2+size])
 		if err != nil {
-			return nil, common.ContextError(err)
+			if err != io.EOF {
+				err = common.ContextError(err)
+			}
+			return nil, err
 		}
 
 		flags := buffer[2]