Add --rpcmaxwebsockets option with default of 25.

This commit adds a new configuration option, --rpcmaxwebsockets, to limit the
number of max RPC websocket clients that are served concurrently.

config.go

@@ -34,6 +34,7 @@ const (
 	defaultMaxPeers         = 125
 	defaultBanDuration      = time.Hour * 24
 	defaultMaxRPCClients    = 10
+	defaultMaxRPCWebsockets = 25
 	defaultVerifyEnabled    = false
 	defaultDbType           = "leveldb"
 )
@@ -73,6 +74,7 @@ type config struct {
 	RPCCert            string        `long:"rpccert" description:"File containing the certificate file"`
 	RPCKey             string        `long:"rpckey" description:"File containing the certificate key"`
 	RPCMaxClients      int           `long:"rpcmaxclients" description:"Max number of RPC clients for standard connections"`
+	RPCMaxWebsockets   int           `long:"rpcmaxwebsockets" description:"Max number of RPC websocket connections"`
 	DisableRPC         bool          `long:"norpc" description:"Disable built-in RPC server -- NOTE: The RPC server is disabled by default if no rpcuser/rpcpass is specified"`
 	DisableDNSSeed     bool          `long:"nodnsseed" description:"Disable DNS seeding for peers"`
 	ExternalIPs        []string      `long:"externalip" description:"Add an ip to the list of local addresses we claim to listen on to peers"`
@@ -285,6 +287,7 @@ func loadConfig() (*config, []string, error) {
 		MaxPeers:         defaultMaxPeers,
 		BanDuration:      defaultBanDuration,
 		RPCMaxClients:    defaultMaxRPCClients,
+		RPCMaxWebsockets: defaultMaxRPCWebsockets,
 		DataDir:          defaultDataDir,
 		LogDir:           defaultLogDir,
 		DbType:           defaultDbType,

doc.go

@@ -43,6 +43,8 @@ Application Options:
       --rpckey=            File containing the certificate key
       --rpcmaxclients=     Max number of RPC clients for standard connections
                            (10)
+      --rpcmaxwebsockets=  Max number of RPC clients for standard connections
+                           (25)
       --norpc              Disable built-in RPC server -- NOTE: The RPC server
                            is disabled by default if no rpcuser/rpcpass is
                            specified

rpcwebsocket.go

@@ -26,9 +26,6 @@ import (
 )
 
 const (
-	// TODO(davec): This should be a config option.
-	maxWebsocketClients = 10
-
 	// websocketSendBufferSize is the number of elements the send channel
 	// can queue before blocking.  Note that this only applies to requests
 	// handled directly in the websocket client input handler or the async
@@ -79,9 +76,9 @@ func (s *rpcServer) WebsocketHandler(conn *websocket.Conn, remoteAddr string,
 
 	// Limit max number of websocket clients.
 	rpcsLog.Infof("New websocket client %s", remoteAddr)
-	if s.ntfnMgr.NumClients()+1 > maxWebsocketClients {
+	if s.ntfnMgr.NumClients()+1 > cfg.RPCMaxWebsockets {
 		rpcsLog.Infof("Max websocket clients exceeded [%d] - "+
-			"disconnecting client %s", maxWebsocketClients,
+			"disconnecting client %s", cfg.RPCMaxWebsockets,
 			remoteAddr)
 		conn.Close()
 		return

sample-btcd.conf

@@ -146,6 +146,9 @@
 ; Specify the maximum number of concurrent RPC clients for standard connections.
 ; rpcmaxclients=10
 
+; Specify the maximum number of concurrent RPC websocket clients.
+; rpcmaxwebsockets=25
+
 ; Use the following setting to disable the RPC server even if the rpcuser and
 ; rpcpass are specified above.  This allows one to quickly disable the RPC
 ; server without having to remove credentials from the config file.