Add a websocket session RPC.

btcjson/chainsvrwscmds.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2014 The btcsuite developers
+// Copyright (c) 2014-2015 The btcsuite developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -56,6 +56,15 @@ func NewNotifyNewTransactionsCmd(verbose *bool) *NotifyNewTransactionsCmd {
 	}
 }
 
+// SessionCmd defines the session JSON-RPC command.
+type SessionCmd struct{}
+
+// NewSessionCmd returns a new instance which can be used to issue a session
+// JSON-RPC command.
+func NewSessionCmd() *SessionCmd {
+	return &SessionCmd{}
+}
+
 // StopNotifyNewTransactionsCmd defines the stopnotifynewtransactions JSON-RPC command.
 type StopNotifyNewTransactionsCmd struct{}
 
@@ -158,6 +167,7 @@ func init() {
 	MustRegisterCmd("notifynewtransactions", (*NotifyNewTransactionsCmd)(nil), flags)
 	MustRegisterCmd("notifyreceived", (*NotifyReceivedCmd)(nil), flags)
 	MustRegisterCmd("notifyspent", (*NotifySpentCmd)(nil), flags)
+	MustRegisterCmd("session", (*SessionCmd)(nil), flags)
 	MustRegisterCmd("stopnotifyblocks", (*StopNotifyBlocksCmd)(nil), flags)
 	MustRegisterCmd("stopnotifynewtransactions", (*StopNotifyNewTransactionsCmd)(nil), flags)
 	MustRegisterCmd("stopnotifyspent", (*StopNotifySpentCmd)(nil), flags)

btcjson/chainsvrwsresults.go

@@ -0,0 +1,10 @@
+// Copyright (c) 2015 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package btcjson
+
+// SessionResult models the data from the session command.
+type SessionResult struct {
+	SessionID uint64 `json:"sessionid"`
+}

docs/json_rpc_api.md

@@ -685,6 +685,7 @@ user.  Click the method name for further details such as parameter and return in
 |8|[rescan](#rescan)|Rescan block chain for transactions to addresses and spent transaction outpoints.|[recvtx](#recvtx), [redeemingtx](#redeemingtx), [rescanprogress](#rescanprogress), and [rescanfinished](#rescanfinished) |
 |9|[notifynewtransactions](#notifynewtransactions)|Send notifications for all new transactions as they are accepted into the mempool.|[txaccepted](#txaccepted) or [txacceptedverbose](#txacceptedverbose)|
 |10|[stopnotifynewtransactions](#stopnotifynewtransactions)|Stop sending either a txaccepted or a txacceptedverbose notification when a new transaction is accepted into the mempool.|None|
+|11|[session](#session)|Return details regarding a websocket client's current connection.|None|
 
 <a name="WSExtMethodDetails" />
 **7.2 Method Details**<br />
@@ -815,6 +816,20 @@ user.  Click the method name for further details such as parameter and return in
 |Returns|Nothing|
 [Return to Overview](#WSExtMethodOverview)<br />
 
+***
+
+<a name="session"/>
+
+|   |   |
+|---|---|
+|Method|session|
+|Notifications|None|
+|Parameters|None|
+|Description|Return a JSON object with details regarding a websocket client's current connection to the RPC server.  This currently only includes the session ID, a random unsigned 64-bit integer that is created for each newly connected client.  Session IDs may be used to verify that the current connection was not lost and subsequently reestablished.|
+|Returns|`{ (json object)`<br />&nbsp;&nbsp;`"sessionid": n  (numeric) the session ID`<br />`}`|
+|Example Return|`{`<br />&nbsp;&nbsp;`"sessionid": 67089679842`<br />`}`|
+[Return to Overview](#WSExtMethodOverview)<br />
+
 
 <a name="Notifications" />
 ### 8. Notifications (Websocket-specific)

rpcserverhelp.go

@@ -525,6 +525,10 @@ var helpDescsEnUS = map[string]string{
 
 	// -------- Websocket-specific help --------
 
+	// Session help.
+	"session--synopsis":       "Return details regarding a websocket client's current connection session.",
+	"sessionresult-sessionid": "The unique session ID for a client's websocket connection.",
+
 	// NotifyBlocksCmd help.
 	"notifyblocks--synopsis": "Request notifications for whenever a block is connected or disconnected from the main (best) chain.",
 
@@ -616,6 +620,7 @@ var rpcResultTypes = map[string][]interface{}{
 	"verifymessage":         []interface{}{(*bool)(nil)},
 
 	// Websocket commands.
+	"session":                   []interface{}{(*btcjson.SessionResult)(nil)},
 	"notifyblocks":              nil,
 	"stopnotifyblocks":          nil,
 	"notifynewtransactions":     nil,

rpcwebsocket.go

@@ -54,6 +54,7 @@ var wsHandlersBeforeInit = map[string]wsCommandHandler{
 	"notifynewtransactions":     handleNotifyNewTransactions,
 	"notifyreceived":            handleNotifyReceived,
 	"notifyspent":               handleNotifySpent,
+	"session":                   handleSession,
 	"stopnotifyblocks":          handleStopNotifyBlocks,
 	"stopnotifynewtransactions": handleStopNotifyNewTransactions,
 	"stopnotifyspent":           handleStopNotifySpent,
@@ -94,7 +95,12 @@ func (s *rpcServer) WebsocketHandler(conn *websocket.Conn, remoteAddr string,
 	// Create a new websocket client to handle the new websocket connection
 	// and wait for it to shutdown.  Once it has shutdown (and hence
 	// disconnected), remove it and any notifications it registered for.
-	client := newWebsocketClient(s, conn, remoteAddr, authenticated, isAdmin)
+	client, err := newWebsocketClient(s, conn, remoteAddr, authenticated, isAdmin)
+	if err != nil {
+		rpcsLog.Errorf("Failed to serve client %s: %v", remoteAddr, err)
+		conn.Close()
+		return
+	}
 	s.ntfnMgr.AddClient(client)
 	client.Start()
 	client.WaitForShutdown()
@@ -869,6 +875,11 @@ type wsClient struct {
 	// false means its access is only to the limited set of RPC calls.
 	isAdmin bool
 
+	// sessionID is a random ID generated for each client when connected.
+	// These IDs may be queried by a client using the session RPC.  A change
+	// to the session ID indicates that the client reconnected.
+	sessionID uint64
+
 	// verboseTxUpdates specifies whether a client has requested verbose
 	// information about all new transactions.
 	verboseTxUpdates bool
@@ -1383,13 +1394,19 @@ func (c *wsClient) WaitForShutdown() {
 // incoming and outgoing messages in separate goroutines complete with queueing
 // and asynchrous handling for long-running operations.
 func newWebsocketClient(server *rpcServer, conn *websocket.Conn,
-	remoteAddr string, authenticated bool, isAdmin bool) *wsClient {
+	remoteAddr string, authenticated bool, isAdmin bool) (*wsClient, error) {
 
-	return &wsClient{
+	sessionID, err := wire.RandomUint64()
+	if err != nil {
+		return nil, err
+	}
+
+	client := &wsClient{
 		conn:          conn,
 		addr:          remoteAddr,
 		authenticated: authenticated,
 		isAdmin:       isAdmin,
+		sessionID:     sessionID,
 		server:        server,
 		addrRequests:  make(map[string]struct{}),
 		spentRequests: make(map[wire.OutPoint]struct{}),
@@ -1398,6 +1415,7 @@ func newWebsocketClient(server *rpcServer, conn *websocket.Conn,
 		sendChan:      make(chan wsResponse, websocketSendBufferSize),
 		quit:          make(chan struct{}),
 	}
+	return client, nil
 }
 
 // handleWebsocketHelp implements the help command for websocket connections.
@@ -1454,6 +1472,12 @@ func handleNotifyBlocks(wsc *wsClient, icmd interface{}) (interface{}, error) {
 	return nil, nil
 }
 
+// handleSession implements the session command extension for websocket
+// connections.
+func handleSession(wsc *wsClient, icmd interface{}) (interface{}, error) {
+	return &btcjson.SessionResult{SessionID: wsc.sessionID}, nil
+}
+
 // handleStopNotifyBlocks implements the stopnotifyblocks command extension for
 // websocket connections.
 func handleStopNotifyBlocks(wsc *wsClient, icmd interface{}) (interface{}, error) {