blocknotify: sample decred relay daemon

go websocket connector which call our blocknotify tool
its specific to decred, which doesn't handle the "blocknotify=" config key

Thanks to Davec for the sample tool :)

blocknotifygo/Makefile

@@ -0,0 +1,3 @@
+all:
+	rm -f blocknotifygo
+	go build

blocknotifygo/blocknotify.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2016 The btcsuite developers
+// Copyright (c) 2015-2016 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+// Sample blocknofify tool compatible with decred
+// will call the standard blocknotify yiimp tool on new block event.
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os/exec"
+	"path/filepath"
+	"time"
+
+	"github.com/decred/dcrd/chaincfg/chainhash"
+	"github.com/decred/dcrrpcclient"
+	"github.com/decred/dcrutil"
+)
+
+const (
+	processName = "blocknotify"    // set the full path if required
+	stratumDest = "yaamp.com:5744" // stratum host:port
+	coinId = "1574"                // decred database coin id
+
+	walletUser = "yiimprpc"
+	walletPass = "myDecredPassword"
+)
+
+func main() {
+	// Only override the handlers for notifications you care about.
+	// Also note most of these handlers will only be called if you register
+	// for notifications.  See the documentation of the dcrrpcclient
+	// NotificationHandlers type for more details about each handler.
+	ntfnHandlers := dcrrpcclient.NotificationHandlers{
+		OnBlockConnected: func(hash *chainhash.Hash, height int32, time time.Time, vb uint16) {
+
+			// Find the process path.
+			cmd := exec.Command(processName, stratumDest, coinId, hash.String())
+			if err := cmd.Run(); err != nil {
+				log.Fatalln(err)
+			}
+
+			log.Printf("Block connected: %v (%d)", hash, height)
+		},
+	}
+
+	// Connect to local dcrd RPC server using websockets.
+	dcrdHomeDir := dcrutil.AppDataDir("dcrd", false)
+	certs, err := ioutil.ReadFile(filepath.Join(dcrdHomeDir, "rpc.cert"))
+	if err != nil {
+		certs = nil
+		log.Printf("%s, trying without TLS...", err)
+	}
+
+	connCfg := &dcrrpcclient.ConnConfig{
+		Host:         "127.0.0.1:15740",
+		Endpoint:     "ws", // websocket
+
+		User:         walletUser,
+		Pass:         walletPass,
+
+		DisableTLS: (certs == nil),
+		Certificates: certs,
+	}
+
+	client, err := dcrrpcclient.New(connCfg, &ntfnHandlers)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	// Register for block connect and disconnect notifications.
+	if err := client.NotifyBlocks(); err != nil {
+		log.Fatalln(err)
+	}
+	log.Println("NotifyBlocks: Registration Complete")
+
+	// Wait until the client either shuts down gracefully (or the user
+	// terminates the process with Ctrl+C).
+	client.WaitForShutdown()
+}