From fb2aef2ce65d605cf0e56c3ab926be01545d2c58 Mon Sep 17 00:00:00 2001
From: Plamen Todorov <plamen@debimac.quint8.net>
Date: Sun, 6 Oct 2019 22:08:43 +0300
Subject: [PATCH 1/3] MQTT clientId should be unique

Each mqtt hook establishes separate connection to the MQTT broker. If
their clientIds are all equal the MQTT broker will disconnect the clients - the
protocol does not allow 2 connected clients with the same name
---
 internal/endpoint/mqtt.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/internal/endpoint/mqtt.go b/internal/endpoint/mqtt.go
index eea4682f..3bd6431f 100644
--- a/internal/endpoint/mqtt.go
+++ b/internal/endpoint/mqtt.go
@@ -83,7 +83,9 @@ func (conn *MQTTConn) Send(msg string) error {
 			}
 			ops = ops.SetTLSConfig(&config)
 		}
-		ops = ops.SetClientID("tile38").AddBroker(uri)
+		nano := time.Now().UnixNano()
+		clientID := fmt.Sprintf("tile38_%x", nano) //the id of connected clients should be unique
+		ops = ops.SetClientID(clientID).AddBroker(uri)
 		c := paho.NewClient(ops)
 
 		if token := c.Connect(); token.Wait() && token.Error() != nil {

From c3b9a689bb0fbb6986259f373213ad4240abef65 Mon Sep 17 00:00:00 2001
From: Plamen Todorov <plamen@abrites.com>
Date: Tue, 8 Oct 2019 09:34:31 +0300
Subject: [PATCH 2/3] Use uuid as mqtt clientId

Use crypto/random to generate unique mqtt client id. The tile38 prefix
makes the connections easily identifiable in the mqtt broker logs.
---
 internal/endpoint/mqtt.go | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/internal/endpoint/mqtt.go b/internal/endpoint/mqtt.go
index 3bd6431f..f4184725 100644
--- a/internal/endpoint/mqtt.go
+++ b/internal/endpoint/mqtt.go
@@ -3,12 +3,14 @@ package endpoint
 import (
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/rand"
 	"fmt"
 	"io/ioutil"
 	"sync"
 	"time"
 
 	paho "github.com/eclipse/paho.mqtt.golang"
+	"github.com/tidwall/tile38/internal/log"
 )
 
 const (
@@ -83,9 +85,16 @@ func (conn *MQTTConn) Send(msg string) error {
 			}
 			ops = ops.SetTLSConfig(&config)
 		}
-		nano := time.Now().UnixNano()
-		clientID := fmt.Sprintf("tile38_%x", nano) //the id of connected clients should be unique
-		ops = ops.SetClientID(clientID).AddBroker(uri)
+		//generate UUID for the client-id. 
+		b := make([]byte, 16)
+		_, err := rand.Read(b)
+		if err != nil {
+			log.Debugf("Failed to generate guid for the mqtt client. The endpoint will not work")
+			return err;
+		}
+		uuid := fmt.Sprintf("tile38-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
+
+		ops = ops.SetClientID(uuid).AddBroker(uri)
 		c := paho.NewClient(ops)
 
 		if token := c.Connect(); token.Wait() && token.Error() != nil {

From 6b82fd94eb9f179d6cb5389af6b1531e6a3c1939 Mon Sep 17 00:00:00 2001
From: Plamen Todorov <plamen@abrites.com>
Date: Tue, 8 Oct 2019 20:24:31 +0300
Subject: [PATCH 3/3] randomize mqtt client id with math/rand

Cryptographic randomizer is not required for mqtt clientIds. They
should be unique only among currently selected clients.
---
 internal/endpoint/mqtt.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/internal/endpoint/mqtt.go b/internal/endpoint/mqtt.go
index f4184725..98003675 100644
--- a/internal/endpoint/mqtt.go
+++ b/internal/endpoint/mqtt.go
@@ -3,7 +3,7 @@ package endpoint
 import (
 	"crypto/tls"
 	"crypto/x509"
-	"crypto/rand"
+	"math/rand"
 	"fmt"
 	"io/ioutil"
 	"sync"