From 21069c230b9df9e27beb73378f0fd15040435abc Mon Sep 17 00:00:00 2001
From: Dominic Prittie <dom.prittie@mavensecurities.com>
Date: Sat, 21 Aug 2021 09:32:45 +0100
Subject: [PATCH 1/3] add test for rand.NewSource concurrent usage

---
 nrpe_test.go | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/nrpe_test.go b/nrpe_test.go
index a59c91c..d6af0c2 100644
--- a/nrpe_test.go
+++ b/nrpe_test.go
@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"fmt"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 	"unsafe"
@@ -217,6 +218,21 @@ func TestClientServerTimeoutClient(t *testing.T) {
 	<-c
 }
 
+func TestRandSource(t *testing.T) {
+	const c = 1000000
+	var wg sync.WaitGroup
+	wg.Add(c)
+
+	for i := 0; i < c; i++ {
+		go func(i int) {
+			defer wg.Done()
+			randSource.Seed(0)
+			randSource.Uint32()
+		}(i)
+	}
+	wg.Wait()
+}
+
 func TestBufferRandomizer(t *testing.T) {
 	randSource.Seed(0)
 

From 5449aef2ceead892a39a085a96677c7db46ea027 Mon Sep 17 00:00:00 2001
From: Dominic Prittie <dom.prittie@mavensecurities.com>
Date: Fri, 20 Aug 2021 09:42:18 +0100
Subject: [PATCH 2/3] make safe for concurrent use

---
 nrpe.go | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/nrpe.go b/nrpe.go
index 5b94ad9..1a26707 100644
--- a/nrpe.go
+++ b/nrpe.go
@@ -13,13 +13,31 @@ import (
 	"math/rand"
 	"net"
 	"strings"
+	"sync"
 	"time"
 	"unsafe"
 )
 
 var crc32Table []uint32
 
-var randSource *rand.Rand
+type syncedRand struct {
+	ra *rand.Rand
+	mu *sync.Mutex
+}
+
+func (r *syncedRand) Uint32() uint32 {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.ra.Uint32()
+}
+
+func (r *syncedRand) Seed(seed int64) {
+	r.mu.Lock()
+	r.ra.Seed(seed)
+	r.mu.Unlock()
+}
+
+var randSource *syncedRand
 
 const (
 	maxPacketDataLength = 1024
@@ -86,7 +104,9 @@ func init() {
 		crc32Table[i] = crc
 	}
 
-	randSource = rand.New(rand.NewSource(time.Now().UnixNano()))
+	// rand.NewSource returns a new pseudo-random Source seeded with the given value.
+	// Unlike the default Source used by top-level functions, this source is not safe for concurrent use by multiple goroutines.
+	randSource = &syncedRand{rand.New(rand.NewSource(time.Now().UnixNano())), &sync.Mutex{}}
 }
 
 //Builds crc32 from the given input

From e8e231e08041c3847a762c4e51d8766eb64c5073 Mon Sep 17 00:00:00 2001
From: Dominic Prittie <dom.prittie@mavensecurities.com>
Date: Sat, 21 Aug 2021 13:11:22 +0100
Subject: [PATCH 3/3] remove test, it is not deterministic

This reverts commit 21069c230b9df9e27beb73378f0fd15040435abc.
---
 nrpe_test.go | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/nrpe_test.go b/nrpe_test.go
index d6af0c2..a59c91c 100644
--- a/nrpe_test.go
+++ b/nrpe_test.go
@@ -9,7 +9,6 @@ import (
 	"bytes"
 	"fmt"
 	"strings"
-	"sync"
 	"testing"
 	"time"
 	"unsafe"
@@ -218,21 +217,6 @@ func TestClientServerTimeoutClient(t *testing.T) {
 	<-c
 }
 
-func TestRandSource(t *testing.T) {
-	const c = 1000000
-	var wg sync.WaitGroup
-	wg.Add(c)
-
-	for i := 0; i < c; i++ {
-		go func(i int) {
-			defer wg.Done()
-			randSource.Seed(0)
-			randSource.Uint32()
-		}(i)
-	}
-	wg.Wait()
-}
-
 func TestBufferRandomizer(t *testing.T) {
 	randSource.Seed(0)