From 8f31ed51e18e80d8e9ceaadf11e03899290a7286 Mon Sep 17 00:00:00 2001
From: Anton Schubert <anton.schubert@riedel.net>
Date: Tue, 14 Jun 2022 11:33:01 +0200
Subject: [PATCH] fix occasional panic on registration

GenerateRandomStringDNSSafe will panic occasionally if the random base64
string contains too many - and _ due to the replacement. Fix by looping.
---
 utils.go      | 14 ++++++++++----
 utils_test.go | 18 +++++++++++++++---
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/utils.go b/utils.go
index 8d9dec5b..fd4cda86 100644
--- a/utils.go
+++ b/utils.go
@@ -325,11 +325,17 @@ func GenerateRandomStringURLSafe(n int) (string, error) {
 // number generator fails to function correctly, in which
 // case the caller should not continue.
 func GenerateRandomStringDNSSafe(n int) (string, error) {
-	str, err := GenerateRandomStringURLSafe(n)
+	var str string
+	var err error
+	for len(str) < n {
+		str, err = GenerateRandomStringURLSafe(n)
+		if err != nil {
+			return "", err
+		}
+		str = strings.ToLower(strings.ReplaceAll(strings.ReplaceAll(str, "_", ""), "-", ""))
+	}
 
-	str = strings.ToLower(strings.ReplaceAll(strings.ReplaceAll(str, "_", ""), "-", ""))
-
-	return str[:n], err
+	return str[:n], nil
 }
 
 func IsStringInSlice(slice []string, str string) bool {
diff --git a/utils_test.go b/utils_test.go
index ff85ac8a..07fa62d8 100644
--- a/utils_test.go
+++ b/utils_test.go
@@ -34,7 +34,7 @@ func (s *Suite) TestGetUsedIps(c *check.C) {
 		MachineKey:     "foo",
 		NodeKey:        "bar",
 		DiscoKey:       "faa",
-		Hostname:           "testmachine",
+		Hostname:       "testmachine",
 		NamespaceID:    namespace.ID,
 		RegisterMethod: RegisterMethodAuthKey,
 		AuthKeyID:      uint(pak.ID),
@@ -82,7 +82,7 @@ func (s *Suite) TestGetMultiIp(c *check.C) {
 			MachineKey:     "foo",
 			NodeKey:        "bar",
 			DiscoKey:       "faa",
-			Hostname:           "testmachine",
+			Hostname:       "testmachine",
 			NamespaceID:    namespace.ID,
 			RegisterMethod: RegisterMethodAuthKey,
 			AuthKeyID:      uint(pak.ID),
@@ -172,7 +172,7 @@ func (s *Suite) TestGetAvailableIpMachineWithoutIP(c *check.C) {
 		MachineKey:     "foo",
 		NodeKey:        "bar",
 		DiscoKey:       "faa",
-		Hostname:           "testmachine",
+		Hostname:       "testmachine",
 		NamespaceID:    namespace.ID,
 		RegisterMethod: RegisterMethodAuthKey,
 		AuthKeyID:      uint(pak.ID),
@@ -185,3 +185,15 @@ func (s *Suite) TestGetAvailableIpMachineWithoutIP(c *check.C) {
 	c.Assert(len(ips2), check.Equals, 1)
 	c.Assert(ips2[0].String(), check.Equals, expected.String())
 }
+
+func (s *Suite) TestGenerateRandomStringDNSSafe(c *check.C) {
+	for i := 0; i < 100000; i++ {
+		str, err := GenerateRandomStringDNSSafe(8)
+		if err != nil {
+			c.Error(err)
+		}
+		if len(str) != 8 {
+			c.Error("invalid length", len(str), str)
+		}
+	}
+}