From 39450823e4cebe05f7b92d98fab209c08264cbfd Mon Sep 17 00:00:00 2001
From: Yann Soubeyrand <yann.soubeyrand@camptocamp.com>
Date: Thu, 29 Jun 2023 17:04:51 +0200
Subject: [PATCH] feat(config)!: handle dns_canonicalize_hostname=fallback
 setting

---
 config/krb5conf.go      | 23 ++++++++++++++++++-----
 config/krb5conf_test.go |  8 ++++----
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/config/krb5conf.go b/config/krb5conf.go
index bcfae8e1..563a380e 100644
--- a/config/krb5conf.go
+++ b/config/krb5conf.go
@@ -57,7 +57,7 @@ type LibDefaults struct {
 	DefaultTktEnctypes      []string //default aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
 	DefaultTGSEnctypeIDs    []int32  //default aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
 	DefaultTktEnctypeIDs    []int32  //default aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
-	DNSCanonicalizeHostname bool     //default true
+	DNSCanonicalizeHostname int      //default true
 	DNSLookupKDC            bool     //default false
 	DNSLookupRealm          bool
 	ExtraAddresses          []net.IP       //Not implementing yet
@@ -83,6 +83,12 @@ type LibDefaults struct {
 	VerifyAPReqNofail     bool          //default false
 }
 
+const (
+	DNSCanonicalizeHostnameFalse    = iota
+	DNSCanonicalizeHostnameTrue     = iota
+	DNSCanonicalizeHostnameFallback = iota
+)
+
 // Create a new LibDefaults struct.
 func newLibDefaults() LibDefaults {
 	uid := "0"
@@ -102,7 +108,7 @@ func newLibDefaults() LibDefaults {
 		DefaultKeytabName:       "/etc/krb5.keytab",
 		DefaultTGSEnctypes:      []string{"aes256-cts-hmac-sha1-96", "aes128-cts-hmac-sha1-96", "des3-cbc-sha1", "arcfour-hmac-md5", "camellia256-cts-cmac", "camellia128-cts-cmac", "des-cbc-crc", "des-cbc-md5", "des-cbc-md4"},
 		DefaultTktEnctypes:      []string{"aes256-cts-hmac-sha1-96", "aes128-cts-hmac-sha1-96", "des3-cbc-sha1", "arcfour-hmac-md5", "camellia256-cts-cmac", "camellia128-cts-cmac", "des-cbc-crc", "des-cbc-md5", "des-cbc-md4"},
-		DNSCanonicalizeHostname: true,
+		DNSCanonicalizeHostname: DNSCanonicalizeHostnameTrue,
 		K5LoginDirectory:        hdir,
 		KDCDefaultOptions:       opts,
 		KDCTimeSync:             1,
@@ -176,10 +182,17 @@ func (l *LibDefaults) parseLines(lines []string) error {
 			l.DefaultTktEnctypes = strings.Fields(p[1])
 		case "dns_canonicalize_hostname":
 			v, err := parseBoolean(p[1])
-			if err != nil {
-				return InvalidErrorf("libdefaults section line (%s): %v", line, err)
+			if err == nil {
+				if v {
+					l.DNSCanonicalizeHostname = DNSCanonicalizeHostnameTrue
+				} else {
+					l.DNSCanonicalizeHostname = DNSCanonicalizeHostnameFalse
+				}
+			} else if strings.TrimSpace(p[1]) == "fallback" {
+				l.DNSCanonicalizeHostname = DNSCanonicalizeHostnameFallback
+			} else {
+				return InvalidErrorf("libdefaults section line (%s)", line)
 			}
-			l.DNSCanonicalizeHostname = v
 		case "dns_lookup_kdc":
 			v, err := parseBoolean(p[1])
 			if err != nil {
diff --git a/config/krb5conf_test.go b/config/krb5conf_test.go
index 306ec8f9..ac214860 100644
--- a/config/krb5conf_test.go
+++ b/config/krb5conf_test.go
@@ -60,7 +60,7 @@ const (
  .test.gokrb5 = TEST.GOKRB5 #comment to be ignored
 
  test.gokrb5 = TEST.GOKRB5 ;comment to be ignored
- 
+
   .example.com = EXAMPLE.COM # comment to be ignored
  hostname1.example.com = EXAMPLE.COM ; comment to be ignored
  hostname2.example.com = TEST.GOKRB5
@@ -111,7 +111,7 @@ const (
       18,
       17
     ],
-    "DNSCanonicalizeHostname": true,
+    "DNSCanonicalizeHostname": 1,
     "DNSLookupKDC": false,
     "DNSLookupRealm": false,
     "ExtraAddresses": null,
@@ -354,7 +354,7 @@ const (
 	.test.gokrb5 = TEST.GOKRB5
 
 	test.gokrb5 = TEST.GOKRB5
- 
+
 	.example.com = EXAMPLE.COM
 	hostname1.example.com = EXAMPLE.COM
 	hostname2.example.com = TEST.GOKRB5
@@ -423,7 +423,7 @@ const (
  .test.gokrb5 = TEST.GOKRB5
 
  test.gokrb5 = TEST.GOKRB5
- 
+
   .example.com = EXAMPLE.COM
  hostname1.example.com = EXAMPLE.COM
  hostname2.example.com = TEST.GOKRB5