From e4c9668412963baed52fe85dbe442c8dbcaf3aa6 Mon Sep 17 00:00:00 2001
From: Jonathan Turner <jt@jtnet.co.uk>
Date: Sat, 4 Apr 2020 07:15:22 +0100
Subject: [PATCH] handle port on http request when deriving spn

---
 v8/spnego/http.go | 40 +++++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/v8/spnego/http.go b/v8/spnego/http.go
index 4e1d2bda..3971dbc1 100644
--- a/v8/spnego/http.go
+++ b/v8/spnego/http.go
@@ -18,6 +18,7 @@ import (
 	"github.com/jcmturner/gokrb5/v8/client"
 	"github.com/jcmturner/gokrb5/v8/credentials"
 	"github.com/jcmturner/gokrb5/v8/gssapi"
+	"github.com/jcmturner/gokrb5/v8/iana/nametype"
 	"github.com/jcmturner/gokrb5/v8/keytab"
 	"github.com/jcmturner/gokrb5/v8/krberror"
 	"github.com/jcmturner/gokrb5/v8/service"
@@ -162,18 +163,43 @@ func respUnauthorizedNegotiate(resp *http.Response) bool {
 	return false
 }
 
+func setRequestSPN(r *http.Request) (types.PrincipalName, error) {
+	h := strings.TrimSuffix(r.URL.Host, ".")
+	// This if statement checks if the host includes a port number
+	if strings.LastIndex(r.URL.Host, ":") > strings.LastIndex(r.URL.Host, "]") {
+		// There is a port number in the URL
+		h, p, err := net.SplitHostPort(h)
+		if err != nil {
+			return types.PrincipalName{}, err
+		}
+		name, err := net.LookupCNAME(h)
+		if err == nil {
+			// Underlyng canonical name should be used for SPN
+			h = name
+		}
+		h = strings.TrimSuffix(h, ".")
+		r.Host = fmt.Sprintf("%s:%s", h, p)
+		return types.NewPrincipalName(nametype.KRB_NT_PRINCIPAL, "HTTP/"+h), nil
+	}
+	name, err := net.LookupCNAME(h)
+	if err == nil {
+		// Underlyng canonical name should be used for SPN
+		h = name
+	}
+	h = strings.TrimSuffix(h, ".")
+	r.Host = h
+	return types.NewPrincipalName(nametype.KRB_NT_PRINCIPAL, "HTTP/"+h), nil
+}
+
 // SetSPNEGOHeader gets the service ticket and sets it as the SPNEGO authorization header on HTTP request object.
 // To auto generate the SPN from the request object pass a null string "".
 func SetSPNEGOHeader(cl *client.Client, r *http.Request, spn string) error {
 	if spn == "" {
-		h := strings.TrimSuffix(strings.SplitN(r.URL.Host, ":", 2)[0], ".")
-		name, err := net.LookupCNAME(h)
-		if err == nil {
-			// Underlyng canonical name should be used for SPN
-			h = strings.TrimSuffix(name, ".")
+		pn, err := setRequestSPN(r)
+		if err != nil {
+			return err
 		}
-		spn = "HTTP/" + h
-		r.Host = h
+		spn = pn.PrincipalNameString()
 	}
 	cl.Log("using SPN %s", spn)
 	s := SPNEGOClient(cl, spn)