From 89332e037aeaf1223de4c24805719f733e4c0977 Mon Sep 17 00:00:00 2001
From: Constantin Konstantinidis <constantinkonstantinidis@gmail.com>
Date: Sat, 23 Jul 2022 09:11:32 +0200
Subject: [PATCH] encoding/xml: error when more than one colon in qualified
 names

Add test.

Fixes #20396

Change-Id: I89e9013eb338f831e1908e390b284794df78fb6b
Reviewed-on: https://go-review.googlesource.com/c/go/+/103875
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
---
 src/encoding/xml/xml.go      |  2 +-
 src/encoding/xml/xml_test.go | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/encoding/xml/xml.go b/src/encoding/xml/xml.go
index 2e32324415..9df556a136 100644
--- a/src/encoding/xml/xml.go
+++ b/src/encoding/xml/xml.go
@@ -1167,7 +1167,7 @@ func (d *Decoder) nsname() (name Name, ok bool) {
 		return
 	}
 	if strings.Count(s, ":") > 1 {
-		name.Local = s
+		return name, false
 	} else if space, local, ok := strings.Cut(s, ":"); !ok || space == "" || local == "" {
 		name.Local = s
 	} else {
diff --git a/src/encoding/xml/xml_test.go b/src/encoding/xml/xml_test.go
index 26c4a8a74b..df25812521 100644
--- a/src/encoding/xml/xml_test.go
+++ b/src/encoding/xml/xml_test.go
@@ -1088,6 +1088,40 @@ func TestIssue12417(t *testing.T) {
 	}
 }
 
+func TestIssue20396(t *testing.T) {
+
+	var attrError = UnmarshalError("XML syntax error on line 1: expected attribute name in element")
+
+	testCases := []struct {
+		s       string
+		wantErr error
+	}{
+		{`<a:te:st xmlns:a="abcd"/>`, // Issue 20396
+			UnmarshalError("XML syntax error on line 1: expected element name after <")},
+		{`<a:te=st xmlns:a="abcd"/>`, attrError},
+		{`<a:te&st xmlns:a="abcd"/>`, attrError},
+		{`<a:test xmlns:a="abcd"/>`, nil},
+		{`<a:te:st xmlns:a="abcd">1</a:te:st>`,
+			UnmarshalError("XML syntax error on line 1: expected element name after <")},
+		{`<a:te=st xmlns:a="abcd">1</a:te=st>`, attrError},
+		{`<a:te&st xmlns:a="abcd">1</a:te&st>`, attrError},
+		{`<a:test xmlns:a="abcd">1</a:test>`, nil},
+	}
+
+	var dest string
+	for _, tc := range testCases {
+		if got, want := Unmarshal([]byte(tc.s), &dest), tc.wantErr; got != want {
+			if got == nil {
+				t.Errorf("%s: Unexpected success, want %v", tc.s, want)
+			} else if want == nil {
+				t.Errorf("%s: Unexpected error, got %v", tc.s, got)
+			} else if got.Error() != want.Error() {
+				t.Errorf("%s: got %v, want %v", tc.s, got, want)
+			}
+		}
+	}
+}
+
 func TestIssue20685(t *testing.T) {
 	testCases := []struct {
 		s  string
@@ -1257,9 +1291,7 @@ func testRoundTrip(t *testing.T, input string) {
 
 func TestRoundTrip(t *testing.T) {
 	tests := map[string]string{
-		"leading colon":          `<::Test ::foo="bar"><:::Hello></:::Hello><Hello></Hello></::Test>`,
 		"trailing colon":         `<foo abc:="x"></foo>`,
-		"double colon":           `<x:y:foo></x:y:foo>`,
 		"comments in directives": `<!ENTITY x<!<!-- c1 [ " -->--x --> > <e></e> <!DOCTYPE xxx [ x<!-- c2 " -->--x ]>`,
 	}
 	for name, input := range tests {
-- 
2.50.0