From 4d1604cc04415f0ebb739b295f8b4165c88b76a5 Mon Sep 17 00:00:00 2001
From: dfawley <dfawley@google.com>
Date: Fri, 28 Apr 2017 11:32:27 -0700
Subject: [PATCH] Use unpadded base64 encoding for binary metadata headers;
 handle padded or unpadded input (#1209)

---
 transport/http_util.go      | 8 ++++++--
 transport/http_util_test.go | 3 ++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/transport/http_util.go b/transport/http_util.go
index e5120ebf0079..795d5d18a4f8 100644
--- a/transport/http_util.go
+++ b/transport/http_util.go
@@ -167,11 +167,15 @@ func (d *decodeState) status() *status.Status {
 const binHdrSuffix = "-bin"
 
 func encodeBinHeader(v []byte) string {
-	return base64.StdEncoding.EncodeToString(v)
+	return base64.RawStdEncoding.EncodeToString(v)
 }
 
 func decodeBinHeader(v string) ([]byte, error) {
-	return base64.StdEncoding.DecodeString(v)
+	if len(v)%4 == 0 {
+		// Input was padded, or padding was not necessary.
+		return base64.StdEncoding.DecodeString(v)
+	}
+	return base64.RawStdEncoding.DecodeString(v)
 }
 
 func encodeMetadataHeader(k, v string) string {
diff --git a/transport/http_util_test.go b/transport/http_util_test.go
index 8e2c488d8717..b3698018bdab 100644
--- a/transport/http_util_test.go
+++ b/transport/http_util_test.go
@@ -158,7 +158,7 @@ func TestEncodeMetadataHeader(t *testing.T) {
 		{"key", "abc", "abc"},
 		{"KEY", "abc", "abc"},
 		{"key-bin", "abc", "YWJj"},
-		{"key-bin", binaryValue, "woA="},
+		{"key-bin", binaryValue, "woA"},
 	} {
 		v := encodeMetadataHeader(test.kin, test.vin)
 		if !reflect.DeepEqual(v, test.vout) {
@@ -178,6 +178,7 @@ func TestDecodeMetadataHeader(t *testing.T) {
 	}{
 		{"a", "abc", "abc", nil},
 		{"key-bin", "Zm9vAGJhcg==", "foo\x00bar", nil},
+		{"key-bin", "Zm9vAGJhcg", "foo\x00bar", nil},
 		{"key-bin", "woA=", binaryValue, nil},
 		{"a", "abc,efg", "abc,efg", nil},
 	} {