encoding/base64: add DecodeString and EncodeToString

... like encoding/hex. Same signatures.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4530070

src/pkg/encoding/base64/base64.go

@@ -106,6 +106,13 @@ func (enc *Encoding) Encode(dst, src []byte) {
 	}
 }
 
+// EncodeToString returns the base64 encoding of src.
+func (enc *Encoding) EncodeToString(src []byte) string {
+	buf := make([]byte, enc.EncodedLen(len(src)))
+	enc.Encode(buf, src)
+	return string(buf)
+}
+
 type encoder struct {
 	err  os.Error
 	enc  *Encoding
@@ -260,6 +267,13 @@ func (enc *Encoding) Decode(dst, src []byte) (n int, err os.Error) {
 	return
 }
 
+// DecodeString returns the bytes represented by the base64 string s.
+func (enc *Encoding) DecodeString(s string) ([]byte, os.Error) {
+	dbuf := make([]byte, enc.DecodedLen(len(s)))
+	n, err := enc.Decode(dbuf, []byte(s))
+	return dbuf[:n], err
+}
+
 type decoder struct {
 	err    os.Error
 	enc    *Encoding

src/pkg/encoding/base64/base64_test.go

@@ -56,9 +56,8 @@ func testEqual(t *testing.T, msg string, args ...interface{}) bool {
 
 func TestEncode(t *testing.T) {
 	for _, p := range pairs {
-		buf := make([]byte, StdEncoding.EncodedLen(len(p.decoded)))
-		StdEncoding.Encode(buf, []byte(p.decoded))
-		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, string(buf), p.encoded)
+		got := StdEncoding.EncodeToString([]byte(p.decoded))
+		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, got, p.encoded)
 	}
 }
 
@@ -102,6 +101,10 @@ func TestDecode(t *testing.T) {
 			testEqual(t, "Decode(%q) = end %v, want %v", p.encoded, end, (p.encoded[len(p.encoded)-1] == '='))
 		}
 		testEqual(t, "Decode(%q) = %q, want %q", p.encoded, string(dbuf[0:count]), p.decoded)
+
+		dbuf, err = StdEncoding.DecodeString(p.encoded)
+		testEqual(t, "DecodeString(%q) = error %v, want %v", p.encoded, err, os.Error(nil))
+		testEqual(t, "DecodeString(%q) = %q, want %q", string(dbuf), p.decoded)
 	}
 }
 

src/pkg/http/client.go

@@ -100,13 +100,10 @@ func send(req *Request, t RoundTripper) (resp *Response, err os.Error) {
 
 	info := req.URL.RawUserinfo
 	if len(info) > 0 {
-		enc := base64.URLEncoding
-		encoded := make([]byte, enc.EncodedLen(len(info)))
-		enc.Encode(encoded, []byte(info))
 		if req.Header == nil {
 			req.Header = make(Header)
 		}
-		req.Header.Set("Authorization", "Basic "+string(encoded))
+		req.Header.Set("Authorization", "Basic "+base64.URLEncoding.EncodeToString([]byte(info)))
 	}
 	return t.RoundTrip(req)
 }

src/pkg/http/request.go

@@ -485,9 +485,7 @@ func NewRequest(method, url string, body io.Reader) (*Request, os.Error) {
 // are not encrypted.
 func (r *Request) SetBasicAuth(username, password string) {
 	s := username + ":" + password
-	buf := make([]byte, base64.StdEncoding.EncodedLen(len(s)))
-	base64.StdEncoding.Encode(buf, []byte(s))
-	r.Header.Set("Authorization", "Basic "+string(buf))
+	r.Header.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(s)))
 }
 
 // ReadRequest reads and parses a request from b.

src/pkg/http/transport.go

@@ -169,10 +169,7 @@ func (cm *connectMethod) proxyAuth() string {
 	}
 	proxyInfo := cm.proxyURL.RawUserinfo
 	if proxyInfo != "" {
-		enc := base64.URLEncoding
-		encoded := make([]byte, enc.EncodedLen(len(proxyInfo)))
-		enc.Encode(encoded, []byte(proxyInfo))
-		return "Basic " + string(encoded)
+		return "Basic " + base64.URLEncoding.EncodeToString([]byte(proxyInfo))
 	}
 	return ""
 }

src/pkg/smtp/smtp.go

@@ -151,8 +151,7 @@ func (c *Client) Auth(a Auth) os.Error {
 		var msg []byte
 		switch code {
 		case 334:
-			msg = make([]byte, encoding.DecodedLen(len(msg64)))
-			_, err = encoding.Decode(msg, []byte(msg64))
+			msg, err = encoding.DecodeString(msg64)
 		case 235:
 			// the last message isn't base64 because it isn't a challenge
 			msg = []byte(msg64)