encoding/base64: ignore new line characters during decode.

Fixes #2541.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5610045

diff --git a/src/pkg/encoding/base64/base64.go b/src/pkg/encoding/base64/base64.go
index 889b565e3f5a475b6c86672b5af6184c030c2c4c..55f9f67a43a566bcd466193dc1404a4f55ee7aae 100644 (file)
--- a/src/pkg/encoding/base64/base64.go
+++ b/src/pkg/encoding/base64/base64.go
@@ -208,22 +208,30 @@ func (e CorruptInputError) Error() string {
 
 // decode is like Decode but returns an additional 'end' value, which
 // indicates if end-of-message padding was encountered and thus any
-// additional data is an error.  decode also assumes len(src)%4==0,
-// since it is meant for internal use.
+// additional data is an error.
 func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
-       for i := 0; i < len(src)/4 && !end; i++ {
+       osrc := src
+       for len(src) > 0 && !end {
                // Decode quantum using the base64 alphabet
                var dbuf [4]byte
                dlen := 4
 
        dbufloop:
-               for j := 0; j < 4; j++ {
-                       in := src[i*4+j]
-                       if in == '=' && j >= 2 && i == len(src)/4-1 {
+               for j := 0; j < 4; {
+                       if len(src) == 0 {
+                               return n, false, CorruptInputError(len(osrc) - len(src) - j)
+                       }
+                       in := src[0]
+                       src = src[1:]
+                       if in == '\r' || in == '\n' {
+                               // Ignore this character.
+                               continue
+                       }
+                       if in == '=' && j >= 2 && len(src) < 4 {
                                // We've reached the end and there's
                                // padding
-                               if src[i*4+3] != '=' {
-                                       return n, false, CorruptInputError(i*4 + 2)
+                               if len(src) > 0 && src[0] != '=' {
+                                       return n, false, CorruptInputError(len(osrc) - len(src) - 1)
                                }
                                dlen = j
                                end = true
@@ -231,22 +239,24 @@ func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
                        }
                        dbuf[j] = enc.decodeMap[in]
                        if dbuf[j] == 0xFF {
-                               return n, false, CorruptInputError(i*4 + j)
+                               return n, false, CorruptInputError(len(osrc) - len(src) - 1)
                        }
+                       j++
                }
 
                // Pack 4x 6-bit source blocks into 3 byte destination
                // quantum
                switch dlen {
                case 4:
-                       dst[i*3+2] = dbuf[2]<<6 | dbuf[3]
+                       dst[2] = dbuf[2]<<6 | dbuf[3]
                        fallthrough
                case 3:
-                       dst[i*3+1] = dbuf[1]<<4 | dbuf[2]>>2
+                       dst[1] = dbuf[1]<<4 | dbuf[2]>>2
                        fallthrough
                case 2:
-                       dst[i*3+0] = dbuf[0]<<2 | dbuf[1]>>4
+                       dst[0] = dbuf[0]<<2 | dbuf[1]>>4
                }
+               dst = dst[3:]
                n += dlen - 1
        }
 
@@ -257,11 +267,8 @@ func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
 // DecodedLen(len(src)) bytes to dst and returns the number of bytes
 // written.  If src contains invalid base64 data, it will return the
 // number of bytes successfully written and CorruptInputError.
+// New line characters (\r and \n) are ignored.
 func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
-       if len(src)%4 != 0 {
-               return 0, CorruptInputError(len(src) / 4 * 4)
-       }
-
        n, _, err = enc.decode(dst, src)
        return
 }

diff --git a/src/pkg/encoding/base64/base64_test.go b/src/pkg/encoding/base64/base64_test.go
index 8310d8ab9e3d1a0cce7a55ce1425ec3085bc7216..3e9a84393b60150f22eb88d0bc60342daeba82c1 100644 (file)
--- a/src/pkg/encoding/base64/base64_test.go
+++ b/src/pkg/encoding/base64/base64_test.go
@@ -197,3 +197,29 @@ func TestBig(t *testing.T) {
                t.Errorf("Decode(Encode(%d-byte string)) failed at offset %d", n, i)
        }
 }
+
+func TestNewLineCharacters(t *testing.T) {
+       // Each of these should decode to the string "sure", without errors.
+       const expected = "sure"
+       examples := []string{
+               "c3VyZQ==",
+               "c3VyZQ==\r",
+               "c3VyZQ==\n",
+               "c3VyZQ==\r\n",
+               "c3VyZ\r\nQ==",
+               "c3V\ryZ\nQ==",
+               "c3V\nyZ\rQ==",
+               "c3VyZ\nQ==",
+               "c3VyZQ\n==",
+       }
+       for _, e := range examples {
+               buf, err := StdEncoding.DecodeString(e)
+               if err != nil {
+                       t.Errorf("Decode(%q) failed: %v", e, err)
+                       continue
+               }
+               if s := string(buf); s != expected {
+                       t.Errorf("Decode(%q) = %q, want %q", e, s, expected)
+               }
+       }
+}