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/*-
* Copyright 2014 Square Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jose
import (
"bytes"
"compress/flate"
"encoding/base64"
"encoding/binary"
"io"
"math/big"
"regexp"
"strings"
"gopkg.in/square/go-jose.v1/json"
)
var stripWhitespaceRegex = regexp.MustCompile("\\s")
// Url-safe base64 encode that strips padding
func base64URLEncode(data []byte) string {
var result = base64.URLEncoding.EncodeToString(data)
return strings.TrimRight(result, "=")
}
// Url-safe base64 decoder that adds padding
func base64URLDecode(data string) ([]byte, error) {
var missing = (4 - len(data)%4) % 4
data += strings.Repeat("=", missing)
return base64.URLEncoding.DecodeString(data)
}
// Helper function to serialize known-good objects.
// Precondition: value is not a nil pointer.
func mustSerializeJSON(value interface{}) []byte {
out, err := json.Marshal(value)
if err != nil {
panic(err)
}
// We never want to serialize the top-level value "null," since it's not a
// valid JOSE message. But if a caller passes in a nil pointer to this method,
// MarshalJSON will happily serialize it as the top-level value "null". If
// that value is then embedded in another operation, for instance by being
// base64-encoded and fed as input to a signing algorithm
// (https://github.com/square/go-jose/issues/22), the result will be
// incorrect. Because this method is intended for known-good objects, and a nil
// pointer is not a known-good object, we are free to panic in this case.
// Note: It's not possible to directly check whether the data pointed at by an
// interface is a nil pointer, so we do this hacky workaround.
// https://groups.google.com/forum/#!topic/golang-nuts/wnH302gBa4I
if string(out) == "null" {
panic("Tried to serialize a nil pointer.")
}
return out
}
// Strip all newlines and whitespace
func stripWhitespace(data string) string {
return stripWhitespaceRegex.ReplaceAllString(data, "")
}
// Perform compression based on algorithm
func compress(algorithm CompressionAlgorithm, input []byte) ([]byte, error) {
switch algorithm {
case DEFLATE:
return deflate(input)
default:
return nil, ErrUnsupportedAlgorithm
}
}
// Perform decompression based on algorithm
func decompress(algorithm CompressionAlgorithm, input []byte) ([]byte, error) {
switch algorithm {
case DEFLATE:
return inflate(input)
default:
return nil, ErrUnsupportedAlgorithm
}
}
// Compress with DEFLATE
func deflate(input []byte) ([]byte, error) {
output := new(bytes.Buffer)
// Writing to byte buffer, err is always nil
writer, _ := flate.NewWriter(output, 1)
_, _ = io.Copy(writer, bytes.NewBuffer(input))
err := writer.Close()
return output.Bytes(), err
}
// Decompress with DEFLATE
func inflate(input []byte) ([]byte, error) {
output := new(bytes.Buffer)
reader := flate.NewReader(bytes.NewBuffer(input))
_, err := io.Copy(output, reader)
if err != nil {
return nil, err
}
err = reader.Close()
return output.Bytes(), err
}
// byteBuffer represents a slice of bytes that can be serialized to url-safe base64.
type byteBuffer struct {
data []byte
}
func newBuffer(data []byte) *byteBuffer {
if data == nil {
return nil
}
return &byteBuffer{
data: data,
}
}
func newFixedSizeBuffer(data []byte, length int) *byteBuffer {
if len(data) > length {
panic("square/go-jose: invalid call to newFixedSizeBuffer (len(data) > length)")
}
pad := make([]byte, length-len(data))
return newBuffer(append(pad, data...))
}
func newBufferFromInt(num uint64) *byteBuffer {
data := make([]byte, 8)
binary.BigEndian.PutUint64(data, num)
return newBuffer(bytes.TrimLeft(data, "\x00"))
}
func (b *byteBuffer) MarshalJSON() ([]byte, error) {
return json.Marshal(b.base64())
}
func (b *byteBuffer) UnmarshalJSON(data []byte) error {
var encoded string
err := json.Unmarshal(data, &encoded)
if err != nil {
return err
}
if encoded == "" {
return nil
}
decoded, err := base64URLDecode(encoded)
if err != nil {
return err
}
*b = *newBuffer(decoded)
return nil
}
func (b *byteBuffer) base64() string {
return base64URLEncode(b.data)
}
func (b *byteBuffer) bytes() []byte {
// Handling nil here allows us to transparently handle nil slices when serializing.
if b == nil {
return nil
}
return b.data
}
func (b byteBuffer) bigInt() *big.Int {
return new(big.Int).SetBytes(b.data)
}
func (b byteBuffer) toInt() int {
return int(b.bigInt().Int64())
}
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