seaweedfs/weed/s3api/chunked_reader_v4.go
2018-09-03 16:47:00 -07:00

277 lines
7.1 KiB
Go

package s3api
// the related code is copied and modified from minio source code
/*
* Minio Cloud Storage, (C) 2016 Minio, 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.
*/
import (
"bufio"
"bytes"
"errors"
"github.com/dustin/go-humanize"
"io"
"net/http"
)
// Streaming AWS Signature Version '4' constants.
const (
streamingContentSHA256 = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"
)
const maxLineLength = 4 * humanize.KiByte // assumed <= bufio.defaultBufSize 4KiB
// lineTooLong is generated as chunk header is bigger than 4KiB.
var errLineTooLong = errors.New("header line too long")
// Malformed encoding is generated when chunk header is wrongly formed.
var errMalformedEncoding = errors.New("malformed chunked encoding")
// newSignV4ChunkedReader returns a new s3ChunkedReader that translates the data read from r
// out of HTTP "chunked" format before returning it.
// The s3ChunkedReader returns io.EOF when the final 0-length chunk is read.
func newSignV4ChunkedReader(req *http.Request) io.ReadCloser {
return &s3ChunkedReader{
reader: bufio.NewReader(req.Body),
state: readChunkHeader,
}
}
// Represents the overall state that is required for decoding a
// AWS Signature V4 chunked reader.
type s3ChunkedReader struct {
reader *bufio.Reader
state chunkState
lastChunk bool
chunkSignature string
n uint64 // Unread bytes in chunk
err error
}
// Read chunk reads the chunk token signature portion.
func (cr *s3ChunkedReader) readS3ChunkHeader() {
// Read the first chunk line until CRLF.
var hexChunkSize, hexChunkSignature []byte
hexChunkSize, hexChunkSignature, cr.err = readChunkLine(cr.reader)
if cr.err != nil {
return
}
// <hex>;token=value - converts the hex into its uint64 form.
cr.n, cr.err = parseHexUint(hexChunkSize)
if cr.err != nil {
return
}
if cr.n == 0 {
cr.err = io.EOF
}
// Save the incoming chunk signature.
cr.chunkSignature = string(hexChunkSignature)
}
type chunkState int
const (
readChunkHeader chunkState = iota
readChunkTrailer
readChunk
verifyChunk
eofChunk
)
func (cs chunkState) String() string {
stateString := ""
switch cs {
case readChunkHeader:
stateString = "readChunkHeader"
case readChunkTrailer:
stateString = "readChunkTrailer"
case readChunk:
stateString = "readChunk"
case verifyChunk:
stateString = "verifyChunk"
case eofChunk:
stateString = "eofChunk"
}
return stateString
}
func (cr *s3ChunkedReader) Close() (err error) {
return nil
}
// Read - implements `io.Reader`, which transparently decodes
// the incoming AWS Signature V4 streaming signature.
func (cr *s3ChunkedReader) Read(buf []byte) (n int, err error) {
for {
switch cr.state {
case readChunkHeader:
cr.readS3ChunkHeader()
// If we're at the end of a chunk.
if cr.n == 0 && cr.err == io.EOF {
cr.state = readChunkTrailer
cr.lastChunk = true
continue
}
if cr.err != nil {
return 0, cr.err
}
cr.state = readChunk
case readChunkTrailer:
cr.err = readCRLF(cr.reader)
if cr.err != nil {
return 0, errMalformedEncoding
}
cr.state = verifyChunk
case readChunk:
// There is no more space left in the request buffer.
if len(buf) == 0 {
return n, nil
}
rbuf := buf
// The request buffer is larger than the current chunk size.
// Read only the current chunk from the underlying reader.
if uint64(len(rbuf)) > cr.n {
rbuf = rbuf[:cr.n]
}
var n0 int
n0, cr.err = cr.reader.Read(rbuf)
if cr.err != nil {
// We have lesser than chunk size advertised in chunkHeader, this is 'unexpected'.
if cr.err == io.EOF {
cr.err = io.ErrUnexpectedEOF
}
return 0, cr.err
}
// Update the bytes read into request buffer so far.
n += n0
buf = buf[n0:]
// Update bytes to be read of the current chunk before verifying chunk's signature.
cr.n -= uint64(n0)
// If we're at the end of a chunk.
if cr.n == 0 {
cr.state = readChunkTrailer
continue
}
case verifyChunk:
if cr.lastChunk {
cr.state = eofChunk
} else {
cr.state = readChunkHeader
}
case eofChunk:
return n, io.EOF
}
}
}
// readCRLF - check if reader only has '\r\n' CRLF character.
// returns malformed encoding if it doesn't.
func readCRLF(reader io.Reader) error {
buf := make([]byte, 2)
_, err := io.ReadFull(reader, buf[:2])
if err != nil {
return err
}
if buf[0] != '\r' || buf[1] != '\n' {
return errMalformedEncoding
}
return nil
}
// Read a line of bytes (up to \n) from b.
// Give up if the line exceeds maxLineLength.
// The returned bytes are owned by the bufio.Reader
// so they are only valid until the next bufio read.
func readChunkLine(b *bufio.Reader) ([]byte, []byte, error) {
buf, err := b.ReadSlice('\n')
if err != nil {
// We always know when EOF is coming.
// If the caller asked for a line, there should be a line.
if err == io.EOF {
err = io.ErrUnexpectedEOF
} else if err == bufio.ErrBufferFull {
err = errLineTooLong
}
return nil, nil, err
}
if len(buf) >= maxLineLength {
return nil, nil, errLineTooLong
}
// Parse s3 specific chunk extension and fetch the values.
hexChunkSize, hexChunkSignature := parseS3ChunkExtension(buf)
return hexChunkSize, hexChunkSignature, nil
}
// trimTrailingWhitespace - trim trailing white space.
func trimTrailingWhitespace(b []byte) []byte {
for len(b) > 0 && isASCIISpace(b[len(b)-1]) {
b = b[:len(b)-1]
}
return b
}
// isASCIISpace - is ascii space?
func isASCIISpace(b byte) bool {
return b == ' ' || b == '\t' || b == '\n' || b == '\r'
}
// Constant s3 chunk encoding signature.
const s3ChunkSignatureStr = ";chunk-signature="
// parses3ChunkExtension removes any s3 specific chunk-extension from buf.
// For example,
// "10000;chunk-signature=..." => "10000", "chunk-signature=..."
func parseS3ChunkExtension(buf []byte) ([]byte, []byte) {
buf = trimTrailingWhitespace(buf)
semi := bytes.Index(buf, []byte(s3ChunkSignatureStr))
// Chunk signature not found, return the whole buffer.
if semi == -1 {
return buf, nil
}
return buf[:semi], parseChunkSignature(buf[semi:])
}
// parseChunkSignature - parse chunk signature.
func parseChunkSignature(chunk []byte) []byte {
chunkSplits := bytes.SplitN(chunk, []byte(s3ChunkSignatureStr), 2)
return chunkSplits[1]
}
// parse hex to uint64.
func parseHexUint(v []byte) (n uint64, err error) {
for i, b := range v {
switch {
case '0' <= b && b <= '9':
b = b - '0'
case 'a' <= b && b <= 'f':
b = b - 'a' + 10
case 'A' <= b && b <= 'F':
b = b - 'A' + 10
default:
return 0, errors.New("invalid byte in chunk length")
}
if i == 16 {
return 0, errors.New("http chunk length too large")
}
n <<= 4
n |= uint64(b)
}
return
}