frostfs-s3-gw/api/handler/s3reader.go

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package handler
import (
"bufio"
"bytes"
"encoding/hex"
"errors"
"io"
"net/http"
"time"
v4 "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/auth/signer/v4"
errs "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
"github.com/aws/aws-sdk-go/aws/credentials"
)
const (
chunkSignatureHeader = "chunk-signature="
maxChunkSize = 16 << 20
)
type (
s3ChunkReader struct {
reader *bufio.Reader
streamSigner *v4.StreamSigner
requestTime time.Time
buffer []byte
offset int
err error
}
)
var (
errGiantChunk = errors.New("chunk too big: choose chunk size <= 16MiB")
errMalformedChunkedEncoding = errors.New("malformed chunked encoding")
)
func (c *s3ChunkReader) Close() (err error) {
return nil
}
func (c *s3ChunkReader) Read(buf []byte) (num int, err error) {
if c.offset > 0 {
num = copy(buf, c.buffer[c.offset:])
if num == len(buf) {
c.offset += num
return num, nil
}
c.offset = 0
buf = buf[num:]
}
var size int
for {
b, err := c.reader.ReadByte()
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if err != nil {
c.err = err
return num, c.err
}
if b == ';' { // separating character
break
}
// Manually deserialize the size since AWS specified
// the chunk size to be of variable width. In particular,
// a size of 16 is encoded as `10` while a size of 64 KB
// is `10000`.
switch {
case b >= '0' && b <= '9':
size = size<<4 | int(b-'0')
case b >= 'a' && b <= 'f':
size = size<<4 | int(b-('a'-10))
case b >= 'A' && b <= 'F':
size = size<<4 | int(b-('A'-10))
default:
c.err = errMalformedChunkedEncoding
return num, c.err
}
if size > maxChunkSize {
c.err = errGiantChunk
return num, c.err
}
}
// Now, we read the signature of the following payload and expect:
// chunk-signature=" + <signature-as-hex> + "\r\n"
//
// The signature is 64 bytes long (hex-encoded SHA256 hash) and
// starts with a 16 byte header: len("chunk-signature=") + 64 == 80.
var signature [80]byte
_, err = io.ReadFull(c.reader, signature[:])
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if err != nil {
c.err = err
return num, c.err
}
if !bytes.HasPrefix(signature[:], []byte(chunkSignatureHeader)) {
c.err = errMalformedChunkedEncoding
return num, c.err
}
b, err := c.reader.ReadByte()
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if err != nil {
c.err = err
return num, c.err
}
if b != '\r' {
c.err = errMalformedChunkedEncoding
return num, c.err
}
b, err = c.reader.ReadByte()
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if err != nil {
c.err = err
return num, c.err
}
if b != '\n' {
c.err = errMalformedChunkedEncoding
return num, c.err
}
if cap(c.buffer) < size {
c.buffer = make([]byte, size)
} else {
c.buffer = c.buffer[:size]
}
// Now, we read the payload and compute its SHA-256 hash.
_, err = io.ReadFull(c.reader, c.buffer)
if err == io.EOF && size != 0 {
err = io.ErrUnexpectedEOF
}
if err != nil && err != io.EOF {
c.err = err
return num, c.err
}
b, err = c.reader.ReadByte()
if b != '\r' || err != nil {
c.err = errMalformedChunkedEncoding
return num, c.err
}
b, err = c.reader.ReadByte()
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if err != nil {
c.err = err
return num, c.err
}
if b != '\n' {
c.err = errMalformedChunkedEncoding
return num, c.err
}
// Once we have read the entire chunk successfully, we verify
// that the received signature matches our computed signature.
calculatedSignature, err := c.streamSigner.GetSignature(nil, c.buffer, c.requestTime)
if err != nil {
c.err = err
return num, c.err
}
if string(signature[16:]) != hex.EncodeToString(calculatedSignature) {
c.err = errs.GetAPIError(errs.ErrSignatureDoesNotMatch)
return num, c.err
}
// If the chunk size is zero we return io.EOF. As specified by AWS,
// only the last chunk is zero-sized.
if size == 0 {
c.err = io.EOF
return num, c.err
}
c.offset = copy(buf, c.buffer)
num += c.offset
return num, err
}
func newSignV4ChunkedReader(req *http.Request) (io.ReadCloser, error) {
box, err := middleware.GetBoxData(req.Context())
if err != nil {
return nil, errs.GetAPIError(errs.ErrAuthorizationHeaderMalformed)
}
authHeaders, err := middleware.GetAuthHeaders(req.Context())
if err != nil {
return nil, errs.GetAPIError(errs.ErrAuthorizationHeaderMalformed)
}
currentCredentials := credentials.NewStaticCredentials(authHeaders.AccessKeyID, box.Gate.SecretKey, "")
seed, err := hex.DecodeString(authHeaders.SignatureV4)
if err != nil {
return nil, errs.GetAPIError(errs.ErrSignatureDoesNotMatch)
}
reqTime, err := middleware.GetClientTime(req.Context())
if err != nil {
return nil, errs.GetAPIError(errs.ErrMalformedDate)
}
newStreamSigner := v4.NewStreamSigner(authHeaders.Region, "s3", seed, currentCredentials)
return &s3ChunkReader{
reader: bufio.NewReader(req.Body),
streamSigner: newStreamSigner,
requestTime: reqTime,
buffer: make([]byte, 64*1024),
}, nil
}