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p2p: remove lazy decompression, enforce 16MB limit

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This commit is contained in:
Péter Szilágyi 2017-09-08 16:22:06 +03:00
parent d0f783101d
commit db38c4dd31
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GPG key ID: E9AE538CEDF8293D
1 changed files with 14 additions and 24 deletions
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38
p2p/rlpx.go
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@ -70,6 +70,10 @@ const (
discWriteTimeout = 1 * time.Second discWriteTimeout = 1 * time.Second
) )
// errPlainMessageTooLarge is returned if a decompressed message length exceeds
// the allowed 24 bits (i.e. length >= 16MB).
var errPlainMessageTooLarge = errors.New("message length >= 16MB")
// rlpx is the transport protocol used by actual (non-test) connections. // rlpx is the transport protocol used by actual (non-test) connections.
// It wraps the frame encoder with locks and read/write deadlines. // It wraps the frame encoder with locks and read/write deadlines.
type rlpx struct { type rlpx struct {
@ -590,8 +594,11 @@ func newRLPXFrameRW(conn io.ReadWriter, s secrets) *rlpxFrameRW {
func (rw *rlpxFrameRW) WriteMsg(msg Msg) error { func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
ptype, _ := rlp.EncodeToBytes(msg.Code) ptype, _ := rlp.EncodeToBytes(msg.Code)
// if snappy compression is needed, do it now // if snappy is enabled, compress message now
if rw.snappy { if rw.snappy {
if msg.Size > maxUint24 {
return errPlainMessageTooLarge
}
payload, _ := ioutil.ReadAll(msg.Payload) payload, _ := ioutil.ReadAll(msg.Payload)
payload = snappy.Encode(nil, payload) payload = snappy.Encode(nil, payload)
@ -684,7 +691,7 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
msg.Size = uint32(content.Len()) msg.Size = uint32(content.Len())
msg.Payload = content msg.Payload = content
// if snappy compression was used, configure lazy decoder // if snappy is enabled, verify and decompress message
if rw.snappy { if rw.snappy {
payload, err := ioutil.ReadAll(msg.Payload) payload, err := ioutil.ReadAll(msg.Payload)
if err != nil { if err != nil {
@ -694,33 +701,16 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
if err != nil { if err != nil {
return msg, err return msg, err
} }
msg.Size = uint32(size) if size > int(maxUint24) {
msg.Payload = &snappyReader{payload: bytes.NewReader(payload)} return msg, errPlainMessageTooLarge
}
return msg, nil
}
// snappyReader is a lazy decompressor that expands a snappy encoded stream
// only upon first read request. This is useful to allow protocols to skip
// large messages without having to decode them (DOS protection).
type snappyReader struct {
payload io.Reader
decoded bool
}
func (r *snappyReader) Read(p []byte) (n int, err error) {
if !r.decoded {
payload, err := ioutil.ReadAll(r.payload)
if err != nil {
return 0, err
} }
payload, err = snappy.Decode(nil, payload) payload, err = snappy.Decode(nil, payload)
if err != nil { if err != nil {
return 0, err return msg, err
} }
r.payload, r.decoded = bytes.NewReader(payload), true msg.Size, msg.Payload = uint32(size), bytes.NewReader(payload)
} }
return r.payload.Read(p) return msg, nil
} }
// updateMAC reseeds the given hash with encrypted seed. // updateMAC reseeds the given hash with encrypted seed.