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validation.go
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validation.go
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package io
import (
"errors"
"hash/fnv"
"io"
"github.com/v2ray/v2ray-core/common/alloc"
"github.com/v2ray/v2ray-core/transport"
)
var (
TruncatedPayload = errors.New("Truncated payload.")
)
type ValidationReader struct {
reader io.Reader
buffer *alloc.Buffer
}
func NewValidationReader(reader io.Reader) *ValidationReader {
return &ValidationReader{
reader: reader,
buffer: alloc.NewLargeBuffer().Clear(),
}
}
func (this *ValidationReader) Read(data []byte) (int, error) {
nBytes, err := this.reader.Read(data)
if err != nil {
return nBytes, err
}
nBytesActual := 0
dataActual := data[:]
for {
payload, rest, err := parsePayload(data)
if err != nil {
return nBytesActual, err
}
copy(dataActual, payload)
nBytesActual += len(payload)
dataActual = dataActual[nBytesActual:]
if len(rest) == 0 {
break
}
data = rest
}
return nBytesActual, nil
}
func parsePayload(data []byte) (payload []byte, rest []byte, err error) {
dataLen := len(data)
if dataLen < 6 {
err = TruncatedPayload
return
}
payloadLen := int(data[0])<<8 + int(data[1])
if dataLen < payloadLen+6 {
err = TruncatedPayload
return
}
payload = data[6 : 6+payloadLen]
rest = data[6+payloadLen:]
fnv1a := fnv.New32a()
fnv1a.Write(payload)
actualHash := fnv1a.Sum32()
expectedHash := uint32(data[2])<<24 + uint32(data[3])<<16 + uint32(data[4])<<8 + uint32(data[5])
if actualHash != expectedHash {
err = transport.CorruptedPacket
return
}
return
}