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io.go
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io.go
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package kcp
import (
"crypto/cipher"
"crypto/rand"
"io"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/transport/internet"
)
type PacketReader interface {
Read([]byte) []Segment
}
type PacketWriter interface {
Overhead() int
io.Writer
}
type KCPPacketReader struct {
Security cipher.AEAD
Header internet.PacketHeader
}
func (r *KCPPacketReader) Read(b []byte) []Segment {
if r.Header != nil {
if int32(len(b)) <= r.Header.Size() {
return nil
}
b = b[r.Header.Size():]
}
if r.Security != nil {
nonceSize := r.Security.NonceSize()
overhead := r.Security.Overhead()
if len(b) <= nonceSize+overhead {
return nil
}
out, err := r.Security.Open(b[nonceSize:nonceSize], b[:nonceSize], b[nonceSize:], nil)
if err != nil {
return nil
}
b = out
}
var result []Segment
for len(b) > 0 {
seg, x := ReadSegment(b)
if seg == nil {
break
}
result = append(result, seg)
b = x
}
return result
}
type KCPPacketWriter struct {
Header internet.PacketHeader
Security cipher.AEAD
Writer io.Writer
}
func (w *KCPPacketWriter) Overhead() int {
overhead := 0
if w.Header != nil {
overhead += int(w.Header.Size())
}
if w.Security != nil {
overhead += w.Security.Overhead()
}
return overhead
}
func (w *KCPPacketWriter) Write(b []byte) (int, error) {
bb := buf.StackNew()
defer bb.Release()
if w.Header != nil {
w.Header.Serialize(bb.Extend(w.Header.Size()))
}
if w.Security != nil {
nonceSize := w.Security.NonceSize()
common.Must2(bb.ReadFullFrom(rand.Reader, int32(nonceSize)))
nonce := bb.BytesFrom(int32(-nonceSize))
encrypted := bb.Extend(int32(w.Security.Overhead() + len(b)))
w.Security.Seal(encrypted[:0], nonce, b, nil)
} else {
bb.Write(b)
}
_, err := w.Writer.Write(bb.Bytes())
return len(b), err
}