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v2fly/transport/internet/kcp/io.go

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package kcp
import (
"crypto/cipher"
"crypto/rand"
"io"
"github.com/v2fly/v2ray-core/v5/common"
"github.com/v2fly/v2ray-core/v5/common/buf"
"github.com/v2fly/v2ray-core/v5/transport/internet"
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)
type PacketReader interface {
Read([]byte) []Segment
}
type PacketWriter interface {
Overhead() int
io.Writer
}
type KCPPacketReader struct { // nolint: revive
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Security cipher.AEAD
Header internet.PacketHeader
}
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func (r *KCPPacketReader) Read(b []byte) []Segment {
if r.Header != nil {
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if int32(len(b)) <= r.Header.Size() {
return nil
}
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b = b[r.Header.Size():]
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}
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if r.Security != nil {
nonceSize := r.Security.NonceSize()
overhead := r.Security.Overhead()
if len(b) <= nonceSize+overhead {
return nil
}
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out, err := r.Security.Open(b[nonceSize:nonceSize], b[:nonceSize], b[nonceSize:], nil)
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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 { // nolint: revive
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Header internet.PacketHeader
Security cipher.AEAD
Writer io.Writer
}
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func (w *KCPPacketWriter) Overhead() int {
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overhead := 0
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if w.Header != nil {
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overhead += int(w.Header.Size())
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}
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if w.Security != nil {
overhead += w.Security.Overhead()
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}
return overhead
}
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func (w *KCPPacketWriter) Write(b []byte) (int, error) {
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bb := buf.StackNew()
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defer bb.Release()
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if w.Header != nil {
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w.Header.Serialize(bb.Extend(w.Header.Size()))
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}
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if w.Security != nil {
nonceSize := w.Security.NonceSize()
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common.Must2(bb.ReadFullFrom(rand.Reader, int32(nonceSize)))
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nonce := bb.BytesFrom(int32(-nonceSize))
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encrypted := bb.Extend(int32(w.Security.Overhead() + len(b)))
w.Security.Seal(encrypted[:0], nonce, b, nil)
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} else {
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bb.Write(b)
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}
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_, err := w.Writer.Write(bb.Bytes())
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return len(b), err
}