package kcp import ( "hash/fnv" "github.com/v2ray/v2ray-core/common/alloc" "github.com/v2ray/v2ray-core/common/serial" ) type Authenticator interface { HeaderSize() int // Encrypt encrypts the whole block in src into dst. // Dst and src may point at the same memory. Seal(buffer *alloc.Buffer) // Decrypt decrypts the whole block in src into dst. // Dst and src may point at the same memory. Open(buffer *alloc.Buffer) bool } type SimpleAuthenticator struct{} func NewSimpleAuthenticator() Authenticator { return &SimpleAuthenticator{} } func (this *SimpleAuthenticator) HeaderSize() int { return 6 } func (this *SimpleAuthenticator) Seal(buffer *alloc.Buffer) { var length uint16 = uint16(buffer.Len()) buffer.Prepend(serial.Uint16ToBytes(length)) fnvHash := fnv.New32a() fnvHash.Write(buffer.Value) buffer.SliceBack(4) fnvHash.Sum(buffer.Value[:0]) len := buffer.Len() xtra := 4 - len%4 if xtra != 0 { buffer.Slice(0, len+xtra) } xorfwd(buffer.Value) if xtra != 0 { buffer.Slice(0, len) } } func (this *SimpleAuthenticator) Open(buffer *alloc.Buffer) bool { len := buffer.Len() xtra := 4 - len%4 if xtra != 0 { buffer.Slice(0, len+xtra) } xorbkd(buffer.Value) if xtra != 0 { buffer.Slice(0, len) } fnvHash := fnv.New32a() fnvHash.Write(buffer.Value[4:]) if serial.BytesToUint32(buffer.Value[:4]) != fnvHash.Sum32() { return false } length := serial.BytesToUint16(buffer.Value[4:6]) if buffer.Len()-6 != int(length) { return false } buffer.SliceFrom(6) return true }