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2017-10-24 22:53:20 +08:00
parent 0559865fe5
commit 9e0fd0c4ef
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24
vendor/github.com/fatedier/kcp-go/.gitignore generated vendored Normal file
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# Compiled Object files, Static and Dynamic libs (Shared Objects)
*.o
*.a
*.so
# Folders
_obj
_test
# Architecture specific extensions/prefixes
*.[568vq]
[568vq].out
*.cgo1.go
*.cgo2.c
_cgo_defun.c
_cgo_gotypes.go
_cgo_export.*
_testmain.go
*.exe
*.test
*.prof

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vendor/github.com/fatedier/kcp-go/.travis.yml generated vendored Normal file
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language: go
go:
- 1.9
before_install:
- go get -t -v ./...
install:
- go get github.com/xtaci/kcp-go
script:
- go test -coverprofile=coverage.txt -covermode=atomic -bench .
after_success:
- bash <(curl -s https://codecov.io/bash)

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vendor/github.com/fatedier/kcp-go/LICENSE generated vendored Normal file
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The MIT License (MIT)
Copyright (c) 2015 Daniel Fu
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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vendor/github.com/fatedier/kcp-go/README.md generated vendored Normal file
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<img src="kcp-go.png" alt="kcp-go" height="50px" />
[![GoDoc][1]][2] [![Powered][9]][10] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Coverage Statusd][7]][8]
[1]: https://godoc.org/github.com/xtaci/kcp-go?status.svg
[2]: https://godoc.org/github.com/xtaci/kcp-go
[3]: https://travis-ci.org/xtaci/kcp-go.svg?branch=master
[4]: https://travis-ci.org/xtaci/kcp-go
[5]: https://goreportcard.com/badge/github.com/xtaci/kcp-go
[6]: https://goreportcard.com/report/github.com/xtaci/kcp-go
[7]: https://codecov.io/gh/xtaci/kcp-go/branch/master/graph/badge.svg
[8]: https://codecov.io/gh/xtaci/kcp-go
[9]: https://img.shields.io/badge/KCP-Powered-blue.svg
[10]: https://github.com/skywind3000/kcp
[11]: https://img.shields.io/badge/license-MIT-blue.svg
[12]: LICENSE
## Introduction
**kcp-go** is a **Production-Grade Reliable-UDP** library for [golang](https://golang.org/).
It provides **fast, ordered and error-checked** delivery of streams over **UDP** packets, has been well tested with opensource project [kcptun](https://github.com/xtaci/kcptun). Millions of devices(from low-end MIPS routers to high-end servers) are running with **kcp-go** at present, including applications like **online games, live broadcasting, file synchronization and network acceleration**.
[Lastest Release](https://github.com/xtaci/kcp-go/releases)
## Features
1. Optimized for **Realtime Online Games, Audio/Video Streaming and Latency-Sensitive Distributed Consensus**.
1. Compatible with [skywind3000's](https://github.com/skywind3000) C version with language specific optimizations.
1. **Cache friendly** and **Memory optimized** design, offers extremely **High Performance** core.
1. Handles **>5K concurrent connections** on a single commodity server.
1. Compatible with [net.Conn](https://golang.org/pkg/net/#Conn) and [net.Listener](https://golang.org/pkg/net/#Listener), a drop-in replacement for [net.TCPConn](https://golang.org/pkg/net/#TCPConn).
1. [FEC(Forward Error Correction)](https://en.wikipedia.org/wiki/Forward_error_correction) Support with [Reed-Solomon Codes](https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction)
1. Packet level encryption support with [AES](https://en.wikipedia.org/wiki/Advanced_Encryption_Standard), [TEA](https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm), [3DES](https://en.wikipedia.org/wiki/Triple_DES), [Blowfish](https://en.wikipedia.org/wiki/Blowfish_(cipher)), [Cast5](https://en.wikipedia.org/wiki/CAST-128), [Salsa20]( https://en.wikipedia.org/wiki/Salsa20), etc. in [CFB](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Feedback_.28CFB.29) mode.
1. **Fixed number of goroutines** created for the entire server application, minimized goroutine context switch.
## Conventions
Control messages like **SYN/FIN/RST** in TCP **are not defined** in KCP, you need some **keepalive/heartbeat mechanism** in the application-level. A real world example is to use some **multiplexing** protocol over session, such as [smux](https://github.com/xtaci/smux)(with embedded keepalive mechanism), see [kcptun](https://github.com/xtaci/kcptun) for example.
## Documentation
For complete documentation, see the associated [Godoc](https://godoc.org/github.com/xtaci/kcp-go).
## Specification
<img src="frame.png" alt="Frame Format" height="109px" />
```
+-----------------+
| SESSION |
+-----------------+
| KCP(ARQ) |
+-----------------+
| FEC(OPTIONAL) |
+-----------------+
| CRYPTO(OPTIONAL)|
+-----------------+
| UDP(PACKET) |
+-----------------+
| IP |
+-----------------+
| LINK |
+-----------------+
| PHY |
+-----------------+
(LAYER MODEL OF KCP-GO)
```
## Usage
Client: [full demo](https://github.com/xtaci/kcptun/blob/master/client/main.go)
```go
kcpconn, err := kcp.DialWithOptions("192.168.0.1:10000", nil, 10, 3)
```
Server: [full demo](https://github.com/xtaci/kcptun/blob/master/server/main.go)
```go
lis, err := kcp.ListenWithOptions(":10000", nil, 10, 3)
```
## Performance
```
Model Name: MacBook Pro
Model Identifier: MacBookPro12,1
Processor Name: Intel Core i5
Processor Speed: 2.7 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache (per Core): 256 KB
L3 Cache: 3 MB
Memory: 8 GB
```
```
$ go test -v -run=^$ -bench .
beginning tests, encryption:salsa20, fec:10/3
BenchmarkAES128-4 200000 8256 ns/op 363.33 MB/s 0 B/op 0 allocs/op
BenchmarkAES192-4 200000 9153 ns/op 327.74 MB/s 0 B/op 0 allocs/op
BenchmarkAES256-4 200000 10079 ns/op 297.64 MB/s 0 B/op 0 allocs/op
BenchmarkTEA-4 100000 18643 ns/op 160.91 MB/s 0 B/op 0 allocs/op
BenchmarkXOR-4 5000000 316 ns/op 9486.46 MB/s 0 B/op 0 allocs/op
BenchmarkBlowfish-4 50000 35643 ns/op 84.17 MB/s 0 B/op 0 allocs/op
BenchmarkNone-4 30000000 56.2 ns/op 53371.83 MB/s 0 B/op 0 allocs/op
BenchmarkCast5-4 30000 44744 ns/op 67.05 MB/s 0 B/op 0 allocs/op
Benchmark3DES-4 2000 639839 ns/op 4.69 MB/s 2 B/op 0 allocs/op
BenchmarkTwofish-4 30000 43368 ns/op 69.17 MB/s 0 B/op 0 allocs/op
BenchmarkXTEA-4 30000 57673 ns/op 52.02 MB/s 0 B/op 0 allocs/op
BenchmarkSalsa20-4 300000 3917 ns/op 765.80 MB/s 0 B/op 0 allocs/op
BenchmarkFlush-4 10000000 226 ns/op 0 B/op 0 allocs/op
BenchmarkEchoSpeed4K-4 5000 300030 ns/op 13.65 MB/s 5672 B/op 177 allocs/op
BenchmarkEchoSpeed64K-4 500 3202335 ns/op 20.47 MB/s 73295 B/op 2198 allocs/op
BenchmarkEchoSpeed512K-4 50 24926924 ns/op 21.03 MB/s 659339 B/op 17602 allocs/op
BenchmarkEchoSpeed1M-4 20 64857821 ns/op 16.17 MB/s 1772437 B/op 42869 allocs/op
BenchmarkSinkSpeed4K-4 30000 50230 ns/op 81.54 MB/s 2058 B/op 48 allocs/op
BenchmarkSinkSpeed64K-4 2000 648718 ns/op 101.02 MB/s 31165 B/op 687 allocs/op
BenchmarkSinkSpeed256K-4 300 4635905 ns/op 113.09 MB/s 286229 B/op 5516 allocs/op
BenchmarkSinkSpeed1M-4 200 9566933 ns/op 109.60 MB/s 463771 B/op 10701 allocs/op
PASS
ok _/Users/xtaci/.godeps/src/github.com/xtaci/kcp-go 39.689s
```
## Design Considerations
1. slice vs. container/list
`kcp.flush()` loops through the send queue for retransmission checking for every 20ms(interval).
I've wrote a benchmark for comparing sequential loop through *slice* and *container/list* here:
https://github.com/xtaci/notes/blob/master/golang/benchmark2/cachemiss_test.go
```
BenchmarkLoopSlice-4 2000000000 0.39 ns/op
BenchmarkLoopList-4 100000000 54.6 ns/op
```
List structure introduces **heavy cache misses** compared to slice which owns better **locality**, 5000 connections with 32 window size and 20ms interval will cost 6us/0.03%(cpu) using slice, and 8.7ms/43.5%(cpu) for list for each `kcp.flush()`.
2. Timing accuracy vs. syscall clock_gettime
Timing is **critical** to **RTT estimator**, inaccurate timing introduces false retransmissions in KCP, but calling `time.Now()` costs 42 cycles(10.5ns on 4GHz CPU, 15.6ns on my MacBook Pro 2.7GHz), the benchmark for time.Now():
https://github.com/xtaci/notes/blob/master/golang/benchmark2/syscall_test.go
```
BenchmarkNow-4 100000000 15.6 ns/op
```
In kcp-go, after each `kcp.output()` function call, current time will be updated upon return, and each `kcp.flush()` will get current time once. For most of the time, 5000 connections costs 5000 * 15.6ns = 78us(no packet needs to be sent by `kcp.output()`), as for 10MB/s data transfering with 1400 MTU, `kcp.output()` will be called around 7500 times and costs 117us for `time.Now()` in **every second**.
## Tuning
Q: I'm handling >5K connections on my server. the CPU utilization is high.
A: A standalone `agent` or `gate` server for kcp-go is suggested, not only for CPU utilization, but also important to the **precision** of RTT measurements which indirectly affects retransmission. By increasing update `interval` with `SetNoDelay` like `conn.SetNoDelay(1, 40, 1, 1)` will dramatically reduce system load.
## Who is using this?
1. https://github.com/xtaci/kcptun -- A Secure Tunnel Based On KCP over UDP.
2. https://github.com/getlantern/lantern -- Lantern delivers fast access to the open Internet.
3. https://github.com/smallnest/rpcx -- A RPC service framework based on net/rpc like alibaba Dubbo and weibo Motan.
4. https://github.com/gonet2/agent -- A gateway for games with stream multiplexing.
5. https://github.com/syncthing/syncthing -- Open Source Continuous File Synchronization.
6. https://play.google.com/store/apps/details?id=com.k17game.k3 -- Battle Zone - Earth 2048, a world-wide strategy game.
## Links
1. https://github.com/xtaci/libkcp -- FEC enhanced KCP session library for iOS/Android in C++
2. https://github.com/skywind3000/kcp -- A Fast and Reliable ARQ Protocol
3. https://github.com/templexxx/reedsolomon -- Reed-Solomon Erasure Coding in Go

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package kcp
import (
"crypto/aes"
"crypto/cipher"
"crypto/des"
"crypto/sha1"
"github.com/templexxx/xor"
"github.com/tjfoc/gmsm/sm4"
"golang.org/x/crypto/blowfish"
"golang.org/x/crypto/cast5"
"golang.org/x/crypto/pbkdf2"
"golang.org/x/crypto/salsa20"
"golang.org/x/crypto/tea"
"golang.org/x/crypto/twofish"
"golang.org/x/crypto/xtea"
)
var (
initialVector = []byte{167, 115, 79, 156, 18, 172, 27, 1, 164, 21, 242, 193, 252, 120, 230, 107}
saltxor = `sH3CIVoF#rWLtJo6`
)
// BlockCrypt defines encryption/decryption methods for a given byte slice.
// Notes on implementing: the data to be encrypted contains a builtin
// nonce at the first 16 bytes
type BlockCrypt interface {
// Encrypt encrypts the whole block in src into dst.
// Dst and src may point at the same memory.
Encrypt(dst, src []byte)
// Decrypt decrypts the whole block in src into dst.
// Dst and src may point at the same memory.
Decrypt(dst, src []byte)
}
type salsa20BlockCrypt struct {
key [32]byte
}
// NewSalsa20BlockCrypt https://en.wikipedia.org/wiki/Salsa20
func NewSalsa20BlockCrypt(key []byte) (BlockCrypt, error) {
c := new(salsa20BlockCrypt)
copy(c.key[:], key)
return c, nil
}
func (c *salsa20BlockCrypt) Encrypt(dst, src []byte) {
salsa20.XORKeyStream(dst[8:], src[8:], src[:8], &c.key)
copy(dst[:8], src[:8])
}
func (c *salsa20BlockCrypt) Decrypt(dst, src []byte) {
salsa20.XORKeyStream(dst[8:], src[8:], src[:8], &c.key)
copy(dst[:8], src[:8])
}
type sm4BlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewSM4BlockCrypt https://github.com/tjfoc/gmsm/tree/master/sm4
func NewSM4BlockCrypt(key []byte) (BlockCrypt, error) {
c := new(sm4BlockCrypt)
block, err := sm4.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, sm4.BlockSize)
c.decbuf = make([]byte, 2*sm4.BlockSize)
return c, nil
}
func (c *sm4BlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *sm4BlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type twofishBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewTwofishBlockCrypt https://en.wikipedia.org/wiki/Twofish
func NewTwofishBlockCrypt(key []byte) (BlockCrypt, error) {
c := new(twofishBlockCrypt)
block, err := twofish.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, twofish.BlockSize)
c.decbuf = make([]byte, 2*twofish.BlockSize)
return c, nil
}
func (c *twofishBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *twofishBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type tripleDESBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewTripleDESBlockCrypt https://en.wikipedia.org/wiki/Triple_DES
func NewTripleDESBlockCrypt(key []byte) (BlockCrypt, error) {
c := new(tripleDESBlockCrypt)
block, err := des.NewTripleDESCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, des.BlockSize)
c.decbuf = make([]byte, 2*des.BlockSize)
return c, nil
}
func (c *tripleDESBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *tripleDESBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type cast5BlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewCast5BlockCrypt https://en.wikipedia.org/wiki/CAST-128
func NewCast5BlockCrypt(key []byte) (BlockCrypt, error) {
c := new(cast5BlockCrypt)
block, err := cast5.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, cast5.BlockSize)
c.decbuf = make([]byte, 2*cast5.BlockSize)
return c, nil
}
func (c *cast5BlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *cast5BlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type blowfishBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewBlowfishBlockCrypt https://en.wikipedia.org/wiki/Blowfish_(cipher)
func NewBlowfishBlockCrypt(key []byte) (BlockCrypt, error) {
c := new(blowfishBlockCrypt)
block, err := blowfish.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, blowfish.BlockSize)
c.decbuf = make([]byte, 2*blowfish.BlockSize)
return c, nil
}
func (c *blowfishBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *blowfishBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type aesBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewAESBlockCrypt https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
func NewAESBlockCrypt(key []byte) (BlockCrypt, error) {
c := new(aesBlockCrypt)
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, aes.BlockSize)
c.decbuf = make([]byte, 2*aes.BlockSize)
return c, nil
}
func (c *aesBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *aesBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type teaBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewTEABlockCrypt https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm
func NewTEABlockCrypt(key []byte) (BlockCrypt, error) {
c := new(teaBlockCrypt)
block, err := tea.NewCipherWithRounds(key, 16)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, tea.BlockSize)
c.decbuf = make([]byte, 2*tea.BlockSize)
return c, nil
}
func (c *teaBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *teaBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type xteaBlockCrypt struct {
encbuf []byte
decbuf []byte
block cipher.Block
}
// NewXTEABlockCrypt https://en.wikipedia.org/wiki/XTEA
func NewXTEABlockCrypt(key []byte) (BlockCrypt, error) {
c := new(xteaBlockCrypt)
block, err := xtea.NewCipher(key)
if err != nil {
return nil, err
}
c.block = block
c.encbuf = make([]byte, xtea.BlockSize)
c.decbuf = make([]byte, 2*xtea.BlockSize)
return c, nil
}
func (c *xteaBlockCrypt) Encrypt(dst, src []byte) { encrypt(c.block, dst, src, c.encbuf) }
func (c *xteaBlockCrypt) Decrypt(dst, src []byte) { decrypt(c.block, dst, src, c.decbuf) }
type simpleXORBlockCrypt struct {
xortbl []byte
}
// NewSimpleXORBlockCrypt simple xor with key expanding
func NewSimpleXORBlockCrypt(key []byte) (BlockCrypt, error) {
c := new(simpleXORBlockCrypt)
c.xortbl = pbkdf2.Key(key, []byte(saltxor), 32, mtuLimit, sha1.New)
return c, nil
}
func (c *simpleXORBlockCrypt) Encrypt(dst, src []byte) { xor.Bytes(dst, src, c.xortbl) }
func (c *simpleXORBlockCrypt) Decrypt(dst, src []byte) { xor.Bytes(dst, src, c.xortbl) }
type noneBlockCrypt struct{}
// NewNoneBlockCrypt does nothing but copying
func NewNoneBlockCrypt(key []byte) (BlockCrypt, error) {
return new(noneBlockCrypt), nil
}
func (c *noneBlockCrypt) Encrypt(dst, src []byte) { copy(dst, src) }
func (c *noneBlockCrypt) Decrypt(dst, src []byte) { copy(dst, src) }
// packet encryption with local CFB mode
func encrypt(block cipher.Block, dst, src, buf []byte) {
blocksize := block.BlockSize()
tbl := buf[:blocksize]
block.Encrypt(tbl, initialVector)
n := len(src) / blocksize
base := 0
for i := 0; i < n; i++ {
xor.BytesSrc1(dst[base:], src[base:], tbl)
block.Encrypt(tbl, dst[base:])
base += blocksize
}
xor.BytesSrc0(dst[base:], src[base:], tbl)
}
func decrypt(block cipher.Block, dst, src, buf []byte) {
blocksize := block.BlockSize()
tbl := buf[:blocksize]
next := buf[blocksize:]
block.Encrypt(tbl, initialVector)
n := len(src) / blocksize
base := 0
for i := 0; i < n; i++ {
block.Encrypt(next, src[base:])
xor.BytesSrc1(dst[base:], src[base:], tbl)
tbl, next = next, tbl
base += blocksize
}
xor.BytesSrc0(dst[base:], src[base:], tbl)
}

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package kcp
import (
"encoding/binary"
"sync/atomic"
"github.com/templexxx/reedsolomon"
)
const (
fecHeaderSize = 6
fecHeaderSizePlus2 = fecHeaderSize + 2 // plus 2B data size
typeData = 0xf1
typeFEC = 0xf2
)
type (
// fecPacket is a decoded FEC packet
fecPacket struct {
seqid uint32
flag uint16
data []byte
}
// fecDecoder for decoding incoming packets
fecDecoder struct {
rxlimit int // queue size limit
dataShards int
parityShards int
shardSize int
rx []fecPacket // ordered receive queue
// caches
decodeCache [][]byte
flagCache []bool
// RS decoder
codec reedsolomon.Encoder
}
)
func newFECDecoder(rxlimit, dataShards, parityShards int) *fecDecoder {
if dataShards <= 0 || parityShards <= 0 {
return nil
}
if rxlimit < dataShards+parityShards {
return nil
}
fec := new(fecDecoder)
fec.rxlimit = rxlimit
fec.dataShards = dataShards
fec.parityShards = parityShards
fec.shardSize = dataShards + parityShards
enc, err := reedsolomon.New(dataShards, parityShards)
if err != nil {
return nil
}
fec.codec = enc
fec.decodeCache = make([][]byte, fec.shardSize)
fec.flagCache = make([]bool, fec.shardSize)
return fec
}
// decodeBytes a fec packet
func (dec *fecDecoder) decodeBytes(data []byte) fecPacket {
var pkt fecPacket
pkt.seqid = binary.LittleEndian.Uint32(data)
pkt.flag = binary.LittleEndian.Uint16(data[4:])
// allocate memory & copy
buf := xmitBuf.Get().([]byte)[:len(data)-6]
copy(buf, data[6:])
pkt.data = buf
return pkt
}
// decode a fec packet
func (dec *fecDecoder) decode(pkt fecPacket) (recovered [][]byte) {
// insertion
n := len(dec.rx) - 1
insertIdx := 0
for i := n; i >= 0; i-- {
if pkt.seqid == dec.rx[i].seqid { // de-duplicate
xmitBuf.Put(pkt.data)
return nil
} else if _itimediff(pkt.seqid, dec.rx[i].seqid) > 0 { // insertion
insertIdx = i + 1
break
}
}
// insert into ordered rx queue
if insertIdx == n+1 {
dec.rx = append(dec.rx, pkt)
} else {
dec.rx = append(dec.rx, fecPacket{})
copy(dec.rx[insertIdx+1:], dec.rx[insertIdx:]) // shift right
dec.rx[insertIdx] = pkt
}
// shard range for current packet
shardBegin := pkt.seqid - pkt.seqid%uint32(dec.shardSize)
shardEnd := shardBegin + uint32(dec.shardSize) - 1
// max search range in ordered queue for current shard
searchBegin := insertIdx - int(pkt.seqid%uint32(dec.shardSize))
if searchBegin < 0 {
searchBegin = 0
}
searchEnd := searchBegin + dec.shardSize - 1
if searchEnd >= len(dec.rx) {
searchEnd = len(dec.rx) - 1
}
// re-construct datashards
if searchEnd-searchBegin+1 >= dec.dataShards {
var numshard, numDataShard, first, maxlen int
// zero cache
shards := dec.decodeCache
shardsflag := dec.flagCache
for k := range dec.decodeCache {
shards[k] = nil
shardsflag[k] = false
}
// shard assembly
for i := searchBegin; i <= searchEnd; i++ {
seqid := dec.rx[i].seqid
if _itimediff(seqid, shardEnd) > 0 {
break
} else if _itimediff(seqid, shardBegin) >= 0 {
shards[seqid%uint32(dec.shardSize)] = dec.rx[i].data
shardsflag[seqid%uint32(dec.shardSize)] = true
numshard++
if dec.rx[i].flag == typeData {
numDataShard++
}
if numshard == 1 {
first = i
}
if len(dec.rx[i].data) > maxlen {
maxlen = len(dec.rx[i].data)
}
}
}
if numDataShard == dec.dataShards {
// case 1: no lost data shards
dec.rx = dec.freeRange(first, numshard, dec.rx)
} else if numshard >= dec.dataShards {
// case 2: data shard lost, but recoverable from parity shard
for k := range shards {
if shards[k] != nil {
dlen := len(shards[k])
shards[k] = shards[k][:maxlen]
xorBytes(shards[k][dlen:], shards[k][dlen:], shards[k][dlen:])
}
}
if err := dec.codec.ReconstructData(shards); err == nil {
for k := range shards[:dec.dataShards] {
if !shardsflag[k] {
recovered = append(recovered, shards[k])
}
}
}
dec.rx = dec.freeRange(first, numshard, dec.rx)
}
}
// keep rxlimit
if len(dec.rx) > dec.rxlimit {
if dec.rx[0].flag == typeData { // record unrecoverable data
atomic.AddUint64(&DefaultSnmp.FECShortShards, 1)
}
dec.rx = dec.freeRange(0, 1, dec.rx)
}
return
}
// free a range of fecPacket, and zero for GC recycling
func (dec *fecDecoder) freeRange(first, n int, q []fecPacket) []fecPacket {
for i := first; i < first+n; i++ { // free
xmitBuf.Put(q[i].data)
}
copy(q[first:], q[first+n:])
for i := 0; i < n; i++ { // dereference data
q[len(q)-1-i].data = nil
}
return q[:len(q)-n]
}
type (
// fecEncoder for encoding outgoing packets
fecEncoder struct {
dataShards int
parityShards int
shardSize int
paws uint32 // Protect Against Wrapped Sequence numbers
next uint32 // next seqid
shardCount int // count the number of datashards collected
maxSize int // record maximum data length in datashard
headerOffset int // FEC header offset
payloadOffset int // FEC payload offset
// caches
shardCache [][]byte
encodeCache [][]byte
// RS encoder
codec reedsolomon.Encoder
}
)
func newFECEncoder(dataShards, parityShards, offset int) *fecEncoder {
if dataShards <= 0 || parityShards <= 0 {
return nil
}
fec := new(fecEncoder)
fec.dataShards = dataShards
fec.parityShards = parityShards
fec.shardSize = dataShards + parityShards
fec.paws = (0xffffffff/uint32(fec.shardSize) - 1) * uint32(fec.shardSize)
fec.headerOffset = offset
fec.payloadOffset = fec.headerOffset + fecHeaderSize
enc, err := reedsolomon.New(dataShards, parityShards)
if err != nil {
return nil
}
fec.codec = enc
// caches
fec.encodeCache = make([][]byte, fec.shardSize)
fec.shardCache = make([][]byte, fec.shardSize)
for k := range fec.shardCache {
fec.shardCache[k] = make([]byte, mtuLimit)
}
return fec
}
// encode the packet, output parity shards if we have enough datashards
// the content of returned parityshards will change in next encode
func (enc *fecEncoder) encode(b []byte) (ps [][]byte) {
enc.markData(b[enc.headerOffset:])
binary.LittleEndian.PutUint16(b[enc.payloadOffset:], uint16(len(b[enc.payloadOffset:])))
// copy data to fec datashards
sz := len(b)
enc.shardCache[enc.shardCount] = enc.shardCache[enc.shardCount][:sz]
copy(enc.shardCache[enc.shardCount], b)
enc.shardCount++
// record max datashard length
if sz > enc.maxSize {
enc.maxSize = sz
}
// calculate Reed-Solomon Erasure Code
if enc.shardCount == enc.dataShards {
// bzero each datashard's tail
for i := 0; i < enc.dataShards; i++ {
shard := enc.shardCache[i]
slen := len(shard)
xorBytes(shard[slen:enc.maxSize], shard[slen:enc.maxSize], shard[slen:enc.maxSize])
}
// construct equal-sized slice with stripped header
cache := enc.encodeCache
for k := range cache {
cache[k] = enc.shardCache[k][enc.payloadOffset:enc.maxSize]
}
// rs encode
if err := enc.codec.Encode(cache); err == nil {
ps = enc.shardCache[enc.dataShards:]
for k := range ps {
enc.markFEC(ps[k][enc.headerOffset:])
ps[k] = ps[k][:enc.maxSize]
}
}
// reset counters to zero
enc.shardCount = 0
enc.maxSize = 0
}
return
}
func (enc *fecEncoder) markData(data []byte) {
binary.LittleEndian.PutUint32(data, enc.next)
binary.LittleEndian.PutUint16(data[4:], typeData)
enc.next++
}
func (enc *fecEncoder) markFEC(data []byte) {
binary.LittleEndian.PutUint32(data, enc.next)
binary.LittleEndian.PutUint16(data[4:], typeFEC)
enc.next = (enc.next + 1) % enc.paws
}

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// Package kcp - A Fast and Reliable ARQ Protocol
package kcp
import (
"encoding/binary"
"sync/atomic"
)
const (
IKCP_RTO_NDL = 30 // no delay min rto
IKCP_RTO_MIN = 100 // normal min rto
IKCP_RTO_DEF = 200
IKCP_RTO_MAX = 60000
IKCP_CMD_PUSH = 81 // cmd: push data
IKCP_CMD_ACK = 82 // cmd: ack
IKCP_CMD_WASK = 83 // cmd: window probe (ask)
IKCP_CMD_WINS = 84 // cmd: window size (tell)
IKCP_ASK_SEND = 1 // need to send IKCP_CMD_WASK
IKCP_ASK_TELL = 2 // need to send IKCP_CMD_WINS
IKCP_WND_SND = 32
IKCP_WND_RCV = 32
IKCP_MTU_DEF = 1400
IKCP_ACK_FAST = 3
IKCP_INTERVAL = 100
IKCP_OVERHEAD = 24
IKCP_DEADLINK = 20
IKCP_THRESH_INIT = 2
IKCP_THRESH_MIN = 2
IKCP_PROBE_INIT = 7000 // 7 secs to probe window size
IKCP_PROBE_LIMIT = 120000 // up to 120 secs to probe window
)
// output_callback is a prototype which ought capture conn and call conn.Write
type output_callback func(buf []byte, size int)
/* encode 8 bits unsigned int */
func ikcp_encode8u(p []byte, c byte) []byte {
p[0] = c
return p[1:]
}
/* decode 8 bits unsigned int */
func ikcp_decode8u(p []byte, c *byte) []byte {
*c = p[0]
return p[1:]
}
/* encode 16 bits unsigned int (lsb) */
func ikcp_encode16u(p []byte, w uint16) []byte {
binary.LittleEndian.PutUint16(p, w)
return p[2:]
}
/* decode 16 bits unsigned int (lsb) */
func ikcp_decode16u(p []byte, w *uint16) []byte {
*w = binary.LittleEndian.Uint16(p)
return p[2:]
}
/* encode 32 bits unsigned int (lsb) */
func ikcp_encode32u(p []byte, l uint32) []byte {
binary.LittleEndian.PutUint32(p, l)
return p[4:]
}
/* decode 32 bits unsigned int (lsb) */
func ikcp_decode32u(p []byte, l *uint32) []byte {
*l = binary.LittleEndian.Uint32(p)
return p[4:]
}
func _imin_(a, b uint32) uint32 {
if a <= b {
return a
}
return b
}
func _imax_(a, b uint32) uint32 {
if a >= b {
return a
}
return b
}
func _ibound_(lower, middle, upper uint32) uint32 {
return _imin_(_imax_(lower, middle), upper)
}
func _itimediff(later, earlier uint32) int32 {
return (int32)(later - earlier)
}
// segment defines a KCP segment
type segment struct {
conv uint32
cmd uint8
frg uint8
wnd uint16
ts uint32
sn uint32
una uint32
rto uint32
xmit uint32
resendts uint32
fastack uint32
data []byte
}
// encode a segment into buffer
func (seg *segment) encode(ptr []byte) []byte {
ptr = ikcp_encode32u(ptr, seg.conv)
ptr = ikcp_encode8u(ptr, seg.cmd)
ptr = ikcp_encode8u(ptr, seg.frg)
ptr = ikcp_encode16u(ptr, seg.wnd)
ptr = ikcp_encode32u(ptr, seg.ts)
ptr = ikcp_encode32u(ptr, seg.sn)
ptr = ikcp_encode32u(ptr, seg.una)
ptr = ikcp_encode32u(ptr, uint32(len(seg.data)))
atomic.AddUint64(&DefaultSnmp.OutSegs, 1)
return ptr
}
// KCP defines a single KCP connection
type KCP struct {
conv, mtu, mss, state uint32
snd_una, snd_nxt, rcv_nxt uint32
ssthresh uint32
rx_rttvar, rx_srtt int32
rx_rto, rx_minrto uint32
snd_wnd, rcv_wnd, rmt_wnd, cwnd, probe uint32
interval, ts_flush uint32
nodelay, updated uint32
ts_probe, probe_wait uint32
dead_link, incr uint32
fastresend int32
nocwnd, stream int32
snd_queue []segment
rcv_queue []segment
snd_buf []segment
rcv_buf []segment
acklist []ackItem
buffer []byte
output output_callback
}
type ackItem struct {
sn uint32
ts uint32
}
// NewKCP create a new kcp control object, 'conv' must equal in two endpoint
// from the same connection.
func NewKCP(conv uint32, output output_callback) *KCP {
kcp := new(KCP)
kcp.conv = conv
kcp.snd_wnd = IKCP_WND_SND
kcp.rcv_wnd = IKCP_WND_RCV
kcp.rmt_wnd = IKCP_WND_RCV
kcp.mtu = IKCP_MTU_DEF
kcp.mss = kcp.mtu - IKCP_OVERHEAD
kcp.buffer = make([]byte, (kcp.mtu+IKCP_OVERHEAD)*3)
kcp.rx_rto = IKCP_RTO_DEF
kcp.rx_minrto = IKCP_RTO_MIN
kcp.interval = IKCP_INTERVAL
kcp.ts_flush = IKCP_INTERVAL
kcp.ssthresh = IKCP_THRESH_INIT
kcp.dead_link = IKCP_DEADLINK
kcp.output = output
return kcp
}
// newSegment creates a KCP segment
func (kcp *KCP) newSegment(size int) (seg segment) {
seg.data = xmitBuf.Get().([]byte)[:size]
return
}
// delSegment recycles a KCP segment
func (kcp *KCP) delSegment(seg segment) {
xmitBuf.Put(seg.data)
}
// PeekSize checks the size of next message in the recv queue
func (kcp *KCP) PeekSize() (length int) {
if len(kcp.rcv_queue) == 0 {
return -1
}
seg := &kcp.rcv_queue[0]
if seg.frg == 0 {
return len(seg.data)
}
if len(kcp.rcv_queue) < int(seg.frg+1) {
return -1
}
for k := range kcp.rcv_queue {
seg := &kcp.rcv_queue[k]
length += len(seg.data)
if seg.frg == 0 {
break
}
}
return
}
// Recv is user/upper level recv: returns size, returns below zero for EAGAIN
func (kcp *KCP) Recv(buffer []byte) (n int) {
if len(kcp.rcv_queue) == 0 {
return -1
}
peeksize := kcp.PeekSize()
if peeksize < 0 {
return -2
}
if peeksize > len(buffer) {
return -3
}
var fast_recover bool
if len(kcp.rcv_queue) >= int(kcp.rcv_wnd) {
fast_recover = true
}
// merge fragment
count := 0
for k := range kcp.rcv_queue {
seg := &kcp.rcv_queue[k]
copy(buffer, seg.data)
buffer = buffer[len(seg.data):]
n += len(seg.data)
count++
kcp.delSegment(*seg)
if seg.frg == 0 {
break
}
}
if count > 0 {
kcp.rcv_queue = kcp.remove_front(kcp.rcv_queue, count)
}
// move available data from rcv_buf -> rcv_queue
count = 0
for k := range kcp.rcv_buf {
seg := &kcp.rcv_buf[k]
if seg.sn == kcp.rcv_nxt && len(kcp.rcv_queue) < int(kcp.rcv_wnd) {
kcp.rcv_nxt++
count++
} else {
break
}
}
if count > 0 {
kcp.rcv_queue = append(kcp.rcv_queue, kcp.rcv_buf[:count]...)
kcp.rcv_buf = kcp.remove_front(kcp.rcv_buf, count)
}
// fast recover
if len(kcp.rcv_queue) < int(kcp.rcv_wnd) && fast_recover {
// ready to send back IKCP_CMD_WINS in ikcp_flush
// tell remote my window size
kcp.probe |= IKCP_ASK_TELL
}
return
}
// Send is user/upper level send, returns below zero for error
func (kcp *KCP) Send(buffer []byte) int {
var count int
if len(buffer) == 0 {
return -1
}
// append to previous segment in streaming mode (if possible)
if kcp.stream != 0 {
n := len(kcp.snd_queue)
if n > 0 {
seg := &kcp.snd_queue[n-1]
if len(seg.data) < int(kcp.mss) {
capacity := int(kcp.mss) - len(seg.data)
extend := capacity
if len(buffer) < capacity {
extend = len(buffer)
}
// grow slice, the underlying cap is guaranteed to
// be larger than kcp.mss
oldlen := len(seg.data)
seg.data = seg.data[:oldlen+extend]
copy(seg.data[oldlen:], buffer)
buffer = buffer[extend:]
}
}
if len(buffer) == 0 {
return 0
}
}
if len(buffer) <= int(kcp.mss) {
count = 1
} else {
count = (len(buffer) + int(kcp.mss) - 1) / int(kcp.mss)
}
if count > 255 {
return -2
}
if count == 0 {
count = 1
}
for i := 0; i < count; i++ {
var size int
if len(buffer) > int(kcp.mss) {
size = int(kcp.mss)
} else {
size = len(buffer)
}
seg := kcp.newSegment(size)
copy(seg.data, buffer[:size])
if kcp.stream == 0 { // message mode
seg.frg = uint8(count - i - 1)
} else { // stream mode
seg.frg = 0
}
kcp.snd_queue = append(kcp.snd_queue, seg)
buffer = buffer[size:]
}
return 0
}
func (kcp *KCP) update_ack(rtt int32) {
// https://tools.ietf.org/html/rfc6298
var rto uint32
if kcp.rx_srtt == 0 {
kcp.rx_srtt = rtt
kcp.rx_rttvar = rtt >> 1
} else {
delta := rtt - kcp.rx_srtt
kcp.rx_srtt += delta >> 3
if delta < 0 {
delta = -delta
}
if rtt < kcp.rx_srtt-kcp.rx_rttvar {
// if the new RTT sample is below the bottom of the range of
// what an RTT measurement is expected to be.
// give an 8x reduced weight versus its normal weighting
kcp.rx_rttvar += (delta - kcp.rx_rttvar) >> 5
} else {
kcp.rx_rttvar += (delta - kcp.rx_rttvar) >> 2
}
}
rto = uint32(kcp.rx_srtt) + _imax_(kcp.interval, uint32(kcp.rx_rttvar)<<2)
kcp.rx_rto = _ibound_(kcp.rx_minrto, rto, IKCP_RTO_MAX)
}
func (kcp *KCP) shrink_buf() {
if len(kcp.snd_buf) > 0 {
seg := &kcp.snd_buf[0]
kcp.snd_una = seg.sn
} else {
kcp.snd_una = kcp.snd_nxt
}
}
func (kcp *KCP) parse_ack(sn uint32) {
if _itimediff(sn, kcp.snd_una) < 0 || _itimediff(sn, kcp.snd_nxt) >= 0 {
return
}
for k := range kcp.snd_buf {
seg := &kcp.snd_buf[k]
if sn == seg.sn {
kcp.delSegment(*seg)
copy(kcp.snd_buf[k:], kcp.snd_buf[k+1:])
kcp.snd_buf[len(kcp.snd_buf)-1] = segment{}
kcp.snd_buf = kcp.snd_buf[:len(kcp.snd_buf)-1]
break
}
if _itimediff(sn, seg.sn) < 0 {
break
}
}
}
func (kcp *KCP) parse_fastack(sn uint32) {
if _itimediff(sn, kcp.snd_una) < 0 || _itimediff(sn, kcp.snd_nxt) >= 0 {
return
}
for k := range kcp.snd_buf {
seg := &kcp.snd_buf[k]
if _itimediff(sn, seg.sn) < 0 {
break
} else if sn != seg.sn {
seg.fastack++
}
}
}
func (kcp *KCP) parse_una(una uint32) {
count := 0
for k := range kcp.snd_buf {
seg := &kcp.snd_buf[k]
if _itimediff(una, seg.sn) > 0 {
kcp.delSegment(*seg)
count++
} else {
break
}
}
if count > 0 {
kcp.snd_buf = kcp.remove_front(kcp.snd_buf, count)
}
}
// ack append
func (kcp *KCP) ack_push(sn, ts uint32) {
kcp.acklist = append(kcp.acklist, ackItem{sn, ts})
}
func (kcp *KCP) parse_data(newseg segment) {
sn := newseg.sn
if _itimediff(sn, kcp.rcv_nxt+kcp.rcv_wnd) >= 0 ||
_itimediff(sn, kcp.rcv_nxt) < 0 {
kcp.delSegment(newseg)
return
}
n := len(kcp.rcv_buf) - 1
insert_idx := 0
repeat := false
for i := n; i >= 0; i-- {
seg := &kcp.rcv_buf[i]
if seg.sn == sn {
repeat = true
atomic.AddUint64(&DefaultSnmp.RepeatSegs, 1)
break
}
if _itimediff(sn, seg.sn) > 0 {
insert_idx = i + 1
break
}
}
if !repeat {
if insert_idx == n+1 {
kcp.rcv_buf = append(kcp.rcv_buf, newseg)
} else {
kcp.rcv_buf = append(kcp.rcv_buf, segment{})
copy(kcp.rcv_buf[insert_idx+1:], kcp.rcv_buf[insert_idx:])
kcp.rcv_buf[insert_idx] = newseg
}
} else {
kcp.delSegment(newseg)
}
// move available data from rcv_buf -> rcv_queue
count := 0
for k := range kcp.rcv_buf {
seg := &kcp.rcv_buf[k]
if seg.sn == kcp.rcv_nxt && len(kcp.rcv_queue) < int(kcp.rcv_wnd) {
kcp.rcv_nxt++
count++
} else {
break
}
}
if count > 0 {
kcp.rcv_queue = append(kcp.rcv_queue, kcp.rcv_buf[:count]...)
kcp.rcv_buf = kcp.remove_front(kcp.rcv_buf, count)
}
}
// Input when you received a low level packet (eg. UDP packet), call it
// regular indicates a regular packet has received(not from FEC)
func (kcp *KCP) Input(data []byte, regular, ackNoDelay bool) int {
una := kcp.snd_una
if len(data) < IKCP_OVERHEAD {
return -1
}
var maxack uint32
var lastackts uint32
var flag int
var inSegs uint64
for {
var ts, sn, length, una, conv uint32
var wnd uint16
var cmd, frg uint8
if len(data) < int(IKCP_OVERHEAD) {
break
}
data = ikcp_decode32u(data, &conv)
if conv != kcp.conv {
return -1
}
data = ikcp_decode8u(data, &cmd)
data = ikcp_decode8u(data, &frg)
data = ikcp_decode16u(data, &wnd)
data = ikcp_decode32u(data, &ts)
data = ikcp_decode32u(data, &sn)
data = ikcp_decode32u(data, &una)
data = ikcp_decode32u(data, &length)
if len(data) < int(length) {
return -2
}
if cmd != IKCP_CMD_PUSH && cmd != IKCP_CMD_ACK &&
cmd != IKCP_CMD_WASK && cmd != IKCP_CMD_WINS {
return -3
}
// only trust window updates from regular packets. i.e: latest update
if regular {
kcp.rmt_wnd = uint32(wnd)
}
kcp.parse_una(una)
kcp.shrink_buf()
if cmd == IKCP_CMD_ACK {
kcp.parse_ack(sn)
kcp.shrink_buf()
if flag == 0 {
flag = 1
maxack = sn
} else if _itimediff(sn, maxack) > 0 {
maxack = sn
}
lastackts = ts
} else if cmd == IKCP_CMD_PUSH {
if _itimediff(sn, kcp.rcv_nxt+kcp.rcv_wnd) < 0 {
kcp.ack_push(sn, ts)
if _itimediff(sn, kcp.rcv_nxt) >= 0 {
seg := kcp.newSegment(int(length))
seg.conv = conv
seg.cmd = cmd
seg.frg = frg
seg.wnd = wnd
seg.ts = ts
seg.sn = sn
seg.una = una
copy(seg.data, data[:length])
kcp.parse_data(seg)
} else {
atomic.AddUint64(&DefaultSnmp.RepeatSegs, 1)
}
} else {
atomic.AddUint64(&DefaultSnmp.RepeatSegs, 1)
}
} else if cmd == IKCP_CMD_WASK {
// ready to send back IKCP_CMD_WINS in Ikcp_flush
// tell remote my window size
kcp.probe |= IKCP_ASK_TELL
} else if cmd == IKCP_CMD_WINS {
// do nothing
} else {
return -3
}
inSegs++
data = data[length:]
}
atomic.AddUint64(&DefaultSnmp.InSegs, inSegs)
if flag != 0 && regular {
kcp.parse_fastack(maxack)
current := currentMs()
if _itimediff(current, lastackts) >= 0 {
kcp.update_ack(_itimediff(current, lastackts))
}
}
if _itimediff(kcp.snd_una, una) > 0 {
if kcp.cwnd < kcp.rmt_wnd {
mss := kcp.mss
if kcp.cwnd < kcp.ssthresh {
kcp.cwnd++
kcp.incr += mss
} else {
if kcp.incr < mss {
kcp.incr = mss
}
kcp.incr += (mss*mss)/kcp.incr + (mss / 16)
if (kcp.cwnd+1)*mss <= kcp.incr {
kcp.cwnd++
}
}
if kcp.cwnd > kcp.rmt_wnd {
kcp.cwnd = kcp.rmt_wnd
kcp.incr = kcp.rmt_wnd * mss
}
}
}
if ackNoDelay && len(kcp.acklist) > 0 { // ack immediately
kcp.flush(true)
} else if kcp.rmt_wnd == 0 && len(kcp.acklist) > 0 { // window zero
kcp.flush(true)
}
return 0
}
func (kcp *KCP) wnd_unused() uint16 {
if len(kcp.rcv_queue) < int(kcp.rcv_wnd) {
return uint16(int(kcp.rcv_wnd) - len(kcp.rcv_queue))
}
return 0
}
// flush pending data
func (kcp *KCP) flush(ackOnly bool) {
var seg segment
seg.conv = kcp.conv
seg.cmd = IKCP_CMD_ACK
seg.wnd = kcp.wnd_unused()
seg.una = kcp.rcv_nxt
buffer := kcp.buffer
// flush acknowledges
ptr := buffer
for i, ack := range kcp.acklist {
size := len(buffer) - len(ptr)
if size+IKCP_OVERHEAD > int(kcp.mtu) {
kcp.output(buffer, size)
ptr = buffer
}
// filter jitters caused by bufferbloat
if ack.sn >= kcp.rcv_nxt || len(kcp.acklist)-1 == i {
seg.sn, seg.ts = ack.sn, ack.ts
ptr = seg.encode(ptr)
}
}
kcp.acklist = kcp.acklist[0:0]
if ackOnly { // flash remain ack segments
size := len(buffer) - len(ptr)
if size > 0 {
kcp.output(buffer, size)
}
return
}
// probe window size (if remote window size equals zero)
if kcp.rmt_wnd == 0 {
current := currentMs()
if kcp.probe_wait == 0 {
kcp.probe_wait = IKCP_PROBE_INIT
kcp.ts_probe = current + kcp.probe_wait
} else {
if _itimediff(current, kcp.ts_probe) >= 0 {
if kcp.probe_wait < IKCP_PROBE_INIT {
kcp.probe_wait = IKCP_PROBE_INIT
}
kcp.probe_wait += kcp.probe_wait / 2
if kcp.probe_wait > IKCP_PROBE_LIMIT {
kcp.probe_wait = IKCP_PROBE_LIMIT
}
kcp.ts_probe = current + kcp.probe_wait
kcp.probe |= IKCP_ASK_SEND
}
}
} else {
kcp.ts_probe = 0
kcp.probe_wait = 0
}
// flush window probing commands
if (kcp.probe & IKCP_ASK_SEND) != 0 {
seg.cmd = IKCP_CMD_WASK
size := len(buffer) - len(ptr)
if size+IKCP_OVERHEAD > int(kcp.mtu) {
kcp.output(buffer, size)
ptr = buffer
}
ptr = seg.encode(ptr)
}
// flush window probing commands
if (kcp.probe & IKCP_ASK_TELL) != 0 {
seg.cmd = IKCP_CMD_WINS
size := len(buffer) - len(ptr)
if size+IKCP_OVERHEAD > int(kcp.mtu) {
kcp.output(buffer, size)
ptr = buffer
}
ptr = seg.encode(ptr)
}
kcp.probe = 0
// calculate window size
cwnd := _imin_(kcp.snd_wnd, kcp.rmt_wnd)
if kcp.nocwnd == 0 {
cwnd = _imin_(kcp.cwnd, cwnd)
}
// sliding window, controlled by snd_nxt && sna_una+cwnd
newSegsCount := 0
for k := range kcp.snd_queue {
if _itimediff(kcp.snd_nxt, kcp.snd_una+cwnd) >= 0 {
break
}
newseg := kcp.snd_queue[k]
newseg.conv = kcp.conv
newseg.cmd = IKCP_CMD_PUSH
newseg.sn = kcp.snd_nxt
kcp.snd_buf = append(kcp.snd_buf, newseg)
kcp.snd_nxt++
newSegsCount++
kcp.snd_queue[k].data = nil
}
if newSegsCount > 0 {
kcp.snd_queue = kcp.remove_front(kcp.snd_queue, newSegsCount)
}
// calculate resent
resent := uint32(kcp.fastresend)
if kcp.fastresend <= 0 {
resent = 0xffffffff
}
// check for retransmissions
current := currentMs()
var change, lost, lostSegs, fastRetransSegs, earlyRetransSegs uint64
for k := range kcp.snd_buf {
segment := &kcp.snd_buf[k]
needsend := false
if segment.xmit == 0 { // initial transmit
needsend = true
segment.rto = kcp.rx_rto
segment.resendts = current + segment.rto
} else if _itimediff(current, segment.resendts) >= 0 { // RTO
needsend = true
if kcp.nodelay == 0 {
segment.rto += kcp.rx_rto
} else {
segment.rto += kcp.rx_rto / 2
}
segment.resendts = current + segment.rto
lost++
lostSegs++
} else if segment.fastack >= resent { // fast retransmit
needsend = true
segment.fastack = 0
segment.rto = kcp.rx_rto
segment.resendts = current + segment.rto
change++
fastRetransSegs++
} else if segment.fastack > 0 && newSegsCount == 0 { // early retransmit
needsend = true
segment.fastack = 0
segment.rto = kcp.rx_rto
segment.resendts = current + segment.rto
change++
earlyRetransSegs++
}
if needsend {
segment.xmit++
segment.ts = current
segment.wnd = seg.wnd
segment.una = seg.una
size := len(buffer) - len(ptr)
need := IKCP_OVERHEAD + len(segment.data)
if size+need > int(kcp.mtu) {
kcp.output(buffer, size)
current = currentMs() // time update for a blocking call
ptr = buffer
}
ptr = segment.encode(ptr)
copy(ptr, segment.data)
ptr = ptr[len(segment.data):]
if segment.xmit >= kcp.dead_link {
kcp.state = 0xFFFFFFFF
}
}
}
// flash remain segments
size := len(buffer) - len(ptr)
if size > 0 {
kcp.output(buffer, size)
}
// counter updates
sum := lostSegs
if lostSegs > 0 {
atomic.AddUint64(&DefaultSnmp.LostSegs, lostSegs)
}
if fastRetransSegs > 0 {
atomic.AddUint64(&DefaultSnmp.FastRetransSegs, fastRetransSegs)
sum += fastRetransSegs
}
if earlyRetransSegs > 0 {
atomic.AddUint64(&DefaultSnmp.EarlyRetransSegs, earlyRetransSegs)
sum += earlyRetransSegs
}
if sum > 0 {
atomic.AddUint64(&DefaultSnmp.RetransSegs, sum)
}
// update ssthresh
// rate halving, https://tools.ietf.org/html/rfc6937
if change > 0 {
inflight := kcp.snd_nxt - kcp.snd_una
kcp.ssthresh = inflight / 2
if kcp.ssthresh < IKCP_THRESH_MIN {
kcp.ssthresh = IKCP_THRESH_MIN
}
kcp.cwnd = kcp.ssthresh + resent
kcp.incr = kcp.cwnd * kcp.mss
}
// congestion control, https://tools.ietf.org/html/rfc5681
if lost > 0 {
kcp.ssthresh = cwnd / 2
if kcp.ssthresh < IKCP_THRESH_MIN {
kcp.ssthresh = IKCP_THRESH_MIN
}
kcp.cwnd = 1
kcp.incr = kcp.mss
}
if kcp.cwnd < 1 {
kcp.cwnd = 1
kcp.incr = kcp.mss
}
}
// Update updates state (call it repeatedly, every 10ms-100ms), or you can ask
// ikcp_check when to call it again (without ikcp_input/_send calling).
// 'current' - current timestamp in millisec.
func (kcp *KCP) Update() {
var slap int32
current := currentMs()
if kcp.updated == 0 {
kcp.updated = 1
kcp.ts_flush = current
}
slap = _itimediff(current, kcp.ts_flush)
if slap >= 10000 || slap < -10000 {
kcp.ts_flush = current
slap = 0
}
if slap >= 0 {
kcp.ts_flush += kcp.interval
if _itimediff(current, kcp.ts_flush) >= 0 {
kcp.ts_flush = current + kcp.interval
}
kcp.flush(false)
}
}
// Check determines when should you invoke ikcp_update:
// returns when you should invoke ikcp_update in millisec, if there
// is no ikcp_input/_send calling. you can call ikcp_update in that
// time, instead of call update repeatly.
// Important to reduce unnacessary ikcp_update invoking. use it to
// schedule ikcp_update (eg. implementing an epoll-like mechanism,
// or optimize ikcp_update when handling massive kcp connections)
func (kcp *KCP) Check() uint32 {
current := currentMs()
ts_flush := kcp.ts_flush
tm_flush := int32(0x7fffffff)
tm_packet := int32(0x7fffffff)
minimal := uint32(0)
if kcp.updated == 0 {
return current
}
if _itimediff(current, ts_flush) >= 10000 ||
_itimediff(current, ts_flush) < -10000 {
ts_flush = current
}
if _itimediff(current, ts_flush) >= 0 {
return current
}
tm_flush = _itimediff(ts_flush, current)
for k := range kcp.snd_buf {
seg := &kcp.snd_buf[k]
diff := _itimediff(seg.resendts, current)
if diff <= 0 {
return current
}
if diff < tm_packet {
tm_packet = diff
}
}
minimal = uint32(tm_packet)
if tm_packet >= tm_flush {
minimal = uint32(tm_flush)
}
if minimal >= kcp.interval {
minimal = kcp.interval
}
return current + minimal
}
// SetMtu changes MTU size, default is 1400
func (kcp *KCP) SetMtu(mtu int) int {
if mtu < 50 || mtu < IKCP_OVERHEAD {
return -1
}
buffer := make([]byte, (mtu+IKCP_OVERHEAD)*3)
if buffer == nil {
return -2
}
kcp.mtu = uint32(mtu)
kcp.mss = kcp.mtu - IKCP_OVERHEAD
kcp.buffer = buffer
return 0
}
// NoDelay options
// fastest: ikcp_nodelay(kcp, 1, 20, 2, 1)
// nodelay: 0:disable(default), 1:enable
// interval: internal update timer interval in millisec, default is 100ms
// resend: 0:disable fast resend(default), 1:enable fast resend
// nc: 0:normal congestion control(default), 1:disable congestion control
func (kcp *KCP) NoDelay(nodelay, interval, resend, nc int) int {
if nodelay >= 0 {
kcp.nodelay = uint32(nodelay)
if nodelay != 0 {
kcp.rx_minrto = IKCP_RTO_NDL
} else {
kcp.rx_minrto = IKCP_RTO_MIN
}
}
if interval >= 0 {
if interval > 5000 {
interval = 5000
} else if interval < 10 {
interval = 10
}
kcp.interval = uint32(interval)
}
if resend >= 0 {
kcp.fastresend = int32(resend)
}
if nc >= 0 {
kcp.nocwnd = int32(nc)
}
return 0
}
// WndSize sets maximum window size: sndwnd=32, rcvwnd=32 by default
func (kcp *KCP) WndSize(sndwnd, rcvwnd int) int {
if sndwnd > 0 {
kcp.snd_wnd = uint32(sndwnd)
}
if rcvwnd > 0 {
kcp.rcv_wnd = uint32(rcvwnd)
}
return 0
}
// WaitSnd gets how many packet is waiting to be sent
func (kcp *KCP) WaitSnd() int {
return len(kcp.snd_buf) + len(kcp.snd_queue)
}
// remove front n elements from queue
func (kcp *KCP) remove_front(q []segment, n int) []segment {
newn := copy(q, q[n:])
for i := newn; i < len(q); i++ {
q[i] = segment{} // manual set nil for GC
}
return q[:newn]
}

975
vendor/github.com/fatedier/kcp-go/sess.go generated vendored Normal file
View File

@@ -0,0 +1,975 @@
package kcp
import (
"crypto/rand"
"encoding/binary"
"hash/crc32"
"io"
"net"
"sync"
"sync/atomic"
"time"
"github.com/pkg/errors"
"golang.org/x/net/ipv4"
)
type errTimeout struct {
error
}
func (errTimeout) Timeout() bool { return true }
func (errTimeout) Temporary() bool { return true }
func (errTimeout) Error() string { return "i/o timeout" }
const (
// 16-bytes magic number for each packet
nonceSize = 16
// 4-bytes packet checksum
crcSize = 4
// overall crypto header size
cryptHeaderSize = nonceSize + crcSize
// maximum packet size
mtuLimit = 1500
// FEC keeps rxFECMulti* (dataShard+parityShard) ordered packets in memory
rxFECMulti = 3
// accept backlog
acceptBacklog = 128
// prerouting(to session) queue
qlen = 128
)
const (
errBrokenPipe = "broken pipe"
errInvalidOperation = "invalid operation"
)
var (
// global packet buffer
// shared among sending/receiving/FEC
xmitBuf sync.Pool
)
func init() {
xmitBuf.New = func() interface{} {
return make([]byte, mtuLimit)
}
}
type (
// UDPSession defines a KCP session implemented by UDP
UDPSession struct {
updaterIdx int // record slice index in updater
conn net.PacketConn // the underlying packet connection
kcp *KCP // KCP ARQ protocol
l *Listener // point to the Listener if it's accepted by Listener
block BlockCrypt // block encryption
// kcp receiving is based on packets
// recvbuf turns packets into stream
recvbuf []byte
bufptr []byte
// extended output buffer(with header)
ext []byte
// FEC
fecDecoder *fecDecoder
fecEncoder *fecEncoder
// settings
remote net.Addr // remote peer address
rd time.Time // read deadline
wd time.Time // write deadline
headerSize int // the overall header size added before KCP frame
ackNoDelay bool // send ack immediately for each incoming packet
writeDelay bool // delay kcp.flush() for Write() for bulk transfer
dup int // duplicate udp packets
// notifications
die chan struct{} // notify session has Closed
chReadEvent chan struct{} // notify Read() can be called without blocking
chWriteEvent chan struct{} // notify Write() can be called without blocking
chErrorEvent chan error // notify Read() have an error
isClosed bool // flag the session has Closed
mu sync.Mutex
}
setReadBuffer interface {
SetReadBuffer(bytes int) error
}
setWriteBuffer interface {
SetWriteBuffer(bytes int) error
}
)
// newUDPSession create a new udp session for client or server
func newUDPSession(conv uint32, dataShards, parityShards int, l *Listener, conn net.PacketConn, remote net.Addr, block BlockCrypt) *UDPSession {
sess := new(UDPSession)
sess.die = make(chan struct{})
sess.chReadEvent = make(chan struct{}, 1)
sess.chWriteEvent = make(chan struct{}, 1)
sess.chErrorEvent = make(chan error, 1)
sess.remote = remote
sess.conn = conn
sess.l = l
sess.block = block
sess.recvbuf = make([]byte, mtuLimit)
// FEC initialization
sess.fecDecoder = newFECDecoder(rxFECMulti*(dataShards+parityShards), dataShards, parityShards)
if sess.block != nil {
sess.fecEncoder = newFECEncoder(dataShards, parityShards, cryptHeaderSize)
} else {
sess.fecEncoder = newFECEncoder(dataShards, parityShards, 0)
}
// calculate header size
if sess.block != nil {
sess.headerSize += cryptHeaderSize
}
if sess.fecEncoder != nil {
sess.headerSize += fecHeaderSizePlus2
}
// only allocate extended packet buffer
// when the extra header is required
if sess.headerSize > 0 {
sess.ext = make([]byte, mtuLimit)
}
sess.kcp = NewKCP(conv, func(buf []byte, size int) {
if size >= IKCP_OVERHEAD {
sess.output(buf[:size])
}
})
sess.kcp.SetMtu(IKCP_MTU_DEF - sess.headerSize)
// add current session to the global updater,
// which periodically calls sess.update()
updater.addSession(sess)
if sess.l == nil { // it's a client connection
go sess.readLoop()
atomic.AddUint64(&DefaultSnmp.ActiveOpens, 1)
} else {
atomic.AddUint64(&DefaultSnmp.PassiveOpens, 1)
}
currestab := atomic.AddUint64(&DefaultSnmp.CurrEstab, 1)
maxconn := atomic.LoadUint64(&DefaultSnmp.MaxConn)
if currestab > maxconn {
atomic.CompareAndSwapUint64(&DefaultSnmp.MaxConn, maxconn, currestab)
}
return sess
}
// Read implements net.Conn
func (s *UDPSession) Read(b []byte) (n int, err error) {
for {
s.mu.Lock()
if len(s.bufptr) > 0 { // copy from buffer into b
n = copy(b, s.bufptr)
s.bufptr = s.bufptr[n:]
s.mu.Unlock()
return n, nil
}
if s.isClosed {
s.mu.Unlock()
return 0, errors.New(errBrokenPipe)
}
if size := s.kcp.PeekSize(); size > 0 { // peek data size from kcp
atomic.AddUint64(&DefaultSnmp.BytesReceived, uint64(size))
if len(b) >= size { // direct write to b
s.kcp.Recv(b)
s.mu.Unlock()
return size, nil
}
// resize kcp receive buffer
// to make sure recvbuf has enough capacity
if cap(s.recvbuf) < size {
s.recvbuf = make([]byte, size)
}
// resize recvbuf slice length
s.recvbuf = s.recvbuf[:size]
s.kcp.Recv(s.recvbuf)
n = copy(b, s.recvbuf) // copy to b
s.bufptr = s.recvbuf[n:] // update pointer
s.mu.Unlock()
return n, nil
}
// read deadline
var timeout *time.Timer
var c <-chan time.Time
if !s.rd.IsZero() {
if time.Now().After(s.rd) {
s.mu.Unlock()
return 0, errTimeout{}
}
delay := s.rd.Sub(time.Now())
timeout = time.NewTimer(delay)
c = timeout.C
}
s.mu.Unlock()
// wait for read event or timeout
select {
case <-s.chReadEvent:
case <-c:
case <-s.die:
case err = <-s.chErrorEvent:
if timeout != nil {
timeout.Stop()
}
return n, err
}
if timeout != nil {
timeout.Stop()
}
}
}
// Write implements net.Conn
func (s *UDPSession) Write(b []byte) (n int, err error) {
for {
s.mu.Lock()
if s.isClosed {
s.mu.Unlock()
return 0, errors.New(errBrokenPipe)
}
// api flow control
if s.kcp.WaitSnd() < int(s.kcp.snd_wnd) {
n = len(b)
for {
if len(b) <= int(s.kcp.mss) {
s.kcp.Send(b)
break
} else {
s.kcp.Send(b[:s.kcp.mss])
b = b[s.kcp.mss:]
}
}
if !s.writeDelay {
s.kcp.flush(false)
}
s.mu.Unlock()
atomic.AddUint64(&DefaultSnmp.BytesSent, uint64(n))
return n, nil
}
// write deadline
var timeout *time.Timer
var c <-chan time.Time
if !s.wd.IsZero() {
if time.Now().After(s.wd) {
s.mu.Unlock()
return 0, errTimeout{}
}
delay := s.wd.Sub(time.Now())
timeout = time.NewTimer(delay)
c = timeout.C
}
s.mu.Unlock()
// wait for write event or timeout
select {
case <-s.chWriteEvent:
case <-c:
case <-s.die:
}
if timeout != nil {
timeout.Stop()
}
}
}
// Close closes the connection.
func (s *UDPSession) Close() error {
// remove this session from updater & listener(if necessary)
updater.removeSession(s)
if s.l != nil { // notify listener
s.l.closeSession(sessionKey{
addr: s.remote.String(),
convID: s.kcp.conv,
})
}
s.mu.Lock()
defer s.mu.Unlock()
if s.isClosed {
return errors.New(errBrokenPipe)
}
close(s.die)
s.isClosed = true
atomic.AddUint64(&DefaultSnmp.CurrEstab, ^uint64(0))
if s.l == nil { // client socket close
return s.conn.Close()
}
return nil
}
// LocalAddr returns the local network address. The Addr returned is shared by all invocations of LocalAddr, so do not modify it.
func (s *UDPSession) LocalAddr() net.Addr { return s.conn.LocalAddr() }
// RemoteAddr returns the remote network address. The Addr returned is shared by all invocations of RemoteAddr, so do not modify it.
func (s *UDPSession) RemoteAddr() net.Addr { return s.remote }
// SetDeadline sets the deadline associated with the listener. A zero time value disables the deadline.
func (s *UDPSession) SetDeadline(t time.Time) error {
s.mu.Lock()
defer s.mu.Unlock()
s.rd = t
s.wd = t
return nil
}
// SetReadDeadline implements the Conn SetReadDeadline method.
func (s *UDPSession) SetReadDeadline(t time.Time) error {
s.mu.Lock()
defer s.mu.Unlock()
s.rd = t
return nil
}
// SetWriteDeadline implements the Conn SetWriteDeadline method.
func (s *UDPSession) SetWriteDeadline(t time.Time) error {
s.mu.Lock()
defer s.mu.Unlock()
s.wd = t
return nil
}
// SetWriteDelay delays write for bulk transfer until the next update interval
func (s *UDPSession) SetWriteDelay(delay bool) {
s.mu.Lock()
defer s.mu.Unlock()
s.writeDelay = delay
}
// SetWindowSize set maximum window size
func (s *UDPSession) SetWindowSize(sndwnd, rcvwnd int) {
s.mu.Lock()
defer s.mu.Unlock()
s.kcp.WndSize(sndwnd, rcvwnd)
}
// SetMtu sets the maximum transmission unit(not including UDP header)
func (s *UDPSession) SetMtu(mtu int) bool {
if mtu > mtuLimit {
return false
}
s.mu.Lock()
defer s.mu.Unlock()
s.kcp.SetMtu(mtu - s.headerSize)
return true
}
// SetStreamMode toggles the stream mode on/off
func (s *UDPSession) SetStreamMode(enable bool) {
s.mu.Lock()
defer s.mu.Unlock()
if enable {
s.kcp.stream = 1
} else {
s.kcp.stream = 0
}
}
// SetACKNoDelay changes ack flush option, set true to flush ack immediately,
func (s *UDPSession) SetACKNoDelay(nodelay bool) {
s.mu.Lock()
defer s.mu.Unlock()
s.ackNoDelay = nodelay
}
// SetDUP duplicates udp packets for kcp output, for testing purpose only
func (s *UDPSession) SetDUP(dup int) {
s.mu.Lock()
defer s.mu.Unlock()
s.dup = dup
}
// SetNoDelay calls nodelay() of kcp
// https://github.com/skywind3000/kcp/blob/master/README.en.md#protocol-configuration
func (s *UDPSession) SetNoDelay(nodelay, interval, resend, nc int) {
s.mu.Lock()
defer s.mu.Unlock()
s.kcp.NoDelay(nodelay, interval, resend, nc)
}
// SetDSCP sets the 6bit DSCP field of IP header, no effect if it's accepted from Listener
func (s *UDPSession) SetDSCP(dscp int) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.l == nil {
if nc, ok := s.conn.(*connectedUDPConn); ok {
return ipv4.NewConn(nc.UDPConn).SetTOS(dscp << 2)
} else if nc, ok := s.conn.(net.Conn); ok {
return ipv4.NewConn(nc).SetTOS(dscp << 2)
}
}
return errors.New(errInvalidOperation)
}
// SetReadBuffer sets the socket read buffer, no effect if it's accepted from Listener
func (s *UDPSession) SetReadBuffer(bytes int) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.l == nil {
if nc, ok := s.conn.(setReadBuffer); ok {
return nc.SetReadBuffer(bytes)
}
}
return errors.New(errInvalidOperation)
}
// SetWriteBuffer sets the socket write buffer, no effect if it's accepted from Listener
func (s *UDPSession) SetWriteBuffer(bytes int) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.l == nil {
if nc, ok := s.conn.(setWriteBuffer); ok {
return nc.SetWriteBuffer(bytes)
}
}
return errors.New(errInvalidOperation)
}
// output pipeline entry
// steps for output data processing:
// 0. Header extends
// 1. FEC
// 2. CRC32
// 3. Encryption
// 4. WriteTo kernel
func (s *UDPSession) output(buf []byte) {
var ecc [][]byte
// 0. extend buf's header space(if necessary)
ext := buf
if s.headerSize > 0 {
ext = s.ext[:s.headerSize+len(buf)]
copy(ext[s.headerSize:], buf)
}
// 1. FEC encoding
if s.fecEncoder != nil {
ecc = s.fecEncoder.encode(ext)
}
// 2&3. crc32 & encryption
if s.block != nil {
io.ReadFull(rand.Reader, ext[:nonceSize])
checksum := crc32.ChecksumIEEE(ext[cryptHeaderSize:])
binary.LittleEndian.PutUint32(ext[nonceSize:], checksum)
s.block.Encrypt(ext, ext)
for k := range ecc {
io.ReadFull(rand.Reader, ecc[k][:nonceSize])
checksum := crc32.ChecksumIEEE(ecc[k][cryptHeaderSize:])
binary.LittleEndian.PutUint32(ecc[k][nonceSize:], checksum)
s.block.Encrypt(ecc[k], ecc[k])
}
}
// 4. WriteTo kernel
nbytes := 0
npkts := 0
for i := 0; i < s.dup+1; i++ {
if n, err := s.conn.WriteTo(ext, s.remote); err == nil {
nbytes += n
npkts++
}
}
for k := range ecc {
if n, err := s.conn.WriteTo(ecc[k], s.remote); err == nil {
nbytes += n
npkts++
}
}
atomic.AddUint64(&DefaultSnmp.OutPkts, uint64(npkts))
atomic.AddUint64(&DefaultSnmp.OutBytes, uint64(nbytes))
}
// kcp update, returns interval for next calling
func (s *UDPSession) update() (interval time.Duration) {
s.mu.Lock()
s.kcp.flush(false)
if s.kcp.WaitSnd() < int(s.kcp.snd_wnd) {
s.notifyWriteEvent()
}
interval = time.Duration(s.kcp.interval) * time.Millisecond
s.mu.Unlock()
return
}
// GetConv gets conversation id of a session
func (s *UDPSession) GetConv() uint32 { return s.kcp.conv }
func (s *UDPSession) notifyReadEvent() {
select {
case s.chReadEvent <- struct{}{}:
default:
}
}
func (s *UDPSession) notifyWriteEvent() {
select {
case s.chWriteEvent <- struct{}{}:
default:
}
}
func (s *UDPSession) kcpInput(data []byte) {
var kcpInErrors, fecErrs, fecRecovered, fecParityShards uint64
if s.fecDecoder != nil {
f := s.fecDecoder.decodeBytes(data)
s.mu.Lock()
if f.flag == typeData {
if ret := s.kcp.Input(data[fecHeaderSizePlus2:], true, s.ackNoDelay); ret != 0 {
kcpInErrors++
}
}
if f.flag == typeData || f.flag == typeFEC {
if f.flag == typeFEC {
fecParityShards++
}
recovers := s.fecDecoder.decode(f)
for _, r := range recovers {
if len(r) >= 2 { // must be larger than 2bytes
sz := binary.LittleEndian.Uint16(r)
if int(sz) <= len(r) && sz >= 2 {
if ret := s.kcp.Input(r[2:sz], false, s.ackNoDelay); ret == 0 {
fecRecovered++
} else {
kcpInErrors++
}
} else {
fecErrs++
}
} else {
fecErrs++
}
}
}
// notify reader
if n := s.kcp.PeekSize(); n > 0 {
s.notifyReadEvent()
}
s.mu.Unlock()
} else {
s.mu.Lock()
if ret := s.kcp.Input(data, true, s.ackNoDelay); ret != 0 {
kcpInErrors++
}
// notify reader
if n := s.kcp.PeekSize(); n > 0 {
s.notifyReadEvent()
}
s.mu.Unlock()
}
atomic.AddUint64(&DefaultSnmp.InPkts, 1)
atomic.AddUint64(&DefaultSnmp.InBytes, uint64(len(data)))
if fecParityShards > 0 {
atomic.AddUint64(&DefaultSnmp.FECParityShards, fecParityShards)
}
if kcpInErrors > 0 {
atomic.AddUint64(&DefaultSnmp.KCPInErrors, kcpInErrors)
}
if fecErrs > 0 {
atomic.AddUint64(&DefaultSnmp.FECErrs, fecErrs)
}
if fecRecovered > 0 {
atomic.AddUint64(&DefaultSnmp.FECRecovered, fecRecovered)
}
}
func (s *UDPSession) receiver(ch chan<- []byte) {
for {
data := xmitBuf.Get().([]byte)[:mtuLimit]
if n, _, err := s.conn.ReadFrom(data); err == nil && n >= s.headerSize+IKCP_OVERHEAD {
select {
case ch <- data[:n]:
case <-s.die:
return
}
} else if err != nil {
s.chErrorEvent <- err
return
} else {
atomic.AddUint64(&DefaultSnmp.InErrs, 1)
}
}
}
// read loop for client session
func (s *UDPSession) readLoop() {
chPacket := make(chan []byte, qlen)
go s.receiver(chPacket)
for {
select {
case data := <-chPacket:
raw := data
dataValid := false
if s.block != nil {
s.block.Decrypt(data, data)
data = data[nonceSize:]
checksum := crc32.ChecksumIEEE(data[crcSize:])
if checksum == binary.LittleEndian.Uint32(data) {
data = data[crcSize:]
dataValid = true
} else {
atomic.AddUint64(&DefaultSnmp.InCsumErrors, 1)
}
} else if s.block == nil {
dataValid = true
}
if dataValid {
s.kcpInput(data)
}
xmitBuf.Put(raw)
case <-s.die:
return
}
}
}
type (
sessionKey struct {
addr string
convID uint32
}
// Listener defines a server listening for connections
Listener struct {
block BlockCrypt // block encryption
dataShards int // FEC data shard
parityShards int // FEC parity shard
fecDecoder *fecDecoder // FEC mock initialization
conn net.PacketConn // the underlying packet connection
sessions map[sessionKey]*UDPSession // all sessions accepted by this Listener
chAccepts chan *UDPSession // Listen() backlog
chSessionClosed chan sessionKey // session close queue
headerSize int // the overall header size added before KCP frame
die chan struct{} // notify the listener has closed
rd atomic.Value // read deadline for Accept()
wd atomic.Value
}
// incoming packet
inPacket struct {
from net.Addr
data []byte
}
)
// monitor incoming data for all connections of server
func (l *Listener) monitor() {
// cache last session
var lastKey sessionKey
var lastSession *UDPSession
chPacket := make(chan inPacket, qlen)
go l.receiver(chPacket)
for {
select {
case p := <-chPacket:
raw := p.data
data := p.data
from := p.from
dataValid := false
if l.block != nil {
l.block.Decrypt(data, data)
data = data[nonceSize:]
checksum := crc32.ChecksumIEEE(data[crcSize:])
if checksum == binary.LittleEndian.Uint32(data) {
data = data[crcSize:]
dataValid = true
} else {
atomic.AddUint64(&DefaultSnmp.InCsumErrors, 1)
}
} else if l.block == nil {
dataValid = true
}
if dataValid {
var conv uint32
convValid := false
if l.fecDecoder != nil {
isfec := binary.LittleEndian.Uint16(data[4:])
if isfec == typeData {
conv = binary.LittleEndian.Uint32(data[fecHeaderSizePlus2:])
convValid = true
}
} else {
conv = binary.LittleEndian.Uint32(data)
convValid = true
}
if convValid {
key := sessionKey{
addr: from.String(),
convID: conv,
}
var s *UDPSession
var ok bool
// packets received from an address always come in batch.
// cache the session for next packet, without querying map.
if key == lastKey {
s, ok = lastSession, true
} else if s, ok = l.sessions[key]; ok {
lastSession = s
lastKey = key
}
if !ok { // new session
if len(l.chAccepts) < cap(l.chAccepts) && len(l.sessions) < 4096 { // do not let new session overwhelm accept queue and connection count
s := newUDPSession(conv, l.dataShards, l.parityShards, l, l.conn, from, l.block)
s.kcpInput(data)
l.sessions[key] = s
l.chAccepts <- s
}
} else {
s.kcpInput(data)
}
}
}
xmitBuf.Put(raw)
case key := <-l.chSessionClosed:
if key == lastKey {
lastKey = sessionKey{}
}
delete(l.sessions, key)
case <-l.die:
return
}
}
}
func (l *Listener) receiver(ch chan<- inPacket) {
for {
data := xmitBuf.Get().([]byte)[:mtuLimit]
if n, from, err := l.conn.ReadFrom(data); err == nil && n >= l.headerSize+IKCP_OVERHEAD {
select {
case ch <- inPacket{from, data[:n]}:
case <-l.die:
return
}
} else if err != nil {
return
} else {
atomic.AddUint64(&DefaultSnmp.InErrs, 1)
}
}
}
// SetReadBuffer sets the socket read buffer for the Listener
func (l *Listener) SetReadBuffer(bytes int) error {
if nc, ok := l.conn.(setReadBuffer); ok {
return nc.SetReadBuffer(bytes)
}
return errors.New(errInvalidOperation)
}
// SetWriteBuffer sets the socket write buffer for the Listener
func (l *Listener) SetWriteBuffer(bytes int) error {
if nc, ok := l.conn.(setWriteBuffer); ok {
return nc.SetWriteBuffer(bytes)
}
return errors.New(errInvalidOperation)
}
// SetDSCP sets the 6bit DSCP field of IP header
func (l *Listener) SetDSCP(dscp int) error {
if nc, ok := l.conn.(net.Conn); ok {
return ipv4.NewConn(nc).SetTOS(dscp << 2)
}
return errors.New(errInvalidOperation)
}
// Accept implements the Accept method in the Listener interface; it waits for the next call and returns a generic Conn.
func (l *Listener) Accept() (net.Conn, error) {
return l.AcceptKCP()
}
// AcceptKCP accepts a KCP connection
func (l *Listener) AcceptKCP() (*UDPSession, error) {
var timeout <-chan time.Time
if tdeadline, ok := l.rd.Load().(time.Time); ok && !tdeadline.IsZero() {
timeout = time.After(tdeadline.Sub(time.Now()))
}
select {
case <-timeout:
return nil, &errTimeout{}
case c := <-l.chAccepts:
return c, nil
case <-l.die:
return nil, errors.New(errBrokenPipe)
}
}
// SetDeadline sets the deadline associated with the listener. A zero time value disables the deadline.
func (l *Listener) SetDeadline(t time.Time) error {
l.SetReadDeadline(t)
l.SetWriteDeadline(t)
return nil
}
// SetReadDeadline implements the Conn SetReadDeadline method.
func (l *Listener) SetReadDeadline(t time.Time) error {
l.rd.Store(t)
return nil
}
// SetWriteDeadline implements the Conn SetWriteDeadline method.
func (l *Listener) SetWriteDeadline(t time.Time) error {
l.wd.Store(t)
return nil
}
// Close stops listening on the UDP address. Already Accepted connections are not closed.
func (l *Listener) Close() error {
close(l.die)
return l.conn.Close()
}
// closeSession notify the listener that a session has closed
func (l *Listener) closeSession(key sessionKey) bool {
select {
case l.chSessionClosed <- key:
return true
case <-l.die:
return false
}
}
// Addr returns the listener's network address, The Addr returned is shared by all invocations of Addr, so do not modify it.
func (l *Listener) Addr() net.Addr { return l.conn.LocalAddr() }
// Listen listens for incoming KCP packets addressed to the local address laddr on the network "udp",
func Listen(laddr string) (net.Listener, error) { return ListenWithOptions(laddr, nil, 0, 0) }
// ListenWithOptions listens for incoming KCP packets addressed to the local address laddr on the network "udp" with packet encryption,
// dataShards, parityShards defines Reed-Solomon Erasure Coding parameters
func ListenWithOptions(laddr string, block BlockCrypt, dataShards, parityShards int) (*Listener, error) {
udpaddr, err := net.ResolveUDPAddr("udp", laddr)
if err != nil {
return nil, errors.Wrap(err, "net.ResolveUDPAddr")
}
conn, err := net.ListenUDP("udp", udpaddr)
if err != nil {
return nil, errors.Wrap(err, "net.ListenUDP")
}
return ServeConn(block, dataShards, parityShards, conn)
}
// ServeConn serves KCP protocol for a single packet connection.
func ServeConn(block BlockCrypt, dataShards, parityShards int, conn net.PacketConn) (*Listener, error) {
l := new(Listener)
l.conn = conn
l.sessions = make(map[sessionKey]*UDPSession)
l.chAccepts = make(chan *UDPSession, acceptBacklog)
l.chSessionClosed = make(chan sessionKey)
l.die = make(chan struct{})
l.dataShards = dataShards
l.parityShards = parityShards
l.block = block
l.fecDecoder = newFECDecoder(rxFECMulti*(dataShards+parityShards), dataShards, parityShards)
// calculate header size
if l.block != nil {
l.headerSize += cryptHeaderSize
}
if l.fecDecoder != nil {
l.headerSize += fecHeaderSizePlus2
}
go l.monitor()
return l, nil
}
// Dial connects to the remote address "raddr" on the network "udp"
func Dial(raddr string) (net.Conn, error) { return DialWithOptions(raddr, nil, 0, 0) }
// DialWithOptions connects to the remote address "raddr" on the network "udp" with packet encryption
func DialWithOptions(raddr string, block BlockCrypt, dataShards, parityShards int) (*UDPSession, error) {
udpaddr, err := net.ResolveUDPAddr("udp", raddr)
if err != nil {
return nil, errors.Wrap(err, "net.ResolveUDPAddr")
}
udpconn, err := net.DialUDP("udp", nil, udpaddr)
if err != nil {
return nil, errors.Wrap(err, "net.DialUDP")
}
return NewConn(raddr, block, dataShards, parityShards, &connectedUDPConn{udpconn})
}
// NewConn establishes a session and talks KCP protocol over a packet connection.
func NewConn(raddr string, block BlockCrypt, dataShards, parityShards int, conn net.PacketConn) (*UDPSession, error) {
udpaddr, err := net.ResolveUDPAddr("udp", raddr)
if err != nil {
return nil, errors.Wrap(err, "net.ResolveUDPAddr")
}
var convid uint32
binary.Read(rand.Reader, binary.LittleEndian, &convid)
return newUDPSession(convid, dataShards, parityShards, nil, conn, udpaddr, block), nil
}
func NewConnEx(convid uint32, connected bool, raddr string, block BlockCrypt, dataShards, parityShards int, conn *net.UDPConn) (*UDPSession, error) {
udpaddr, err := net.ResolveUDPAddr("udp", raddr)
if err != nil {
return nil, errors.Wrap(err, "net.ResolveUDPAddr")
}
var pConn net.PacketConn = conn
if connected {
pConn = &connectedUDPConn{conn}
}
return newUDPSession(convid, dataShards, parityShards, nil, pConn, udpaddr, block), nil
}
// returns current time in milliseconds
func currentMs() uint32 { return uint32(time.Now().UnixNano() / int64(time.Millisecond)) }
// connectedUDPConn is a wrapper for net.UDPConn which converts WriteTo syscalls
// to Write syscalls that are 4 times faster on some OS'es. This should only be
// used for connections that were produced by a net.Dial* call.
type connectedUDPConn struct{ *net.UDPConn }
// WriteTo redirects all writes to the Write syscall, which is 4 times faster.
func (c *connectedUDPConn) WriteTo(b []byte, addr net.Addr) (int, error) { return c.Write(b) }

164
vendor/github.com/fatedier/kcp-go/snmp.go generated vendored Normal file
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@@ -0,0 +1,164 @@
package kcp
import (
"fmt"
"sync/atomic"
)
// Snmp defines network statistics indicator
type Snmp struct {
BytesSent uint64 // bytes sent from upper level
BytesReceived uint64 // bytes received to upper level
MaxConn uint64 // max number of connections ever reached
ActiveOpens uint64 // accumulated active open connections
PassiveOpens uint64 // accumulated passive open connections
CurrEstab uint64 // current number of established connections
InErrs uint64 // UDP read errors reported from net.PacketConn
InCsumErrors uint64 // checksum errors from CRC32
KCPInErrors uint64 // packet iput errors reported from KCP
InPkts uint64 // incoming packets count
OutPkts uint64 // outgoing packets count
InSegs uint64 // incoming KCP segments
OutSegs uint64 // outgoing KCP segments
InBytes uint64 // UDP bytes received
OutBytes uint64 // UDP bytes sent
RetransSegs uint64 // accmulated retransmited segments
FastRetransSegs uint64 // accmulated fast retransmitted segments
EarlyRetransSegs uint64 // accmulated early retransmitted segments
LostSegs uint64 // number of segs infered as lost
RepeatSegs uint64 // number of segs duplicated
FECRecovered uint64 // correct packets recovered from FEC
FECErrs uint64 // incorrect packets recovered from FEC
FECParityShards uint64 // FEC segments received
FECShortShards uint64 // number of data shards that's not enough for recovery
}
func newSnmp() *Snmp {
return new(Snmp)
}
// Header returns all field names
func (s *Snmp) Header() []string {
return []string{
"BytesSent",
"BytesReceived",
"MaxConn",
"ActiveOpens",
"PassiveOpens",
"CurrEstab",
"InErrs",
"InCsumErrors",
"KCPInErrors",
"InPkts",
"OutPkts",
"InSegs",
"OutSegs",
"InBytes",
"OutBytes",
"RetransSegs",
"FastRetransSegs",
"EarlyRetransSegs",
"LostSegs",
"RepeatSegs",
"FECParityShards",
"FECErrs",
"FECRecovered",
"FECShortShards",
}
}
// ToSlice returns current snmp info as slice
func (s *Snmp) ToSlice() []string {
snmp := s.Copy()
return []string{
fmt.Sprint(snmp.BytesSent),
fmt.Sprint(snmp.BytesReceived),
fmt.Sprint(snmp.MaxConn),
fmt.Sprint(snmp.ActiveOpens),
fmt.Sprint(snmp.PassiveOpens),
fmt.Sprint(snmp.CurrEstab),
fmt.Sprint(snmp.InErrs),
fmt.Sprint(snmp.InCsumErrors),
fmt.Sprint(snmp.KCPInErrors),
fmt.Sprint(snmp.InPkts),
fmt.Sprint(snmp.OutPkts),
fmt.Sprint(snmp.InSegs),
fmt.Sprint(snmp.OutSegs),
fmt.Sprint(snmp.InBytes),
fmt.Sprint(snmp.OutBytes),
fmt.Sprint(snmp.RetransSegs),
fmt.Sprint(snmp.FastRetransSegs),
fmt.Sprint(snmp.EarlyRetransSegs),
fmt.Sprint(snmp.LostSegs),
fmt.Sprint(snmp.RepeatSegs),
fmt.Sprint(snmp.FECParityShards),
fmt.Sprint(snmp.FECErrs),
fmt.Sprint(snmp.FECRecovered),
fmt.Sprint(snmp.FECShortShards),
}
}
// Copy make a copy of current snmp snapshot
func (s *Snmp) Copy() *Snmp {
d := newSnmp()
d.BytesSent = atomic.LoadUint64(&s.BytesSent)
d.BytesReceived = atomic.LoadUint64(&s.BytesReceived)
d.MaxConn = atomic.LoadUint64(&s.MaxConn)
d.ActiveOpens = atomic.LoadUint64(&s.ActiveOpens)
d.PassiveOpens = atomic.LoadUint64(&s.PassiveOpens)
d.CurrEstab = atomic.LoadUint64(&s.CurrEstab)
d.InErrs = atomic.LoadUint64(&s.InErrs)
d.InCsumErrors = atomic.LoadUint64(&s.InCsumErrors)
d.KCPInErrors = atomic.LoadUint64(&s.KCPInErrors)
d.InPkts = atomic.LoadUint64(&s.InPkts)
d.OutPkts = atomic.LoadUint64(&s.OutPkts)
d.InSegs = atomic.LoadUint64(&s.InSegs)
d.OutSegs = atomic.LoadUint64(&s.OutSegs)
d.InBytes = atomic.LoadUint64(&s.InBytes)
d.OutBytes = atomic.LoadUint64(&s.OutBytes)
d.RetransSegs = atomic.LoadUint64(&s.RetransSegs)
d.FastRetransSegs = atomic.LoadUint64(&s.FastRetransSegs)
d.EarlyRetransSegs = atomic.LoadUint64(&s.EarlyRetransSegs)
d.LostSegs = atomic.LoadUint64(&s.LostSegs)
d.RepeatSegs = atomic.LoadUint64(&s.RepeatSegs)
d.FECParityShards = atomic.LoadUint64(&s.FECParityShards)
d.FECErrs = atomic.LoadUint64(&s.FECErrs)
d.FECRecovered = atomic.LoadUint64(&s.FECRecovered)
d.FECShortShards = atomic.LoadUint64(&s.FECShortShards)
return d
}
// Reset values to zero
func (s *Snmp) Reset() {
atomic.StoreUint64(&s.BytesSent, 0)
atomic.StoreUint64(&s.BytesReceived, 0)
atomic.StoreUint64(&s.MaxConn, 0)
atomic.StoreUint64(&s.ActiveOpens, 0)
atomic.StoreUint64(&s.PassiveOpens, 0)
atomic.StoreUint64(&s.CurrEstab, 0)
atomic.StoreUint64(&s.InErrs, 0)
atomic.StoreUint64(&s.InCsumErrors, 0)
atomic.StoreUint64(&s.KCPInErrors, 0)
atomic.StoreUint64(&s.InPkts, 0)
atomic.StoreUint64(&s.OutPkts, 0)
atomic.StoreUint64(&s.InSegs, 0)
atomic.StoreUint64(&s.OutSegs, 0)
atomic.StoreUint64(&s.InBytes, 0)
atomic.StoreUint64(&s.OutBytes, 0)
atomic.StoreUint64(&s.RetransSegs, 0)
atomic.StoreUint64(&s.FastRetransSegs, 0)
atomic.StoreUint64(&s.EarlyRetransSegs, 0)
atomic.StoreUint64(&s.LostSegs, 0)
atomic.StoreUint64(&s.RepeatSegs, 0)
atomic.StoreUint64(&s.FECParityShards, 0)
atomic.StoreUint64(&s.FECErrs, 0)
atomic.StoreUint64(&s.FECRecovered, 0)
atomic.StoreUint64(&s.FECShortShards, 0)
}
// DefaultSnmp is the global KCP connection statistics collector
var DefaultSnmp *Snmp
func init() {
DefaultSnmp = newSnmp()
}

105
vendor/github.com/fatedier/kcp-go/updater.go generated vendored Normal file
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@@ -0,0 +1,105 @@
package kcp
import (
"container/heap"
"sync"
"time"
)
var updater updateHeap
func init() {
updater.init()
go updater.updateTask()
}
// entry contains a session update info
type entry struct {
ts time.Time
s *UDPSession
}
// a global heap managed kcp.flush() caller
type updateHeap struct {
entries []entry
mu sync.Mutex
chWakeUp chan struct{}
}
func (h *updateHeap) Len() int { return len(h.entries) }
func (h *updateHeap) Less(i, j int) bool { return h.entries[i].ts.Before(h.entries[j].ts) }
func (h *updateHeap) Swap(i, j int) {
h.entries[i], h.entries[j] = h.entries[j], h.entries[i]
h.entries[i].s.updaterIdx = i
h.entries[j].s.updaterIdx = j
}
func (h *updateHeap) Push(x interface{}) {
h.entries = append(h.entries, x.(entry))
n := len(h.entries)
h.entries[n-1].s.updaterIdx = n - 1
}
func (h *updateHeap) Pop() interface{} {
n := len(h.entries)
x := h.entries[n-1]
h.entries[n-1].s.updaterIdx = -1
h.entries[n-1] = entry{} // manual set nil for GC
h.entries = h.entries[0 : n-1]
return x
}
func (h *updateHeap) init() {
h.chWakeUp = make(chan struct{}, 1)
}
func (h *updateHeap) addSession(s *UDPSession) {
h.mu.Lock()
heap.Push(h, entry{time.Now(), s})
h.mu.Unlock()
h.wakeup()
}
func (h *updateHeap) removeSession(s *UDPSession) {
h.mu.Lock()
if s.updaterIdx != -1 {
heap.Remove(h, s.updaterIdx)
}
h.mu.Unlock()
}
func (h *updateHeap) wakeup() {
select {
case h.chWakeUp <- struct{}{}:
default:
}
}
func (h *updateHeap) updateTask() {
var timer <-chan time.Time
for {
select {
case <-timer:
case <-h.chWakeUp:
}
h.mu.Lock()
hlen := h.Len()
now := time.Now()
for i := 0; i < hlen; i++ {
entry := heap.Pop(h).(entry)
if now.After(entry.ts) {
entry.ts = now.Add(entry.s.update())
heap.Push(h, entry)
} else {
heap.Push(h, entry)
break
}
}
if hlen > 0 {
timer = time.After(h.entries[0].ts.Sub(now))
}
h.mu.Unlock()
}
}

110
vendor/github.com/fatedier/kcp-go/xor.go generated vendored Normal file
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@@ -0,0 +1,110 @@
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package kcp
import (
"runtime"
"unsafe"
)
const wordSize = int(unsafe.Sizeof(uintptr(0)))
const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x"
// fastXORBytes xors in bulk. It only works on architectures that
// support unaligned read/writes.
func fastXORBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
w := n / wordSize
if w > 0 {
wordBytes := w * wordSize
fastXORWords(dst[:wordBytes], a[:wordBytes], b[:wordBytes])
}
for i := (n - n%wordSize); i < n; i++ {
dst[i] = a[i] ^ b[i]
}
return n
}
func safeXORBytes(dst, a, b []byte) int {
n := len(a)
if len(b) < n {
n = len(b)
}
ex := n % 8
for i := 0; i < ex; i++ {
dst[i] = a[i] ^ b[i]
}
for i := ex; i < n; i += 8 {
_dst := dst[i : i+8]
_a := a[i : i+8]
_b := b[i : i+8]
_dst[0] = _a[0] ^ _b[0]
_dst[1] = _a[1] ^ _b[1]
_dst[2] = _a[2] ^ _b[2]
_dst[3] = _a[3] ^ _b[3]
_dst[4] = _a[4] ^ _b[4]
_dst[5] = _a[5] ^ _b[5]
_dst[6] = _a[6] ^ _b[6]
_dst[7] = _a[7] ^ _b[7]
}
return n
}
// xorBytes xors the bytes in a and b. The destination is assumed to have enough
// space. Returns the number of bytes xor'd.
func xorBytes(dst, a, b []byte) int {
if supportsUnaligned {
return fastXORBytes(dst, a, b)
}
// TODO(hanwen): if (dst, a, b) have common alignment
// we could still try fastXORBytes. It is not clear
// how often this happens, and it's only worth it if
// the block encryption itself is hardware
// accelerated.
return safeXORBytes(dst, a, b)
}
// fastXORWords XORs multiples of 4 or 8 bytes (depending on architecture.)
// The arguments are assumed to be of equal length.
func fastXORWords(dst, a, b []byte) {
dw := *(*[]uintptr)(unsafe.Pointer(&dst))
aw := *(*[]uintptr)(unsafe.Pointer(&a))
bw := *(*[]uintptr)(unsafe.Pointer(&b))
n := len(b) / wordSize
ex := n % 8
for i := 0; i < ex; i++ {
dw[i] = aw[i] ^ bw[i]
}
for i := ex; i < n; i += 8 {
_dw := dw[i : i+8]
_aw := aw[i : i+8]
_bw := bw[i : i+8]
_dw[0] = _aw[0] ^ _bw[0]
_dw[1] = _aw[1] ^ _bw[1]
_dw[2] = _aw[2] ^ _bw[2]
_dw[3] = _aw[3] ^ _bw[3]
_dw[4] = _aw[4] ^ _bw[4]
_dw[5] = _aw[5] ^ _bw[5]
_dw[6] = _aw[6] ^ _bw[6]
_dw[7] = _aw[7] ^ _bw[7]
}
}
func xorWords(dst, a, b []byte) {
if supportsUnaligned {
fastXORWords(dst, a, b)
} else {
safeXORBytes(dst, a, b)
}
}