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+ GNU GENERAL PUBLIC LICENSE
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+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) <year> <name of author>
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ <program> Copyright (C) <year> <name of author>
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+++ /dev/null
-/*
-udpobfs -- simple point-to-point UDP obfuscation proxy
-Copyright (C) 2023 Sergey Matveev <stargrave@stargrave.org>
-
-This program is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, version 3 of the License.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this program. If not, see <http://www.gnu.org/licenses/>.
-*/
-
-package main
-
-import (
- "bufio"
- "crypto/rand"
- "crypto/subtle"
- "encoding/base32"
- "flag"
- "fmt"
- "io"
- "log"
- "net"
- "os"
- "os/signal"
- "syscall"
-
- "golang.org/x/crypto/blowfish"
- "golang.org/x/crypto/chacha20"
- "golang.org/x/crypto/poly1305"
- "golang.org/x/crypto/sha3"
-)
-
-const KeyLen = 32
-
-func mustWrite(w io.Writer, data []byte) {
- if n, err := w.Write(data); err != nil || n != len(data) {
- log.Fatal("non full write")
- }
-}
-
-func incr(buf []byte) (overflow bool) {
- for i := len(buf) - 1; i >= 0; i-- {
- buf[i]++
- if buf[i] != 0 {
- return
- }
- }
- overflow = true
- return
-}
-
-type State struct {
- ourKey, theirKey []byte
- ourObfs, theirObfs *blowfish.Cipher
- ourNonce, theirNonce []byte
- ourSeq, theirSeq []byte
-}
-
-var Base32Codec *base32.Encoding = base32.StdEncoding.WithPadding(base32.NoPadding)
-
-func main() {
- keygen := flag.Bool("keygen", false, "Generate random key")
- responder := flag.Bool("responder", false, "Are we responder?")
- bind := flag.String("bind", "[::]:1194", "Address to bind to")
- dst := flag.String("dst", "[2001:db8::1234]::1194", "Address to connect to")
- flag.Parse()
- log.SetFlags(log.Ldate | log.Lmicroseconds | log.Lshortfile)
-
- if *keygen {
- key := make([]byte, KeyLen)
- if _, err := io.ReadFull(rand.Reader, key); err != nil {
- log.Fatal(err)
- }
- fmt.Println(Base32Codec.EncodeToString(key))
- return
- }
-
- var state *State
- stateReady := make(chan struct{})
- go func() {
- first := true
- s := bufio.NewScanner(os.Stdin)
- h := sha3.NewShake128()
- for s.Scan() {
- key, err := Base32Codec.DecodeString(s.Text())
- if err != nil {
- log.Fatal(err)
- }
- if len(key) != KeyLen {
- log.Fatal("wrong key length")
- }
- h.Reset()
- mustWrite(h, []byte("go.cypherpunks.ru/udpobfs"))
- mustWrite(h, key)
- iEncKey := make([]byte, chacha20.KeySize)
- iBlkKey := make([]byte, 32)
- rEncKey := make([]byte, chacha20.KeySize)
- rBlkKey := make([]byte, 32)
- if _, err := io.ReadFull(h, iEncKey); err != nil {
- log.Fatal(err)
- }
- if _, err := io.ReadFull(h, iBlkKey); err != nil {
- log.Fatal(err)
- }
- if _, err := io.ReadFull(h, rEncKey); err != nil {
- log.Fatal(err)
- }
- if _, err := io.ReadFull(h, rBlkKey); err != nil {
- log.Fatal(err)
- }
- iObfs, err := blowfish.NewCipher(iBlkKey)
- if err != nil {
- log.Fatal(err)
- }
- rObfs, err := blowfish.NewCipher(rBlkKey)
- if err != nil {
- log.Fatal(err)
- }
- var newState State
- if *responder {
- newState = State{
- ourKey: rEncKey,
- theirKey: iEncKey,
- ourObfs: rObfs,
- theirObfs: iObfs,
- ourNonce: make([]byte, chacha20.NonceSize),
- theirNonce: make([]byte, chacha20.NonceSize),
- }
- } else {
- newState = State{
- ourKey: iEncKey,
- theirKey: rEncKey,
- ourObfs: iObfs,
- theirObfs: rObfs,
- ourNonce: make([]byte, chacha20.NonceSize),
- theirNonce: make([]byte, chacha20.NonceSize),
- }
- }
- newState.ourSeq = newState.ourNonce[4:]
- newState.theirSeq = newState.theirNonce[4:]
- state = &newState
- if first {
- close(stateReady)
- first = false
- }
- }
- if s.Err() != nil {
- log.Fatal(s.Err())
- }
- }()
- <-stateReady
-
- addr, err := net.ResolveUDPAddr("udp", *bind)
- if err != nil {
- log.Fatal(err)
- }
- connBind, err := net.ListenUDP("udp", addr)
- if err != nil {
- log.Fatal(err)
- }
-
- var connLocal *net.UDPConn
- var connRemote *net.UDPConn
- var addrLocal *net.UDPAddr
- var addrRemote *net.UDPAddr
- addr, err = net.ResolveUDPAddr("udp", *dst)
- if err != nil {
- log.Fatal(err)
- }
- if *responder {
- connLocal, err = net.DialUDP("udp", nil, addr)
- } else {
- connRemote, err = net.DialUDP("udp", nil, addr)
- }
- if err != nil {
- log.Fatal(err)
- }
- log.Println(*bind, "->", *dst)
-
- go func() {
- rx := make([]byte, 1<<14)
- tx := make([]byte, 1<<14)
- var n int
- var polyKey [32]byte
- var s *chacha20.Cipher
- var p *poly1305.MAC
- tag := make([]byte, poly1305.TagSize)
- var from *net.UDPAddr
- for {
- if *responder {
- n, err = connLocal.Read(rx)
- } else {
- n, from, err = connBind.ReadFromUDP(rx)
- }
- if err != nil {
- log.Fatal(err)
- }
- if *responder && addrRemote == nil {
- continue
- }
- if !*responder && (addrLocal == nil ||
- from.Port != addrLocal.Port || !from.IP.Equal(addrLocal.IP)) {
- addrLocal = from
- }
- if incr(state.ourSeq[5:]) {
- incr(state.ourSeq[:5])
- }
- copy(tx, state.ourSeq[5:])
- s, err = chacha20.NewUnauthenticatedCipher(state.ourKey, state.ourNonce)
- if err != nil {
- log.Fatal(err)
- }
- clear(polyKey[:])
- s.XORKeyStream(polyKey[:], polyKey[:])
- s.SetCounter(1)
- s.XORKeyStream(tx[8:], rx[:n])
- p = poly1305.New(&polyKey)
- mustWrite(p, state.ourSeq)
- mustWrite(p, tx[8:8+n])
- p.Sum(tag[:0])
- copy(tx[3:8], tag)
- state.ourObfs.Encrypt(tx[:8], tx[:8])
- if *responder {
- connBind.WriteTo(tx[:8+n], addrRemote)
- } else {
- connRemote.Write(tx[:8+n])
- }
- }
- }()
- go func(state **State) {
- rx := make([]byte, 1<<14)
- tx := make([]byte, 1<<14)
- var n int
- var polyKey [32]byte
- var s *chacha20.Cipher
- var p *poly1305.MAC
- var from *net.UDPAddr
- tag := make([]byte, poly1305.TagSize)
- nonce := make([]byte, chacha20.NonceSize)
- seq := nonce[4:]
- var seqOur, seqTheir uint32
- for {
- if *responder {
- n, from, err = connBind.ReadFromUDP(rx)
- } else {
- n, err = connRemote.Read(rx)
- }
- if err != nil {
- log.Fatal(err)
- }
- if n < 8 {
- log.Println("too short")
- continue
- }
- if *responder && (addrRemote == nil ||
- from.Port != addrRemote.Port || !from.IP.Equal(addrRemote.IP)) {
- addrRemote = from
- }
- (*state).theirObfs.Decrypt(rx[:8], rx[:8])
- seqOur = uint32((*state).theirSeq[0])<<16 |
- uint32((*state).theirSeq[1])<<8 |
- uint32((*state).theirSeq[2])
- seqTheir = uint32(rx[0])<<16 | uint32(rx[1])<<8 | uint32(rx[2])
- if seqOur == seqTheir {
- log.Println("replay")
- continue
- }
- copy(seq, (*state).theirNonce[:5])
- copy(seq[5:], rx[:3])
- if seqTheir < seqOur && incr(seq[:5]) {
- log.Fatal("seq is overflowed")
- }
- s, err = chacha20.NewUnauthenticatedCipher((*state).theirKey, nonce)
- if err != nil {
- log.Fatal(err)
- }
- clear(polyKey[:])
- s.XORKeyStream(polyKey[:], polyKey[:])
- s.SetCounter(1)
- p = poly1305.New(&polyKey)
- mustWrite(p, seq)
- mustWrite(p, rx[8:n])
- p.Sum(tag[:0])
- if subtle.ConstantTimeCompare(tag[:5], rx[3:8]) != 1 {
- log.Print("bad MAC")
- continue
- }
- copy((*state).theirSeq, seq)
- s.XORKeyStream(tx, rx[8:n])
- if *responder {
- connLocal.Write(tx[:n-8])
- } else {
- connBind.WriteTo(tx[:n-8], addrLocal)
- }
- }
- }(&state)
- exit := make(chan os.Signal, 1)
- signal.Notify(exit, syscall.SIGTERM, syscall.SIGINT)
- <-exit
-}