Merge pull request #312 from cbeuw/renovate/github.com-refraction-networking-utls-1.x

Update utls and increase server first packet buffer size

.github/workflows/build.yml

@@ -7,11 +7,85 @@ jobs:
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-      - uses: actions/setup-go@v2
+      - uses: actions/setup-go@v5
         with:
-          go-version: '^1.22' # The Go version to download (if necessary) and use.
+          go-version: '^1.24' # The Go version to download (if necessary) and use.
       - run: go test -race -coverprofile coverage.txt -coverpkg ./... -covermode atomic ./...
-      - uses: codecov/codecov-action@v1
+      - uses: codecov/codecov-action@v4
         with:
-          file: coverage.txt
+          files: coverage.txt
+          token: ${{ secrets.CODECOV_TOKEN }}
+
+  compat-test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        encryption-method: [ plain, chacha20-poly1305 ]
+        num-conn: [ 0, 1, 4 ]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '^1.24'
+      - name: Build Cloak
+        run: make
+      - name: Create configs
+        run: |
+          mkdir config
+          cat << EOF > config/ckclient.json
+            {
+              "Transport": "direct",
+              "ProxyMethod": "iperf",
+              "EncryptionMethod": "${{ matrix.encryption-method }}",
+              "UID": "Q4GAXHVgnDLXsdTpw6bmoQ==",
+              "PublicKey": "4dae/bF43FKGq+QbCc5P/E/MPM5qQeGIArjmJEHiZxc=",
+              "ServerName": "cloudflare.com",
+              "BrowserSig": "firefox",
+              "NumConn": ${{ matrix.num-conn }}
+            }
+          EOF
+          cat << EOF > config/ckserver.json
+            {
+              "ProxyBook": {
+                "iperf": [
+                  "tcp",
+                  "127.0.0.1:5201"
+                ]
+              },
+              "BindAddr": [
+                ":8443"
+              ],
+              "BypassUID": [
+                "Q4GAXHVgnDLXsdTpw6bmoQ=="
+              ],
+              "RedirAddr": "cloudflare.com",
+              "PrivateKey": "AAaskZJRPIAbiuaRLHsvZPvE6gzOeSjg+ZRg1ENau0Y="
+            }
+          EOF
+      - name: Start iperf3 server
+        run: docker run -d --name iperf-server --network host ajoergensen/iperf3:latest --server
+      - name: Test new client against old server
+        run: |
+          docker run -d --name old-cloak-server --network host -v $PWD/config:/go/Cloak/config cbeuw/cloak:latest build/ck-server -c config/ckserver.json --verbosity debug
+          build/ck-client -c config/ckclient.json -s 127.0.0.1 -p 8443 --verbosity debug | tee new-cloak-client.log &
+          docker run --network host ajoergensen/iperf3:latest --client 127.0.0.1 -p 1984
+          docker stop old-cloak-server
+      - name: Test old client against new server
+        run: |
+          build/ck-server -c config/ckserver.json --verbosity debug | tee new-cloak-server.log &
+          docker run -d --name old-cloak-client --network host -v $PWD/config:/go/Cloak/config cbeuw/cloak:latest build/ck-client -c config/ckclient.json -s 127.0.0.1 -p 8443 --verbosity debug
+          docker run --network host ajoergensen/iperf3:latest --client 127.0.0.1 -p 1984
+          docker stop old-cloak-client
+      - name: Dump docker logs
+        if: always()
+        run: |
+          docker container logs iperf-server > iperf-server.log
+          docker container logs old-cloak-server > old-cloak-server.log
+          docker container logs old-cloak-client > old-cloak-client.log
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.encryption-method }}-${{ matrix.num-conn }}-conn-logs
+          path: ./*.log

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Build
         run: |
           export PATH=${PATH}:`go env GOPATH`/bin
@@ -20,3 +20,31 @@ jobs:
           files: release/*
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  build-docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            cbeuw/cloak
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

Dockerfile

@@ -0,0 +1,5 @@
+FROM golang:latest
+
+RUN git clone https://github.com/cbeuw/Cloak.git
+WORKDIR Cloak
+RUN make

README.md

@@ -12,7 +12,7 @@
   <img src="https://user-images.githubusercontent.com/7034308/155629720-54dd8758-ec98-4fed-b603-623f0ad83b6c.svg" />
 </p>
 
-Cloak is a [pluggable transport](https://www.ietf.org/proceedings/103/slides/slides-103-pearg-pt-slides-01) that enhances
+Cloak is a [pluggable transport](https://datatracker.ietf.org/meeting/103/materials/slides-103-pearg-pt-slides-01) that enhances
 traditional proxy tools like OpenVPN to evade [sophisticated censorship](https://en.wikipedia.org/wiki/Deep_packet_inspection) and [data discrimination](https://en.wikipedia.org/wiki/Net_bias).
 
 Cloak is not a standalone proxy program. Rather, it works by masquerading proxied traffic as normal web browsing

go.mod

@@ -1,30 +1,30 @@
 module github.com/cbeuw/Cloak
 
-go 1.21
+go 1.24.0
 
-toolchain go1.22.2
+toolchain go1.24.2
 
 require (
 	github.com/cbeuw/connutil v0.0.0-20200411215123-966bfaa51ee3
 	github.com/gorilla/mux v1.8.1
-	github.com/gorilla/websocket v1.5.1
+	github.com/gorilla/websocket v1.5.3
 	github.com/juju/ratelimit v1.0.2
-	github.com/refraction-networking/utls v1.6.4
+	github.com/refraction-networking/utls v1.8.0
 	github.com/sirupsen/logrus v1.9.3
-	github.com/stretchr/testify v1.9.0
+	github.com/stretchr/testify v1.10.0
-	go.etcd.io/bbolt v1.3.9
+	go.etcd.io/bbolt v1.4.0
-	golang.org/x/crypto v0.22.0
+	golang.org/x/crypto v0.37.0
 )
 
 require (
-	github.com/andybalholm/brotli v1.0.6 // indirect
+	github.com/andybalholm/brotli v1.1.1 // indirect
-	github.com/cloudflare/circl v1.3.7 // indirect
+	github.com/cloudflare/circl v1.6.1 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/klauspost/compress v1.17.4 // indirect
+	github.com/klauspost/compress v1.18.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/net v0.21.0 // indirect
+	github.com/rogpeppe/go-internal v1.14.1 // indirect
-	golang.org/x/sys v0.19.0 // indirect
+	golang.org/x/sys v0.32.0 // indirect
-	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,52 +1,61 @@
-github.com/andybalholm/brotli v1.0.6 h1:Yf9fFpf49Zrxb9NlQaluyE92/+X7UVHlhMNJN2sxfOI=
+github.com/andybalholm/brotli v1.1.1 h1:PR2pgnyFznKEugtsUo0xLdDop5SKXd5Qf5ysW+7XdTA=
-github.com/andybalholm/brotli v1.0.6/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
+github.com/andybalholm/brotli v1.1.1/go.mod h1:05ib4cKhjx3OQYUY22hTVd34Bc8upXjOLL2rKwwZBoA=
 github.com/cbeuw/connutil v0.0.0-20200411215123-966bfaa51ee3 h1:LRxW8pdmWmyhoNh+TxUjxsAinGtCsVGjsl3xg6zoRSs=
 github.com/cbeuw/connutil v0.0.0-20200411215123-966bfaa51ee3/go.mod h1:6jR2SzckGv8hIIS9zWJ160mzGVVOYp4AXZMDtacL6LE=
-github.com/cloudflare/circl v1.3.7 h1:qlCDlTPz2n9fu58M0Nh1J/JzcFpfgkFHHX3O35r5vcU=
+github.com/cloudflare/circl v1.6.1 h1:zqIqSPIndyBh1bjLVVDHMPpVKqp8Su/V+6MeDzzQBQ0=
-github.com/cloudflare/circl v1.3.7/go.mod h1:sRTcRWXGLrKw6yIGJ+l7amYJFfAXbZG0kBSc8r4zxgA=
+github.com/cloudflare/circl v1.6.1/go.mod h1:uddAzsPgqdMAYatqJ0lsjX1oECcQLIlRpzZh3pJrofs=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gorilla/mux v1.8.1 h1:TuBL49tXwgrFYWhqrNgrUNEY92u81SPhu7sTdzQEiWY=
 github.com/gorilla/mux v1.8.1/go.mod h1:AKf9I4AEqPTmMytcMc0KkNouC66V3BtZ4qD5fmWSiMQ=
-github.com/gorilla/websocket v1.5.1 h1:gmztn0JnHVt9JZquRuzLw3g4wouNVzKL15iLr/zn/QY=
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-github.com/gorilla/websocket v1.5.1/go.mod h1:x3kM2JMyaluk02fnUJpQuwD2dCS5NDG2ZHL0uE0tcaY=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/juju/ratelimit v1.0.2 h1:sRxmtRiajbvrcLQT7S+JbqU0ntsb9W2yhSdNN8tWfaI=
 github.com/juju/ratelimit v1.0.2/go.mod h1:qapgC/Gy+xNh9UxzV13HGGl/6UXNN+ct+vwSgWNm/qk=
-github.com/klauspost/compress v1.17.4 h1:Ej5ixsIri7BrIjBkRZLTo6ghwrEtHFk7ijlczPW4fZ4=
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-github.com/klauspost/compress v1.17.4/go.mod h1:/dCuZOvVtNoHsyb+cuJD3itjs3NbnF6KH9zAO4BDxPM=
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+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
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 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
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 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/refraction-networking/utls v1.6.4 h1:aeynTroaYn7y+mFtqv8D0bQ4bw0y9nJHneGxJ7lvRDM=
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-github.com/refraction-networking/utls v1.6.4/go.mod h1:2VL2xfiqgFAZtJKeUTlf+PSYFs3Eu7km0gCtXJ3m8zs=
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-github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
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-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
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-go.etcd.io/bbolt v1.3.9 h1:8x7aARPEXiXbHmtUwAIv7eV2fQFHrLLavdiJ3uzJXoI=
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-go.etcd.io/bbolt v1.3.9/go.mod h1:zaO32+Ti0PK1ivdPtgMESzuzL2VPoIG1PCQNvOdo/dE=
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-golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=
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-golang.org/x/crypto v0.22.0/go.mod h1:vr6Su+7cTlO45qkww3VDJlzDn0ctJvRgYbC2NvXHt+M=
+go.etcd.io/bbolt v1.4.0/go.mod h1:AsD+OCi/qPN1giOX1aiLAha3o1U8rAz65bvN4j0sRuk=
-golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
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-golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
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-golang.org/x/sync v0.5.0 h1:60k92dhOjHxJkrqnwsfl8KuaHbn/5dl0lUPUklKo3qE=
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 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
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-golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
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 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
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+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/client/connector.go

@@ -21,8 +21,10 @@ func MakeSession(connConfig RemoteConnConfig, authInfo AuthInfo, dialer common.D
 	var wg sync.WaitGroup
 	for i := 0; i < connConfig.NumConn; i++ {
 		wg.Add(1)
+		transportConfig := connConfig.Transport
 		go func() {
 		makeconn:
+			transportConn := transportConfig.CreateTransport()
 			remoteConn, err := dialer.Dial("tcp", connConfig.RemoteAddr)
 			if err != nil {
 				log.Errorf("Failed to establish new connections to remote: %v", err)
@@ -31,12 +33,20 @@ func MakeSession(connConfig RemoteConnConfig, authInfo AuthInfo, dialer common.D
 				goto makeconn
 			}
 
-			transportConn := connConfig.TransportMaker()
 			sk, err := transportConn.Handshake(remoteConn, authInfo)
 			if err != nil {
 				log.Errorf("Failed to prepare connection to remote: %v", err)
 				transportConn.Close()
+
+				// In Cloak v2.11.0, we've updated uTLS version and subsequently increased the first packet size for chrome above 1500
+				// https://github.com/cbeuw/Cloak/pull/306#issuecomment-2862728738. As a backwards compatibility feature, if we fail
+				// to connect using chrome signature, retry with firefox which has a smaller packet size.
+				if transportConfig.mode == "direct" && transportConfig.browser == chrome {
+					transportConfig.browser = firefox
+					log.Warnf("failed to connect with chrome signature, falling back to retry with firefox")
+				}
 				time.Sleep(time.Second * 3)
+
 				goto makeconn
 			}
 			// sessionKey given by each connection should be identical

internal/client/state.go

@@ -47,7 +47,7 @@ type RemoteConnConfig struct {
 	NumConn    int
 	KeepAlive  time.Duration
 	RemoteAddr string
-	TransportMaker func() Transport
+	Transport  TransportConfig
 }
 
 type LocalConnConfig struct {
@@ -230,11 +230,10 @@ func (raw *RawConfig) ProcessRawConfig(worldState common.WorldState) (local Loca
 			raw.CDNWsUrlPath = "/"
 		}
 
-		remote.TransportMaker = func() Transport {
+		remote.Transport = TransportConfig{
-			return &WSOverTLS{
+			mode:  "cdn",
 			wsUrl: "ws://" + cdnDomainPort + raw.CDNWsUrlPath,
 		}
-		}
 	case "direct":
 		fallthrough
 	default:
@@ -249,12 +248,11 @@ func (raw *RawConfig) ProcessRawConfig(worldState common.WorldState) (local Loca
 		default:
 			browser = chrome
 		}
-		remote.TransportMaker = func() Transport {
+		remote.Transport = TransportConfig{
-			return &DirectTLS{
+			mode:    "direct",
 			browser: browser,
 		}
 	}
-	}
 
 	// KeepAlive
 	if raw.KeepAlive <= 0 {

internal/client/transport.go

@@ -8,3 +8,26 @@ type Transport interface {
 	Handshake(rawConn net.Conn, authInfo AuthInfo) (sessionKey [32]byte, err error)
 	net.Conn
 }
+
+type TransportConfig struct {
+	mode string
+
+	wsUrl string
+
+	browser browser
+}
+
+func (t TransportConfig) CreateTransport() Transport {
+	switch t.mode {
+	case "cdn":
+		return &WSOverTLS{
+			wsUrl: t.wsUrl,
+		}
+	case "direct":
+		return &DirectTLS{
+			browser: t.browser,
+		}
+	default:
+		return nil
+	}
+}

internal/multiplex/obfs.go

@@ -3,10 +3,10 @@ package multiplex
 import (
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/rand"
 	"encoding/binary"
 	"errors"
 	"fmt"
-
 	"github.com/cbeuw/Cloak/internal/common"
 	"golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/crypto/salsa20"
@@ -15,6 +15,14 @@ import (
 const frameHeaderLength = 14
 const salsa20NonceSize = 8
 
+// maxExtraLen equals the max length of padding + AEAD tag.
+// It is 255 bytes because the extra len field in frame header is only one byte.
+const maxExtraLen = 1<<8 - 1
+
+// padFirstNFrames specifies the number of initial frames to pad,
+// to avoid TLS-in-TLS detection
+const padFirstNFrames = 5
+
 const (
 	EncryptionMethodPlain = iota
 	EncryptionMethodAES256GCM
@@ -27,8 +35,6 @@ type Obfuscator struct {
 	payloadCipher cipher.AEAD
 
 	sessionKey [32]byte
-
-	maxOverhead int
 }
 
 // obfuscate adds multiplexing headers, encrypt and add TLS header
@@ -49,45 +55,34 @@ func (o *Obfuscator) obfuscate(f *Frame, buf []byte, payloadOffsetInBuf int) (in
 	// to be large enough that they may never happen in reasonable time frames. Of course, different sessions
 	// will produce the same combination of stream id and frame sequence, but they will have different session keys.
 	//
-	// Salsa20 is assumed to be given a unique nonce each time because we assume the tags produced by payloadCipher
-	// AEAD is unique each time, as payloadCipher itself is given a unique iv/nonce each time due to points made above.
-	// This is relatively a weak guarantee as we are assuming AEADs to produce different tags given different iv/nonces.
-	// This is almost certainly true but I cannot find a source that outright states this.
 	//
 	// Because the frame header, before it being encrypted, is fed into the AEAD, it is also authenticated.
 	// (rfc5116 s.2.1 "The nonce is authenticated internally to the algorithm").
 	//
 	// In case the user chooses to not encrypt the frame payload, payloadCipher will be nil. In this scenario,
-	// we pad the frame payload with random bytes until it reaches Salsa20's nonce size (8 bytes). Then we simply
+	// we generate random bytes to be used as salsa20 nonce.
-	// encrypt the frame header with the last 8 bytes of frame payload as nonce.
-	// If the payload provided by the user is greater than 8 bytes, then we use entirely the user input as nonce.
-	// We can't ensure its uniqueness ourselves, which is why plaintext mode must only be used when the user input
-	// is already random-like. For Cloak it would normally mean that the user is using a proxy protocol that sends
-	// encrypted data.
 	payloadLen := len(f.Payload)
 	if payloadLen == 0 {
 		return 0, errors.New("payload cannot be empty")
 	}
-	var extraLen int
+	tagLen := 0
-	if o.payloadCipher == nil {
+	if o.payloadCipher != nil {
-		extraLen = salsa20NonceSize - payloadLen
+		tagLen = o.payloadCipher.Overhead()
-		if extraLen < 0 {
-			// if our payload is already greater than 8 bytes
-			extraLen = 0
-		}
 	} else {
-		extraLen = o.payloadCipher.Overhead()
+		tagLen = salsa20NonceSize
-		if extraLen < salsa20NonceSize {
-			return 0, errors.New("AEAD's Overhead cannot be fewer than 8 bytes")
 	}
+	// Pad to avoid size side channel leak
+	padLen := 0
+	if f.Seq < padFirstNFrames {
+		padLen = common.RandInt(maxExtraLen - tagLen + 1)
 	}
 
-	usefulLen := frameHeaderLength + payloadLen + extraLen
+	usefulLen := frameHeaderLength + payloadLen + padLen + tagLen
 	if len(buf) < usefulLen {
 		return 0, errors.New("obfs buffer too small")
 	}
 	// we do as much in-place as possible to save allocation
-	payload := buf[frameHeaderLength : frameHeaderLength+payloadLen]
+	payload := buf[frameHeaderLength : frameHeaderLength+payloadLen+padLen]
 	if payloadOffsetInBuf != frameHeaderLength {
 		// if payload is not at the correct location in buffer
 		copy(payload, f.Payload)
@@ -97,14 +92,15 @@ func (o *Obfuscator) obfuscate(f *Frame, buf []byte, payloadOffsetInBuf int) (in
 	binary.BigEndian.PutUint32(header[0:4], f.StreamID)
 	binary.BigEndian.PutUint64(header[4:12], f.Seq)
 	header[12] = f.Closing
-	header[13] = byte(extraLen)
+	header[13] = byte(padLen + tagLen)
 
-	if o.payloadCipher == nil {
+	// Random bytes for padding and nonce
-		if extraLen != 0 { // read nonce
+	_, err := rand.Read(buf[frameHeaderLength+payloadLen : usefulLen])
-			extra := buf[usefulLen-extraLen : usefulLen]
+	if err != nil {
-			common.CryptoRandRead(extra)
+		return 0, fmt.Errorf("failed to pad random: %w", err)
 	}
-	} else {
+
+	if o.payloadCipher != nil {
 		o.payloadCipher.Seal(payload[:0], header[:o.payloadCipher.NonceSize()], payload, nil)
 	}
 
@@ -166,7 +162,6 @@ func MakeObfuscator(encryptionMethod byte, sessionKey [32]byte) (o Obfuscator, e
 	switch encryptionMethod {
 	case EncryptionMethodPlain:
 		o.payloadCipher = nil
-		o.maxOverhead = salsa20NonceSize
 	case EncryptionMethodAES256GCM:
 		var c cipher.Block
 		c, err = aes.NewCipher(sessionKey[:])
@@ -177,7 +172,6 @@ func MakeObfuscator(encryptionMethod byte, sessionKey [32]byte) (o Obfuscator, e
 		if err != nil {
 			return
 		}
-		o.maxOverhead = o.payloadCipher.Overhead()
 	case EncryptionMethodAES128GCM:
 		var c cipher.Block
 		c, err = aes.NewCipher(sessionKey[:16])
@@ -188,13 +182,11 @@ func MakeObfuscator(encryptionMethod byte, sessionKey [32]byte) (o Obfuscator, e
 		if err != nil {
 			return
 		}
-		o.maxOverhead = o.payloadCipher.Overhead()
 	case EncryptionMethodChaha20Poly1305:
 		o.payloadCipher, err = chacha20poly1305.New(sessionKey[:])
 		if err != nil {
 			return
 		}
-		o.maxOverhead = o.payloadCipher.Overhead()
 	default:
 		return o, fmt.Errorf("unknown encryption method valued %v", encryptionMethod)
 	}

internal/multiplex/obfs_test.go

@@ -85,7 +85,6 @@ func TestObfuscate(t *testing.T) {
 		o := Obfuscator{
 			payloadCipher: nil,
 			sessionKey:    sessionKey,
-			maxOverhead:   salsa20NonceSize,
 		}
 		runTest(t, o)
 	})
@@ -98,7 +97,6 @@ func TestObfuscate(t *testing.T) {
 		o := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    sessionKey,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		runTest(t, o)
 	})
@@ -111,7 +109,6 @@ func TestObfuscate(t *testing.T) {
 		o := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    sessionKey,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		runTest(t, o)
 	})
@@ -122,7 +119,6 @@ func TestObfuscate(t *testing.T) {
 		o := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    sessionKey,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		runTest(t, o)
 	})
@@ -150,7 +146,6 @@ func BenchmarkObfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 
 		b.SetBytes(int64(len(testFrame.Payload)))
@@ -166,7 +161,6 @@ func BenchmarkObfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
@@ -178,7 +172,6 @@ func BenchmarkObfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: nil,
 			sessionKey:    key,
-			maxOverhead:   salsa20NonceSize,
 		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
@@ -192,7 +185,6 @@ func BenchmarkObfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
@@ -222,7 +214,6 @@ func BenchmarkDeobfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 
 		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
@@ -241,7 +232,6 @@ func BenchmarkDeobfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
 
@@ -256,7 +246,6 @@ func BenchmarkDeobfs(b *testing.B) {
 		obfuscator := Obfuscator{
 			payloadCipher: nil,
 			sessionKey:    key,
-			maxOverhead:   salsa20NonceSize,
 		}
 		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
 
@@ -271,9 +260,8 @@ func BenchmarkDeobfs(b *testing.B) {
 		payloadCipher, _ := chacha20poly1305.New(key[:])
 
 		obfuscator := Obfuscator{
-			payloadCipher: nil,
+			payloadCipher: payloadCipher,
 			sessionKey:    key,
-			maxOverhead:   payloadCipher.Overhead(),
 		}
 
 		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)

internal/multiplex/session.go

@@ -108,7 +108,7 @@ func MakeSession(id uint32, config SessionConfig) *Session {
 		sesh.InactivityTimeout = defaultInactivityTimeout
 	}
 
-	sesh.maxStreamUnitWrite = sesh.MsgOnWireSizeLimit - frameHeaderLength - sesh.maxOverhead
+	sesh.maxStreamUnitWrite = sesh.MsgOnWireSizeLimit - frameHeaderLength - maxExtraLen
 	sesh.streamSendBufferSize = sesh.MsgOnWireSizeLimit
 	sesh.connReceiveBufferSize = 20480 // for backwards compatibility
 

internal/server/auth.go

@@ -61,7 +61,7 @@ func decryptClientInfo(fragments authFragments, serverTime time.Time) (info Clie
 
 var ErrReplay = errors.New("duplicate random")
 var ErrBadProxyMethod = errors.New("invalid proxy method")
-var ErrBadDecryption = errors.New("decryption/authentication faliure")
+var ErrBadDecryption = errors.New("decryption/authentication failure")
 
 // AuthFirstPacket checks if the first packet of data is ClientHello or HTTP GET, and checks if it was from a Cloak client
 // if it is from a Cloak client, it returns the ClientInfo with the decrypted fields. It doesn't check if the user

internal/server/dispatcher.go

@@ -20,6 +20,8 @@ import (
 
 var b64 = base64.StdEncoding.EncodeToString
 
+const firstPacketSize = 3000
+
 func Serve(l net.Listener, sta *State) {
 	waitDur := [10]time.Duration{
 		50 * time.Millisecond, 100 * time.Millisecond, 300 * time.Millisecond, 500 * time.Millisecond, 1 * time.Second,
@@ -124,7 +126,7 @@ func readFirstPacket(conn net.Conn, buf []byte, timeout time.Duration) (int, Tra
 
 func dispatchConnection(conn net.Conn, sta *State) {
 	var err error
-	buf := make([]byte, 1500)
+	buf := make([]byte, firstPacketSize)
 
 	i, transport, redirOnErr, err := readFirstPacket(conn, buf, 15*time.Second)
 	data := buf[:i]

internal/server/state_test.go

@@ -43,13 +43,22 @@ func TestParseRedirAddr(t *testing.T) {
 			t.Errorf("parsing %v error: %v", domainNoPort, err)
 			return
 		}
-		expHost, err := net.ResolveIPAddr("ip", "example.com")
+
+		expIPs, err := net.LookupIP("example.com")
 		if err != nil {
 			t.Errorf("tester error: cannot resolve example.com: %v", err)
 			return
 		}
-		if host.String() != expHost.String() {
+
-			t.Errorf("expected %v got %v", expHost.String(), host.String())
+		contain := false
+		for _, expIP := range expIPs {
+			if expIP.String() == host.String() {
+				contain = true
+			}
+		}
+
+		if !contain {
+			t.Errorf("expected one of %v got %v", expIPs, host.String())
 		}
 		if port != "" {
 			t.Errorf("port not empty when there is no port")
@@ -63,13 +72,22 @@ func TestParseRedirAddr(t *testing.T) {
 			t.Errorf("parsing %v error: %v", domainWPort, err)
 			return
 		}
-		expHost, err := net.ResolveIPAddr("ip", "example.com")
+
+		expIPs, err := net.LookupIP("example.com")
 		if err != nil {
 			t.Errorf("tester error: cannot resolve example.com: %v", err)
 			return
 		}
-		if host.String() != expHost.String() {
+
-			t.Errorf("expected %v got %v", expHost.String(), host.String())
+		contain := false
+		for _, expIP := range expIPs {
+			if expIP.String() == host.String() {
+				contain = true
+			}
+		}
+
+		if !contain {
+			t.Errorf("expected one of %v got %v", expIPs, host.String())
 		}
 		if port != "80" {
 			t.Errorf("wrong port: expected %v, got %v", "80", port)