read from env var Q3RCON_STALE_SESSION_TIMEOUT

add a trace level log when a session gets deleted.

.gitignore

@@ -19,3 +19,7 @@
 
 # Go workspace file
 go.work
+
+# testing
+run.sh
+server.yaml

CHANGELOG.md

@@ -11,12 +11,47 @@ Before any major/minor/patch bump all unit tests will be run to verify they pass
 
 -   [x]
 
+## [0.6.0] - 2024-03-21
+
+### Added
+
+-   new environment variable `Q3RCON_DEBUG` for enabling debug logging. Defaults to 0.
+-   rcon responses are now logged at debug level
+-   invalid responses (rcon and query) now logged
+
+### Changed
+
+-   All packet header checking methods moved into Session struct.
+
+### Fixed
+
+-   a bug causing the proxy not to send back query responses
+
+## [0.3.0] - 2024-03-08
+
+### Added
+
+-   outgoing rcon requests now logged at info level
+-   new environment variable `Q3RCON_HOST` for specifying which ip to bind the proxy to. Defaults to `0.0.0.0`.
+
+### Changed
+
+-   now using [logrus][logrus] package for logging.
+
+### Fixed
+
+-   a `slice bounds out of range` error due to query packets being logged.
+
 ## [0.1.0] - 2024-01-27
 
--   ignore any packets whose header does match a q3 rcon/query packet.
+### Added
+
+-   only forward packets if the header matches q3 rcon/query.
 
 ## [0.0.1] - 2024-01-27
 
 ### Added
 
 -   All source files for lilproxy including full commit history.
+
+[logrus]: https://github.com/sirupsen/logrus

Dockerfile

@@ -1,12 +1,14 @@
-FROM golang:alpine
+FROM golang:1.21
 
-WORKDIR /dist
+WORKDIR /usr/src/app
 
-COPY . .
-
-# build binary and place into /usr/local/bin
+# pre-copy/cache go.mod for pre-downloading dependencies and only redownloading them in subsequent builds if they change
+COPY go.mod go.sum ./
 RUN go mod download && go mod verify
-RUN go build -v -o /usr/local/bin/q3rcon-proxy ./cmd/q3rcon-proxy
+
+# build binary and place into /usr/local/bin/
+COPY . .
+RUN go build -v -o /usr/local/bin/q3rcon-proxy ./cmd/q3rcon-proxy/
 
 # Command to run when starting the container
 ENTRYPOINT [ "q3rcon-proxy" ]

README.md

@@ -2,6 +2,10 @@
 
 A modification of [lilproxy][lilproxy_url] that forwards only Q3 rcon/query packets. Useful for separating the rcon port from the game server port.
 
+### Why
+
+Unfortunately the Q3Rcon engine ties the rcon port to the game servers public port used for client connections. This proxy will allow you to run rcon through a separate whitelisted port.
+
 ### Use
 
 Run one or multiple rcon proxies by setting an environment variable `Q3RCON_PROXY`
@@ -12,17 +16,19 @@ for example:
 export Q3RCON_PROXY="20000:28960;20001:28961;20002:28962"
 ```
 
-This would run 3 proxy servers listening on ports `20000`, `20001` and `20002` that redirect rcon requests to game servers on ports `28960`, `28961` and `28962` respectively.
+This would configure q3rcon-proxy to run 3 proxy servers listening on ports `20000`, `20001` and `20002` that redirect rcon requests to game servers on ports `28960`, `28961` and `28962` respectively.
 
-### Why
+Then just run the binary which you can compile yourself, download from `Releases` or use the included Dockerfile.
 
-Avoid sending plaintext rcon requests (that include the password) to public ports. Instead send them to whitelisted ports.
+### Logging
 
-Gives you the option to disable remote rcon entirely and have the server accept requests only from localhost.
+Set the log level with environment variable `Q3RCON_LOGLEVEL`:
+
+`0 = Panic, 1 = Fatal, 2 = Error, 3 = Warning, 4 = Info, 5 = Debug, 6 = Trace`
 
 ### Special Thanks
 
-[Dylan][user_link] For writing this proxy.
+[Dylan][user_link] For writing [lilproxy][lilproxy_url].
 
 [lilproxy_url]: https://github.com/dgparker/lilproxy
 [user_link]: https://github.com/dgparker

cmd/q3rcon-proxy/main.go

@@ -2,38 +2,62 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"os"
+	"slices"
 	"strings"
+	"time"
+
+	log "github.com/sirupsen/logrus"
 
 	"github.com/onyx-and-iris/q3rcon-proxy/pkg/udpproxy"
 )
 
-func start(proxy string) {
-	port, target := func() (string, string) {
-		x := strings.Split(proxy, ":")
-		return x[0], x[1]
-	}()
-
-	c, err := udpproxy.New(fmt.Sprintf("0.0.0.0:%s", port), fmt.Sprintf("127.0.0.1:%s", target))
+func main() {
+	logLevel, err := getEnvInt("Q3RCON_LOGLEVEL")
 	if err != nil {
-		log.Fatal(err)
+		log.Fatalf("unable to parse Q3RCON_LEVEL: %s", err.Error())
+	}
+	if slices.Contains(log.AllLevels, log.Level(logLevel)) {
+		log.SetLevel(log.Level(logLevel))
 	}
 
-	log.Printf("q3rcon-proxy initialized: [proxy] (0.0.0.0:%s) [target] (127.0.0.1:%s)", port, target)
-
-	log.Fatal(c.ListenAndServe())
-}
-
-func main() {
 	proxies := os.Getenv("Q3RCON_PROXY")
 	if proxies == "" {
 		log.Fatal("env Q3RCON_PROXY required")
 	}
 
+	host := os.Getenv("Q3RCON_HOST")
+	if host == "" {
+		host = "0.0.0.0"
+	}
+
+	staleTimeout, err := getEnvInt("Q3RCON_STALE_SESSION_TIMEOUT")
+	if err != nil {
+		log.Fatalf("unable to parse Q3RCON_STALE_SESSION_TIMEOUT: %s", err.Error())
+	}
+
 	for _, proxy := range strings.Split(proxies, ";") {
-		go start(proxy)
+		go start(host, proxy, staleTimeout)
 	}
 
 	<-make(chan int)
 }
+
+func start(host, proxy string, staleTimeout int) {
+	port, target := func() (string, string) {
+		x := strings.Split(proxy, ":")
+		return x[0], x[1]
+	}()
+
+	c, err := udpproxy.New(
+		fmt.Sprintf("%s:%s", host, port),
+		fmt.Sprintf("127.0.0.1:%s", target),
+		udpproxy.WithStaleTimeout(time.Duration(staleTimeout)*time.Minute))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Printf("q3rcon-proxy initialized: [proxy] (%s:%s) [target] (127.0.0.1:%s)", host, port, target)
+
+	log.Fatal(c.ListenAndServe())
+}

cmd/q3rcon-proxy/util.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"os"
+	"strconv"
+)
+
+func getEnvInt(key string) (int, error) {
+	s := os.Getenv(key)
+	if s == "" {
+		return 0, nil
+	}
+	v, err := strconv.Atoi(s)
+	if err != nil {
+		return 0, err
+	}
+	return v, nil
+}

debian/q3rcon-proxy.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Q3Rcon Proxy Service
+Wants=network.target
+After=network.target
+
+[Service]
+Type=simple
+User=gameservers
+Environment="Q3RCON_PROXY=20000:28960;20001:28961;20002:28962"
+Environment="Q3RCON_HOST=0.0.0.0"
+Environment="Q3RCON_DEBUG=0"
+
+ExecStart=/usr/local/bin/q3rcon-proxy
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target

go.mod

@@ -1,3 +1,7 @@
 module github.com/onyx-and-iris/q3rcon-proxy
 
 go 1.18
+
+require github.com/sirupsen/logrus v1.9.3
+
+require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect

go.sum

@@ -0,0 +1,15 @@
+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/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

pkg/udpproxy/session.go

@@ -1,29 +1,36 @@
 package udpproxy
 
 import (
-	"log"
+	"errors"
+	"fmt"
 	"net"
+	"strings"
 	"time"
+
+	log "github.com/sirupsen/logrus"
 )
 
-type Session struct {
+type session struct {
 	serverConn *net.UDPConn
 	proxyConn  *net.UDPConn
 	caddr      *net.UDPAddr
 	updateTime time.Time
+
+	validator
 }
 
-func createSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn) (*Session, error) {
+func newSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn) (*session, error) {
 	serverConn, err := net.DialUDP("udp", nil, raddr)
 	if err != nil {
 		return nil, err
 	}
 
-	session := &Session{
+	session := &session{
 		serverConn: serverConn,
 		proxyConn:  proxyConn,
 		caddr:      caddr,
 		updateTime: time.Now(),
+		validator:  newValidator(),
 	}
 
 	go session.listen()
@@ -31,12 +38,12 @@ func createSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPCon
 	return session, nil
 }
 
-func (s *Session) listen() error {
+func (s *session) listen() error {
+	buf := make([]byte, 2048)
 	for {
-		buf := make([]byte, 2048)
 		n, err := s.serverConn.Read(buf)
 		if err != nil {
-			log.Println(err)
+			log.Error(err)
 			continue
 		}
 
@@ -44,24 +51,55 @@ func (s *Session) listen() error {
 	}
 }
 
-func (s *Session) proxyFrom(buf []byte) error {
+func (s *session) proxyFrom(buf []byte) error {
+	if !s.isValidResponsePacket(buf) {
+		err := errors.New("not a rcon or query response packet")
+		log.Error(err.Error())
+		return err
+	}
+
 	s.updateTime = time.Now()
 	_, err := s.proxyConn.WriteToUDP(buf, s.caddr)
 	if err != nil {
-		log.Println(err)
+		log.Error(err)
 		return err
 	}
 
+	if s.isRconResponsePacket(buf) {
+		if s.isBadRconResponse(buf) {
+			log.Infof("Response: Bad rcon from %s", s.caddr.IP)
+		} else {
+			log.Debugf("Response: %s", string(buf[len(s.rconResponseHeader):]))
+		}
+	}
+
 	return nil
 }
 
-func (s *Session) proxyTo(buf []byte) error {
+func (s *session) proxyTo(buf []byte) error {
+	if !s.isValidRequestPacket(buf) {
+		var err error
+		if s.isChallengeRequestPacket(buf) {
+			parts := strings.SplitN(string(buf), " ", 3)
+			err = fmt.Errorf("invalid challenge from %s with GUID: %s", s.caddr.IP, parts[len(parts)-1])
+		} else {
+			err = errors.New("not a rcon or query request packet")
+		}
+		log.Error(err.Error())
+		return err
+	}
+
 	s.updateTime = time.Now()
 	_, err := s.serverConn.Write(buf)
 	if err != nil {
-		log.Println(err)
+		log.Error(err)
 		return err
 	}
 
+	if s.isRconRequestPacket(buf) {
+		parts := strings.SplitN(string(buf), " ", 3)
+		log.Infof("From [%s] To [%s] Command: %s", s.caddr.IP, s.serverConn.RemoteAddr(), parts[len(parts)-1])
+	}
+
 	return nil
 }

pkg/udpproxy/udpproxy.go

@@ -1,12 +1,28 @@
 package udpproxy
 
 import (
-	"log"
 	"net"
 	"sync"
 	"time"
+
+	log "github.com/sirupsen/logrus"
 )
 
+// Option is a functional option type that allows us to configure the Client.
+type Option func(*Client)
+
+// WithStaleTimeout is a functional option to set the stale session timeout
+func WithStaleTimeout(timeout time.Duration) Option {
+	return func(c *Client) {
+		if timeout < time.Minute {
+			log.Warnf("cannot set stale session timeout to less than 1 minute.. defaulting to 5 minutes")
+			return
+		}
+
+		c.timeout = timeout
+	}
+}
+
 type Client struct {
 	laddr *net.UDPAddr
 	raddr *net.UDPAddr
@@ -14,10 +30,12 @@ type Client struct {
 	proxyConn *net.UDPConn
 
 	mutex    sync.RWMutex
-	sessions map[string]*Session
+	sessions map[string]*session
+
+	timeout time.Duration
 }
 
-func New(port, target string) (*Client, error) {
+func New(port, target string, options ...Option) (*Client, error) {
 	laddr, err := net.ResolveUDPAddr("udp", port)
 	if err != nil {
 		return nil, err
@@ -28,16 +46,19 @@ func New(port, target string) (*Client, error) {
 		return nil, err
 	}
 
-	return &Client{
+	c := &Client{
 		laddr:    laddr,
 		raddr:    raddr,
 		mutex:    sync.RWMutex{},
-		sessions: map[string]*Session{},
-	}, nil
-}
+		sessions: map[string]*session{},
+		timeout:  5 * time.Minute,
+	}
 
-func (c *Client) isValidPacket(header []byte) bool {
-	return string(header[:8]) == "\xff\xff\xff\xffrcon" || string(header[:13]) == "\xff\xff\xff\xffgetstatus" || string(header[:11]) == "\xff\xff\xff\xffgetinfo"
+	for _, o := range options {
+		o(c)
+	}
+
+	return c, nil
 }
 
 func (c *Client) ListenAndServe() error {
@@ -49,22 +70,18 @@ func (c *Client) ListenAndServe() error {
 
 	go c.pruneSessions()
 
+	buf := make([]byte, 2048)
 	for {
-		buf := make([]byte, 2048)
 		n, caddr, err := c.proxyConn.ReadFromUDP(buf)
 		if err != nil {
-			log.Println(err)
+			log.Error(err)
 		}
 
-		if !c.isValidPacket(buf[:16]) {
-			continue
-		}
-
-		session, found := c.sessions[caddr.String()]
-		if !found {
-			session, err = createSession(caddr, c.raddr, c.proxyConn)
+		session, ok := c.sessions[caddr.String()]
+		if !ok {
+			session, err = newSession(caddr, c.raddr, c.proxyConn)
 			if err != nil {
-				log.Println(err)
+				log.Error(err)
 				continue
 			}
 
@@ -83,8 +100,9 @@ func (c *Client) pruneSessions() {
 	for range ticker.C {
 		for _, session := range c.sessions {
 			c.mutex.RLock()
-			if time.Since(session.updateTime) > time.Minute*5 {
+			if time.Since(session.updateTime) > c.timeout {
 				delete(c.sessions, session.caddr.String())
+				log.Tracef("session for %s deleted", session.caddr)
 			}
 			c.mutex.RUnlock()
 		}

pkg/udpproxy/udpproxy_test.go

@@ -1,83 +0,0 @@
-package udpproxy
-
-import (
-	"log"
-	"net"
-	"testing"
-	"time"
-)
-
-func TestSendAndReceive(t *testing.T) {
-	go runLilProxy()
-	go runUDPServer()
-
-	paddr, err := net.ResolveUDPAddr("udp", "localhost:9000")
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	conn, err := net.DialUDP("udp", nil, paddr)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	go func() {
-		for {
-			buf := make([]byte, 2048)
-			_, _, err = conn.ReadFromUDP(buf)
-			if err != nil {
-				log.Fatal(err)
-			}
-
-			log.Printf("response received: %s", string(buf))
-		}
-	}()
-
-	for {
-		time.Sleep(1 * time.Second)
-		_, err = conn.Write([]byte("hi\n"))
-		if err != nil {
-			log.Fatal(err)
-		}
-	}
-}
-
-func runLilProxy() {
-	port := ":9000"
-	target := "localhost:9001"
-
-	c, err := New(port, target)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	log.Fatal(c.ListenAndServe())
-}
-
-func runUDPServer() {
-	taddr, err := net.ResolveUDPAddr("udp", ":9001")
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	conn, err := net.ListenUDP("udp", taddr)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	for {
-		buf := make([]byte, 2048)
-		_, caddr, err := conn.ReadFromUDP(buf)
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		log.Printf("request received: %s", string(buf))
-
-		_, err = conn.WriteToUDP([]byte("bye\n"), caddr)
-		if err != nil {
-			log.Fatal(err)
-		}
-
-	}
-}

pkg/udpproxy/validator.go

@@ -0,0 +1,65 @@
+package udpproxy
+
+import "bytes"
+
+type validator struct {
+	rconRequestHeader         []byte
+	getstatusRequestHeader    []byte
+	getinfoRequestHeader      []byte
+	getchallengeRequestHeader []byte
+	rconResponseHeader        []byte
+	getstatusResponseHeader   []byte
+	getinfoResponseHeader     []byte
+	badRconIdentifier         []byte
+}
+
+func newValidator() validator {
+	return validator{
+		rconRequestHeader:         []byte("\xff\xff\xff\xffrcon"),
+		getstatusRequestHeader:    []byte("\xff\xff\xff\xffgetstatus"),
+		getinfoRequestHeader:      []byte("\xff\xff\xff\xffgetinfo"),
+		getchallengeRequestHeader: []byte("\xff\xff\xff\xffgetchallenge"),
+		rconResponseHeader:        []byte("\xff\xff\xff\xffprint\n"),
+		getstatusResponseHeader:   []byte("\xff\xff\xff\xffstatusResponse\n"),
+		getinfoResponseHeader:     []byte("\xff\xff\xff\xffinfoResponse\n"),
+		badRconIdentifier:         []byte("Bad rcon"),
+	}
+}
+
+func (v validator) compare(buf, c []byte) bool {
+	return bytes.Equal(buf[:len(c)], c)
+}
+
+func (v validator) isRconRequestPacket(buf []byte) bool {
+	return v.compare(buf, v.rconRequestHeader)
+}
+
+func (v validator) isQueryRequestPacket(buf []byte) bool {
+	return v.compare(buf, v.getstatusRequestHeader) ||
+		v.compare(buf, v.getinfoRequestHeader)
+}
+
+func (v validator) isValidRequestPacket(buf []byte) bool {
+	return v.isRconRequestPacket(buf) || v.isQueryRequestPacket(buf)
+}
+
+func (v validator) isChallengeRequestPacket(buf []byte) bool {
+	return v.compare(buf, v.getchallengeRequestHeader)
+}
+
+func (v validator) isRconResponsePacket(buf []byte) bool {
+	return v.compare(buf, v.rconResponseHeader)
+}
+
+func (v validator) isQueryResponsePacket(buf []byte) bool {
+	return v.compare(buf, v.getstatusResponseHeader) ||
+		v.compare(buf, v.getinfoResponseHeader)
+}
+
+func (v validator) isValidResponsePacket(buf []byte) bool {
+	return v.isRconResponsePacket(buf) || v.isQueryResponsePacket(buf)
+}
+
+func (v validator) isBadRconResponse(buf []byte) bool {
+	return v.compare(buf[len(v.rconResponseHeader):], v.badRconIdentifier)
+}