remove string casts

compare byte slices

CHANGELOG.md

@@ -11,8 +11,41 @@ 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
 
+### Added
+
 -   only forward packets if the header matches q3 rcon/query.
 
 ## [0.0.1] - 2024-01-27
@@ -20,3 +53,5 @@ Before any major/minor/patch bump all unit tests will be run to verify they pass
 ### Added
 
 -   All source files for lilproxy including full commit history.
+
+[logrus]: https://github.com/sirupsen/logrus

README.md

@@ -22,7 +22,7 @@ Avoid sending plaintext rcon commands to the public game server port. In general
 
 ### 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

@@ -2,10 +2,12 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"os"
+	"strconv"
 	"strings"
 
+	log "github.com/sirupsen/logrus"
+
 	"github.com/onyx-and-iris/q3rcon-proxy/pkg/udpproxy"
 )
 
@@ -29,6 +31,18 @@ var (
 	proxies, host string
 )
 
+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
+}
+
 func init() {
 	proxies = os.Getenv("Q3RCON_PROXY")
 	if proxies == "" {
@@ -39,6 +53,18 @@ func init() {
 	if host == "" {
 		host = "0.0.0.0"
 	}
+
+	debug, err := getenvInt("Q3RCON_DEBUG")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if debug == 1 {
+		log.SetLevel(log.DebugLevel)
+	} else {
+		log.SetLevel(log.InfoLevel)
+	}
+
 }
 
 func main() {

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

pkg/udpproxy/session.go

@@ -1,6 +1,7 @@
 package udpproxy
 
 import (
+	"errors"
 	"net"
 	"strings"
 	"time"
@@ -8,24 +9,27 @@ import (
 	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()
@@ -33,12 +37,12 @@ func createSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPCon
 	return session, nil
 }
 
-func (s *Session) listen() error {
+func (s *session) listen() error {
 	for {
 		buf := make([]byte, 2048)
 		n, err := s.serverConn.Read(buf)
 		if err != nil {
-			log.Println(err)
+			log.Error(err)
 			continue
 		}
 
@@ -46,29 +50,48 @@ 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[10:]))
+		}
+	}
+
 	return nil
 }
 
-func (s *Session) proxyTo(buf []byte) error {
+func (s *session) proxyTo(buf []byte) error {
+	if !s.isValidRequestPacket(buf) {
+		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
 	}
 
-	cmd := string(buf)
+	if s.isRconRequestPacket(buf) {
-	if cmd[:8] == "\xff\xff\xff\xffrcon" {
+		parts := strings.SplitN(string(buf), " ", 3)
-		parts := strings.Split(cmd, " ")
+		log.Infof("From [%s] To [%s] Command: %s", s.caddr.IP, s.serverConn.RemoteAddr(), parts[len(parts)-1])
-		log.Info("From [", s.caddr.IP, "] To [", s.serverConn.RemoteAddr().String(), "] Command: ", strings.Join(parts[2:], " "))
 	}
 
 	return nil

pkg/udpproxy/udpproxy.go

@@ -15,7 +15,7 @@ type Client struct {
 	proxyConn *net.UDPConn
 
 	mutex    sync.RWMutex
-	sessions map[string]*Session
+	sessions map[string]*session
 }
 
 func New(port, target string) (*Client, error) {
@@ -33,14 +33,10 @@ func New(port, target string) (*Client, error) {
 		laddr:    laddr,
 		raddr:    raddr,
 		mutex:    sync.RWMutex{},
-		sessions: map[string]*Session{},
+		sessions: map[string]*session{},
 	}, nil
 }
 
-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"
-}
-
 func (c *Client) ListenAndServe() error {
 	var err error
 	c.proxyConn, err = net.ListenUDP("udp", c.laddr)
@@ -54,18 +50,14 @@ func (c *Client) ListenAndServe() error {
 		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, err = newSession(caddr, c.raddr, c.proxyConn)
 			if err != nil {
-				log.Println(err)
+				log.Error(err)
 				continue
 			}
 

pkg/udpproxy/validator.go

@@ -0,0 +1,53 @@
+package udpproxy
+
+import "bytes"
+
+type validator struct {
+	rconRequestHeader       []byte
+	getstatusRequestHeader  []byte
+	getinfoRequestHeader    []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"),
+		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) isRconRequestPacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.rconRequestHeader)], v.rconRequestHeader)
+}
+
+func (v *validator) isQueryRequestPacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.getstatusRequestHeader)], v.getstatusRequestHeader) || bytes.Equal(buf[:len(v.getinfoRequestHeader)], v.getinfoRequestHeader)
+}
+
+func (v *validator) isValidRequestPacket(buf []byte) bool {
+	return v.isRconRequestPacket(buf) || v.isQueryRequestPacket(buf)
+}
+
+func (v *validator) isRconResponsePacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.rconResponseHeader)], v.rconResponseHeader)
+}
+
+func (v *validator) isQueryResponsePacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.getstatusResponseHeader)], v.getstatusResponseHeader) || bytes.Equal(buf[:len(v.getinfoResponseHeader)], v.getinfoResponseHeader)
+}
+
+func (v *validator) isValidResponsePacket(buf []byte) bool {
+	return v.isRconResponsePacket(buf) || v.isQueryResponsePacket(buf)
+}
+
+func (v *validator) isBadRconResponse(buf []byte) bool {
+	return bytes.Equal(buf[len(v.rconResponseHeader):len(v.rconResponseHeader)+len(v.badRconIdentifier)], v.badRconIdentifier)
+}