use net.JoinHostPort to build addresses

fix date of 1.7.3

CHANGELOG.md

@@ -11,7 +11,14 @@ Before any major/minor/patch bump all unit tests will be run to verify they pass
 
 -   [x]
 
-## [1.7.3] - 2026-02-26
+## [1.8.0] - 2026-02-18
+
+### Changed
+
+-   *--ports-mapping* flag has been replaced with *--port-map*, which may be called several times. See [Flags](https://github.com/onyx-and-iris/q3rcon-proxy?tab=readme-ov-file#flags).
+    -   This also affects the env variable which is now `Q3RCON_PORT_MAP`, see [Environment Variables](https://github.com/onyx-and-iris/q3rcon-proxy?tab=readme-ov-file#environment-variables)
+
+## [1.7.3] - 2026-02-16
 
 ### Added
 

README.md

@@ -6,6 +6,8 @@ A modification of [lilproxy][lilproxy_url] that forwards only Q3 rcon/query pack
 
 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
 
 #### Flags
@@ -16,7 +18,7 @@ Unfortunately the Q3Rcon engine ties the rcon port to the game servers public po
 /usr/local/bin/q3rcon-proxy \
     --proxy-host=0.0.0.0 \
     --target-host=localhost \
-    --ports-mapping=28961:28960 \
+    --port-map=20000:28960 --port-map=20001:28961 --port-map=20002:28962 \
     --session-timeout=20 \
     --loglevel=debug
 ```
@@ -27,18 +29,25 @@ Each of the flags has a corresponding environment variable:
 
 -   `Q3RCON_PROXY_HOST`: The host the proxy server sits on.
 -   `Q3RCON_TARGET_HOST`: The host the game servers sit on.
--   `Q3RCON_PORTS_MAPPING`: A mapping as a string with `source:target` pairs delimited by `;`.
+-   `Q3RCON_PORT_MAP`: A mapping as a string with `source:target` pairs delimited by `,`.
 -   `Q3RCON_SESSION_TIMEOUT`: Timeout in seconds for each udp session.
 -   `Q3RCON_LOGLEVEL`: The application's logging level (see [Logging][logging]).
 
-Multiple rcon proxies may be configured by setting *--ports-mapping/Q3RCON_PORTS_MAPPING* like so:
+example .envrc:
 
-```console
+```bash
-export Q3RCON_PORTS_MAPPING="20000:28960;20001:28961;20002:28962"
+#!/usr/bin/env bash
+
+export Q3RCON_PROXY_HOST="0.0.0.0"
+export Q3RCON_TARGET_HOST="localhost"
+export Q3RCON_PORT_MAP="20000:28960,20001:28961,20002:28962"
+export Q3RCON_SESSION_TIMEOUT=20
 ```
 
 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.
 
+---
+
 ### Logging
 
 Set the log level with environment variable `Q3RCON_LOGLEVEL`.
@@ -53,7 +62,9 @@ Acceptable values are:
 - `fatal`
 - `panic`
 
-If not set it will default to `info`.
+It defaults to `info`.
+
+---
 
 ### Special Thanks
 

Taskfile.yml

@@ -74,6 +74,6 @@ tasks:
         go run ./cmd/{{.PROGRAM}} \
         --proxy-host=0.0.0.0 \
         --target-host=localhost \
-        --ports-mapping=28961:28960 \
+        --port-map=28961:28960 \
         --session-timeout=20 \
         --loglevel=debug

cmd/q3rcon-proxy/main.go

@@ -4,6 +4,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"net"
 	"os"
 	"runtime/debug"
 	"strconv"
@@ -61,32 +62,47 @@ func main() {
 				Usage:   "Target host address",
 				Sources: cli.EnvVars("Q3RCON_TARGET_HOST"),
 			},
-			&cli.StringFlag{
+			&cli.StringSliceFlag{
-				Name:     "ports-mapping",
+				Name:     "port-map",
-				Usage:    "Proxy and target ports (proxy:target)",
+				Usage:    "Ports mapping in the format proxyPort:targetPort (e.g., 27950:27960)",
-				Sources:  cli.EnvVars("Q3RCON_PORTS_MAPPING"),
+				Sources:  cli.EnvVars("Q3RCON_PORT_MAP"),
 				Required: true,
-				Action: func(_ context.Context, _ *cli.Command, v string) error {
+				Action: func(_ context.Context, cmd *cli.Command, v []string) error {
-					// Validate the ports mapping
+					// Validate the ports mapping format and values
-					for mapping := range strings.SplitSeq(v, ";") {
+					for _, mapping := range v {
-						ports := strings.Split(mapping, ":")
+						src, dst := func(m string) (string, string) {
-						if len(ports) != 2 {
+							parts := strings.Split(m, ":")
-							return fmt.Errorf("invalid ports mapping: %s", mapping)
+							if len(parts) != 2 {
+								return "", ""
 							}
-						proxyPort, err := strconv.Atoi(ports[0])
+							return parts[0], parts[1]
-						if err != nil || proxyPort < 1 || proxyPort > 65535 {
+						}(mapping)
-							return fmt.Errorf("invalid proxy port: %s", ports[0])
+
-						}
+						if src == "" || dst == "" {
-						targetPort, err := strconv.Atoi(ports[1])
-						if err != nil || targetPort < 1 || targetPort > 65535 {
-							return fmt.Errorf("invalid target port: %s", ports[1])
-						}
-						if proxyPort == targetPort {
 							return fmt.Errorf(
-								"proxy and target ports cannot be the same: %s",
+								"invalid ports mapping: %s (expected format: proxyPort:targetPort)",
 								mapping,
 							)
 						}
+						n, err := strconv.Atoi(src)
+						if err != nil || n <= 0 || n > 65535 {
+							return fmt.Errorf("invalid proxy port: %s", src)
+						}
+						n, err = strconv.Atoi(dst)
+						if err != nil || n <= 0 || n > 65535 {
+							return fmt.Errorf("invalid target port: %s", dst)
+						}
+						if src == dst {
+							return fmt.Errorf(
+								"proxy port and target port cannot be the same: %s",
+								src,
+							)
+						}
+						log.Debugf(
+							"Validated ports mapping: proxy port %s -> target port %s",
+							src,
+							dst,
+						)
 					}
 					return nil
 				},
@@ -115,7 +131,7 @@ func main() {
 		Action: func(_ context.Context, cmd *cli.Command) error {
 			errChan := make(chan error)
 
-			for mapping := range strings.SplitSeq(cmd.String("ports-mapping"), ";") {
+			for _, mapping := range cmd.StringSlice("port-map") {
 				cfg := proxyConfig{
 					proxyHost:      cmd.String("proxy-host"),
 					targetHost:     cmd.String("target-host"),
@@ -143,18 +159,18 @@ func main() {
 func launchProxy(cfg proxyConfig, errChan chan<- error) {
 	proxyPort, targetPort := cfg.portsMapping[0], cfg.portsMapping[1]
 
-	hostAddr := fmt.Sprintf("%s:%s", cfg.proxyHost, proxyPort)
+	proxyAddr := net.JoinHostPort(cfg.proxyHost, proxyPort)
-	proxyAddr := fmt.Sprintf("%s:%s", cfg.targetHost, targetPort)
+	targetAddr := net.JoinHostPort(cfg.targetHost, targetPort)
 
 	server, err := udpproxy.New(
-		hostAddr, proxyAddr,
+		proxyAddr, targetAddr,
 		udpproxy.WithSessionTimeout(time.Duration(cfg.sessionTimeout)*time.Minute))
 	if err != nil {
 		errChan <- fmt.Errorf("failed to create proxy: %w", err)
 		return
 	}
 
-	log.Infof("q3rcon-proxy initialised: [proxy] (%s) [target] (%s)", hostAddr, proxyAddr)
+	log.Infof("q3rcon-proxy initialised: [proxy] (%s) [target] (%s)", proxyAddr, targetAddr)
 
 	errChan <- server.ListenAndServe()
 }