From 0bd16947755b7e45c525f758f593bce9c76a854ee47adb0d625d1723b6705153 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 16 Apr 2024 21:55:29 +0300
Subject: [PATCH] Ability to prefer legacy IPv4

---
 cmd/client/main.go  |  3 +++
 cmd/server/main.go  |  3 +++
 internal/resolve.go | 27 ++++++++++++++++++---------
 internal/version.go |  2 +-
 4 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/cmd/client/main.go b/cmd/client/main.go
index 44e5f63..c54d41d 100644
--- a/cmd/client/main.go
+++ b/cmd/client/main.go
@@ -87,6 +87,8 @@ func main() {
 	vadRaw := flag.Uint("vad", 0, "VAD threshold")
 	passwd := flag.String("passwd", "", "protected room's password")
 	muteToggle := flag.String("mute-toggle", "", "path to FIFO to toggle mute")
+	prefer4 := flag.Bool("4", false,
+		"Prefer obsolete legacy IPv4 address during name resolution")
 	version := flag.Bool("version", false, "print version")
 	warranty := flag.Bool("warranty", false, "print warranty information")
 	flag.Parse()
@@ -144,6 +146,7 @@ func main() {
 		}
 	}
 
+	vors.PreferIPv4 = *prefer4
 	ctrl, err := net.DialTCP("tcp", nil, vors.MustResolveTCP(*srvAddr))
 	if err != nil {
 		log.Fatalln("dial server:", err)
diff --git a/cmd/server/main.go b/cmd/server/main.go
index 51dd019..4764ad1 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -309,6 +309,8 @@ func main() {
 	bind := flag.String("bind", "[::1]:"+strconv.Itoa(vors.DefaultPort),
 		"host:TCP/UDP port to listen on")
 	kpFile := flag.String("key", "key", "path to keypair file")
+	prefer4 := flag.Bool("4", false,
+		"Prefer obsolete legacy IPv4 address during name resolution")
 	version := flag.Bool("version", false, "print version")
 	warranty := flag.Bool("warranty", false, "print warranty information")
 	flag.Parse()
@@ -331,6 +333,7 @@ func main() {
 		Prv, Pub = data[:len(data)/2], data[len(data)/2:]
 	}
 
+	vors.PreferIPv4 = *prefer4
 	lnTCP, err := net.ListenTCP("tcp",
 		net.TCPAddrFromAddrPort(netip.MustParseAddrPort(*bind)))
 	if err != nil {
diff --git a/internal/resolve.go b/internal/resolve.go
index ceffc33..d64156c 100644
--- a/internal/resolve.go
+++ b/internal/resolve.go
@@ -1,31 +1,40 @@
 package internal
 
-import "net"
+import (
+	"log"
+	"net"
+)
 
 const DefaultPort = 12978
 
+var PreferIPv4 bool
+
 func MustResolveTCP(s string) (addr *net.TCPAddr) {
 	var err error
-	addr, err = net.ResolveTCPAddr("tcp6", s)
-	if err == nil {
-		return addr
+	if !PreferIPv4 {
+		addr, err = net.ResolveTCPAddr("tcp6", s)
+		if err == nil {
+			return addr
+		}
 	}
 	addr, err = net.ResolveTCPAddr("tcp4", s)
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 	return
 }
 
 func MustResolveUDP(s string) (addr *net.UDPAddr) {
 	var err error
-	addr, err = net.ResolveUDPAddr("udp6", s)
-	if err == nil {
-		return addr
+	if !PreferIPv4 {
+		addr, err = net.ResolveUDPAddr("udp6", s)
+		if err == nil {
+			return addr
+		}
 	}
 	addr, err = net.ResolveUDPAddr("udp4", s)
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 	return
 }
diff --git a/internal/version.go b/internal/version.go
index ecc49fb..741fb40 100644
--- a/internal/version.go
+++ b/internal/version.go
@@ -3,7 +3,7 @@ package internal
 import "runtime"
 
 const (
-	Version  = "2.2.0"
+	Version  = "2.3.0"
 	Warranty = `Copyright (C) 2024 Sergey Matveev
 
 This program is free software: you can redistribute it and/or modify
-- 
2.48.1