Honor bind address passed as --bind also for RTC ports (#1815)

* Use net.JoinHostPort to build "host:port" strings for `net.Listen`

net.JoinHostPort provides a unified way of building strings of the form
"Host:Port", abstracting the particular syntax requirements of some
methods in the `net` package (namely, that IPv4 addresses can be given
as-is to `net.Listen`, but IPv6 addresses must be given enclosed in
square brackets).

This change makes sense because an address such as `[::1]` is *not* a
valid IPv6 address; the square brackets are just a detail particular to
the Go `net` library. As such, this syntax shouldn't be exposed to the
user, and configuration should just accept valid IPv6 addresses and
convert them as needed for usage within the code.

* Use '--bind' CLI flag to also filter RTC bind address

The local address passed to a command such as

    livekit-server --dev --bind 127.0.0.1

was being used as binding address for the TCP WebSocket port, but was
being ignored for RTC connections.

With `--dev`, the conf.RTC.UDPPort config is set to 7882, which enables
"UDP muxing" mechanism. Without interface or address filtering, Pion
would try to bind to port 7882 on *all* interfaces.

This was failing on a system with IPv6 enabled, when trying to bind to
an IPv6 address of the `docker0` interface. It seems to make sense that
the user-passed bind addresses are also honored for the RTC port
bindings.

cmd/server/main.go

@@ -208,9 +208,12 @@ func getConfig(c *cli.Context) (*config.Config, error) {
 			if conf.BindAddresses == nil {
 				conf.BindAddresses = []string{
 					"127.0.0.1",
-					"[::1]",
+					"::1",
 				}
 			}
+			for _, bindAddr := range conf.BindAddresses {
+				conf.RTC.IPs.Includes = append(conf.RTC.IPs.Includes, bindAddr + "/24")
+			}
 		}
 	}
 	return conf, nil

pkg/service/server.go

@@ -10,6 +10,7 @@ import (
 	_ "net/http/pprof"
 	"runtime"
 	"runtime/pprof"
+	"strconv"
 	"time"
 
 	"github.com/pion/turn/v2"
@@ -177,14 +178,14 @@ func (s *LivekitServer) Start() error {
 	listeners := make([]net.Listener, 0)
 	promListeners := make([]net.Listener, 0)
 	for _, addr := range addresses {
-		ln, err := net.Listen("tcp", fmt.Sprintf("%s:%d", addr, s.config.Port))
+		ln, err := net.Listen("tcp", net.JoinHostPort(addr, strconv.Itoa(int(s.config.Port))))
 		if err != nil {
 			return err
 		}
 		listeners = append(listeners, ln)
 
 		if s.promServer != nil {
-			ln, err = net.Listen("tcp", fmt.Sprintf("%s:%d", addr, s.config.PrometheusPort))
+			ln, err = net.Listen("tcp", net.JoinHostPort(addr, strconv.Itoa(int(s.config.PrometheusPort))))
 			if err != nil {
 				return err
 			}