fix: network.SetInterfaceChannel won't exec iwconfig if the interface is already on the requested channel.

network/net_linux.go

@@ -7,6 +7,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/bettercap/bettercap/core"
 )
@@ -18,6 +19,9 @@ var IPv4RouteCmd = "ip"
 var IPv4RouteCmdOpts = []string{"route"}
 var WiFiFreqParser = regexp.MustCompile(`^\s+Channel.([0-9]+)\s+:\s+([0-9\.]+)\s+GHz.*$`)
 
+var currChannels = make(map[string]int)
+var currChannelLock = sync.Mutex{}
+
 func IPv4RouteIsGateway(ifname string, tokens []string, f func(gateway string) (*Endpoint, error)) (*Endpoint, error) {
 	ifname2 := tokens[3]
 
@@ -35,12 +39,23 @@ func getInterfaceName(iface net.Interface) string {
 }
 
 func SetInterfaceChannel(iface string, channel int) error {
+	currChannelLock.Lock()
+	defer currChannelLock.Unlock()
+
+	// the interface is already on this channel
+	if curr, found := currChannels[iface]; found && curr == channel {
+		return nil
+	}
+
 	out, err := core.Exec("iwconfig", []string{iface, "channel", fmt.Sprintf("%d", channel)})
 	if err != nil {
 		return err
 	} else if out != "" {
 		return fmt.Errorf("Unexpected output while setting interface %s to channel %d: %s", iface, channel, out)
 	}
+
+	currChannels[iface] = channel
+
 	return nil
 }