datapath/loader: refactor function to remove iptables chain

We do the same thing for IPv4 and IPv6, with just the name of the
program changing. Then we do nearly the same thing for flushing and
deleting a chain. Let's refactor (no functional change).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>

pkg/datapath/iptables/iptables.go

@@ -204,33 +204,25 @@ func (m *IptablesManager) removeCiliumRules(table, prog, match string) {
 }
 
 func (c *customChain) remove(waitArgs []string, quiet bool) {
-	if option.Config.EnableIPv4 {
-		prog := "iptables"
-		args := append(waitArgs, "-t", c.table, "-F", c.name)
+	doProcess := func(c *customChain, prog string, args []string, operation string, quiet bool) {
 		err := runProg(prog, args, true)
 		if err != nil && !quiet {
-			log.WithError(err).WithField(logfields.Object, args).Warnf("Unable to flush Cilium %s chain", prog)
-		}
-
-		args = append(waitArgs, "-t", c.table, "-X", c.name)
-		err = runProg(prog, args, true)
-		if err != nil && !quiet {
-			log.WithError(err).WithField(logfields.Object, args).Warnf("Unable to delete Cilium %s chain", prog)
+			log.WithError(err).WithField(logfields.Object, args).Warnf("Unable to %s Cilium %s chain", operation, prog)
 		}
 	}
-	if option.Config.EnableIPv6 && c.ipv6 == true {
-		prog := "ip6tables"
+	doRemove := func(c *customChain, prog string, waitArgs []string, quiet bool) {
 		args := append(waitArgs, "-t", c.table, "-F", c.name)
-		err := runProg(prog, args, true)
-		if err != nil && !quiet {
-			log.WithError(err).WithField(logfields.Object, args).Warnf("Unable to flush Cilium %s chain", prog)
-		}
-
+		doProcess(c, prog, args, "flush", quiet)
 		args = append(waitArgs, "-t", c.table, "-X", c.name)
-		err = runProg(prog, args, true)
-		if err != nil && !quiet {
-			log.WithError(err).WithField(logfields.Object, args).Warnf("Unable to delete Cilium %s chain", prog)
-		}
+		doProcess(c, prog, args, "delete", quiet)
+	}
+	if option.Config.EnableIPv4 {
+		prog := "iptables"
+		doRemove(c, prog, waitArgs, quiet)
+	}
+	if option.Config.EnableIPv6 && c.ipv6 {
+		prog := "ip6tables"
+		doRemove(c, prog, waitArgs, quiet)
 	}
 }