Update dependencies

vendor/tailscale.com/util/linuxfw/iptables_for_svcs.go

@@ -0,0 +1,79 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build linux
+
+package linuxfw
+
+import (
+	"fmt"
+	"net/netip"
+)
+
+// This file contains functionality to insert portmapping rules for a 'service'.
+// These are currently only used by the Kubernetes operator proxies.
+// An iptables rule for such a service contains a comment with the service name.
+
+// EnsurePortMapRuleForSvc adds a prerouting rule that forwards traffic received
+// on match port and NOT on the provided interface to target IP and target port.
+// Rule will only be added if it does not already exists.
+func (i *iptablesRunner) EnsurePortMapRuleForSvc(svc, tun string, targetIP netip.Addr, pm PortMap) error {
+	table := i.getIPTByAddr(targetIP)
+	args := argsForPortMapRule(svc, tun, targetIP, pm)
+	exists, err := table.Exists("nat", "PREROUTING", args...)
+	if err != nil {
+		return fmt.Errorf("error checking if rule exists: %w", err)
+	}
+	if !exists {
+		return table.Append("nat", "PREROUTING", args...)
+	}
+	return nil
+}
+
+// DeleteMapRuleForSvc constructs a prerouting rule as would be created by
+// EnsurePortMapRuleForSvc with the provided args and, if such a rule exists,
+// deletes it.
+func (i *iptablesRunner) DeletePortMapRuleForSvc(svc, excludeI string, targetIP netip.Addr, pm PortMap) error {
+	table := i.getIPTByAddr(targetIP)
+	args := argsForPortMapRule(svc, excludeI, targetIP, pm)
+	exists, err := table.Exists("nat", "PREROUTING", args...)
+	if err != nil {
+		return fmt.Errorf("error checking if rule exists: %w", err)
+	}
+	if exists {
+		return table.Delete("nat", "PREROUTING", args...)
+	}
+	return nil
+}
+
+// DeleteSvc constructs all possible rules that would have been created by
+// EnsurePortMapRuleForSvc from the provided args and ensures that each one that
+// exists is deleted.
+func (i *iptablesRunner) DeleteSvc(svc, tun string, targetIPs []netip.Addr, pms []PortMap) error {
+	for _, tip := range targetIPs {
+		for _, pm := range pms {
+			if err := i.DeletePortMapRuleForSvc(svc, tun, tip, pm); err != nil {
+				return fmt.Errorf("error deleting rule: %w", err)
+			}
+		}
+	}
+	return nil
+}
+
+func argsForPortMapRule(svc, excludeI string, targetIP netip.Addr, pm PortMap) []string {
+	c := commentForSvc(svc, pm)
+	return []string{
+		"!", "-i", excludeI,
+		"-p", pm.Protocol,
+		"--dport", fmt.Sprintf("%d", pm.MatchPort),
+		"-m", "comment", "--comment", c,
+		"-j", "DNAT",
+		"--to-destination", fmt.Sprintf("%v:%v", targetIP, pm.TargetPort),
+	}
+}
+
+// commentForSvc generates a comment to be added to an iptables DNAT rule for a
+// service. This is for iptables debugging/readability purposes only.
+func commentForSvc(svc string, pm PortMap) string {
+	return fmt.Sprintf("%s:%s:%d -> %s:%d", svc, pm.Protocol, pm.MatchPort, pm.Protocol, pm.TargetPort)
+}