chore(netlink): define own types with minimal fields

- Allow to swap `github.com/vishvananda/netlink`
- Allow to add build tags for each platform
- One step closer to development on non-Linux platforms

internal/netlink/rule.go

@@ -1,21 +1,90 @@
 package netlink
 
-import "github.com/vishvananda/netlink"
+import (
+	"fmt"
+	"net/netip"
 
-type Rule = netlink.Rule
+	"github.com/vishvananda/netlink"
+)
 
-func NewRule() *Rule {
-	return netlink.NewRule()
+type Rule struct {
+	Priority int
+	Family   int
+	Table    int
+	Mark     int
+	Src      netip.Prefix
+	Dst      netip.Prefix
+	Invert   bool
+}
+
+func (r Rule) String() string {
+	from := "all"
+	if r.Src.IsValid() {
+		from = r.Src.String()
+	}
+
+	to := "all"
+	if r.Dst.IsValid() {
+		to = r.Dst.String()
+	}
+
+	return fmt.Sprintf("ip rule %d: from %s to %s table %d",
+		r.Priority, from, to, r.Table)
+}
+
+func NewRule() Rule {
+	// defaults found from netlink.NewRule() for fields we use,
+	// the rest of the defaults is set when converting from a `Rule`
+	// to a `netlink.Rule`
+	return Rule{
+		Priority: -1,
+		Mark:     -1,
+	}
 }
 
 func (n *NetLink) RuleList(family int) (rules []Rule, err error) {
-	return netlink.RuleList(family)
+	netlinkRules, err := netlink.RuleList(family)
+	if err != nil {
+		return nil, err
+	}
+
+	rules = make([]Rule, len(netlinkRules))
+	for i := range netlinkRules {
+		rules[i] = netlinkRuleToRule(netlinkRules[i])
+	}
+	return rules, nil
 }
 
-func (n *NetLink) RuleAdd(rule *Rule) error {
-	return netlink.RuleAdd(rule)
+func (n *NetLink) RuleAdd(rule Rule) error {
+	netlinkRule := ruleToNetlinkRule(rule)
+	return netlink.RuleAdd(&netlinkRule)
 }
 
-func (n *NetLink) RuleDel(rule *Rule) error {
-	return netlink.RuleDel(rule)
+func (n *NetLink) RuleDel(rule Rule) error {
+	netlinkRule := ruleToNetlinkRule(rule)
+	return netlink.RuleDel(&netlinkRule)
+}
+
+func ruleToNetlinkRule(rule Rule) (netlinkRule netlink.Rule) {
+	netlinkRule = *netlink.NewRule()
+	netlinkRule.Priority = rule.Priority
+	netlinkRule.Family = rule.Family
+	netlinkRule.Table = rule.Table
+	netlinkRule.Mark = rule.Mark
+	netlinkRule.Src = netipPrefixToIPNet(rule.Src)
+	netlinkRule.Dst = netipPrefixToIPNet(rule.Dst)
+	netlinkRule.Invert = rule.Invert
+	return netlinkRule
+}
+
+func netlinkRuleToRule(netlinkRule netlink.Rule) (rule Rule) {
+	return Rule{
+		Priority: netlinkRule.Priority,
+		Family:   netlinkRule.Family,
+		Table:    netlinkRule.Table,
+		Mark:     netlinkRule.Mark,
+		Src:      netIPNetToNetipPrefix(netlinkRule.Src),
+		Dst:      netIPNetToNetipPrefix(netlinkRule.Dst),
+		Invert:   netlinkRule.Invert,
+	}
 }