util/netconv: add package to convert between netip and netaddr types

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

util/netconv/netconv_test.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package netconv
+
+import (
+	"net/netip"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"inet.af/netaddr"
+)
+
+func TestAddr(t *testing.T) {
+	c := qt.New(t)
+
+	c.Assert(netip.Addr{}, qt.Equals, AsAddr(netaddr.IP{}))
+	c.Assert(netaddr.IP{}, qt.Equals, AsIP(netip.Addr{}))
+
+	// Cover IPv4, IPv6, 4in6, and zones.
+	addrStrs := []string{
+		"0.0.0.0",
+		"123.45.67.89",
+		"::",
+		"fd7a:115c:a1e0:ab12:4843:cd96:626b:430b",
+		"fd7a:115c:a1e0:ab12:4843:cd96:626b:430b%eth0",
+		"::ffff:192.0.2.128",
+		"::ffff:192.0.2.128%eth0",
+	}
+	for _, s := range addrStrs {
+		ip := netaddr.MustParseIP(s)
+		addr := netip.MustParseAddr(s)
+		c.Assert(addr, qt.Equals, AsAddr(ip))
+		c.Assert(ip, qt.Equals, AsIP(addr))
+	}
+}
+
+func TestAddrPort(t *testing.T) {
+	c := qt.New(t)
+
+	c.Assert(netip.AddrPort{}, qt.Equals, AsAddrPort(netaddr.IPPort{}))
+	c.Assert(netaddr.IPPort{}, qt.Equals, AsIPPort(netip.AddrPort{}))
+
+	// Test just a single AddrPort conversion;
+	// there's almost nothing happening in the code.
+	portStr := "1.2.4.5:8"
+	ipPort := netaddr.MustParseIPPort(portStr)
+	ap := netip.MustParseAddrPort(portStr)
+	c.Assert(ipPort, qt.Equals, AsIPPort(ap))
+	c.Assert(ap, qt.Equals, AsAddrPort(ipPort))
+}
+
+func TestPrefix(t *testing.T) {
+	c := qt.New(t)
+
+	// The interesting Prefix cases are invalid bits.
+	addr := netip.MustParseAddr("1.2.3.4")
+	ip := AsIP(addr)
+
+	tests := []struct {
+		ipp netaddr.IPPrefix // input IPPrefix, output from converting pfx
+		pfx netip.Prefix     // input Prefix, output from converting ipp
+		out netaddr.IPPrefix // output from converting pfx
+	}{
+		{netaddr.IPPrefix{}, netip.Prefix{}, netaddr.IPPrefix{}},
+		{netaddr.IPPrefixFrom(ip, 24), netip.PrefixFrom(addr, 24), netaddr.IPPrefixFrom(ip, 24)},
+		{netaddr.IPPrefixFrom(ip, 255), netip.PrefixFrom(addr, -1), netaddr.IPPrefixFrom(ip, 255)},
+		{netaddr.IPPrefixFrom(ip, 204), netip.PrefixFrom(addr, -1), netaddr.IPPrefixFrom(ip, 255)},
+	}
+
+	for _, test := range tests {
+		c.Assert(test.out, qt.Equals, AsIPPrefix(test.pfx))
+		c.Assert(test.pfx, qt.Equals, AsPrefix(test.ipp))
+	}
+}