1 files changed, 105 insertions, 0 deletions
diff --git a/cmd/tailscaled/cli/ip.go b/cmd/tailscaled/cli/ip.go
new file mode 100644
index 000000000..2122d6022
--- /dev/null
+++ b/cmd/tailscaled/cli/ip.go
@@ -0,0 +1,105 @@
+// Copyright (c) 2020 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 cli
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+
+	"github.com/peterbourgon/ff/v2/ffcli"
+	"inet.af/netaddr"
+	"tailscale.com/client/tailscale"
+	"tailscale.com/ipn/ipnstate"
+)
+
+var ipCmd = &ffcli.Command{
+	Name:       "ip",
+	ShortUsage: "ip [-4] [-6] [peername]",
+	ShortHelp:  "Show current Tailscale IP address(es)",
+	LongHelp:   "Shows the Tailscale IP address of the current machine without an argument. With an argument, it shows the IP of a named peer.",
+	Exec:       runIP,
+	FlagSet: (func() *flag.FlagSet {
+		fs := flag.NewFlagSet("ip", flag.ExitOnError)
+		fs.BoolVar(&ipArgs.want4, "4", false, "only print IPv4 address")
+		fs.BoolVar(&ipArgs.want6, "6", false, "only print IPv6 address")
+		return fs
+	})(),
+}
+
+var ipArgs struct {
+	want4 bool
+	want6 bool
+}
+
+func runIP(ctx context.Context, args []string) error {
+	if len(args) > 1 {
+		return errors.New("unknown arguments")
+	}
+	var of string
+	if len(args) == 1 {
+		of = args[0]
+	}
+
+	v4, v6 := ipArgs.want4, ipArgs.want6
+	if v4 && v6 {
+		return errors.New("tailscale up -4 and -6 are mutually exclusive")
+	}
+	if !v4 && !v6 {
+		v4, v6 = true, true
+	}
+	st, err := tailscale.Status(ctx)
+	if err != nil {
+		return err
+	}
+	ips := st.TailscaleIPs
+	if of != "" {
+		ip, err := tailscaleIPFromArg(ctx, of)
+		if err != nil {
+			return err
+		}
+		peer, ok := peerMatchingIP(st, ip)
+		if !ok {
+			return fmt.Errorf("no peer found with IP %v", ip)
+		}
+		ips = peer.TailscaleIPs
+	}
+	if len(ips) == 0 {
+		return fmt.Errorf("no current Tailscale IPs; state: %v", st.BackendState)
+	}
+
+	match := false
+	for _, ip := range ips {
+		if ip.Is4() && v4 || ip.Is6() && v6 {
+			match = true
+			fmt.Println(ip)
+		}
+	}
+	if !match {
+		if ipArgs.want4 {
+			return errors.New("no Tailscale IPv4 address")
+		}
+		if ipArgs.want6 {
+			return errors.New("no Tailscale IPv6 address")
+		}
+	}
+	return nil
+}
+
+func peerMatchingIP(st *ipnstate.Status, ipStr string) (ps *ipnstate.PeerStatus, ok bool) {
+	ip, err := netaddr.ParseIP(ipStr)
+	if err != nil {
+		return
+	}
+	for _, ps = range st.Peer {
+		for _, pip := range ps.TailscaleIPs {
+			if ip == pip {
+				return ps, true
+			}
+		}
+	}
+	return nil, false
+}