From 692a011b54ec183129650a6e5d9167b128a8c847 Mon Sep 17 00:00:00 2001
From: David Anderson <danderson@tailscale.com>
Date: Tue, 26 Jan 2021 15:00:05 -0800
Subject: [PATCH] net/interfaces: remove IsTailscaleIP, make callers use
 tsaddr.

Signed-off-by: David Anderson <danderson@tailscale.com>
---
 cmd/tsshd/tsshd.go                | 10 +++++++++-
 net/interfaces/interfaces.go      | 14 +++++---------
 net/interfaces/interfaces_test.go | 21 ---------------------
 tsweb/tsweb.go                    | 10 +++++++---
 4 files changed, 21 insertions(+), 34 deletions(-)

diff --git a/cmd/tsshd/tsshd.go b/cmd/tsshd/tsshd.go
index a247fb55b..c8bc644d5 100644
--- a/cmd/tsshd/tsshd.go
+++ b/cmd/tsshd/tsshd.go
@@ -32,7 +32,9 @@ import (
 	"github.com/gliderlabs/ssh"
 	"github.com/kr/pty"
 	gossh "golang.org/x/crypto/ssh"
+	"inet.af/netaddr"
 	"tailscale.com/net/interfaces"
+	"tailscale.com/net/tsaddr"
 )
 
 var (
@@ -96,7 +98,13 @@ func handleSSH(s ssh.Session) {
 		s.Exit(1)
 		return
 	}
-	if !interfaces.IsTailscaleIP(ta.IP) {
+	tanetaddr, ok := netaddr.FromStdIP(ta.IP)
+	if !ok {
+		log.Printf("tsshd: rejecting unparseable addr %v", ta.IP)
+		s.Exit(1)
+		return
+	}
+	if !tsaddr.IsTailscaleIP(tanetaddr) {
 		log.Printf("tsshd: rejecting non-Tailscale addr %v", ta.IP)
 		s.Exit(1)
 		return
diff --git a/net/interfaces/interfaces.go b/net/interfaces/interfaces.go
index 609cec1fc..bf81d2a82 100644
--- a/net/interfaces/interfaces.go
+++ b/net/interfaces/interfaces.go
@@ -39,8 +39,11 @@ func Tailscale() (net.IP, *net.Interface, error) {
 			continue
 		}
 		for _, a := range addrs {
-			if ipnet, ok := a.(*net.IPNet); ok && IsTailscaleIP(ipnet.IP) {
-				return ipnet.IP, &iface, nil
+			if ipnet, ok := a.(*net.IPNet); ok {
+				nip, ok := netaddr.FromStdIP(ipnet.IP)
+				if ok && tsaddr.IsTailscaleIP(nip) {
+					return ipnet.IP, &iface, nil
+				}
 			}
 		}
 	}
@@ -57,13 +60,6 @@ func maybeTailscaleInterfaceName(s string) bool {
 		strings.HasPrefix(s, "utun")
 }
 
-// IsTailscaleIP reports whether ip is an IP in a range used by
-// Tailscale virtual network interfaces.
-func IsTailscaleIP(ip net.IP) bool {
-	nip, _ := netaddr.FromStdIP(ip) // TODO: push this up to caller, change func signature
-	return tsaddr.IsTailscaleIP(nip)
-}
-
 func isUp(nif *net.Interface) bool       { return nif.Flags&net.FlagUp != 0 }
 func isLoopback(nif *net.Interface) bool { return nif.Flags&net.FlagLoopback != 0 }
 
diff --git a/net/interfaces/interfaces_test.go b/net/interfaces/interfaces_test.go
index 6d8e04de1..88948b579 100644
--- a/net/interfaces/interfaces_test.go
+++ b/net/interfaces/interfaces_test.go
@@ -5,30 +5,9 @@
 package interfaces
 
 import (
-	"net"
 	"testing"
 )
 
-func TestIsTailscaleIP(t *testing.T) {
-	tests := []struct {
-		ip   string
-		want bool
-	}{
-		{"100.81.251.94", true},
-		{"8.8.8.8", false},
-	}
-	for _, tt := range tests {
-		ip := net.ParseIP(tt.ip)
-		if ip == nil {
-			t.Fatalf("failed to parse IP %q", tt.ip)
-		}
-		got := IsTailscaleIP(ip)
-		if got != tt.want {
-			t.Errorf("F(%q) = %v; want %v", tt.ip, got, tt.want)
-		}
-	}
-}
-
 func TestGetState(t *testing.T) {
 	st, err := GetState()
 	if err != nil {
diff --git a/tsweb/tsweb.go b/tsweb/tsweb.go
index 0cbe2fb82..a7cb50725 100644
--- a/tsweb/tsweb.go
+++ b/tsweb/tsweb.go
@@ -23,8 +23,9 @@ import (
 	"strings"
 	"time"
 
+	"inet.af/netaddr"
 	"tailscale.com/metrics"
-	"tailscale.com/net/interfaces"
+	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
 )
 
@@ -81,8 +82,11 @@ func AllowDebugAccess(r *http.Request) bool {
 	if err != nil {
 		return false
 	}
-	ip := net.ParseIP(ipStr)
-	if interfaces.IsTailscaleIP(ip) || ip.IsLoopback() || ipStr == os.Getenv("TS_ALLOW_DEBUG_IP") {
+	ip, err := netaddr.ParseIP(ipStr)
+	if err != nil {
+		return false
+	}
+	if tsaddr.IsTailscaleIP(ip) || ip.IsLoopback() || ipStr == os.Getenv("TS_ALLOW_DEBUG_IP") {
 		return true
 	}
 	if r.Method == "GET" {