From 9c2ad7086c0daef9c914ef1e59d0142b50f789f3 Mon Sep 17 00:00:00 2001
From: Anton Tolchanov <anton@tailscale.com>
Date: Fri, 14 Oct 2022 09:29:34 +0100
Subject: [PATCH] net/interfaces: deduplicate route table parsing on Darwin and
FreeBSD
Signed-off-by: Anton Tolchanov <anton@tailscale.com>
---
net/interfaces/interfaces_bsd.go | 26 ++---
net/interfaces/interfaces_darwin.go | 116 +----------------------
net/interfaces/interfaces_darwin_test.go | 2 +-
net/interfaces/interfaces_freebsd.go | 26 +++++
4 files changed, 37 insertions(+), 133 deletions(-)
create mode 100644 net/interfaces/interfaces_freebsd.go
diff --git a/net/interfaces/interfaces_bsd.go b/net/interfaces/interfaces_bsd.go
index 60bba1d95..8efda37f5 100644
--- a/net/interfaces/interfaces_bsd.go
+++ b/net/interfaces/interfaces_bsd.go
@@ -2,11 +2,10 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// This might work on other BSDs, but only tested on FreeBSD.
-// Originally a fork of interfaces_darwin.go with slightly different flags.
+// Common code for FreeBSD and Darwin.
-//go:build freebsd
-// +build freebsd
+//go:build darwin || freebsd
+// +build darwin freebsd
package interfaces
@@ -16,7 +15,6 @@ import (
"log"
"net"
"net/netip"
- "syscall"
"golang.org/x/net/route"
"golang.org/x/sys/unix"
@@ -37,11 +35,6 @@ func defaultRoute() (d DefaultRouteDetails, err error) {
return d, nil
}
-// fetchRoutingTable calls route.FetchRIB, fetching NET_RT_DUMP.
-func fetchRoutingTable() (rib []byte, err error) {
- return route.FetchRIB(syscall.AF_UNSPEC, unix.NET_RT_DUMP, 0)
-}
-
func DefaultRouteInterfaceIndex() (int, error) {
// $ netstat -nr
// Routing tables
@@ -61,7 +54,7 @@ func DefaultRouteInterfaceIndex() (int, error) {
if err != nil {
return 0, fmt.Errorf("route.FetchRIB: %w", err)
}
- msgs, err := route.ParseRIB(unix.NET_RT_IFLIST, rib)
+ msgs, err := parseRoutingTable(rib)
if err != nil {
return 0, fmt.Errorf("route.ParseRIB: %w", err)
}
@@ -71,12 +64,10 @@ func DefaultRouteInterfaceIndex() (int, error) {
if !ok {
continue
}
- const RTF_GATEWAY = 0x2
- const RTF_IFSCOPE = 0x1000000
- if rm.Flags&RTF_GATEWAY == 0 {
+ if rm.Flags&unix.RTF_GATEWAY == 0 {
continue
}
- if rm.Flags&RTF_IFSCOPE != 0 {
+ if rm.Flags&unix.RTF_IFSCOPE != 0 {
continue
}
indexSeen[rm.Index]++
@@ -102,7 +93,7 @@ func likelyHomeRouterIPBSDFetchRIB() (ret netip.Addr, ok bool) {
log.Printf("routerIP/FetchRIB: %v", err)
return ret, false
}
- msgs, err := route.ParseRIB(unix.NET_RT_IFLIST, rib)
+ msgs, err := parseRoutingTable(rib)
if err != nil {
log.Printf("routerIP/ParseRIB: %v", err)
return ret, false
@@ -112,11 +103,10 @@ func likelyHomeRouterIPBSDFetchRIB() (ret netip.Addr, ok bool) {
if !ok {
continue
}
- const RTF_IFSCOPE = 0x1000000
if rm.Flags&unix.RTF_GATEWAY == 0 {
continue
}
- if rm.Flags&RTF_IFSCOPE != 0 {
+ if rm.Flags&unix.RTF_IFSCOPE != 0 {
continue
}
if len(rm.Addrs) > unix.RTAX_GATEWAY {
diff --git a/net/interfaces/interfaces_darwin.go b/net/interfaces/interfaces_darwin.go
index 60335bf80..d0a7e8ef7 100644
--- a/net/interfaces/interfaces_darwin.go
+++ b/net/interfaces/interfaces_darwin.go
@@ -5,128 +5,16 @@
package interfaces
import (
- "errors"
- "fmt"
- "log"
- "net"
- "net/netip"
"syscall"
"golang.org/x/net/route"
- "golang.org/x/sys/unix"
- "tailscale.com/net/netaddr"
)
-func defaultRoute() (d DefaultRouteDetails, err error) {
- idx, err := DefaultRouteInterfaceIndex()
- if err != nil {
- return d, err
- }
- iface, err := net.InterfaceByIndex(idx)
- if err != nil {
- return d, err
- }
- d.InterfaceName = iface.Name
- d.InterfaceIndex = idx
- return d, nil
-}
-
// fetchRoutingTable calls route.FetchRIB, fetching NET_RT_DUMP2.
func fetchRoutingTable() (rib []byte, err error) {
return route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_DUMP2, 0)
}
-func DefaultRouteInterfaceIndex() (int, error) {
- // $ netstat -nr
- // Routing tables
- // Internet:
- // Destination Gateway Flags Netif Expire
- // default 10.0.0.1 UGSc en0 <-- want this one
- // default 10.0.0.1 UGScI en1
-
- // From man netstat:
- // U RTF_UP Route usable
- // G RTF_GATEWAY Destination requires forwarding by intermediary
- // S RTF_STATIC Manually added
- // c RTF_PRCLONING Protocol-specified generate new routes on use
- // I RTF_IFSCOPE Route is associated with an interface scope
-
- rib, err := fetchRoutingTable()
- if err != nil {
- return 0, fmt.Errorf("route.FetchRIB: %w", err)
- }
- msgs, err := route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
- if err != nil {
- return 0, fmt.Errorf("route.ParseRIB: %w", err)
- }
- indexSeen := map[int]int{} // index => count
- for _, m := range msgs {
- rm, ok := m.(*route.RouteMessage)
- if !ok {
- continue
- }
- const RTF_GATEWAY = 0x2
- const RTF_IFSCOPE = 0x1000000
- if rm.Flags&RTF_GATEWAY == 0 {
- continue
- }
- if rm.Flags&RTF_IFSCOPE != 0 {
- continue
- }
- indexSeen[rm.Index]++
- }
- if len(indexSeen) == 0 {
- return 0, errors.New("no gateway index found")
- }
- if len(indexSeen) == 1 {
- for idx := range indexSeen {
- return idx, nil
- }
- }
- return 0, fmt.Errorf("ambiguous gateway interfaces found: %v", indexSeen)
-}
-
-func init() {
- likelyHomeRouterIP = likelyHomeRouterIPDarwinFetchRIB
-}
-
-func likelyHomeRouterIPDarwinFetchRIB() (ret netip.Addr, ok bool) {
- rib, err := fetchRoutingTable()
- if err != nil {
- log.Printf("routerIP/FetchRIB: %v", err)
- return ret, false
- }
- msgs, err := route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
- if err != nil {
- log.Printf("routerIP/ParseRIB: %v", err)
- return ret, false
- }
- for _, m := range msgs {
- rm, ok := m.(*route.RouteMessage)
- if !ok {
- continue
- }
- const RTF_GATEWAY = 0x2
- const RTF_IFSCOPE = 0x1000000
- if rm.Flags&RTF_GATEWAY == 0 {
- continue
- }
- if rm.Flags&RTF_IFSCOPE != 0 {
- continue
- }
- if len(rm.Addrs) > unix.RTAX_GATEWAY {
- dst4, ok := rm.Addrs[unix.RTAX_DST].(*route.Inet4Addr)
- if !ok || dst4.IP != ([4]byte{0, 0, 0, 0}) {
- // Expect 0.0.0.0 as DST field.
- continue
- }
- gw, ok := rm.Addrs[unix.RTAX_GATEWAY].(*route.Inet4Addr)
- if !ok {
- continue
- }
- return netaddr.IPv4(gw.IP[0], gw.IP[1], gw.IP[2], gw.IP[3]), true
- }
- }
-
- return ret, false
+func parseRoutingTable(rib []byte) ([]route.Message, error) {
+ return route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
}
diff --git a/net/interfaces/interfaces_darwin_test.go b/net/interfaces/interfaces_darwin_test.go
index 245ea8211..3aff070ae 100644
--- a/net/interfaces/interfaces_darwin_test.go
+++ b/net/interfaces/interfaces_darwin_test.go
@@ -16,7 +16,7 @@ import (
)
func TestLikelyHomeRouterIPSyscallExec(t *testing.T) {
- syscallIP, syscallOK := likelyHomeRouterIPDarwinFetchRIB()
+ syscallIP, syscallOK := likelyHomeRouterIPBSDFetchRIB()
netstatIP, netstatOK := likelyHomeRouterIPDarwinExec()
if syscallOK != netstatOK || syscallIP != netstatIP {
t.Errorf("syscall() = %v, %v, netstat = %v, %v",
diff --git a/net/interfaces/interfaces_freebsd.go b/net/interfaces/interfaces_freebsd.go
new file mode 100644
index 000000000..8a7270071
--- /dev/null
+++ b/net/interfaces/interfaces_freebsd.go
@@ -0,0 +1,26 @@
+// 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.
+
+// This might work on other BSDs, but only tested on FreeBSD.
+
+//go:build freebsd
+// +build freebsd
+
+package interfaces
+
+import (
+ "syscall"
+
+ "golang.org/x/net/route"
+ "golang.org/x/sys/unix"
+)
+
+// fetchRoutingTable calls route.FetchRIB, fetching NET_RT_DUMP.
+func fetchRoutingTable() (rib []byte, err error) {
+ return route.FetchRIB(syscall.AF_UNSPEC, unix.NET_RT_DUMP, 0)
+}
+
+func parseRoutingTable(rib []byte) ([]route.Message, error) {
+ return route.ParseRIB(syscall.NET_RT_IFLIST, rib)
+}