mirror of
https://github.com/tailscale/tailscale.git
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780c56e119
Exposes the delegated interface data added by #7248 in the debug endpoint. I would have found it useful when working on that PR, and it may be handy in the future as well. Also makes the interfaces table slightly easier to parse by adding borders to it. To make then nicer-looking, the CSP was relaxed to allow inline styles. Signed-off-by: Mihai Parparita <mihai@tailscale.com>
112 lines
3.1 KiB
Go
112 lines
3.1 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package interfaces
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import (
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"fmt"
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"net"
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"strings"
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"sync"
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"syscall"
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"unsafe"
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"golang.org/x/net/route"
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"golang.org/x/sys/unix"
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"tailscale.com/util/mak"
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)
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// fetchRoutingTable calls route.FetchRIB, fetching NET_RT_DUMP2.
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func fetchRoutingTable() (rib []byte, err error) {
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return route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_DUMP2, 0)
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}
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func parseRoutingTable(rib []byte) ([]route.Message, error) {
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return route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
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}
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var ifNames struct {
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sync.Mutex
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m map[int]string // ifindex => name
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}
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func init() {
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interfaceDebugExtras = interfaceDebugExtrasDarwin
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}
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// getDelegatedInterface returns the interface index of the underlying interface
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// for the given interface index. 0 is returned if the interface does not
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// delegate.
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func getDelegatedInterface(ifIndex int) (int, error) {
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ifNames.Lock()
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defer ifNames.Unlock()
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// To get the delegated interface, we do what ifconfig does and use the
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// SIOCGIFDELEGATE ioctl. It operates in term of a ifreq struct, which
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// has to be populated with a interface name. To avoid having to do a
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// interface index -> name lookup every time, we cache interface names
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// (since indexes and names are stable after boot).
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ifName, ok := ifNames.m[ifIndex]
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if !ok {
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iface, err := net.InterfaceByIndex(ifIndex)
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if err != nil {
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return 0, err
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}
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ifName = iface.Name
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mak.Set(&ifNames.m, ifIndex, ifName)
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}
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// Only tunnels (like Tailscale itself) have a delegated interface, avoid
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// the ioctl if we can.
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if !strings.HasPrefix(ifName, "utun") {
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return 0, nil
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}
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// We don't cache the result of the ioctl, since the delegated interface can
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// change, e.g. if the user changes the preferred service order in the
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// network preference pane.
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fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
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if err != nil {
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return 0, err
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}
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defer unix.Close(fd)
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// Match the ifreq struct/union from the bsd/net/if.h header in the Darwin
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// open source release.
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var ifr struct {
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ifr_name [unix.IFNAMSIZ]byte
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ifr_delegated uint32
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}
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copy(ifr.ifr_name[:], ifName)
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// SIOCGIFDELEGATE is not in the Go x/sys package or in the public macOS
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// <sys/sockio.h> headers. However, it is in the Darwin/xnu open source
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// release (and is used by ifconfig, see
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// https://github.com/apple-oss-distributions/network_cmds/blob/6ccdc225ad5aa0d23ea5e7d374956245d2462427/ifconfig.tproj/ifconfig.c#L2183-L2187).
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// We generate its value by evaluating the `_IOWR('i', 157, struct ifreq)`
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// macro, which is how it's defined in
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// https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/sys/sockio.h#L264
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const SIOCGIFDELEGATE = 0xc020699d
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_, _, errno := syscall.Syscall(
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syscall.SYS_IOCTL,
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uintptr(fd),
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uintptr(SIOCGIFDELEGATE),
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uintptr(unsafe.Pointer(&ifr)))
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if errno != 0 {
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return 0, errno
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}
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return int(ifr.ifr_delegated), nil
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}
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func interfaceDebugExtrasDarwin(ifIndex int) (string, error) {
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delegated, err := getDelegatedInterface(ifIndex)
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if err != nil {
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return "", err
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}
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if delegated == 0 {
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return "", nil
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}
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return fmt.Sprintf("delegated=%d", delegated), nil
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}
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