net/{interfaces,netmon}, all: merge net/interfaces package into net/netmon
In prep for most of the package funcs in net/interfaces to become methods in a long-lived netmon.Monitor that can cache things. (Many of the funcs are very heavy to call regularly, whereas the long-lived netmon.Monitor can subscribe to things from the OS and remember answers to questions it's asked regularly later) Updates tailscale/corp#10910 Updates tailscale/corp#18960 Updates #7967 Updates #3299 Change-Id: Ie4e8dedb70136af2d611b990b865a822cd1797e5 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
committed by
Brad Fitzpatrick
Brad Fitzpatrick
parent
6b95219e3a
commit
b9adbe2002
278
net/netmon/interfaces_windows.go
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278
net/netmon/interfaces_windows.go
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@ -0,0 +1,278 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package netmon
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import (
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"log"
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"net/netip"
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"net/url"
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"strings"
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"syscall"
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"unsafe"
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"golang.org/x/sys/windows"
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"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
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"tailscale.com/tsconst"
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)
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const (
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fallbackInterfaceMetric = uint32(0) // Used if we cannot get the actual interface metric
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)
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func init() {
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likelyHomeRouterIP = likelyHomeRouterIPWindows
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getPAC = getPACWindows
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}
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func likelyHomeRouterIPWindows() (ret netip.Addr, _ netip.Addr, ok bool) {
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rs, err := winipcfg.GetIPForwardTable2(windows.AF_INET)
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if err != nil {
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log.Printf("routerIP/GetIPForwardTable2 error: %v", err)
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return
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}
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var ifaceMetricCache map[winipcfg.LUID]uint32
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getIfaceMetric := func(luid winipcfg.LUID) (metric uint32) {
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if ifaceMetricCache == nil {
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ifaceMetricCache = make(map[winipcfg.LUID]uint32)
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} else if m, ok := ifaceMetricCache[luid]; ok {
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return m
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}
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if iface, err := luid.IPInterface(windows.AF_INET); err == nil {
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metric = iface.Metric
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} else {
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log.Printf("routerIP/luid.IPInterface error: %v", err)
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metric = fallbackInterfaceMetric
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}
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ifaceMetricCache[luid] = metric
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return
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}
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v4unspec := netip.IPv4Unspecified()
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var best *winipcfg.MibIPforwardRow2 // best (lowest metric) found so far, or nil
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for i := range rs {
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r := &rs[i]
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if r.Loopback || r.DestinationPrefix.PrefixLength != 0 || r.DestinationPrefix.Prefix().Addr().Unmap() != v4unspec {
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// Not a default route, so skip
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continue
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}
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ip := r.NextHop.Addr().Unmap()
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if !ip.IsValid() {
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// Not a valid gateway, so skip (won't happen though)
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continue
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}
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if best == nil {
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best = r
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ret = ip
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continue
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}
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// We can get here only if there are multiple default gateways defined (rare case),
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// in which case we need to calculate the effective metric.
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// Effective metric is sum of interface metric and route metric offset
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if ifaceMetricCache == nil {
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// If we're here it means that previous route still isn't updated, so update it
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best.Metric += getIfaceMetric(best.InterfaceLUID)
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}
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r.Metric += getIfaceMetric(r.InterfaceLUID)
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if best.Metric > r.Metric || best.Metric == r.Metric && ret.Compare(ip) > 0 {
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// Pick the route with lower metric, or lower IP if metrics are equal
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best = r
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ret = ip
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}
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}
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if ret.IsValid() && !ret.IsPrivate() {
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// Default route has a non-private gateway
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return netip.Addr{}, netip.Addr{}, false
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}
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return ret, netip.Addr{}, ret.IsValid()
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}
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// NonTailscaleMTUs returns a map of interface LUID to interface MTU,
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// for all interfaces except Tailscale tunnels.
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func NonTailscaleMTUs() (map[winipcfg.LUID]uint32, error) {
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mtus := map[winipcfg.LUID]uint32{}
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ifs, err := NonTailscaleInterfaces()
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for luid, iface := range ifs {
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mtus[luid] = iface.MTU
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}
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return mtus, err
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}
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func notTailscaleInterface(iface *winipcfg.IPAdapterAddresses) bool {
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// TODO(bradfitz): do this without the Description method's
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// utf16-to-string allocation. But at least we only do it for
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// the virtual interfaces, for which there won't be many.
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if iface.IfType != winipcfg.IfTypePropVirtual {
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return true
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}
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desc := iface.Description()
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return !(strings.Contains(desc, tsconst.WintunInterfaceDesc) ||
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strings.Contains(desc, tsconst.WintunInterfaceDesc0_14))
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}
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// NonTailscaleInterfaces returns a map of interface LUID to interface
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// for all interfaces except Tailscale tunnels.
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func NonTailscaleInterfaces() (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, error) {
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return getInterfaces(windows.AF_UNSPEC, winipcfg.GAAFlagIncludeAllInterfaces, notTailscaleInterface)
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}
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// getInterfaces returns a map of interfaces keyed by their LUID for
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// all interfaces matching the provided match predicate.
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//
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// The family (AF_UNSPEC, AF_INET, or AF_INET6) and flags are passed
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// to winipcfg.GetAdaptersAddresses.
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func getInterfaces(family winipcfg.AddressFamily, flags winipcfg.GAAFlags, match func(*winipcfg.IPAdapterAddresses) bool) (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, error) {
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ifs, err := winipcfg.GetAdaptersAddresses(family, flags)
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if err != nil {
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return nil, err
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}
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ret := map[winipcfg.LUID]*winipcfg.IPAdapterAddresses{}
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for _, iface := range ifs {
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if match(iface) {
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ret[iface.LUID] = iface
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}
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}
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return ret, nil
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}
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// GetWindowsDefault returns the interface that has the non-Tailscale
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// default route for the given address family.
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//
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// It returns (nil, nil) if no interface is found.
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//
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// The family must be one of AF_INET or AF_INET6.
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func GetWindowsDefault(family winipcfg.AddressFamily) (*winipcfg.IPAdapterAddresses, error) {
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ifs, err := getInterfaces(family, winipcfg.GAAFlagIncludeAllInterfaces, func(iface *winipcfg.IPAdapterAddresses) bool {
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switch iface.IfType {
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case winipcfg.IfTypeSoftwareLoopback:
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return false
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}
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switch family {
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case windows.AF_INET:
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if iface.Flags&winipcfg.IPAAFlagIpv4Enabled == 0 {
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return false
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}
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case windows.AF_INET6:
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if iface.Flags&winipcfg.IPAAFlagIpv6Enabled == 0 {
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return false
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}
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}
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return iface.OperStatus == winipcfg.IfOperStatusUp && notTailscaleInterface(iface)
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})
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if err != nil {
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return nil, err
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}
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routes, err := winipcfg.GetIPForwardTable2(family)
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if err != nil {
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return nil, err
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}
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bestMetric := ^uint32(0)
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var bestIface *winipcfg.IPAdapterAddresses
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for _, route := range routes {
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if route.DestinationPrefix.PrefixLength != 0 {
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// Not a default route.
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continue
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}
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iface := ifs[route.InterfaceLUID]
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if iface == nil {
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continue
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}
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// Microsoft docs say:
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//
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// "The actual route metric used to compute the route
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// preferences for IPv4 is the summation of the route
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// metric offset specified in the Metric member of the
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// MIB_IPFORWARD_ROW2 structure and the interface
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// metric specified in this member for IPv4"
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metric := route.Metric
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switch family {
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case windows.AF_INET:
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metric += iface.Ipv4Metric
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case windows.AF_INET6:
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metric += iface.Ipv6Metric
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}
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if metric < bestMetric {
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bestMetric = metric
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bestIface = iface
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}
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}
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return bestIface, nil
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}
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func defaultRoute() (d DefaultRouteDetails, err error) {
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// We always return the IPv4 default route.
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// TODO(bradfitz): adjust API if/when anything cares. They could in theory differ, though,
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// in which case we might send traffic to the wrong interface.
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iface, err := GetWindowsDefault(windows.AF_INET)
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if err != nil {
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return d, err
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}
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if iface != nil {
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d.InterfaceName = iface.FriendlyName()
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d.InterfaceDesc = iface.Description()
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d.InterfaceIndex = int(iface.IfIndex)
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}
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return d, nil
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}
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var (
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winHTTP = windows.NewLazySystemDLL("winhttp.dll")
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detectAutoProxyConfigURL = winHTTP.NewProc("WinHttpDetectAutoProxyConfigUrl")
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kernel32 = windows.NewLazySystemDLL("kernel32.dll")
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globalFree = kernel32.NewProc("GlobalFree")
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)
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const (
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winHTTP_AUTO_DETECT_TYPE_DHCP = 0x00000001
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winHTTP_AUTO_DETECT_TYPE_DNS_A = 0x00000002
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)
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func getPACWindows() string {
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var res *uint16
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r, _, e := detectAutoProxyConfigURL.Call(
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winHTTP_AUTO_DETECT_TYPE_DHCP|winHTTP_AUTO_DETECT_TYPE_DNS_A,
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uintptr(unsafe.Pointer(&res)),
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)
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if r == 1 {
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if res == nil {
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log.Printf("getPACWindows: unexpected success with nil result")
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return ""
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}
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defer globalFree.Call(uintptr(unsafe.Pointer(res)))
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s := windows.UTF16PtrToString(res)
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s = strings.TrimSpace(s)
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if s == "" {
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return "" // Issue 2357: invalid URL "\n" from winhttp; ignoring
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}
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if _, err := url.Parse(s); err != nil {
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log.Printf("getPACWindows: invalid URL %q from winhttp; ignoring", s)
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return ""
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}
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return s
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}
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const (
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ERROR_WINHTTP_AUTODETECTION_FAILED = 12180
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)
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if e == syscall.Errno(ERROR_WINHTTP_AUTODETECTION_FAILED) {
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// Common case on networks without advertised PAC.
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return ""
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}
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log.Printf("getPACWindows: %T=%v", e, e) // syscall.Errno=0x....
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return ""
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}
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