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tailscale/ipn/ipnlocal/peerapi.go

1081 lines
31 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package ipnlocal
import (
"context"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"hash/crc32"
"html"
"io"
"net"
"net/http"
"net/netip"
"net/url"
"os"
"runtime"
"slices"
"sort"
"strconv"
"strings"
"sync"
"time"
"github.com/kortschak/wol"
"golang.org/x/net/dns/dnsmessage"
"golang.org/x/net/http/httpguts"
"tailscale.com/envknob"
"tailscale.com/health"
"tailscale.com/hostinfo"
"tailscale.com/ipn"
"tailscale.com/net/dns/resolver"
"tailscale.com/net/interfaces"
"tailscale.com/net/netaddr"
"tailscale.com/net/netutil"
"tailscale.com/net/sockstats"
"tailscale.com/tailcfg"
"tailscale.com/taildrop"
"tailscale.com/types/views"
"tailscale.com/util/clientmetric"
"tailscale.com/wgengine/filter"
)
var initListenConfig func(*net.ListenConfig, netip.Addr, *interfaces.State, string) error
// addH2C is non-nil on platforms where we want to add H2C
// ("cleartext" HTTP/2) support to the peerAPI.
var addH2C func(*http.Server)
type peerAPIServer struct {
b *LocalBackend
resolver *resolver.Resolver
taildrop *taildrop.Manager
}
var (
errNilPeerAPIServer = errors.New("peerapi unavailable; not listening")
)
func (s *peerAPIServer) listen(ip netip.Addr, ifState *interfaces.State) (ln net.Listener, err error) {
// Android for whatever reason often has problems creating the peerapi listener.
// But since we started intercepting it with netstack, it's not even important that
// we have a real kernel-level listener. So just create a dummy listener on Android
// and let netstack intercept it.
if runtime.GOOS == "android" {
return newFakePeerAPIListener(ip), nil
}
ipStr := ip.String()
var lc net.ListenConfig
if initListenConfig != nil {
// On iOS/macOS, this sets the lc.Control hook to
// setsockopt the interface index to bind to, to get
// out of the network sandbox.
if err := initListenConfig(&lc, ip, ifState, s.b.dialer.TUNName()); err != nil {
return nil, err
}
if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
ipStr = ""
}
}
if s.b.sys.IsNetstack() {
ipStr = ""
}
tcp4or6 := "tcp4"
if ip.Is6() {
tcp4or6 = "tcp6"
}
// Make a best effort to pick a deterministic port number for
// the ip. The lower three bytes are the same for IPv4 and IPv6
// Tailscale addresses (at least currently), so we'll usually
// get the same port number on both address families for
// dev/debugging purposes, which is nice. But it's not so
// deterministic that people will bake this into clients.
// We try a few times just in case something's already
// listening on that port (on all interfaces, probably).
for try := uint8(0); try < 5; try++ {
a16 := ip.As16()
hashData := a16[len(a16)-3:]
hashData[0] += try
tryPort := (32 << 10) | uint16(crc32.ChecksumIEEE(hashData))
ln, err = lc.Listen(context.Background(), tcp4or6, net.JoinHostPort(ipStr, strconv.Itoa(int(tryPort))))
if err == nil {
return ln, nil
}
}
// Fall back to some random ephemeral port.
ln, err = lc.Listen(context.Background(), tcp4or6, net.JoinHostPort(ipStr, "0"))
// And if we're on a platform with netstack (anything but iOS), then just fallback to netstack.
if err != nil && runtime.GOOS != "ios" {
s.b.logf("peerapi: failed to do peerAPI listen, harmless (netstack available) but error was: %v", err)
return newFakePeerAPIListener(ip), nil
}
return ln, err
}
type peerAPIListener struct {
ps *peerAPIServer
ip netip.Addr
lb *LocalBackend
// ln is the Listener. It can be nil in netstack mode if there are more than
// 1 local addresses (e.g. both an IPv4 and IPv6). When it's nil, port
// and urlStr are still populated.
ln net.Listener
// urlStr is the base URL to access the PeerAPI (http://ip:port/).
urlStr string
// port is just the port of urlStr.
port int
}
func (pln *peerAPIListener) Close() error {
if pln.ln != nil {
return pln.ln.Close()
}
return nil
}
func (pln *peerAPIListener) serve() {
if pln.ln == nil {
return
}
defer pln.ln.Close()
logf := pln.lb.logf
for {
c, err := pln.ln.Accept()
if errors.Is(err, net.ErrClosed) {
return
}
if err != nil {
logf("peerapi.Accept: %v", err)
return
}
ta, ok := c.RemoteAddr().(*net.TCPAddr)
if !ok {
c.Close()
logf("peerapi: unexpected RemoteAddr %#v", c.RemoteAddr())
continue
}
ipp := netaddr.Unmap(ta.AddrPort())
if !ipp.IsValid() {
logf("peerapi: bogus TCPAddr %#v", ta)
c.Close()
continue
}
pln.ServeConn(ipp, c)
}
}
func (pln *peerAPIListener) ServeConn(src netip.AddrPort, c net.Conn) {
logf := pln.lb.logf
peerNode, peerUser, ok := pln.lb.WhoIs(src)
if !ok {
logf("peerapi: unknown peer %v", src)
c.Close()
return
}
nm := pln.lb.NetMap()
if nm == nil || !nm.SelfNode.Valid() {
logf("peerapi: no netmap")
c.Close()
return
}
h := &peerAPIHandler{
ps: pln.ps,
isSelf: nm.SelfNode.User() == peerNode.User(),
remoteAddr: src,
selfNode: nm.SelfNode,
peerNode: peerNode,
peerUser: peerUser,
}
httpServer := &http.Server{
Handler: h,
}
if addH2C != nil {
addH2C(httpServer)
}
go httpServer.Serve(netutil.NewOneConnListener(c, nil))
}
// peerAPIHandler serves the PeerAPI for a source specific client.
type peerAPIHandler struct {
ps *peerAPIServer
remoteAddr netip.AddrPort
isSelf bool // whether peerNode is owned by same user as this node
selfNode tailcfg.NodeView // this node; always non-nil
peerNode tailcfg.NodeView // peerNode is who's making the request
peerUser tailcfg.UserProfile // profile of peerNode
}
func (h *peerAPIHandler) logf(format string, a ...any) {
h.ps.b.logf("peerapi: "+format, a...)
}
// isAddressValid reports whether addr is a valid destination address for this
// node originating from the peer.
func (h *peerAPIHandler) isAddressValid(addr netip.Addr) bool {
if v := h.peerNode.SelfNodeV4MasqAddrForThisPeer(); v != nil {
return *v == addr
}
if v := h.peerNode.SelfNodeV6MasqAddrForThisPeer(); v != nil {
return *v == addr
}
pfx := netip.PrefixFrom(addr, addr.BitLen())
return views.SliceContains(h.selfNode.Addresses(), pfx)
}
func (h *peerAPIHandler) validateHost(r *http.Request) error {
if r.Host == "peer" {
return nil
}
ap, err := netip.ParseAddrPort(r.Host)
if err != nil {
return err
}
if !h.isAddressValid(ap.Addr()) {
return fmt.Errorf("%v not found in self addresses", ap.Addr())
}
return nil
}
func (h *peerAPIHandler) validatePeerAPIRequest(r *http.Request) error {
if r.Referer() != "" {
return errors.New("unexpected Referer")
}
if r.Header.Get("Origin") != "" {
return errors.New("unexpected Origin")
}
return h.validateHost(r)
}
// peerAPIRequestShouldGetSecurityHeaders reports whether the PeerAPI request r
// should get security response headers. It aims to report true for any request
// from a browser and false for requests from tailscaled (Go) clients.
//
// PeerAPI is primarily an RPC mechanism between Tailscale instances. Some of
// the HTTP handlers are useful for debugging with curl or browsers, but in
// general the client is always tailscaled itself. Because PeerAPI only uses
// HTTP/1 without HTTP/2 and its HPACK helping with repetitive headers, we try
// to minimize header bytes sent in the common case when the client isn't a
// browser. Minimizing bytes is important in particular with the ExitDNS service
// provided by exit nodes, processing DNS clients from queries. We don't want to
// waste bytes with security headers to non-browser clients. But if there's any
// hint that the request is from a browser, then we do.
func peerAPIRequestShouldGetSecurityHeaders(r *http.Request) bool {
// Accept-Encoding is a forbidden header
// (https://developer.mozilla.org/en-US/docs/Glossary/Forbidden_header_name)
// that Chrome, Firefox, Safari, etc send, but Go does not. So if we see it,
// it's probably a browser and not a Tailscale PeerAPI (Go) client.
if httpguts.HeaderValuesContainsToken(r.Header["Accept-Encoding"], "deflate") {
return true
}
// Clients can mess with their User-Agent, but if they say Mozilla or have a bunch
// of components (spaces) they're likely a browser.
if ua := r.Header.Get("User-Agent"); strings.HasPrefix(ua, "Mozilla/") || strings.Count(ua, " ") > 2 {
return true
}
// Tailscale/PeerAPI/Go clients don't have an Accept-Language.
if r.Header.Get("Accept-Language") != "" {
return true
}
return false
}
func (h *peerAPIHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if err := h.validatePeerAPIRequest(r); err != nil {
metricInvalidRequests.Add(1)
h.logf("invalid request from %v: %v", h.remoteAddr, err)
http.Error(w, "invalid peerapi request", http.StatusForbidden)
return
}
if peerAPIRequestShouldGetSecurityHeaders(r) {
w.Header().Set("Content-Security-Policy", `default-src 'none'; frame-ancestors 'none'; script-src 'none'; script-src-elem 'none'; script-src-attr 'none'; style-src 'unsafe-inline'`)
w.Header().Set("X-Frame-Options", "DENY")
w.Header().Set("X-Content-Type-Options", "nosniff")
}
if strings.HasPrefix(r.URL.Path, "/v0/put/") {
metricPutCalls.Add(1)
h.handlePeerPut(w, r)
return
}
if strings.HasPrefix(r.URL.Path, "/dns-query") {
metricDNSCalls.Add(1)
h.handleDNSQuery(w, r)
return
}
switch r.URL.Path {
case "/v0/goroutines":
h.handleServeGoroutines(w, r)
return
case "/v0/env":
h.handleServeEnv(w, r)
return
case "/v0/metrics":
h.handleServeMetrics(w, r)
return
case "/v0/magicsock":
h.handleServeMagicsock(w, r)
return
case "/v0/dnsfwd":
h.handleServeDNSFwd(w, r)
return
case "/v0/wol":
metricWakeOnLANCalls.Add(1)
h.handleWakeOnLAN(w, r)
return
case "/v0/interfaces":
h.handleServeInterfaces(w, r)
return
case "/v0/doctor":
h.handleServeDoctor(w, r)
case "/v0/sockstats":
h.handleServeSockStats(w, r)
return
case "/v0/ingress":
metricIngressCalls.Add(1)
h.handleServeIngress(w, r)
return
}
who := h.peerUser.DisplayName
fmt.Fprintf(w, `<html>
<meta name="viewport" content="width=device-width, initial-scale=1">
<body>
<h1>Hello, %s (%v)</h1>
This is my Tailscale device. Your device is %v.
`, html.EscapeString(who), h.remoteAddr.Addr(), html.EscapeString(h.peerNode.ComputedName()))
if h.isSelf {
fmt.Fprintf(w, "<p>You are the owner of this node.\n")
}
}
func (h *peerAPIHandler) handleServeIngress(w http.ResponseWriter, r *http.Request) {
// http.Errors only useful if hitting endpoint manually
// otherwise rely on log lines when debugging ingress connections
// as connection is hijacked for bidi and is encrypted tls
if !h.canIngress() {
h.logf("ingress: denied; no ingress cap from %v", h.remoteAddr)
http.Error(w, "denied; no ingress cap", http.StatusForbidden)
return
}
logAndError := func(code int, publicMsg string) {
h.logf("ingress: bad request from %v: %s", h.remoteAddr, publicMsg)
http.Error(w, publicMsg, http.StatusMethodNotAllowed)
}
bad := func(publicMsg string) {
logAndError(http.StatusBadRequest, publicMsg)
}
if r.Method != "POST" {
logAndError(http.StatusMethodNotAllowed, "only POST allowed")
return
}
srcAddrStr := r.Header.Get("Tailscale-Ingress-Src")
if srcAddrStr == "" {
bad("Tailscale-Ingress-Src header not set")
return
}
srcAddr, err := netip.ParseAddrPort(srcAddrStr)
if err != nil {
bad("Tailscale-Ingress-Src header invalid; want ip:port")
return
}
target := ipn.HostPort(r.Header.Get("Tailscale-Ingress-Target"))
if target == "" {
bad("Tailscale-Ingress-Target header not set")
return
}
if _, _, err := net.SplitHostPort(string(target)); err != nil {
bad("Tailscale-Ingress-Target header invalid; want host:port")
return
}
getConnOrReset := func() (net.Conn, bool) {
conn, _, err := w.(http.Hijacker).Hijack()
if err != nil {
h.logf("ingress: failed hijacking conn")
http.Error(w, "failed hijacking conn", http.StatusInternalServerError)
return nil, false
}
io.WriteString(conn, "HTTP/1.1 101 Switching Protocols\r\n\r\n")
return &ipn.FunnelConn{
Conn: conn,
Src: srcAddr,
Target: target,
}, true
}
sendRST := func() {
http.Error(w, "denied", http.StatusForbidden)
}
h.ps.b.HandleIngressTCPConn(h.peerNode, target, srcAddr, getConnOrReset, sendRST)
}
func (h *peerAPIHandler) handleServeInterfaces(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprintln(w, "<h1>Interfaces</h1>")
if dr, err := interfaces.DefaultRoute(); err == nil {
fmt.Fprintf(w, "<h3>Default route is %q(%d)</h3>\n", html.EscapeString(dr.InterfaceName), dr.InterfaceIndex)
} else {
fmt.Fprintf(w, "<h3>Could not get the default route: %s</h3>\n", html.EscapeString(err.Error()))
}
if hasCGNATInterface, err := interfaces.HasCGNATInterface(); hasCGNATInterface {
fmt.Fprintln(w, "<p>There is another interface using the CGNAT range.</p>")
} else if err != nil {
fmt.Fprintf(w, "<p>Could not check for CGNAT interfaces: %s</p>\n", html.EscapeString(err.Error()))
}
i, err := interfaces.GetList()
if err != nil {
fmt.Fprintf(w, "Could not get interfaces: %s\n", html.EscapeString(err.Error()))
return
}
fmt.Fprintln(w, "<table style='border-collapse: collapse' border=1 cellspacing=0 cellpadding=2>")
fmt.Fprint(w, "<tr>")
for _, v := range []any{"Index", "Name", "MTU", "Flags", "Addrs", "Extra"} {
fmt.Fprintf(w, "<th>%v</th> ", v)
}
fmt.Fprint(w, "</tr>\n")
i.ForeachInterface(func(iface interfaces.Interface, ipps []netip.Prefix) {
fmt.Fprint(w, "<tr>")
for _, v := range []any{iface.Index, iface.Name, iface.MTU, iface.Flags, ipps} {
fmt.Fprintf(w, "<td>%s</td> ", html.EscapeString(fmt.Sprintf("%v", v)))
}
if extras, err := interfaces.InterfaceDebugExtras(iface.Index); err == nil && extras != "" {
fmt.Fprintf(w, "<td>%s</td> ", html.EscapeString(extras))
} else if err != nil {
fmt.Fprintf(w, "<td>%s</td> ", html.EscapeString(err.Error()))
}
fmt.Fprint(w, "</tr>\n")
})
fmt.Fprintln(w, "</table>")
}
func (h *peerAPIHandler) handleServeDoctor(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprintln(w, "<h1>Doctor Output</h1>")
fmt.Fprintln(w, "<pre>")
h.ps.b.Doctor(r.Context(), func(format string, args ...any) {
line := fmt.Sprintf(format, args...)
fmt.Fprintln(w, html.EscapeString(line))
})
fmt.Fprintln(w, "</pre>")
}
func (h *peerAPIHandler) handleServeSockStats(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprintln(w, "<!DOCTYPE html><h1>Socket Stats</h1>")
if !sockstats.IsAvailable {
fmt.Fprintln(w, "Socket stats are not available for this client")
return
}
stats, interfaceStats, validation := sockstats.Get(), sockstats.GetInterfaces(), sockstats.GetValidation()
if stats == nil {
fmt.Fprintln(w, "No socket stats available")
return
}
fmt.Fprintln(w, "<table border='1' cellspacing='0' style='border-collapse: collapse;'>")
fmt.Fprintln(w, "<thead>")
fmt.Fprintln(w, "<th>Label</th>")
fmt.Fprintln(w, "<th>Tx</th>")
fmt.Fprintln(w, "<th>Rx</th>")
for _, iface := range interfaceStats.Interfaces {
fmt.Fprintf(w, "<th>Tx (%s)</th>", html.EscapeString(iface))
fmt.Fprintf(w, "<th>Rx (%s)</th>", html.EscapeString(iface))
}
fmt.Fprintln(w, "<th>Validation</th>")
fmt.Fprintln(w, "</thead>")
fmt.Fprintln(w, "<tbody>")
labels := make([]sockstats.Label, 0, len(stats.Stats))
for label := range stats.Stats {
labels = append(labels, label)
}
slices.SortFunc(labels, func(a, b sockstats.Label) int {
return strings.Compare(a.String(), b.String())
})
txTotal := uint64(0)
rxTotal := uint64(0)
txTotalByInterface := map[string]uint64{}
rxTotalByInterface := map[string]uint64{}
for _, label := range labels {
stat := stats.Stats[label]
fmt.Fprintln(w, "<tr>")
fmt.Fprintf(w, "<td>%s</td>", html.EscapeString(label.String()))
fmt.Fprintf(w, "<td align=right>%d</td>", stat.TxBytes)
fmt.Fprintf(w, "<td align=right>%d</td>", stat.RxBytes)
txTotal += stat.TxBytes
rxTotal += stat.RxBytes
if interfaceStat, ok := interfaceStats.Stats[label]; ok {
for _, iface := range interfaceStats.Interfaces {
fmt.Fprintf(w, "<td align=right>%d</td>", interfaceStat.TxBytesByInterface[iface])
fmt.Fprintf(w, "<td align=right>%d</td>", interfaceStat.RxBytesByInterface[iface])
txTotalByInterface[iface] += interfaceStat.TxBytesByInterface[iface]
rxTotalByInterface[iface] += interfaceStat.RxBytesByInterface[iface]
}
}
if validationStat, ok := validation.Stats[label]; ok && (validationStat.RxBytes > 0 || validationStat.TxBytes > 0) {
fmt.Fprintf(w, "<td>Tx=%d (%+d) Rx=%d (%+d)</td>",
validationStat.TxBytes,
int64(validationStat.TxBytes)-int64(stat.TxBytes),
validationStat.RxBytes,
int64(validationStat.RxBytes)-int64(stat.RxBytes))
} else {
fmt.Fprintln(w, "<td></td>")
}
fmt.Fprintln(w, "</tr>")
}
fmt.Fprintln(w, "</tbody>")
fmt.Fprintln(w, "<tfoot>")
fmt.Fprintln(w, "<th>Total</th>")
fmt.Fprintf(w, "<th>%d</th>", txTotal)
fmt.Fprintf(w, "<th>%d</th>", rxTotal)
for _, iface := range interfaceStats.Interfaces {
fmt.Fprintf(w, "<th>%d</th>", txTotalByInterface[iface])
fmt.Fprintf(w, "<th>%d</th>", rxTotalByInterface[iface])
}
fmt.Fprintln(w, "<th></th>")
fmt.Fprintln(w, "</tfoot>")
fmt.Fprintln(w, "</table>")
fmt.Fprintln(w, "<h2>Debug Info</h2>")
fmt.Fprintln(w, "<pre>")
fmt.Fprintln(w, html.EscapeString(sockstats.DebugInfo()))
fmt.Fprintln(w, "</pre>")
}
// canPutFile reports whether h can put a file ("Taildrop") to this node.
func (h *peerAPIHandler) canPutFile() bool {
if h.peerNode.UnsignedPeerAPIOnly() {
// Unsigned peers can't send files.
return false
}
return h.isSelf || h.peerHasCap(tailcfg.PeerCapabilityFileSharingSend)
}
// canDebug reports whether h can debug this node (goroutines, metrics,
// magicsock internal state, etc).
func (h *peerAPIHandler) canDebug() bool {
if !h.selfNode.HasCap(tailcfg.CapabilityDebug) {
// This node does not expose debug info.
return false
}
if h.peerNode.UnsignedPeerAPIOnly() {
// Unsigned peers can't debug.
return false
}
return h.isSelf || h.peerHasCap(tailcfg.PeerCapabilityDebugPeer)
}
// canWakeOnLAN reports whether h can send a Wake-on-LAN packet from this node.
func (h *peerAPIHandler) canWakeOnLAN() bool {
if h.peerNode.UnsignedPeerAPIOnly() {
return false
}
return h.isSelf || h.peerHasCap(tailcfg.PeerCapabilityWakeOnLAN)
}
var allowSelfIngress = envknob.RegisterBool("TS_ALLOW_SELF_INGRESS")
// canIngress reports whether h can send ingress requests to this node.
func (h *peerAPIHandler) canIngress() bool {
return h.peerHasCap(tailcfg.PeerCapabilityIngress) || (allowSelfIngress() && h.isSelf)
}
func (h *peerAPIHandler) peerHasCap(wantCap tailcfg.PeerCapability) bool {
return h.ps.b.PeerCaps(h.remoteAddr.Addr()).HasCapability(wantCap)
}
func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
if !h.canPutFile() {
http.Error(w, "Taildrop access denied", http.StatusForbidden)
return
}
if !h.ps.b.hasCapFileSharing() {
http.Error(w, "file sharing not enabled by Tailscale admin", http.StatusForbidden)
return
}
if r.Method != "PUT" {
http.Error(w, "expected method PUT", http.StatusMethodNotAllowed)
return
}
rawPath := r.URL.EscapedPath()
suffix, ok := strings.CutPrefix(rawPath, "/v0/put/")
if !ok {
http.Error(w, "misconfigured internals", http.StatusInternalServerError)
return
}
if suffix == "" {
http.Error(w, "empty filename", http.StatusBadRequest)
return
}
if strings.Contains(suffix, "/") {
http.Error(w, "directories not supported", http.StatusBadRequest)
return
}
baseName, err := url.PathUnescape(suffix)
if err != nil {
http.Error(w, "bad path encoding", http.StatusBadRequest)
return
}
t0 := h.ps.b.clock.Now()
// TODO(rhea,joetsai): Set the client ID and starting offset.
n, err := h.ps.taildrop.PutFile("", baseName, r.Body, 0, r.ContentLength)
switch err {
case nil:
d := h.ps.b.clock.Since(t0).Round(time.Second / 10)
h.logf("got put of %s in %v from %v/%v", approxSize(n), d, h.remoteAddr.Addr(), h.peerNode.ComputedName)
io.WriteString(w, "{}\n")
case taildrop.ErrNoTaildrop:
http.Error(w, err.Error(), http.StatusForbidden)
case taildrop.ErrInvalidFileName:
http.Error(w, err.Error(), http.StatusBadRequest)
case taildrop.ErrFileExists:
http.Error(w, err.Error(), http.StatusConflict)
default:
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
func approxSize(n int64) string {
if n <= 1<<10 {
return "<=1KB"
}
if n <= 1<<20 {
return "<=1MB"
}
return fmt.Sprintf("~%dMB", n>>20)
}
func (h *peerAPIHandler) handleServeGoroutines(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
var buf []byte
for size := 4 << 10; size <= 2<<20; size *= 2 {
buf = make([]byte, size)
buf = buf[:runtime.Stack(buf, true)]
if len(buf) < size {
break
}
}
w.Write(buf)
}
func (h *peerAPIHandler) handleServeEnv(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
var data struct {
Hostinfo *tailcfg.Hostinfo
Uid int
Args []string
Env []string
}
data.Hostinfo = hostinfo.New()
data.Uid = os.Getuid()
data.Args = os.Args
data.Env = os.Environ()
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(data)
}
func (h *peerAPIHandler) handleServeMagicsock(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
h.ps.b.magicConn().ServeHTTPDebug(w, r)
}
func (h *peerAPIHandler) handleServeMetrics(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
w.Header().Set("Content-Type", "text/plain")
clientmetric.WritePrometheusExpositionFormat(w)
}
func (h *peerAPIHandler) handleServeDNSFwd(w http.ResponseWriter, r *http.Request) {
if !h.canDebug() {
http.Error(w, "denied; no debug access", http.StatusForbidden)
return
}
dh := health.DebugHandler("dnsfwd")
if dh == nil {
http.Error(w, "not wired up", http.StatusInternalServerError)
return
}
dh.ServeHTTP(w, r)
}
func (h *peerAPIHandler) handleWakeOnLAN(w http.ResponseWriter, r *http.Request) {
if !h.canWakeOnLAN() {
http.Error(w, "no WoL access", http.StatusForbidden)
return
}
if r.Method != "POST" {
http.Error(w, "bad method", http.StatusMethodNotAllowed)
return
}
macStr := r.FormValue("mac")
if macStr == "" {
http.Error(w, "missing 'mac' param", http.StatusBadRequest)
return
}
mac, err := net.ParseMAC(macStr)
if err != nil {
http.Error(w, "bad 'mac' param", http.StatusBadRequest)
return
}
var password []byte // TODO(bradfitz): support? does anything use WoL passwords?
st := h.ps.b.sys.NetMon.Get().InterfaceState()
if st == nil {
http.Error(w, "failed to get interfaces state", http.StatusInternalServerError)
return
}
var res struct {
SentTo []string
Errors []string
}
for ifName, ips := range st.InterfaceIPs {
for _, ip := range ips {
if ip.Addr().IsLoopback() || ip.Addr().Is6() {
continue
}
local := &net.UDPAddr{
IP: ip.Addr().AsSlice(),
Port: 0,
}
remote := &net.UDPAddr{
IP: net.IPv4bcast,
Port: 0,
}
if err := wol.Wake(mac, password, local, remote); err != nil {
res.Errors = append(res.Errors, err.Error())
} else {
res.SentTo = append(res.SentTo, ifName)
}
break // one per interface is enough
}
}
sort.Strings(res.SentTo)
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(res)
}
func (h *peerAPIHandler) replyToDNSQueries() bool {
if h.isSelf {
// If the peer is owned by the same user, just allow it
// without further checks.
return true
}
b := h.ps.b
if !b.OfferingExitNode() {
// If we're not an exit node, there's no point to
// being a DNS server for somebody.
return false
}
if !h.remoteAddr.IsValid() {
// This should never be the case if the peerAPIHandler
// was wired up correctly, but just in case.
return false
}
// Otherwise, we're an exit node but the peer is not us, so
// we need to check if they're allowed access to the internet.
// As peerapi bypasses wgengine/filter checks, we need to check
// ourselves. As a proxy for autogroup:internet access, we see
// if we would've accepted a packet to 0.0.0.0:53. We treat
// the IP 0.0.0.0 as being "the internet".
f := b.filterAtomic.Load()
if f == nil {
return false
}
// Note: we check TCP here because the Filter type already had
// a CheckTCP method (for unit tests), but it's pretty
// arbitrary. DNS runs over TCP and UDP, so sure... we check
// TCP.
dstIP := netaddr.IPv4(0, 0, 0, 0)
remoteIP := h.remoteAddr.Addr()
if remoteIP.Is6() {
// autogroup:internet for IPv6 is defined to start with 2000::/3,
// so use 2000::0 as the probe "the internet" address.
dstIP = netip.MustParseAddr("2000::")
}
verdict := f.CheckTCP(remoteIP, dstIP, 53)
return verdict == filter.Accept
}
// handleDNSQuery implements a DoH server (RFC 8484) over the peerapi.
// It's not over HTTPS as the spec dictates, but rather HTTP-over-WireGuard.
func (h *peerAPIHandler) handleDNSQuery(w http.ResponseWriter, r *http.Request) {
if h.ps.resolver == nil {
http.Error(w, "DNS not wired up", http.StatusNotImplemented)
return
}
if !h.replyToDNSQueries() {
http.Error(w, "DNS access denied", http.StatusForbidden)
return
}
pretty := false // non-DoH debug mode for humans
q, publicError := dohQuery(r)
if publicError != "" && r.Method == "GET" {
if name := r.FormValue("q"); name != "" {
pretty = true
publicError = ""
q = dnsQueryForName(name, r.FormValue("t"))
}
}
if publicError != "" {
http.Error(w, publicError, http.StatusBadRequest)
return
}
// Some timeout that's short enough to be noticed by humans
// but long enough that it's longer than real DNS timeouts.
const arbitraryTimeout = 5 * time.Second
ctx, cancel := context.WithTimeout(r.Context(), arbitraryTimeout)
defer cancel()
res, err := h.ps.resolver.HandleExitNodeDNSQuery(ctx, q, h.remoteAddr, h.ps.b.allowExitNodeDNSProxyToServeName)
if err != nil {
h.logf("handleDNS fwd error: %v", err)
if err := ctx.Err(); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
} else {
http.Error(w, "DNS forwarding error", http.StatusInternalServerError)
}
return
}
if pretty {
// Non-standard response for interactive debugging.
w.Header().Set("Content-Type", "application/json")
writePrettyDNSReply(w, res)
return
}
w.Header().Set("Content-Type", "application/dns-message")
w.Header().Set("Content-Length", strconv.Itoa(len(res)))
w.Write(res)
}
func dohQuery(r *http.Request) (dnsQuery []byte, publicErr string) {
const maxQueryLen = 256 << 10
switch r.Method {
default:
return nil, "bad HTTP method"
case "GET":
q64 := r.FormValue("dns")
if q64 == "" {
return nil, "missing 'dns' parameter"
}
if base64.RawURLEncoding.DecodedLen(len(q64)) > maxQueryLen {
return nil, "query too large"
}
q, err := base64.RawURLEncoding.DecodeString(q64)
if err != nil {
return nil, "invalid 'dns' base64 encoding"
}
return q, ""
case "POST":
if r.Header.Get("Content-Type") != "application/dns-message" {
return nil, "unexpected Content-Type"
}
q, err := io.ReadAll(io.LimitReader(r.Body, maxQueryLen+1))
if err != nil {
return nil, "error reading post body with DNS query"
}
if len(q) > maxQueryLen {
return nil, "query too large"
}
return q, ""
}
}
func dnsQueryForName(name, typStr string) []byte {
typ := dnsmessage.TypeA
switch strings.ToLower(typStr) {
case "aaaa":
typ = dnsmessage.TypeAAAA
case "txt":
typ = dnsmessage.TypeTXT
}
b := dnsmessage.NewBuilder(nil, dnsmessage.Header{
OpCode: 0, // query
RecursionDesired: true,
ID: 0,
})
if !strings.HasSuffix(name, ".") {
name += "."
}
b.StartQuestions()
b.Question(dnsmessage.Question{
Name: dnsmessage.MustNewName(name),
Type: typ,
Class: dnsmessage.ClassINET,
})
msg, _ := b.Finish()
return msg
}
func writePrettyDNSReply(w io.Writer, res []byte) (err error) {
defer func() {
if err != nil {
j, _ := json.Marshal(struct {
Error string
}{err.Error()})
j = append(j, '\n')
w.Write(j)
return
}
}()
var p dnsmessage.Parser
hdr, err := p.Start(res)
if err != nil {
return err
}
if hdr.RCode != dnsmessage.RCodeSuccess {
return fmt.Errorf("DNS RCode = %v", hdr.RCode)
}
if err := p.SkipAllQuestions(); err != nil {
return err
}
var gotIPs []string
for {
h, err := p.AnswerHeader()
if err == dnsmessage.ErrSectionDone {
break
}
if err != nil {
return err
}
if h.Class != dnsmessage.ClassINET {
continue
}
switch h.Type {
case dnsmessage.TypeA:
r, err := p.AResource()
if err != nil {
return err
}
gotIPs = append(gotIPs, net.IP(r.A[:]).String())
case dnsmessage.TypeAAAA:
r, err := p.AAAAResource()
if err != nil {
return err
}
gotIPs = append(gotIPs, net.IP(r.AAAA[:]).String())
case dnsmessage.TypeTXT:
r, err := p.TXTResource()
if err != nil {
return err
}
gotIPs = append(gotIPs, r.TXT...)
}
}
j, _ := json.Marshal(gotIPs)
j = append(j, '\n')
w.Write(j)
return nil
}
// newFakePeerAPIListener creates a new net.Listener that acts like
// it's listening on the provided IP address and on TCP port 1.
//
// See docs on fakePeerAPIListener.
func newFakePeerAPIListener(ip netip.Addr) net.Listener {
return &fakePeerAPIListener{
addr: net.TCPAddrFromAddrPort(netip.AddrPortFrom(ip, 1)),
closed: make(chan struct{}),
}
}
// fakePeerAPIListener is a net.Listener that has an Addr method returning a TCPAddr
// for a given IP on port 1 (arbitrary) and can be Closed, but otherwise Accept
// just blocks forever until closed. The purpose of this is to let the rest
// of the LocalBackend/PeerAPI code run and think it's talking to the kernel,
// even if the kernel isn't cooperating (like on Android: Issue 4449, 4293, etc)
// or we lack permission to listen on a port. It's okay to not actually listen via
// the kernel because on almost all platforms (except iOS as of 2022-04-20) we
// also intercept incoming netstack TCP requests to our peerapi port and hand them over
// directly to peerapi, without involving the kernel. So this doesn't need to be
// real. But the port number we return (1, in this case) is the port number we advertise
// to peers and they connect to. 1 seems pretty safe to use. Even if the kernel's
// using it, it doesn't matter, as we intercept it first in netstack and the kernel
// never notices.
//
// Eventually we'll remove this code and do this on all platforms, when iOS also uses
// netstack.
type fakePeerAPIListener struct {
addr net.Addr
closeOnce sync.Once
closed chan struct{}
}
func (fl *fakePeerAPIListener) Close() error {
fl.closeOnce.Do(func() { close(fl.closed) })
return nil
}
func (fl *fakePeerAPIListener) Accept() (net.Conn, error) {
<-fl.closed
return nil, net.ErrClosed
}
func (fl *fakePeerAPIListener) Addr() net.Addr { return fl.addr }
var (
metricInvalidRequests = clientmetric.NewCounter("peerapi_invalid_requests")
// Non-debug PeerAPI endpoints.
metricPutCalls = clientmetric.NewCounter("peerapi_put")
metricDNSCalls = clientmetric.NewCounter("peerapi_dns")
metricWakeOnLANCalls = clientmetric.NewCounter("peerapi_wol")
metricIngressCalls = clientmetric.NewCounter("peerapi_ingress")
)