tailscale/ipn/ipnlocal/c2n.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package ipnlocal
import (
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"os"
"os/exec"
"path/filepath"
"runtime"
"strconv"
"time"
"tailscale.com/envknob"
"tailscale.com/net/sockstats"
"tailscale.com/tailcfg"
"tailscale.com/util/clientmetric"
"tailscale.com/util/goroutines"
"tailscale.com/version"
"tailscale.com/version/distro"
)
func (b *LocalBackend) handleC2N(w http.ResponseWriter, r *http.Request) {
writeJSON := func(v any) {
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(v)
}
switch r.URL.Path {
case "/echo":
// Test handler.
body, _ := io.ReadAll(r.Body)
w.Write(body)
case "/update":
b.handleC2NUpdate(w, r)
case "/logtail/flush":
if r.Method != "POST" {
http.Error(w, "bad method", http.StatusMethodNotAllowed)
return
}
if b.TryFlushLogs() {
w.WriteHeader(http.StatusNoContent)
} else {
http.Error(w, "no log flusher wired up", http.StatusInternalServerError)
}
case "/debug/goroutines":
w.Header().Set("Content-Type", "text/plain")
w.Write(goroutines.ScrubbedGoroutineDump(true))
case "/debug/prefs":
writeJSON(b.Prefs())
case "/debug/metrics":
w.Header().Set("Content-Type", "text/plain")
clientmetric.WritePrometheusExpositionFormat(w)
case "/debug/component-logging":
component := r.FormValue("component")
secs, _ := strconv.Atoi(r.FormValue("secs"))
if secs == 0 {
secs -= 1
}
until := time.Now().Add(time.Duration(secs) * time.Second)
err := b.SetComponentDebugLogging(component, until)
var res struct {
Error string `json:",omitempty"`
}
if err != nil {
res.Error = err.Error()
}
writeJSON(res)
case "/ssh/usernames":
var req tailcfg.C2NSSHUsernamesRequest
if r.Method == "POST" {
if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
}
res, err := b.getSSHUsernames(&req)
if err != nil {
http.Error(w, err.Error(), 500)
return
}
writeJSON(res)
case "/sockstats":
if r.Method != "POST" {
http.Error(w, "bad method", http.StatusMethodNotAllowed)
return
}
w.Header().Set("Content-Type", "text/plain")
if b.sockstatLogger == nil {
http.Error(w, "no sockstatLogger", http.StatusInternalServerError)
return
}
b.sockstatLogger.Flush()
fmt.Fprintf(w, "logid: %s\n", b.sockstatLogger.LogID())
fmt.Fprintf(w, "debug info: %v\n", sockstats.DebugInfo())
default:
http.Error(w, "unknown c2n path", http.StatusBadRequest)
}
}
func (b *LocalBackend) handleC2NUpdate(w http.ResponseWriter, r *http.Request) {
// TODO(bradfitz): add some sort of semaphore that prevents two concurrent
// updates, or if one happened in the past 5 minutes, or something.
// TODO(bradfitz): move this type to some leaf package
type updateResponse struct {
Err string // error message, if any
Enabled bool // user has opted-in to remote updates
Supported bool // Tailscale supports updating this OS/platform
Started bool
}
var res updateResponse
res.Enabled = envknob.AllowsRemoteUpdate()
res.Supported = runtime.GOOS == "windows" || (runtime.GOOS == "linux" && distro.Get() == distro.Debian)
switch r.Method {
case "GET", "POST":
default:
http.Error(w, "bad method", http.StatusMethodNotAllowed)
return
}
defer func() {
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(res)
}()
if r.Method == "GET" {
return
}
if !res.Enabled {
res.Err = "not enabled"
return
}
if !res.Supported {
res.Err = "not supported"
return
}
cmdTS, err := findCmdTailscale()
if err != nil {
res.Err = fmt.Sprintf("failed to find cmd/tailscale binary: %v", err)
return
}
var ver struct {
Long string `json:"long"`
}
out, err := exec.Command(cmdTS, "version", "--json").Output()
if err != nil {
res.Err = fmt.Sprintf("failed to find cmd/tailscale binary: %v", err)
return
}
if err := json.Unmarshal(out, &ver); err != nil {
res.Err = "invalid JSON from cmd/tailscale version --json"
return
}
if ver.Long != version.Long() {
res.Err = "cmd/tailscale version mismatch"
return
}
cmd := exec.Command(cmdTS, "update", "--yes")
if err := cmd.Start(); err != nil {
res.Err = fmt.Sprintf("failed to start cmd/tailscale update: %v", err)
return
}
res.Started = true
// TODO(bradfitz,andrew): There might be a race condition here on Windows:
// * We start the update process.
// * tailscale.exe copies itself and kicks off the update process
// * msiexec stops this process during the update before the selfCopy exits(?)
// * This doesn't return because the process is dead.
//
// This seems fairly unlikely, but worth checking.
defer cmd.Wait()
return
}
// findCmdTailscale looks for the cmd/tailscale that corresponds to the
// currently running cmd/tailscaled. It's up to the caller to verify that the
// two match, but this function does its best to find the right one. Notably, it
// doesn't use $PATH for security reasons.
func findCmdTailscale() (string, error) {
self, err := os.Executable()
if err != nil {
return "", err
}
switch runtime.GOOS {
case "linux":
if self == "/usr/sbin/tailscaled" {
return "/usr/bin/tailscale", nil
}
return "", errors.New("tailscale not found in expected place")
case "windows":
dir := filepath.Dir(self)
ts := filepath.Join(dir, "tailscale.exe")
if fi, err := os.Stat(ts); err == nil && fi.Mode().IsRegular() {
return ts, nil
}
return "", errors.New("tailscale.exe not found in expected place")
}
return "", fmt.Errorf("unsupported OS %v", runtime.GOOS)
}