tailscale/cmd/tsconnect/serve.go

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// 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.
package main
import (
"bytes"
"embed"
"encoding/json"
"fmt"
"io"
"io/fs"
"io/ioutil"
"log"
"net/http"
"os"
"path"
"time"
"tailscale.com/tsweb"
)
//go:embed index.html
var embeddedFS embed.FS
//go:embed dist/*
var embeddedDistFS embed.FS
var serveStartTime = time.Now()
func runServe() {
mux := http.NewServeMux()
var distFS fs.FS
if *distDir == "./dist" {
var err error
distFS, err = fs.Sub(embeddedDistFS, "dist")
if err != nil {
log.Fatalf("Could not drop dist/ prefix from embedded FS: %v", err)
}
} else {
distFS = os.DirFS(*distDir)
}
indexBytes, err := generateServeIndex(distFS)
if err != nil {
log.Fatalf("Could not generate index.html: %v", err)
}
mux.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.ServeContent(w, r, "index.html", serveStartTime, bytes.NewReader(indexBytes))
}))
mux.Handle("/dist/", http.StripPrefix("/dist/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
handleServeDist(w, r, distFS)
})))
tsweb.Debugger(mux)
log.Printf("Listening on %s", *addr)
err = http.ListenAndServe(*addr, mux)
if err != nil {
log.Fatal(err)
}
}
func generateServeIndex(distFS fs.FS) ([]byte, error) {
log.Printf("Generating index.html...\n")
rawIndexBytes, err := embeddedFS.ReadFile("index.html")
if err != nil {
return nil, fmt.Errorf("Could not read index.html: %w", err)
}
esbuildMetadataFile, err := distFS.Open("esbuild-metadata.json")
if err != nil {
return nil, fmt.Errorf("Could not open esbuild-metadata.json: %w", err)
}
defer esbuildMetadataFile.Close()
esbuildMetadataBytes, err := ioutil.ReadAll(esbuildMetadataFile)
if err != nil {
return nil, fmt.Errorf("Could not read esbuild-metadata.json: %w", err)
}
var esbuildMetadata EsbuildMetadata
if err := json.Unmarshal(esbuildMetadataBytes, &esbuildMetadata); err != nil {
return nil, fmt.Errorf("Could not parse esbuild-metadata.json: %w", err)
}
entryPointsToHashedDistPaths := make(map[string]string)
for outputPath, output := range esbuildMetadata.Outputs {
if output.EntryPoint != "" {
entryPointsToHashedDistPaths[output.EntryPoint] = path.Join("dist", outputPath)
}
}
indexBytes := rawIndexBytes
for entryPointPath, defaultDistPath := range entryPointsToDefaultDistPaths {
hashedDistPath := entryPointsToHashedDistPaths[entryPointPath]
if hashedDistPath != "" {
indexBytes = bytes.ReplaceAll(indexBytes, []byte(defaultDistPath), []byte(hashedDistPath))
}
}
return indexBytes, nil
}
var entryPointsToDefaultDistPaths = map[string]string{
"src/index.css": "dist/index.css",
"src/index.js": "dist/index.js",
}
func handleServeDist(w http.ResponseWriter, r *http.Request, distFS fs.FS) {
path := r.URL.Path
var f fs.File
// Prefer pre-compressed versions generated during the build step.
if tsweb.AcceptsEncoding(r, "br") {
if brotliFile, err := distFS.Open(path + ".br"); err == nil {
f = brotliFile
w.Header().Set("Content-Encoding", "br")
}
}
if f == nil && tsweb.AcceptsEncoding(r, "gzip") {
if gzipFile, err := distFS.Open(path + ".gz"); err == nil {
f = gzipFile
w.Header().Set("Content-Encoding", "gzip")
}
}
if f == nil {
if rawFile, err := distFS.Open(path); err == nil {
f = rawFile
} else {
http.Error(w, err.Error(), http.StatusNotFound)
return
}
}
defer f.Close()
// fs.File does not claim to implement Seeker, but in practice it does.
fSeeker, ok := f.(io.ReadSeeker)
if !ok {
http.Error(w, "Not seekable", http.StatusInternalServerError)
return
}
// Aggressively cache static assets, since we cache-bust our assets with
// hashed filenames.
w.Header().Set("Cache-Control", "public, max-age=31535996")
w.Header().Set("Vary", "Accept-Encoding")
http.ServeContent(w, r, path, serveStartTime, fSeeker)
}