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server.go
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server.go
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package server
import (
"archive/zip"
"bytes"
"compress/flate"
"io"
"io/fs"
"net/http"
"os"
"path"
"path/filepath"
"strings"
"time"
"github.com/kjk/common/httputil"
"github.com/kjk/common/u"
)
var (
must = u.Must
)
// Server represents all files known to the server
type Server struct {
Port int
Handlers []Handler
// if true supports clean urls i.e. /foo will match /foo.html URL
CleanURLS bool
// if true forces clean urls i.e. /foo.html will redirect to /foo
ForceCleanURLS bool
}
type HandlerFunc = func(w http.ResponseWriter, r *http.Request)
type GetHandlerFunc = func(string) func(w http.ResponseWriter, r *http.Request)
// Handler represents one or more urls and their content
type Handler interface {
// returns a handler for this url
// if nil, doesn't handle this url
Get(url string) HandlerFunc
// get all urls handled by this Handler
// useful for e.g. saving a static copy to disk
URLS() []string
}
func panicIfAbsoluteURL(uri string) {
u.PanicIf(strings.Contains(uri, "://"), "got absolute url '%s'", uri)
}
// FileWriter implements http.ResponseWriter interface for writing to a io.Writer
type FileWriter struct {
w io.Writer
header http.Header
}
func (w *FileWriter) Header() http.Header {
if w.header == nil {
w.header = http.Header{}
}
return w.header
}
func (w *FileWriter) Write(p []byte) (int, error) {
return w.w.Write(p)
}
func (w *FileWriter) WriteHeader(statusCode int) {
// no-op
}
// d can be nil, in which case no caching
func serve404FileCached(w http.ResponseWriter, r *http.Request, path string, cached *[]byte) {
var d []byte
if cached != nil && len(*cached) > 0 {
d = *cached
} else {
var err error
d, err = os.ReadFile(path)
must(err)
if cached != nil {
*cached = d
}
}
ctype := u.MimeTypeFromFileName(path)
if ctype != "" {
w.Header().Set("Content-Type", ctype)
}
w.Header().Set("X-Content-Type-Options", "nosniff")
w.WriteHeader(http.StatusNotFound)
w.Write(d)
}
func makeServeFile(path string, tryServeCompressed bool) func(w http.ResponseWriter, r *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
if strings.HasSuffix(path, "404.html") {
serve404FileCached(w, r, path, nil)
return
}
dir := filepath.Dir(path)
fsys := os.DirFS(dir)
name := filepath.Base(path)
opts := httputil.ServeFileOptions{
FS: fsys,
ServeCompressed: tryServeCompressed,
}
if !httputil.TryServeFileFromURL(w, r, name, &opts) {
http.ServeFile(w, r, path)
}
}
}
// uri is only used to guess content type
func serveContent(w http.ResponseWriter, r *http.Request, uri string, d []byte, code int, modTime time.Time) {
if r == nil {
_, err := w.Write(d)
must(err)
return
}
content := bytes.NewReader(d)
if code != http.StatusOK {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(code)
w.Write(d)
return
}
http.ServeContent(w, r, uri, modTime, content)
}
func MakeServeContent(uri string, d []byte, code int, modTime time.Time) func(w http.ResponseWriter, r *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
serveContent(w, r, uri, d, code, modTime)
}
}
type FilesHandler struct {
files map[string]string // maps url to a path on disk
TryServeCompressed bool
}
func (h *FilesHandler) AddFile(uri, path string) {
panicIfAbsoluteURL(uri)
u.PanicIf(!u.FileExists(path), "file '%s' doesn't exist", path)
h.files[uri] = path
}
func (h *FilesHandler) AddFilesInDir(dir string, uriPrefix string, files []string) {
for _, f := range files {
uri := uriPrefix + f
path := filepath.Join(dir, f)
h.AddFile(uri, path)
}
}
func (h *FilesHandler) Get(url string) func(w http.ResponseWriter, r *http.Request) {
for uri, path := range h.files {
// we consider URLs case-insensitive
if strings.EqualFold(uri, url) {
return makeServeFile(path, h.TryServeCompressed)
}
}
return nil
}
func (h *FilesHandler) URLS() []string {
urls := []string{}
for uri := range h.files {
urls = append(urls, uri)
}
return urls
}
// files is: uri1, path1, uri2, path2, ...
func NewFilesHandler(files ...string) *FilesHandler {
u.PanicIf(len(files)%2 == 1)
n := len(files)
h := &FilesHandler{
files: map[string]string{},
}
for i := 0; i < n; i += 2 {
h.AddFile(files[i], files[i+1])
}
return h
}
type DirHandler struct {
Dir string
URLPrefix string
TryServeCompressed bool
URL []string
paths []string // same order as URL
}
func (h *DirHandler) Get(url string) func(w http.ResponseWriter, r *http.Request) {
for i, u := range h.URL {
// urls are case-insensitive
if strings.EqualFold(u, url) {
return makeServeFile(h.paths[i], h.TryServeCompressed)
}
}
return nil
}
func (h *DirHandler) URLS() []string {
return h.URL
}
func getURLSForFiles(startDir string, urlPrefix string, acceptFile func(string) bool) (urls []string, paths []string) {
filepath.WalkDir(startDir, func(filePath string, d fs.DirEntry, err error) error {
if err != nil {
return nil
}
if !d.Type().IsRegular() {
return nil
}
if acceptFile != nil && !acceptFile(filePath) {
return nil
}
dir := strings.TrimPrefix(filePath, startDir)
dir = filepath.ToSlash(dir)
dir = strings.TrimPrefix(dir, "/")
uri := path.Join(urlPrefix, dir)
//logf(ctx(), "getURLSForFiles: dir: '%s'\n", dir)
urls = append(urls, uri)
paths = append(paths, filePath)
return nil
})
return
}
func NewDirHandler(dir string, urlPrefix string, acceptFile func(string) bool) *DirHandler {
urls, paths := getURLSForFiles(dir, urlPrefix, acceptFile)
return &DirHandler{
Dir: dir,
URLPrefix: urlPrefix,
URL: urls,
paths: paths,
}
}
type DynamicHandler struct {
get GetHandlerFunc
urls func() []string
}
func (h *DynamicHandler) Get(uri string) func(http.ResponseWriter, *http.Request) {
return h.get(uri)
}
func (h *DynamicHandler) URLS() []string {
return h.urls()
}
func NewDynamicHandler(get GetHandlerFunc, urls func() []string) *DynamicHandler {
return &DynamicHandler{
get: get,
urls: urls,
}
}
type InMemoryFilesHandler struct {
files map[string][]byte
modTime time.Time
}
func (h *InMemoryFilesHandler) Get(uri string) func(http.ResponseWriter, *http.Request) {
for path, d := range h.files {
if strings.EqualFold(path, uri) {
code := http.StatusOK
if strings.HasSuffix(uri, "/404.html") {
code = http.StatusNotFound
}
return MakeServeContent(uri, d, code, h.modTime)
}
}
return nil
}
func (h *InMemoryFilesHandler) URLS() []string {
var urls []string
for path := range h.files {
urls = append(urls, path)
}
return urls
}
func (h *InMemoryFilesHandler) Add(uri string, body []byte) {
panicIfAbsoluteURL(uri)
// in case uri is a windows path, convert to unix path
uri = strings.Replace(uri, "\\", "/", -1)
u.PanicIf(!strings.HasPrefix(uri, "/"))
h.files[uri] = body
}
func NewInMemoryFilesHandler(uri string, d []byte) *InMemoryFilesHandler {
h := &InMemoryFilesHandler{
files: map[string][]byte{},
modTime: time.Now(),
}
h.Add(uri, d)
return h
}
// IterContent calls a function for every url and (optionally) its content
func IterURLS(handlers []Handler, withContent bool, fn func(uri string, d []byte)) {
var buf bytes.Buffer
for _, h := range handlers {
urls := h.URLS()
for _, uri := range urls {
if !withContent {
fn(uri, nil)
continue
}
buf.Reset()
fw := &FileWriter{
w: &buf,
}
serve := h.Get(uri)
u.PanicIf(serve == nil, "must have a handler for '%s'", uri)
serve(fw, nil)
fn(uri, buf.Bytes())
}
}
}
// IterContent calls a function for every url and its content
func IterContent(handlers []Handler, fn func(uri string, d []byte)) {
IterURLS(handlers, true, fn)
}
func (s *Server) FindHandlerExact(uri string) HandlerFunc {
for _, h := range s.Handlers {
if send := h.Get(uri); send != nil {
return send
}
}
return nil
}
func commonExt(uri string) bool {
ext := strings.ToLower(filepath.Ext(uri))
switch ext {
case ".html", ".js", ".css", ".txt", ".xml":
return true
}
return false
}
const (
html404 = "/404.html"
)
func Gen404Candidates(uri string) []string {
idx := strings.LastIndex(uri, "/")
if idx == -1 || idx == 0 {
return []string{html404}
}
var res []string
rest := uri
for idx >= 0 {
last := rest[idx:]
if last != "/" && !commonExt(last) {
res = append(res, path.Join(rest, html404))
}
rest = rest[:idx]
idx = strings.LastIndex(rest, "/")
}
res = append(res, html404)
return res
}
func makePermRedirect(uri string) func(w http.ResponseWriter, r *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
httputil.SmartPermanentRedirect(w, r, uri)
}
}
func (s *Server) FindHandler(uri string) (h HandlerFunc, is404 bool) {
if strings.HasSuffix(uri, "/") {
uri = path.Join(uri, "/index.html")
}
if h = s.FindHandlerExact(uri); h != nil {
if s.ForceCleanURLS && u.ExtEqualFold(uri, ".html") {
uri = u.TrimExt(uri)
h = makePermRedirect(uri)
}
return h, false
}
// if we support clean urls, try find "/foo.html" for "/foo"
if (s.CleanURLS || s.ForceCleanURLS) && !commonExt(uri) {
if h = s.FindHandlerExact(uri + ".html"); h != nil {
return h, false
}
}
// try 404.html
a := Gen404Candidates(uri)
for _, uri404 := range a {
if h = s.FindHandlerExact(uri404); h != nil {
return h, true
}
}
return nil, false
}
// don't really use it
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
uri := r.URL.Path
serve, _ := s.FindHandler(uri)
if serve != nil {
serve(w, r)
return
}
http.NotFound(w, r)
}
func WriteServerFilesToDir(dir string, handlers []Handler, onWritten func(path string, d []byte)) error {
dirCreated := map[string]bool{}
var err error
writeFile := func(uri string, d []byte) {
if err != nil {
return
}
name := strings.TrimPrefix(uri, "/")
name = filepath.FromSlash(name)
path := filepath.Join(dir, name)
// optimize for writing lots of files
// I assume that even a no-op os.MkdirAll()
// might be somewhat expensive
fileDir := filepath.Dir(path)
if !dirCreated[fileDir] {
err = os.MkdirAll(fileDir, 0755)
if err != nil {
return
}
dirCreated[fileDir] = true
}
err = os.WriteFile(path, d, 0644)
}
IterContent(handlers, writeFile)
return err
}
func WriteServerFilesToZip(handlers []Handler, onWritten func(path string, d []byte)) ([]byte, error) {
var buf bytes.Buffer
zw := zip.NewWriter(&buf)
zw.RegisterCompressor(zip.Deflate, func(out io.Writer) (io.WriteCloser, error) {
return flate.NewWriter(out, flate.BestCompression)
})
zipWriteFile := func(zw *zip.Writer, name string, data []byte) error {
fw, err := zw.Create(name)
if err != nil {
return err
}
_, err = fw.Write(data)
return err
}
var err error
writeFile := func(uri string, d []byte) {
if err != nil {
return
}
name := strings.TrimPrefix(uri, "/")
err = zipWriteFile(zw, name, d)
if err != nil {
return
}
}
IterContent(handlers, writeFile)
return buf.Bytes(), err
}