mox/http/webserver.go
Mechiel Lukkien f531a9bf35
don't serve static file when requested as dir, and fix 500 internal server errors when a file below such a file-as-dir is requested
e.g. when /index.html/ returned content. and /index.html/image.png would result
in 500 internal server errors. now they all return 404 not found.
2023-03-20 13:48:17 +01:00

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package http
import (
"errors"
"fmt"
htmltemplate "html/template"
"io"
golog "log"
"net/http"
"net/http/httputil"
"os"
"path/filepath"
"sort"
"strings"
"syscall"
"time"
"github.com/mjl-/mox/config"
"github.com/mjl-/mox/dns"
"github.com/mjl-/mox/mlog"
"github.com/mjl-/mox/mox-"
"github.com/mjl-/mox/moxio"
)
// WebHandle serves an HTTP request by going through the list of WebHandlers,
// check if there is a domain+path match, and running the handler if so.
// WebHandle runs after the built-in handlers for mta-sts, autoconfig, etc.
// If no handler matched, false is returned.
// WebHandle sets w.Name to that of the matching handler.
func WebHandle(w *loggingWriter, r *http.Request, host dns.Domain) (handled bool) {
redirects, handlers := mox.Conf.WebServer()
for from, to := range redirects {
if host != from {
continue
}
u := r.URL
u.Scheme = "https"
u.Host = to.Name()
w.Handler = "(domainredirect)"
http.Redirect(w, r, u.String(), http.StatusPermanentRedirect)
return true
}
for _, h := range handlers {
if host != h.DNSDomain {
continue
}
loc := h.Path.FindStringIndex(r.URL.Path)
if loc == nil {
continue
}
s := loc[0]
e := loc[1]
path := r.URL.Path[s:e]
if r.TLS == nil && !h.DontRedirectPlainHTTP {
u := *r.URL
u.Scheme = "https"
u.Host = h.DNSDomain.Name()
w.Handler = h.Name
http.Redirect(w, r, u.String(), http.StatusPermanentRedirect)
return true
}
if h.WebStatic != nil && HandleStatic(h.WebStatic, w, r) {
w.Handler = h.Name
return true
}
if h.WebRedirect != nil && HandleRedirect(h.WebRedirect, w, r) {
w.Handler = h.Name
return true
}
if h.WebForward != nil && HandleForward(h.WebForward, w, r, path) {
w.Handler = h.Name
return true
}
}
return false
}
var lsTemplate = htmltemplate.Must(htmltemplate.New("ls").Parse(`<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>ls</title>
<style>
body, html { padding: 1em; font-size: 16px; }
* { font-size: inherit; font-family: ubuntu, lato, sans-serif; margin: 0; padding: 0; box-sizing: border-box; }
h1 { margin-bottom: 1ex; font-size: 1.2rem; }
table td, table th { padding: .2em .5em; }
table > tbody > tr:nth-child(odd) { background-color: #f8f8f8; }
[title] { text-decoration: underline; text-decoration-style: dotted; }
</style>
</head>
<body>
<h1>ls</h1>
<table>
<thead>
<tr>
<th>Size in MB</th>
<th>Modified (UTC)</th>
<th>Name</th>
</tr>
</thead>
<tbody>
{{ if not .Files }}
<tr><td colspan="3">No files.</td></tr>
{{ end }}
{{ range .Files }}
<tr>
<td title="{{ .Size }} bytes" style="text-align: right">{{ .SizeReadable }}{{ if .SizePad }}<span style="visibility:hidden">.</span>{{ end }}</td>
<td>{{ .Modified }}</td>
<td><a style="display: block" href="{{ .Name }}">{{ .Name }}</a></td>
</tr>
{{ end }}
</tbody>
</table>
</body>
</html>
`))
// HandleStatic serves static files. If a directory is requested and the URL
// path doesn't end with a slash, a response with a redirect to the URL path with trailing
// slash is written. If a directory is requested and an index.html exists, that
// file is returned. Otherwise, for directories with ListFiles configured, a
// directory listing is returned.
func HandleStatic(h *config.WebStatic, w http.ResponseWriter, r *http.Request) (handled bool) {
log := func() *mlog.Log {
return xlog.WithContext(r.Context())
}
recvid := func() string {
cid := mox.CidFromCtx(r.Context())
if cid <= 0 {
return ""
}
return " (id " + mox.ReceivedID(cid) + ")"
}
if r.Method != "GET" && r.Method != "HEAD" {
if h.ContinueNotFound {
// Give another handler that is presumbly configured, for the same path, a chance.
// E.g. an app that may generate this file for future requests to pick up.
return false
}
http.Error(w, "405 - method not allowed", http.StatusMethodNotAllowed)
return true
}
var fspath string
if h.StripPrefix != "" {
if !strings.HasPrefix(r.URL.Path, h.StripPrefix) {
if h.ContinueNotFound {
// We haven't handled this request, try a next WebHandler in the list.
return false
}
http.NotFound(w, r)
return true
}
fspath = filepath.Join(h.Root, strings.TrimPrefix(r.URL.Path, h.StripPrefix))
} else {
fspath = filepath.Join(h.Root, r.URL.Path)
}
// fspath will not have a trailing slash anymore, we'll correct for it
// later when the path turns out to be file instead of a directory.
serveFile := func(name string, mtime time.Time, content *os.File) {
// ServeContent only sets a content-type if not already present in the response headers.
hdr := w.Header()
for k, v := range h.ResponseHeaders {
hdr.Add(k, v)
}
http.ServeContent(w, r, name, mtime, content)
}
f, err := os.Open(fspath)
if err != nil {
if os.IsNotExist(err) || errors.Is(err, syscall.ENOTDIR) {
if h.ContinueNotFound {
// We haven't handled this request, try a next WebHandler in the list.
return false
}
http.NotFound(w, r)
return true
} else if os.IsPermission(err) {
// If we tried opening a directory, we may not have permission to read it, but
// still access files inside it (execute bit), such as index.html. So try to serve it.
index, err := os.Open(filepath.Join(fspath, "index.html"))
if err == nil {
defer index.Close()
var ifi os.FileInfo
ifi, err = index.Stat()
if err != nil {
log().Errorx("stat index.html in directory we cannot list", err, mlog.Field("url", r.URL), mlog.Field("fspath", fspath))
http.Error(w, "500 - internal server error"+recvid(), http.StatusInternalServerError)
return true
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
serveFile("index.html", ifi.ModTime(), index)
return true
}
http.Error(w, "403 - permission denied", http.StatusForbidden)
return true
}
log().Errorx("open file for static file serving", err, mlog.Field("url", r.URL), mlog.Field("fspath", fspath))
http.Error(w, "500 - internal server error"+recvid(), http.StatusInternalServerError)
return true
}
defer f.Close()
fi, err := f.Stat()
if err != nil {
log().Errorx("stat file for static file serving", err, mlog.Field("url", r.URL), mlog.Field("fspath", fspath))
http.Error(w, "500 - internal server error"+recvid(), http.StatusInternalServerError)
return true
}
// Redirect if the local path is a directory.
if fi.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
http.Redirect(w, r, r.URL.Path+"/", http.StatusTemporaryRedirect)
return true
} else if !fi.IsDir() && strings.HasSuffix(r.URL.Path, "/") {
if h.ContinueNotFound {
return false
}
http.NotFound(w, r)
return true
}
if fi.IsDir() {
index, err := os.Open(filepath.Join(fspath, "index.html"))
if err != nil && os.IsPermission(err) {
http.Error(w, "403 - permission denied", http.StatusForbidden)
return true
} else if err != nil && os.IsNotExist(err) && !h.ListFiles {
if h.ContinueNotFound {
return false
}
http.Error(w, "403 - permission denied", http.StatusForbidden)
return true
} else if err == nil {
defer index.Close()
var ifi os.FileInfo
ifi, err = index.Stat()
if err == nil {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
serveFile("index.html", ifi.ModTime(), index)
return true
}
}
if !os.IsNotExist(err) {
log().Errorx("stat for static file serving", err, mlog.Field("url", r.URL), mlog.Field("fspath", fspath))
http.Error(w, "500 - internal server error"+recvid(), http.StatusInternalServerError)
return true
}
type File struct {
Name string
Size int64
SizeReadable string
SizePad bool // Whether the size needs padding because it has no decimal point.
Modified string
}
files := []File{}
if r.URL.Path != "/" {
files = append(files, File{"..", 0, "", false, ""})
}
for {
l, err := f.Readdir(1000)
for _, e := range l {
mb := float64(e.Size()) / (1024 * 1024)
var size string
var sizepad bool
if !e.IsDir() {
if mb >= 10 {
size = fmt.Sprintf("%d", int64(mb))
sizepad = true
} else {
size = fmt.Sprintf("%.2f", mb)
}
}
const dateTime = "2006-01-02 15:04:05" // time.DateTime, but only since go1.20.
modified := e.ModTime().UTC().Format(dateTime)
f := File{e.Name(), e.Size(), size, sizepad, modified}
if e.IsDir() {
f.Name += "/"
}
files = append(files, f)
}
if err == io.EOF {
break
} else if err != nil {
log().Errorx("reading directory for file listing", err, mlog.Field("url", r.URL), mlog.Field("fspath", fspath))
http.Error(w, "500 - internal server error"+recvid(), http.StatusInternalServerError)
return true
}
}
sort.Slice(files, func(i, j int) bool {
return files[i].Name < files[j].Name
})
hdr := w.Header()
hdr.Set("Content-Type", "text/html; charset=utf-8")
for k, v := range h.ResponseHeaders {
if !strings.EqualFold(k, "content-type") {
hdr.Add(k, v)
}
}
err = lsTemplate.Execute(w, map[string]any{"Files": files})
if err != nil && !moxio.IsClosed(err) {
log().Errorx("executing directory listing template", err)
}
return true
}
serveFile(fspath, fi.ModTime(), f)
return true
}
// HandleRedirect writes a response with an HTTP redirect.
func HandleRedirect(h *config.WebRedirect, w http.ResponseWriter, r *http.Request) (handled bool) {
var dstpath string
if h.OrigPath == nil {
// No path rewrite necessary.
dstpath = r.URL.Path
} else if !h.OrigPath.MatchString(r.URL.Path) {
http.NotFound(w, r)
return true
} else {
dstpath = h.OrigPath.ReplaceAllString(r.URL.Path, h.ReplacePath)
}
u := *r.URL
u.Opaque = ""
u.RawPath = ""
u.OmitHost = false
if h.URL != nil {
u.Scheme = h.URL.Scheme
u.Host = h.URL.Host
u.ForceQuery = h.URL.ForceQuery
u.RawQuery = h.URL.RawQuery
u.Fragment = h.URL.Fragment
if r.URL.RawQuery != "" {
if u.RawQuery != "" {
u.RawQuery += "&"
}
u.RawQuery += r.URL.RawQuery
}
}
u.Path = dstpath
code := http.StatusPermanentRedirect
if h.StatusCode != 0 {
code = h.StatusCode
}
// If we would be redirecting to the same scheme,host,path, we would get here again
// causing a redirect loop. Instead, this causes this redirect to not match,
// allowing to try the next WebHandler. This can be used to redirect all plain http
// requests to https.
reqscheme := "http"
if r.TLS != nil {
reqscheme = "https"
}
if reqscheme == u.Scheme && r.Host == u.Host && r.URL.Path == u.Path {
return false
}
http.Redirect(w, r, u.String(), code)
return true
}
// HandleForward handles a request by forwarding it to another webserver and
// passing the response on. I.e. a reverse proxy.
func HandleForward(h *config.WebForward, w http.ResponseWriter, r *http.Request, path string) (handled bool) {
log := func() *mlog.Log {
return xlog.WithContext(r.Context())
}
recvid := func() string {
cid := mox.CidFromCtx(r.Context())
if cid <= 0 {
return ""
}
return " (id " + mox.ReceivedID(cid) + ")"
}
xr := *r
r = &xr
if h.StripPath {
u := *r.URL
u.Path = r.URL.Path[len(path):]
u.RawPath = ""
r.URL = &u
}
// Remove any forwarded headers passed in by client.
hdr := http.Header{}
for k, vl := range r.Header {
if k == "Forwarded" || k == "X-Forwarded" || strings.HasPrefix(k, "X-Forwarded-") {
continue
}
hdr[k] = vl
}
r.Header = hdr
// Add our own X-Forwarded headers. ReverseProxy will add X-Forwarded-For.
r.Header["X-Forwarded-Host"] = []string{r.Host}
proto := "http"
if r.TLS != nil {
proto = "https"
}
r.Header["X-Forwarded-Proto"] = []string{proto}
// todo: add Forwarded header? is anyone using it?
// ReverseProxy will append any remaining path to the configured target URL.
proxy := httputil.NewSingleHostReverseProxy(h.TargetURL)
proxy.FlushInterval = time.Duration(-1) // Flush after each write.
proxy.ErrorLog = golog.New(mlog.ErrWriter(mlog.New("net/http/httputil").WithContext(r.Context()), mlog.LevelDebug, "reverseproxy error"), "", 0)
proxy.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
log().Errorx("forwarding request to backend webserver", err, mlog.Field("url", r.URL))
if os.IsTimeout(err) {
http.Error(w, "504 - gateway timeout"+recvid(), http.StatusGatewayTimeout)
} else {
http.Error(w, "502 - bad gateway"+recvid(), http.StatusBadGateway)
}
}
whdr := w.Header()
for k, v := range h.ResponseHeaders {
whdr.Add(k, v)
}
proxy.ServeHTTP(w, r)
return true
}