mirror of
https://github.com/mjl-/mox.git
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832 lines
27 KiB
Go
832 lines
27 KiB
Go
package http
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import (
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"bufio"
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"bytes"
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"context"
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"crypto/sha1"
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"crypto/tls"
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"encoding/base64"
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"errors"
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"fmt"
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htmltemplate "html/template"
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"io"
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"io/fs"
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golog "log"
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"log/slog"
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"net"
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"net/http"
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"net/http/httputil"
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"net/textproto"
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"net/url"
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"os"
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"path/filepath"
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"sort"
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"strings"
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"syscall"
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"time"
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"github.com/mjl-/mox/config"
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"github.com/mjl-/mox/dns"
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"github.com/mjl-/mox/mlog"
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"github.com/mjl-/mox/mox-"
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"github.com/mjl-/mox/moxio"
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)
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func recvid(r *http.Request) string {
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cid := mox.CidFromCtx(r.Context())
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if cid <= 0 {
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return ""
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}
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return " (id " + mox.ReceivedID(cid) + ")"
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}
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// WebHandle serves an HTTP request by going through the list of WebHandlers,
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// check if there is a domain+path match, and running the handler if so.
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// WebHandle runs after the built-in handlers for mta-sts, autoconfig, etc.
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// If no handler matched, false is returned.
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// WebHandle sets w.Name to that of the matching handler.
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func WebHandle(w *loggingWriter, r *http.Request, host dns.Domain) (handled bool) {
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redirects, handlers := mox.Conf.WebServer()
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for from, to := range redirects {
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if host != from {
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continue
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}
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u := r.URL
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u.Scheme = "https"
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u.Host = to.Name()
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w.Handler = "(domainredirect)"
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http.Redirect(w, r, u.String(), http.StatusPermanentRedirect)
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return true
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}
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for _, h := range handlers {
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if host != h.DNSDomain {
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continue
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}
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loc := h.Path.FindStringIndex(r.URL.Path)
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if loc == nil {
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continue
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}
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s := loc[0]
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e := loc[1]
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path := r.URL.Path[s:e]
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if r.TLS == nil && !h.DontRedirectPlainHTTP {
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u := *r.URL
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u.Scheme = "https"
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u.Host = h.DNSDomain.Name()
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w.Handler = h.Name
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w.Compress = h.Compress
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http.Redirect(w, r, u.String(), http.StatusPermanentRedirect)
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return true
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}
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// We don't want the loggingWriter to override the static handler's decisions to compress.
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w.Compress = h.Compress
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if h.WebStatic != nil && HandleStatic(h.WebStatic, h.Compress, w, r) {
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w.Handler = h.Name
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return true
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}
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if h.WebRedirect != nil && HandleRedirect(h.WebRedirect, w, r) {
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w.Handler = h.Name
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return true
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}
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if h.WebForward != nil && HandleForward(h.WebForward, w, r, path) {
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w.Handler = h.Name
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return true
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}
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}
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w.Compress = false
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return false
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}
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var lsTemplate = htmltemplate.Must(htmltemplate.New("ls").Parse(`<!doctype html>
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<html>
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<head>
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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<title>ls</title>
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<style>
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body, html { padding: 1em; font-size: 16px; }
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* { font-size: inherit; font-family: ubuntu, lato, sans-serif; margin: 0; padding: 0; box-sizing: border-box; }
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h1 { margin-bottom: 1ex; font-size: 1.2rem; }
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table td, table th { padding: .2em .5em; }
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table > tbody > tr:nth-child(odd) { background-color: #f8f8f8; }
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[title] { text-decoration: underline; text-decoration-style: dotted; }
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</style>
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</head>
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<body>
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<h1>ls</h1>
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<table>
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<thead>
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<tr>
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<th>Size in MB</th>
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<th>Modified (UTC)</th>
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<th>Name</th>
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</tr>
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</thead>
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<tbody>
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{{ if not .Files }}
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<tr><td colspan="3">No files.</td></tr>
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{{ end }}
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{{ range .Files }}
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<tr>
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<td title="{{ .Size }} bytes" style="text-align: right">{{ .SizeReadable }}{{ if .SizePad }}<span style="visibility:hidden">. </span>{{ end }}</td>
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<td>{{ .Modified }}</td>
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<td><a style="display: block" href="{{ .Name }}">{{ .Name }}</a></td>
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</tr>
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{{ end }}
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</tbody>
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</table>
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</body>
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</html>
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`))
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// HandleStatic serves static files. If a directory is requested and the URL
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// path doesn't end with a slash, a response with a redirect to the URL path with trailing
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// slash is written. If a directory is requested and an index.html exists, that
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// file is returned. Otherwise, for directories with ListFiles configured, a
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// directory listing is returned.
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func HandleStatic(h *config.WebStatic, compress bool, w http.ResponseWriter, r *http.Request) (handled bool) {
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log := func() mlog.Log {
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return pkglog.WithContext(r.Context())
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}
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if r.Method != "GET" && r.Method != "HEAD" {
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if h.ContinueNotFound {
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// Give another handler that is presumbly configured, for the same path, a chance.
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// E.g. an app that may generate this file for future requests to pick up.
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return false
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}
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http.Error(w, "405 - method not allowed", http.StatusMethodNotAllowed)
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return true
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}
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var fspath string
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if h.StripPrefix != "" {
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if !strings.HasPrefix(r.URL.Path, h.StripPrefix) {
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if h.ContinueNotFound {
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// We haven't handled this request, try a next WebHandler in the list.
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return false
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}
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http.NotFound(w, r)
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return true
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}
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fspath = filepath.Join(h.Root, strings.TrimPrefix(r.URL.Path, h.StripPrefix))
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} else {
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fspath = filepath.Join(h.Root, r.URL.Path)
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}
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// fspath will not have a trailing slash anymore, we'll correct for it
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// later when the path turns out to be file instead of a directory.
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serveFile := func(name string, fi fs.FileInfo, content *os.File) {
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// ServeContent only sets a content-type if not already present in the response headers.
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hdr := w.Header()
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for k, v := range h.ResponseHeaders {
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hdr.Add(k, v)
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}
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// We transparently compress here, but still use ServeContent, because it handles
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// conditional requests, range requests. It's a bit of a hack, but on first write
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// to staticgzcacheReplacer where we are compressing, we write the full compressed
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// file instead, and return an error to ServeContent so it stops. We still have all
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// the useful behaviour (status code and headers) from ServeContent.
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xw := w
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if compress && acceptsGzip(r) && compressibleContent(content) {
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xw = &staticgzcacheReplacer{w, r, content.Name(), content, fi.ModTime(), fi.Size(), 0, false}
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} else {
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w.(*loggingWriter).Compress = false
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}
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http.ServeContent(xw, r, name, fi.ModTime(), content)
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}
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f, err := os.Open(fspath)
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if err != nil {
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if os.IsNotExist(err) || errors.Is(err, syscall.ENOTDIR) {
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if h.ContinueNotFound {
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// We haven't handled this request, try a next WebHandler in the list.
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return false
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}
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http.NotFound(w, r)
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return true
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} else if os.IsPermission(err) {
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// If we tried opening a directory, we may not have permission to read it, but
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// still access files inside it (execute bit), such as index.html. So try to serve it.
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index, err := os.Open(filepath.Join(fspath, "index.html"))
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if err == nil {
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defer index.Close()
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var ifi os.FileInfo
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ifi, err = index.Stat()
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if err != nil {
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log().Errorx("stat index.html in directory we cannot list", err, slog.Any("url", r.URL), slog.String("fspath", fspath))
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http.Error(w, "500 - internal server error"+recvid(r), http.StatusInternalServerError)
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return true
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}
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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serveFile("index.html", ifi, index)
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return true
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}
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http.Error(w, "403 - permission denied", http.StatusForbidden)
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return true
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}
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log().Errorx("open file for static file serving", err, slog.Any("url", r.URL), slog.String("fspath", fspath))
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http.Error(w, "500 - internal server error"+recvid(r), http.StatusInternalServerError)
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return true
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}
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defer f.Close()
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fi, err := f.Stat()
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if err != nil {
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log().Errorx("stat file for static file serving", err, slog.Any("url", r.URL), slog.String("fspath", fspath))
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http.Error(w, "500 - internal server error"+recvid(r), http.StatusInternalServerError)
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return true
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}
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// Redirect if the local path is a directory.
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if fi.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
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http.Redirect(w, r, r.URL.Path+"/", http.StatusTemporaryRedirect)
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return true
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} else if !fi.IsDir() && strings.HasSuffix(r.URL.Path, "/") {
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if h.ContinueNotFound {
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return false
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}
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http.NotFound(w, r)
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return true
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}
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if fi.IsDir() {
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index, err := os.Open(filepath.Join(fspath, "index.html"))
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if err != nil && os.IsPermission(err) {
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http.Error(w, "403 - permission denied", http.StatusForbidden)
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return true
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} else if err != nil && os.IsNotExist(err) && !h.ListFiles {
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if h.ContinueNotFound {
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return false
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}
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http.Error(w, "403 - permission denied", http.StatusForbidden)
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return true
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} else if err == nil {
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defer index.Close()
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var ifi os.FileInfo
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ifi, err = index.Stat()
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if err == nil {
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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serveFile("index.html", ifi, index)
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return true
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}
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}
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if !os.IsNotExist(err) {
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log().Errorx("stat for static file serving", err, slog.Any("url", r.URL), slog.String("fspath", fspath))
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http.Error(w, "500 - internal server error"+recvid(r), http.StatusInternalServerError)
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return true
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}
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type File struct {
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Name string
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Size int64
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SizeReadable string
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SizePad bool // Whether the size needs padding because it has no decimal point.
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Modified string
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}
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files := []File{}
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if r.URL.Path != "/" {
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files = append(files, File{"..", 0, "", false, ""})
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}
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for {
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l, err := f.Readdir(1000)
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for _, e := range l {
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mb := float64(e.Size()) / (1024 * 1024)
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var size string
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var sizepad bool
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if !e.IsDir() {
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if mb >= 10 {
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size = fmt.Sprintf("%d", int64(mb))
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sizepad = true
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} else {
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size = fmt.Sprintf("%.2f", mb)
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}
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}
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const dateTime = "2006-01-02 15:04:05" // time.DateTime, but only since go1.20.
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modified := e.ModTime().UTC().Format(dateTime)
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f := File{e.Name(), e.Size(), size, sizepad, modified}
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if e.IsDir() {
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f.Name += "/"
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}
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files = append(files, f)
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}
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if err == io.EOF {
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break
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} else if err != nil {
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log().Errorx("reading directory for file listing", err, slog.Any("url", r.URL), slog.String("fspath", fspath))
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http.Error(w, "500 - internal server error"+recvid(r), http.StatusInternalServerError)
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return true
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}
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}
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sort.Slice(files, func(i, j int) bool {
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return files[i].Name < files[j].Name
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})
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hdr := w.Header()
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hdr.Set("Content-Type", "text/html; charset=utf-8")
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for k, v := range h.ResponseHeaders {
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if !strings.EqualFold(k, "content-type") {
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hdr.Add(k, v)
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}
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}
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err = lsTemplate.Execute(w, map[string]any{"Files": files})
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if err != nil && !moxio.IsClosed(err) {
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log().Errorx("executing directory listing template", err)
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}
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return true
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}
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serveFile(fspath, fi, f)
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return true
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}
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// HandleRedirect writes a response with an HTTP redirect.
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func HandleRedirect(h *config.WebRedirect, w http.ResponseWriter, r *http.Request) (handled bool) {
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var dstpath string
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if h.OrigPath == nil {
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// No path rewrite necessary.
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dstpath = r.URL.Path
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} else if !h.OrigPath.MatchString(r.URL.Path) {
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http.NotFound(w, r)
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return true
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} else {
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dstpath = h.OrigPath.ReplaceAllString(r.URL.Path, h.ReplacePath)
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}
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u := *r.URL
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u.Opaque = ""
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u.RawPath = ""
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u.OmitHost = false
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if h.URL != nil {
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u.Scheme = h.URL.Scheme
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u.Host = h.URL.Host
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u.ForceQuery = h.URL.ForceQuery
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u.RawQuery = h.URL.RawQuery
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u.Fragment = h.URL.Fragment
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if r.URL.RawQuery != "" {
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if u.RawQuery != "" {
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u.RawQuery += "&"
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}
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u.RawQuery += r.URL.RawQuery
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}
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}
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u.Path = dstpath
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code := http.StatusPermanentRedirect
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if h.StatusCode != 0 {
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code = h.StatusCode
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}
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// If we would be redirecting to the same scheme,host,path, we would get here again
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// causing a redirect loop. Instead, this causes this redirect to not match,
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// allowing to try the next WebHandler. This can be used to redirect all plain http
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// requests to https.
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reqscheme := "http"
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if r.TLS != nil {
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reqscheme = "https"
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}
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if reqscheme == u.Scheme && r.Host == u.Host && r.URL.Path == u.Path {
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return false
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}
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http.Redirect(w, r, u.String(), code)
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return true
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}
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// HandleForward handles a request by forwarding it to another webserver and
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// passing the response on. I.e. a reverse proxy. It handles websocket
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// connections by monitoring the websocket handshake and then just passing along the
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// websocket frames.
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func HandleForward(h *config.WebForward, w http.ResponseWriter, r *http.Request, path string) (handled bool) {
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log := func() mlog.Log {
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return pkglog.WithContext(r.Context())
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}
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xr := *r
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r = &xr
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if h.StripPath {
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u := *r.URL
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u.Path = r.URL.Path[len(path):]
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if !strings.HasPrefix(u.Path, "/") {
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u.Path = "/" + u.Path
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}
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u.RawPath = ""
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r.URL = &u
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}
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// Remove any forwarded headers passed in by client.
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hdr := http.Header{}
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for k, vl := range r.Header {
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if k == "Forwarded" || k == "X-Forwarded" || strings.HasPrefix(k, "X-Forwarded-") {
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continue
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}
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hdr[k] = vl
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}
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r.Header = hdr
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// Add our own X-Forwarded headers. ReverseProxy will add X-Forwarded-For.
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r.Header["X-Forwarded-Host"] = []string{r.Host}
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proto := "http"
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if r.TLS != nil {
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proto = "https"
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}
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r.Header["X-Forwarded-Proto"] = []string{proto}
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// note: We are not using "ws" or "wss" for websocket. The request we are
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// forwarding is http(s), and we don't yet know if the backend even supports
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// websockets.
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// todo: add Forwarded header? is anyone using it?
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// If we see an Upgrade: websocket, we're going to assume the client needs
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// websocket and only attempt to talk websocket with the backend. If the backend
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// doesn't do websocket, we'll send back a "bad request" response. For other values
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// of Upgrade, we don't do anything special.
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// https://www.iana.org/assignments/http-upgrade-tokens/http-upgrade-tokens.xhtml
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// Upgrade: ../rfc/9110:2798
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// Upgrade headers are not for http/1.0, ../rfc/9110:2880
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// Websocket client "handshake" is described at ../rfc/6455:1134
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upgrade := r.Header.Get("Upgrade")
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if upgrade != "" && !(r.ProtoMajor == 1 && r.ProtoMinor == 0) {
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// Websockets have case-insensitive string "websocket".
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for _, s := range strings.Split(upgrade, ",") {
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if strings.EqualFold(textproto.TrimString(s), "websocket") {
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forwardWebsocket(h, w, r, path)
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return true
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}
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}
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}
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// ReverseProxy will append any remaining path to the configured target URL.
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proxy := httputil.NewSingleHostReverseProxy(h.TargetURL)
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proxy.FlushInterval = time.Duration(-1) // Flush after each write.
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proxy.ErrorLog = golog.New(mlog.LogWriter(mlog.New("net/http/httputil", nil).WithContext(r.Context()), mlog.LevelDebug, "reverseproxy error"), "", 0)
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proxy.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
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if errors.Is(err, context.Canceled) {
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log().Debugx("forwarding request to backend webserver", err, slog.Any("url", r.URL))
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return
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}
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log().Errorx("forwarding request to backend webserver", err, slog.Any("url", r.URL))
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if os.IsTimeout(err) {
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http.Error(w, "504 - gateway timeout"+recvid(r), http.StatusGatewayTimeout)
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} else {
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http.Error(w, "502 - bad gateway"+recvid(r), http.StatusBadGateway)
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}
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}
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whdr := w.Header()
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for k, v := range h.ResponseHeaders {
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whdr.Add(k, v)
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}
|
||
proxy.ServeHTTP(w, r)
|
||
return true
|
||
}
|
||
|
||
var errResponseNotWebsocket = errors.New("not a valid websocket response to request")
|
||
var errNotImplemented = errors.New("functionality not yet implemented")
|
||
|
||
// Request has an Upgrade: websocket header. Check more websocketiness about the
|
||
// request. If it looks good, we forward it to the backend. If the backend responds
|
||
// with a valid websocket response, indicating it is indeed a websocket server, we
|
||
// pass the response along and start copying data between the client and the
|
||
// backend. We don't look at the frames and payloads. The backend already needs to
|
||
// know enough websocket to handle the frames. It wouldn't necessarily hurt to
|
||
// monitor the frames too, and check if they are valid, but it's quite a bit of
|
||
// work for little benefit. Besides, the whole point of websockets is to exchange
|
||
// bytes without HTTP being in the way, so let's do that.
|
||
func forwardWebsocket(h *config.WebForward, w http.ResponseWriter, r *http.Request, path string) (handled bool) {
|
||
log := func() mlog.Log {
|
||
return pkglog.WithContext(r.Context())
|
||
}
|
||
|
||
lw := w.(*loggingWriter)
|
||
lw.WebsocketRequest = true // For correct protocol in metrics.
|
||
|
||
// We check the requested websocket version first. A future websocket version may
|
||
// have different request requirements.
|
||
// ../rfc/6455:1160
|
||
wsversion := r.Header.Get("Sec-WebSocket-Version")
|
||
if wsversion != "13" {
|
||
// Indicate we only support version 13. Should get a client from the future to fall back to version 13.
|
||
// ../rfc/6455:1435
|
||
w.Header().Set("Sec-WebSocket-Version", "13")
|
||
http.Error(w, "400 - bad request - websockets only supported with version 13"+recvid(r), http.StatusBadRequest)
|
||
lw.error(fmt.Errorf("Sec-WebSocket-Version %q not supported", wsversion))
|
||
return true
|
||
}
|
||
|
||
// ../rfc/6455:1143
|
||
if r.Method != "GET" {
|
||
http.Error(w, "400 - bad request - websockets only allowed with method GET"+recvid(r), http.StatusBadRequest)
|
||
lw.error(fmt.Errorf("websocket request only allowed with method GET"))
|
||
return true
|
||
}
|
||
|
||
// ../rfc/6455:1153
|
||
var connectionUpgrade bool
|
||
for _, s := range strings.Split(r.Header.Get("Connection"), ",") {
|
||
if strings.EqualFold(textproto.TrimString(s), "upgrade") {
|
||
connectionUpgrade = true
|
||
break
|
||
}
|
||
}
|
||
if !connectionUpgrade {
|
||
http.Error(w, "400 - bad request - connection header must be \"upgrade\""+recvid(r), http.StatusBadRequest)
|
||
lw.error(fmt.Errorf(`connection header is %q, must be "upgrade"`, r.Header.Get("Connection")))
|
||
return true
|
||
}
|
||
|
||
// ../rfc/6455:1156
|
||
wskey := r.Header.Get("Sec-WebSocket-Key")
|
||
key, err := base64.StdEncoding.DecodeString(wskey)
|
||
if err != nil || len(key) != 16 {
|
||
http.Error(w, "400 - bad request - websockets requires Sec-WebSocket-Key with 16 bytes base64-encoded value"+recvid(r), http.StatusBadRequest)
|
||
lw.error(fmt.Errorf("bad Sec-WebSocket-Key %q, must be 16 byte base64-encoded value", wskey))
|
||
return true
|
||
}
|
||
|
||
// ../rfc/6455:1162
|
||
// We don't look at the origin header. The backend needs to handle it, if it thinks
|
||
// that helps...
|
||
// We also don't look at Sec-WebSocket-Protocol and Sec-WebSocket-Extensions. The
|
||
// backend can set them, but it doesn't influence our forwarding of the data.
|
||
|
||
// If this is not a hijacker, there is not point in connecting to the backend.
|
||
hj, ok := lw.W.(http.Hijacker)
|
||
var cbr *bufio.ReadWriter
|
||
if !ok {
|
||
log().Info("cannot turn http connection into tcp connection (http.Hijacker)")
|
||
http.Error(w, "501 - not implemented - cannot turn this connection into websocket"+recvid(r), http.StatusNotImplemented)
|
||
lw.error(fmt.Errorf("connection not a http.Hijacker (%T)", lw.W))
|
||
return
|
||
}
|
||
|
||
freq := *r
|
||
freq.Proto = "HTTP/1.1"
|
||
freq.ProtoMajor = 1
|
||
freq.ProtoMinor = 1
|
||
fresp, beconn, err := websocketTransact(r.Context(), h.TargetURL, &freq)
|
||
if err != nil {
|
||
if errors.Is(err, errResponseNotWebsocket) {
|
||
http.Error(w, "400 - bad request - websocket not supported"+recvid(r), http.StatusBadRequest)
|
||
} else if errors.Is(err, errNotImplemented) {
|
||
http.Error(w, "501 - not implemented - "+err.Error()+recvid(r), http.StatusNotImplemented)
|
||
} else if os.IsTimeout(err) {
|
||
http.Error(w, "504 - gateway timeout"+recvid(r), http.StatusGatewayTimeout)
|
||
} else {
|
||
http.Error(w, "502 - bad gateway"+recvid(r), http.StatusBadGateway)
|
||
}
|
||
lw.error(err)
|
||
return
|
||
}
|
||
defer func() {
|
||
if beconn != nil {
|
||
beconn.Close()
|
||
}
|
||
}()
|
||
|
||
// Hijack the client connection so we can write the response ourselves, and start
|
||
// copying the websocket frames.
|
||
var cconn net.Conn
|
||
cconn, cbr, err = hj.Hijack()
|
||
if err != nil {
|
||
log().Debugx("cannot turn http transaction into websocket connection", err)
|
||
http.Error(w, "501 - not implemented - cannot turn this connection into websocket"+recvid(r), http.StatusNotImplemented)
|
||
lw.error(err)
|
||
return
|
||
}
|
||
defer func() {
|
||
if cconn != nil {
|
||
cconn.Close()
|
||
}
|
||
}()
|
||
|
||
// Below this point, we can no longer write to the ResponseWriter.
|
||
|
||
// Mark as websocket response, for logging.
|
||
lw.WebsocketResponse = true
|
||
lw.setStatusCode(fresp.StatusCode)
|
||
|
||
for k, v := range h.ResponseHeaders {
|
||
fresp.Header.Add(k, v)
|
||
}
|
||
|
||
// Write the response to the client, completing its websocket handshake.
|
||
if err := fresp.Write(cconn); err != nil {
|
||
lw.error(fmt.Errorf("writing websocket response to client: %w", err))
|
||
return
|
||
}
|
||
|
||
errc := make(chan error, 1)
|
||
|
||
// Copy from client to backend.
|
||
go func() {
|
||
buf, err := cbr.Peek(cbr.Reader.Buffered())
|
||
if err != nil {
|
||
errc <- err
|
||
return
|
||
}
|
||
if len(buf) > 0 {
|
||
n, err := beconn.Write(buf)
|
||
if err != nil {
|
||
errc <- err
|
||
return
|
||
}
|
||
lw.SizeFromClient += int64(n)
|
||
}
|
||
n, err := io.Copy(beconn, cconn)
|
||
lw.SizeFromClient += n
|
||
errc <- err
|
||
}()
|
||
|
||
// Copy from backend to client.
|
||
go func() {
|
||
n, err := io.Copy(cconn, beconn)
|
||
lw.SizeToClient = n
|
||
errc <- err
|
||
}()
|
||
|
||
// Stop and close connection on first error from either size, typically a closed
|
||
// connection whose closing was already announced with a websocket frame.
|
||
lw.error(<-errc)
|
||
// Close connections so other goroutine stops as well.
|
||
cconn.Close()
|
||
beconn.Close()
|
||
// Wait for goroutine so it has updated the logWriter.Size*Client fields before we
|
||
// continue with logging.
|
||
<-errc
|
||
cconn = nil
|
||
return true
|
||
}
|
||
|
||
func websocketTransact(ctx context.Context, targetURL *url.URL, r *http.Request) (rresp *http.Response, rconn net.Conn, rerr error) {
|
||
log := func() mlog.Log {
|
||
return pkglog.WithContext(r.Context())
|
||
}
|
||
|
||
// Dial the backend, possibly doing TLS. We assume the net/http DefaultTransport is
|
||
// unmodified.
|
||
transport := http.DefaultTransport.(*http.Transport)
|
||
|
||
// We haven't implemented using a proxy for websocket requests yet. If we need one,
|
||
// return an error instead of trying to connect directly, which would be a
|
||
// potential security issue.
|
||
treq := *r
|
||
treq.URL = targetURL
|
||
if purl, err := transport.Proxy(&treq); err != nil {
|
||
return nil, nil, fmt.Errorf("determining proxy for websocket backend connection: %w", err)
|
||
} else if purl != nil {
|
||
return nil, nil, fmt.Errorf("%w: proxy required for websocket connection to backend", errNotImplemented) // todo: implement?
|
||
}
|
||
|
||
host, port, err := net.SplitHostPort(targetURL.Host)
|
||
if err != nil {
|
||
host = targetURL.Host
|
||
if targetURL.Scheme == "https" {
|
||
port = "443"
|
||
} else {
|
||
port = "80"
|
||
}
|
||
}
|
||
addr := net.JoinHostPort(host, port)
|
||
conn, err := transport.DialContext(r.Context(), "tcp", addr)
|
||
if err != nil {
|
||
return nil, nil, fmt.Errorf("dial: %w", err)
|
||
}
|
||
if targetURL.Scheme == "https" {
|
||
tlsconn := tls.Client(conn, transport.TLSClientConfig)
|
||
ctx, cancel := context.WithTimeout(r.Context(), transport.TLSHandshakeTimeout)
|
||
defer cancel()
|
||
if err := tlsconn.HandshakeContext(ctx); err != nil {
|
||
return nil, nil, fmt.Errorf("tls handshake: %w", err)
|
||
}
|
||
conn = tlsconn
|
||
}
|
||
defer func() {
|
||
if rerr != nil {
|
||
conn.Close()
|
||
}
|
||
}()
|
||
|
||
// todo: make timeout configurable?
|
||
if err := conn.SetDeadline(time.Now().Add(30 * time.Second)); err != nil {
|
||
log().Check(err, "set deadline for websocket request to backend")
|
||
}
|
||
|
||
// Set clean connection headers.
|
||
removeHopByHopHeaders(r.Header)
|
||
r.Header.Set("Connection", "Upgrade")
|
||
r.Header.Set("Upgrade", "websocket")
|
||
|
||
// Write the websocket request to the backend.
|
||
if err := r.Write(conn); err != nil {
|
||
return nil, nil, fmt.Errorf("writing request to backend: %w", err)
|
||
}
|
||
|
||
// Read response from backend.
|
||
br := bufio.NewReader(conn)
|
||
resp, err := http.ReadResponse(br, r)
|
||
if err != nil {
|
||
return nil, nil, fmt.Errorf("reading response from backend: %w", err)
|
||
}
|
||
defer func() {
|
||
if rerr != nil {
|
||
resp.Body.Close()
|
||
}
|
||
}()
|
||
if err := conn.SetDeadline(time.Time{}); err != nil {
|
||
log().Check(err, "clearing deadline on websocket connection to backend")
|
||
}
|
||
|
||
// Check that the response from the backend server indicates it is websocket. If
|
||
// not, don't pass the backend response, but an error that websocket is not
|
||
// appropriate.
|
||
if err := checkWebsocketResponse(resp, r); err != nil {
|
||
return resp, nil, err
|
||
}
|
||
|
||
// note: net/http.Response.Body documents that it implements io.Writer for a
|
||
// status: 101 response. But that's not the case when the response has been read
|
||
// with http.ReadResponse. We'll write to the connection directly.
|
||
|
||
buf, err := br.Peek(br.Buffered())
|
||
if err != nil {
|
||
return resp, nil, fmt.Errorf("peek at buffered data written by backend: %w", err)
|
||
}
|
||
return resp, websocketConn{io.MultiReader(bytes.NewReader(buf), conn), conn}, nil
|
||
}
|
||
|
||
// A net.Conn but with reads coming from an io multireader (due to buffered reader
|
||
// needed for http.ReadResponse).
|
||
type websocketConn struct {
|
||
r io.Reader
|
||
net.Conn
|
||
}
|
||
|
||
func (c websocketConn) Read(buf []byte) (int, error) {
|
||
return c.r.Read(buf)
|
||
}
|
||
|
||
// Check that an HTTP response (from a backend) is a valid websocket response, i.e.
|
||
// that it accepts the WebSocket "upgrade".
|
||
// ../rfc/6455:1299
|
||
func checkWebsocketResponse(resp *http.Response, req *http.Request) error {
|
||
if resp.StatusCode != 101 {
|
||
return fmt.Errorf("%w: response http status not 101 but %s", errResponseNotWebsocket, resp.Status)
|
||
}
|
||
if upgrade := resp.Header.Get("Upgrade"); !strings.EqualFold(upgrade, "websocket") {
|
||
return fmt.Errorf(`%w: response http status is 101, but Upgrade header is %q, should be "websocket"`, errResponseNotWebsocket, upgrade)
|
||
}
|
||
if connection := resp.Header.Get("Connection"); !strings.EqualFold(connection, "upgrade") {
|
||
return fmt.Errorf(`%w: response http status is 101, Upgrade is websocket, but Connection header is %q, should be "Upgrade"`, errResponseNotWebsocket, connection)
|
||
}
|
||
accept, err := base64.StdEncoding.DecodeString(resp.Header.Get("Sec-WebSocket-Accept"))
|
||
if err != nil {
|
||
return fmt.Errorf(`%w: response http status, Upgrade and Connection header are websocket, but Sec-WebSocket-Accept header is not valid base64: %v`, errResponseNotWebsocket, err)
|
||
}
|
||
exp := sha1.Sum([]byte(req.Header.Get("Sec-WebSocket-Key") + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"))
|
||
if !bytes.Equal(accept, exp[:]) {
|
||
return fmt.Errorf(`%w: response http status, Upgrade and Connection header are websocket, but backend Sec-WebSocket-Accept value does not match`, errResponseNotWebsocket)
|
||
}
|
||
// We don't have requirements for the other Sec-WebSocket headers. ../rfc/6455:1340
|
||
return nil
|
||
}
|
||
|
||
// From Go 1.20.4 src/net/http/httputil/reverseproxy.go:
|
||
// Hop-by-hop headers. These are removed when sent to the backend.
|
||
// As of RFC 7230, hop-by-hop headers are required to appear in the
|
||
// Connection header field. These are the headers defined by the
|
||
// obsoleted RFC 2616 (section 13.5.1) and are used for backward
|
||
// compatibility.
|
||
// ../rfc/2616:5128
|
||
var hopHeaders = []string{
|
||
"Connection",
|
||
"Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
|
||
"Keep-Alive",
|
||
"Proxy-Authenticate",
|
||
"Proxy-Authorization",
|
||
"Te", // canonicalized version of "TE"
|
||
"Trailer", // not Trailers per URL above; https://www.rfc-editor.org/errata_search.php?eid=4522
|
||
"Transfer-Encoding",
|
||
"Upgrade",
|
||
}
|
||
|
||
// From Go 1.20.4 src/net/http/httputil/reverseproxy.go:
|
||
// removeHopByHopHeaders removes hop-by-hop headers.
|
||
func removeHopByHopHeaders(h http.Header) {
|
||
// RFC 7230, section 6.1: Remove headers listed in the "Connection" header.
|
||
// ../rfc/7230:2817
|
||
for _, f := range h["Connection"] {
|
||
for _, sf := range strings.Split(f, ",") {
|
||
if sf = textproto.TrimString(sf); sf != "" {
|
||
h.Del(sf)
|
||
}
|
||
}
|
||
}
|
||
// RFC 2616, section 13.5.1: Remove a set of known hop-by-hop headers.
|
||
// This behavior is superseded by the RFC 7230 Connection header, but
|
||
// preserve it for backwards compatibility.
|
||
// ../rfc/2616:5128
|
||
for _, f := range hopHeaders {
|
||
h.Del(f)
|
||
}
|
||
}
|