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123 lines
3.7 KiB
Go
123 lines
3.7 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package compositedav
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import (
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"bytes"
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"fmt"
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"math"
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"net/http"
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"regexp"
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"strings"
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"tailscale.com/drive/driveimpl/shared"
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)
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var (
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responseHrefRegex = regexp.MustCompile(`(?s)(<D:(response|lockroot)>)<D:href>/?([^<]*)/?</D:href>`)
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ifHrefRegex = regexp.MustCompile(`^<(https?://[^/]+)?([^>]+)>`)
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)
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func (h *Handler) handlePROPFIND(w http.ResponseWriter, r *http.Request, pathComponents []string, mpl int) {
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if shouldDelegateToChild(r, pathComponents, mpl) {
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// Delegate to a Child.
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depth := getDepth(r)
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status, result := h.StatCache.getOr(r.URL.Path, depth, func() (int, []byte) {
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return h.delegateRewriting(w, r, pathComponents, mpl)
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})
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respondRewritten(w, status, result)
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return
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}
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h.handle(w, r)
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}
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func (h *Handler) handleLOCK(w http.ResponseWriter, r *http.Request, pathComponents []string, mpl int) {
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if shouldDelegateToChild(r, pathComponents, mpl) {
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// Delegate to a Child.
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status, result := h.delegateRewriting(w, r, pathComponents, mpl)
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respondRewritten(w, status, result)
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return
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}
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http.Error(w, "locking of top level directories is not allowed", http.StatusMethodNotAllowed)
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}
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// shouldDelegateToChild decides whether a request should be delegated to a
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// child filesystem, as opposed to being handled by this filesystem. It checks
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// the depth of the requested path, and if it's deeper than the portion of the
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// tree that's handled by the parent, returns true.
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func shouldDelegateToChild(r *http.Request, pathComponents []string, mpl int) bool {
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return !shared.IsRoot(r.URL.Path) && len(pathComponents)+getDepth(r) > mpl
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}
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func (h *Handler) delegateRewriting(w http.ResponseWriter, r *http.Request, pathComponents []string, mpl int) (int, []byte) {
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// Use a buffering ResponseWriter so that we can manipulate the result.
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// The only thing we use from the original ResponseWriter is Header().
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bw := &bufferingResponseWriter{ResponseWriter: w}
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h.delegate(mpl, pathComponents[mpl-1:], bw, r)
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// Fixup paths to add the requested path as a prefix, escaped for inclusion in XML.
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pp := shared.EscapeForXML(shared.Join(pathComponents[0:mpl]...))
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b := responseHrefRegex.ReplaceAll(bw.buf.Bytes(), []byte(fmt.Sprintf("$1<D:href>%s/$3</D:href>", pp)))
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return bw.status, b
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}
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func respondRewritten(w http.ResponseWriter, status int, result []byte) {
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w.Header().Del("Content-Length")
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w.WriteHeader(status)
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if result != nil {
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w.Write(result)
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}
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}
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func getDepth(r *http.Request) int {
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switch r.Header.Get("Depth") {
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case "0":
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return 0
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case "1":
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return 1
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case "infinity":
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return math.MaxInt16 // a really large number, but not infinity (avoids wrapping when we do arithmetic with this)
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}
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return 0
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}
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type bufferingResponseWriter struct {
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http.ResponseWriter
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status int
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buf bytes.Buffer
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}
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func (bw *bufferingResponseWriter) WriteHeader(statusCode int) {
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bw.status = statusCode
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}
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func (bw *bufferingResponseWriter) Write(p []byte) (int, error) {
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return bw.buf.Write(p)
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}
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// rewriteIfHeader rewrites URLs in the If header by removing the host and the
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// portion of the path that corresponds to this composite filesystem. This way,
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// when we delegate requests to child filesystems, the If header will reference
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// a path that makes sense on those filesystems.
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//
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// See http://www.webdav.org/specs/rfc4918.html#HEADER_If
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func rewriteIfHeader(r *http.Request, pathComponents []string, mpl int) {
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ih := r.Header.Get("If")
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if ih == "" {
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return
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}
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matches := ifHrefRegex.FindStringSubmatch(ih)
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if len(matches) == 3 {
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pp := shared.JoinEscaped(pathComponents[0:mpl]...)
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p := strings.Replace(shared.JoinEscaped(pathComponents...), pp, "", 1)
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nih := ifHrefRegex.ReplaceAllString(ih, fmt.Sprintf("<%s>", p))
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r.Header.Set("If", nih)
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}
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}
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