From 4ad8aa6a64f7bf6ffc32f746d10f627868f69ea3 Mon Sep 17 00:00:00 2001
From: Henrique Dias <hacdias@gmail.com>
Date: Thu, 3 Aug 2017 08:18:26 +0100
Subject: [PATCH] Init

---
 cmd/webdav/main.go |   1 +
 webdav.go          | 135 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)
 create mode 100644 cmd/webdav/main.go
 create mode 100644 webdav.go

diff --git a/cmd/webdav/main.go b/cmd/webdav/main.go
new file mode 100644
index 0000000..06ab7d0
--- /dev/null
+++ b/cmd/webdav/main.go
@@ -0,0 +1 @@
+package main
diff --git a/webdav.go b/webdav.go
new file mode 100644
index 0000000..a31d832
--- /dev/null
+++ b/webdav.go
@@ -0,0 +1,135 @@
+package webdav
+
+import (
+	"context"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+
+	"golang.org/x/net/webdav"
+)
+
+// Config is the configuration of a WebDAV instance.
+type Config struct {
+	*User
+	BaseURL string
+	Users   map[string]*User
+}
+
+// ServeHTTP determines if the request is for this plugin, and if all prerequisites are met.
+func (c *Config) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	u := c.User
+
+	// Gets the correct user for this request.
+	username, ok := r.Context().Value(httpserver.RemoteUserCtxKey).(string)
+	if ok {
+		if user, ok := c.Users[username]; ok {
+			u = user
+		}
+	}
+
+	// Remove the BaseURL from the url path.
+	r.URL.Path = strings.TrimPrefix(r.URL.Path, c.BaseURL)
+
+	// Checks for user permissions relatively to this PATH.
+	if !u.Allowed(r.URL.Path) {
+		w.WriteHeader(http.StatusForbidden)
+		return
+	}
+
+	if r.Method == "HEAD" {
+		w = newResponseWriterNoBody(w)
+	}
+
+	// If this request modified the files and the user doesn't have permission
+	// to do so, return forbidden.
+	if (r.Method == "PUT" || r.Method == "POST" || r.Method == "MKCOL" ||
+		r.Method == "DELETE" || r.Method == "COPY" || r.Method == "MOVE") &&
+		!u.Modify {
+		w.WriteHeader(http.StatusForbidden)
+		return
+	}
+
+	// Excerpt from RFC4918, section 9.4:
+	//
+	// 		GET, when applied to a collection, may return the contents of an
+	//		"index.html" resource, a human-readable view of the contents of
+	//		the collection, or something else altogether.
+	//
+	// Get, when applied to collection, will return the same as PROPFIND method.
+	if r.Method == "GET" {
+		info, err := u.Handler.FileSystem.Stat(context.TODO(), r.URL.Path)
+		if err == nil && info.IsDir() {
+			r.Method = "PROPFIND"
+		}
+	}
+
+	// Runs the WebDAV.
+	u.Handler.ServeHTTP(w, r)
+}
+
+// Rule is a dissalow/allow rule.
+type Rule struct {
+	Regex  bool
+	Allow  bool
+	Path   string
+	Regexp *regexp.Regexp
+}
+
+// User contains the settings of each user.
+type User struct {
+	Scope   string
+	Modify  bool
+	Rules   []*Rule
+	Handler *webdav.Handler
+}
+
+// Allowed checks if the user has permission to access a directory/file
+func (u User) Allowed(url string) bool {
+	var rule *Rule
+	i := len(u.Rules) - 1
+
+	for i >= 0 {
+		rule = u.Rules[i]
+
+		if rule.Regex {
+			if rule.Regexp.MatchString(url) {
+				return rule.Allow
+			}
+		} else if strings.HasPrefix(url, rule.Path) {
+			return rule.Allow
+		}
+
+		i--
+	}
+
+	return true
+}
+
+// responseWriterNoBody is a wrapper used to suprress the body of the response
+// to a request. Mainly used for HEAD requests.
+type responseWriterNoBody struct {
+	http.ResponseWriter
+}
+
+// newResponseWriterNoBody creates a new responseWriterNoBody.
+func newResponseWriterNoBody(w http.ResponseWriter) *responseWriterNoBody {
+	return &responseWriterNoBody{w}
+}
+
+// Header executes the Header method from the http.ResponseWriter.
+func (w responseWriterNoBody) Header() http.Header {
+	return w.ResponseWriter.Header()
+}
+
+// Write suprresses the body.
+func (w responseWriterNoBody) Write(data []byte) (int, error) {
+	return 0, nil
+}
+
+// WriteHeader writes the header to the http.ResponseWriter.
+func (w responseWriterNoBody) WriteHeader(statusCode int) {
+	w.ResponseWriter.WriteHeader(statusCode)
+}