internal: add Handler

internal/server.go

@@ -0,0 +1,99 @@
+package internal
+
+import (
+	"net/http"
+	"fmt"
+	"mime"
+	"encoding/xml"
+)
+
+type HTTPError struct {
+	Code int
+	Err  error
+}
+
+func HTTPErrorf(code int, format string, a ...interface{}) *HTTPError {
+	return &HTTPError{code, fmt.Errorf(format, a...)}
+}
+
+func (err *HTTPError) Error() string {
+	s := fmt.Sprintf("%v %v", err.Code, http.StatusText(err.Code))
+	if err.Err != nil {
+		return fmt.Sprintf("%v: %v", s, err.Err)
+	} else {
+		return s
+	}
+}
+
+type Backend interface {
+	HeadGet(w http.ResponseWriter, r *http.Request) error
+	Propfind(r *http.Request, pf *Propfind, depth Depth) (*Multistatus, error)
+}
+
+type Handler struct {
+	Backend Backend
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var err error
+	if h.Backend == nil {
+		err = fmt.Errorf("webdav: no backend available")
+	} else {
+		switch r.Method {
+		case http.MethodOptions:
+			err = h.handleOptions(w, r)
+		case http.MethodGet, http.MethodHead:
+			err = h.Backend.HeadGet(w, r)
+		case "PROPFIND":
+			err = h.handlePropfind(w, r)
+		default:
+			err = HTTPErrorf(http.StatusMethodNotAllowed, "webdav: unsupported method")
+		}
+	}
+
+	if err != nil {
+		code := http.StatusInternalServerError
+		if httpErr, ok := err.(*HTTPError); ok {
+			code = httpErr.Code
+		}
+		http.Error(w, err.Error(), code)
+	}
+}
+
+func (h *Handler) handleOptions(w http.ResponseWriter, r *http.Request) error {
+	w.Header().Add("Allow", "OPTIONS, GET, HEAD, PROPFIND")
+	w.Header().Add("DAV", "1, 3")
+	w.WriteHeader(http.StatusNoContent)
+	return nil
+}
+
+func (h *Handler) handlePropfind(w http.ResponseWriter, r *http.Request) error {
+	t, _, err := mime.ParseMediaType(r.Header.Get("Content-Type"))
+	if t != "application/xml" && t != "text/xml" {
+		return HTTPErrorf(http.StatusBadRequest, "webdav: expected application/xml PROPFIND request")
+	}
+
+	var propfind Propfind
+	if err := xml.NewDecoder(r.Body).Decode(&propfind); err != nil {
+		return &HTTPError{http.StatusBadRequest, err}
+	}
+
+	depth := DepthInfinity
+	if s := r.Header.Get("Depth"); s != "" {
+		var err error
+		depth, err = ParseDepth(s)
+		if err != nil {
+			return &HTTPError{http.StatusBadRequest, err}
+		}
+	}
+
+	ms, err := h.Backend.Propfind(r, &propfind, depth)
+	if err != nil {
+		return err
+	}
+
+	w.Header().Add("Content-Type", "text/xml; charset=\"utf-8\"")
+	w.WriteHeader(http.StatusMultiStatus)
+	w.Write([]byte(xml.Header))
+	return xml.NewEncoder(w).Encode(&ms)
+}