webdav: add minimal server implementation

fs_local.go

@@ -0,0 +1,32 @@
+package webdav
+
+import (
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+type LocalFileSystem string
+
+func (fs LocalFileSystem) path(name string) (string, error) {
+	if (filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0) || strings.Contains(name, "\x00") {
+		return "", HTTPErrorf(http.StatusBadRequest, "webdav: invalid character in path")
+	}
+	name = path.Clean(name)
+	if !path.IsAbs(name) {
+		return "", HTTPErrorf(http.StatusBadRequest, "webdav: expected absolute path")
+	}
+	return filepath.Join(string(fs), filepath.FromSlash(name)), nil
+}
+
+func (fs LocalFileSystem) Open(name string) (File, error) {
+	p, err := fs.path(name)
+	if err != nil {
+		return nil, err
+	}
+	return os.Open(p)
+}
+
+var _ FileSystem = LocalFileSystem("")

internal/client.go

@@ -25,6 +25,19 @@ const (
 	DepthInfinity Depth = -1
 )
 
+// ParseDepth parses a Depth header.
+func ParseDepth(s string) (Depth, error) {
+	switch s {
+	case "0":
+		return DepthZero, nil
+	case "1":
+		return DepthOne, nil
+	case "infinity":
+		return DepthInfinity, nil
+	}
+	return 0, fmt.Errorf("webdav: invalid Depth value")
+}
+
 // String formats the depth.
 func (d Depth) String() string {
 	switch d {

internal/elements.go

@@ -8,23 +8,40 @@ import (
 	"strings"
 )
 
+// TODO: cache parsed value
 type Status string
 
-func (s Status) Err() error {
+func NewStatus(code int, msg string) Status {
+	if msg == "" {
+		msg = http.StatusText(code)
+	}
+	return Status(fmt.Sprintf("HTTP/1.1 %v %v", code, msg))
+}
+
+func (s Status) parse() (int, string, error) {
 	if s == "" {
-		return nil
+		return http.StatusOK, "", nil
 	}
 
 	parts := strings.SplitN(string(s), " ", 3)
 	if len(parts) != 3 {
-		return fmt.Errorf("webdav: invalid HTTP status %q: expected 3 fields", s)
+		return 0, "", fmt.Errorf("webdav: invalid HTTP status %q: expected 3 fields", s)
 	}
 	code, err := strconv.Atoi(parts[1])
 	if err != nil {
-		return fmt.Errorf("webdav: invalid HTTP status %q: failed to parse code: %v", s, err)
+		return 0, "", fmt.Errorf("webdav: invalid HTTP status %q: failed to parse code: %v", s, err)
 	}
 	msg := parts[2]
 
+	return code, msg, nil
+}
+
+func (s Status) Err() error {
+	code, msg, err := s.parse()
+	if err != nil {
+		return err
+	}
+
 	// TODO: handle 2xx, 3xx
 	if code != http.StatusOK {
 		return fmt.Errorf("webdav: HTTP error: %v %v", code, msg)
@@ -39,6 +56,10 @@ type Multistatus struct {
 	ResponseDescription string     `xml:"responsedescription,omitempty"`
 }
 
+func NewMultistatus(resps ...Response) *Multistatus {
+	return &Multistatus{Responses: resps}
+}
+
 func (ms *Multistatus) Get(href string) (*Response, error) {
 	for i := range ms.Responses {
 		resp := &ms.Responses[i]
@@ -63,6 +84,13 @@ type Response struct {
 	Location            *Location    `xml:"location,omitempty"`
 }
 
+func NewOKResponse(href string) *Response {
+	return &Response{
+		Hrefs:  []string{href},
+		Status: NewStatus(http.StatusOK, ""),
+	}
+}
+
 func (resp *Response) Href() (string, error) {
 	if err := resp.Status.Err(); err != nil {
 		return "", err
@@ -97,6 +125,28 @@ func (resp *Response) DecodeProp(v interface{}) error {
 	return fmt.Errorf("webdav: missing prop %v %v in response", name.Space, name.Local)
 }
 
+func (resp *Response) EncodeProp(code int, v interface{}) error {
+	raw, err := EncodeRawXMLElement(v)
+	if err != nil {
+		return err
+	}
+
+	for i := range resp.Propstats {
+		propstat := &resp.Propstats[i]
+		c, _, _ := propstat.Status.parse()
+		if c == code {
+			propstat.Prop.Raw = append(propstat.Prop.Raw, *raw)
+			return nil
+		}
+	}
+
+	resp.Propstats = append(resp.Propstats, Propstat{
+		Status: NewStatus(code, ""),
+		Prop:   Prop{Raw: []RawXMLValue{*raw}},
+	})
+	return nil
+}
+
 // https://tools.ietf.org/html/rfc4918#section-14.9
 type Location struct {
 	XMLName xml.Name `xml:"DAV: location"`
@@ -130,6 +180,16 @@ func EncodeProp(values ...interface{}) (*Prop, error) {
 	return &Prop{Raw: l}, nil
 }
 
+func (prop *Prop) XMLNames() []xml.Name {
+	l := make([]xml.Name, 0, len(prop.Raw))
+	for _, raw := range prop.Raw {
+		if start, ok := raw.tok.(xml.StartElement); ok {
+			l = append(l, start.Name)
+		}
+	}
+	return l
+}
+
 // https://tools.ietf.org/html/rfc4918#section-14.20
 type Propfind struct {
 	XMLName xml.Name `xml:"DAV: propfind"`
@@ -137,12 +197,16 @@ type Propfind struct {
 	// TODO: propname | (allprop, include?)
 }
 
-func NewPropNamePropfind(names ...xml.Name) *Propfind {
-	children := make([]RawXMLValue, len(names))
+func xmlNamesToRaw(names []xml.Name) []RawXMLValue {
+	l := make([]RawXMLValue, len(names))
 	for i, name := range names {
-		children[i] = *NewRawXMLElement(name, nil, nil)
+		l[i] = *NewRawXMLElement(name, nil, nil)
 	}
-	return &Propfind{Prop: &Prop{Raw: children}}
+	return l
+}
+
+func NewPropNamePropfind(names ...xml.Name) *Propfind {
+	return &Propfind{Prop: &Prop{Raw: xmlNamesToRaw(names)}}
 }
 
 // https://tools.ietf.org/html/rfc4918#section-15.9
@@ -151,6 +215,10 @@ type ResourceType struct {
 	Raw     []RawXMLValue `xml:",any"`
 }
 
+func NewResourceType(names ...xml.Name) *ResourceType {
+	return &ResourceType{Raw: xmlNamesToRaw(names)}
+}
+
 func (t *ResourceType) Is(name xml.Name) bool {
 	for _, raw := range t.Raw {
 		if start, ok := raw.tok.(xml.StartElement); ok && name == start.Name {

server.go

@@ -0,0 +1,175 @@
+package webdav
+
+import (
+	"encoding/xml"
+	"fmt"
+	"mime"
+	"net/http"
+	"os"
+
+	"github.com/emersion/go-webdav/internal"
+)
+
+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 {
+	return fmt.Sprintf("%v %v: %v", err.Code, http.StatusText(err.Code), err.Err)
+}
+
+type File interface {
+	http.File
+}
+
+type FileSystem interface {
+	Open(name string) (File, error)
+}
+
+type Handler struct {
+	FileSystem FileSystem
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var err error
+	if h.FileSystem == nil {
+		err = HTTPErrorf(http.StatusInternalServerError, "webdav: no filesystem available")
+	} else {
+		switch r.Method {
+		case http.MethodOptions:
+			err = h.handleOptions(w, r)
+		case http.MethodGet, http.MethodHead:
+			err = h.handleGetHead(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")
+	w.Header().Add("DAV", "1")
+	w.WriteHeader(http.StatusNoContent)
+	return nil
+}
+
+func (h *Handler) handleGetHead(w http.ResponseWriter, r *http.Request) error {
+	f, err := h.FileSystem.Open(r.URL.Path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		return err
+	}
+
+	http.ServeContent(w, r, r.URL.Path, fi.ModTime(), f)
+	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 internal.Propfind
+	if err := xml.NewDecoder(r.Body).Decode(&propfind); err != nil {
+		return &HTTPError{http.StatusBadRequest, err}
+	}
+
+	depth := internal.DepthInfinity
+	if s := r.Header.Get("Depth"); s != "" {
+		var err error
+		depth, err = internal.ParseDepth(s)
+		if err != nil {
+			return &HTTPError{http.StatusBadRequest, err}
+		}
+	}
+
+	f, err := h.FileSystem.Open(r.URL.Path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		return err
+	}
+
+	if depth != internal.DepthZero {
+		depth = internal.DepthZero // TODO
+	}
+
+	resp, err := h.propfindFile(&propfind, r.URL.Path, fi)
+	if err != nil {
+		return err
+	}
+
+	ms := internal.NewMultistatus(*resp)
+
+	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)
+}
+
+func (h *Handler) propfindFile(propfind *internal.Propfind, name string, fi os.FileInfo) (*internal.Response, error) {
+	resp := internal.NewOKResponse(name)
+
+	if prop := propfind.Prop; prop != nil {
+		for _, xmlName := range prop.XMLNames() {
+			emptyVal := internal.NewRawXMLElement(xmlName, nil, nil)
+
+			var code int
+			var val interface{} = emptyVal
+			f, ok := liveProps[xmlName]
+			if ok {
+				if v, err := f(h, name, fi); err != nil {
+					code = http.StatusInternalServerError // TODO: better error handling
+				} else {
+					code = http.StatusOK
+					val = v
+				}
+			} else {
+				code = http.StatusNotFound
+			}
+
+			if err := resp.EncodeProp(code, val); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return resp, nil
+}
+
+type PropfindFunc func(h *Handler, name string, fi os.FileInfo) (interface{}, error)
+
+var liveProps = map[xml.Name]PropfindFunc{
+	{"DAV:", "resourcetype"}: func(h *Handler, name string, fi os.FileInfo) (interface{}, error) {
+		var types []xml.Name
+		if fi.IsDir() {
+			types = append(types, internal.CollectionName)
+		}
+		return internal.NewResourceType(types...), nil
+	},
+}