caldav: add basic server

A lot of features a still missing, but basic discovery works.

Co-authored-by: Conrad Hoffmann <ch@bitfehler.net>

caldav/server.go

@@ -0,0 +1,271 @@
+package caldav
+
+import (
+	"encoding/xml"
+	"net/http"
+	"time"
+
+	"github.com/emersion/go-ical"
+
+	"github.com/emersion/go-webdav/internal"
+)
+
+// TODO: add support for multiple calendars
+
+// Backend is a CalDAV server backend.
+type Backend interface {
+	Calendar() (*Calendar, error)
+	GetCalendarObject(path string, req *CalendarCompRequest) (*CalendarObject, error)
+	ListCalendarObjects(req *CalendarCompRequest) ([]CalendarObject, error)
+	QueryCalendarObjects(query *CalendarQuery) ([]CalendarObject, error)
+}
+
+// Handler handles CalDAV HTTP requests. It can be used to create a CalDAV
+// server.
+type Handler struct {
+	Backend Backend
+}
+
+// ServeHTTP implements http.Handler.
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if h.Backend == nil {
+		http.Error(w, "caldav: no backend available", http.StatusInternalServerError)
+		return
+	}
+
+	if r.URL.Path == "/.well-known/caldav" {
+		http.Redirect(w, r, "/", http.StatusMovedPermanently)
+		return
+	}
+
+	var err error
+	switch r.Method {
+	case "REPORT":
+		err = h.handleReport(w, r)
+	default:
+		b := backend{h.Backend}
+		hh := internal.Handler{&b}
+		hh.ServeHTTP(w, r)
+	}
+
+	if err != nil {
+		internal.ServeError(w, err)
+	}
+}
+
+func (h *Handler) handleReport(w http.ResponseWriter, r *http.Request) error {
+	var report reportReq
+	if err := internal.DecodeXMLRequest(r, &report); err != nil {
+		return err
+	}
+
+	if report.Query != nil {
+		return h.handleQuery(w, report.Query)
+	} else if report.Multiget != nil {
+		return h.handleMultiget(w, report.Multiget)
+	}
+	return internal.HTTPErrorf(http.StatusBadRequest, "caldav: expected calendar-query or calendar-multiget element in REPORT request")
+}
+
+func decodePropFilter(el *propFilter) (*PropFilter, error) {
+	pf := &PropFilter{Name: el.Name}
+	if el.TextMatch != nil {
+		pf.TextMatch = &TextMatch{Text: el.TextMatch.Text}
+	}
+	// TODO: IsNotDefined, TimeRange
+	return pf, nil
+}
+
+func decodeCompFilter(el *compFilter) (*CompFilter, error) {
+	cf := &CompFilter{Name: el.Name}
+	if el.TimeRange != nil {
+		cf.Start = time.Time(el.TimeRange.Start)
+		cf.End = time.Time(el.TimeRange.End)
+	}
+	for _, pfEl := range el.PropFilters {
+		pf, err := decodePropFilter(&pfEl)
+		if err != nil {
+			return nil, err
+		}
+		cf.Props = append(cf.Props, *pf)
+	}
+	for _, childEl := range el.CompFilters {
+		child, err := decodeCompFilter(&childEl)
+		if err != nil {
+			return nil, err
+		}
+		cf.Comps = append(cf.Comps, *child)
+	}
+	// TODO: IsNotDefined
+	return cf, nil
+}
+
+func (h *Handler) handleQuery(w http.ResponseWriter, query *calendarQuery) error {
+	var q CalendarQuery
+	// TODO: calendar-data in query.Prop
+	cf, err := decodeCompFilter(&query.Filter.CompFilter)
+	if err != nil {
+		return err
+	}
+	q.CompFilter = *cf
+
+	cos, err := h.Backend.QueryCalendarObjects(&q)
+	if err != nil {
+		return err
+	}
+
+	var resps []internal.Response
+	for _, co := range cos {
+		b := backend{h.Backend}
+		propfind := internal.Propfind{
+			Prop:     query.Prop,
+			AllProp:  query.AllProp,
+			PropName: query.PropName,
+		}
+		resp, err := b.propfindCalendarObject(&propfind, &co)
+		if err != nil {
+			return err
+		}
+		resps = append(resps, *resp)
+	}
+
+	ms := internal.NewMultistatus(resps...)
+
+	return internal.ServeMultistatus(w, ms)
+}
+
+func (h *Handler) handleMultiget(w http.ResponseWriter, multiget *calendarMultiget) error {
+	panic("TODO")
+}
+
+type backend struct {
+	Backend Backend
+}
+
+func (b *backend) Options(r *http.Request) (caps []string, allow []string, err error) {
+	caps = []string{"calendar-access"}
+
+	if r.URL.Path == "/" {
+		return caps, []string{http.MethodOptions, "PROPFIND", "REPORT"}, nil
+	}
+
+	var dataReq CalendarCompRequest
+	_, err = b.Backend.GetCalendarObject(r.URL.Path, &dataReq)
+	if httpErr, ok := err.(*internal.HTTPError); ok && httpErr.Code == http.StatusNotFound {
+		return caps, []string{http.MethodOptions, http.MethodPut}, nil
+	} else if err != nil {
+		return nil, nil, err
+	}
+
+	return caps, []string{
+		http.MethodOptions,
+		http.MethodHead,
+		http.MethodGet,
+		http.MethodPut,
+		http.MethodDelete,
+		"PROPFIND",
+	}, nil
+}
+
+func (b *backend) HeadGet(w http.ResponseWriter, r *http.Request) error {
+	panic("TODO")
+}
+
+func (b *backend) Propfind(r *http.Request, propfind *internal.Propfind, depth internal.Depth) (*internal.Multistatus, error) {
+	var resps []internal.Response
+	if r.URL.Path == "/" {
+		cal, err := b.Backend.Calendar()
+		if err != nil {
+			return nil, err
+		}
+
+		resp, err := b.propfindCalendar(propfind, cal)
+		if err != nil {
+			return nil, err
+		}
+		resps = append(resps, *resp)
+
+		if depth != internal.DepthZero {
+			// TODO
+		}
+	}
+
+	return internal.NewMultistatus(resps...), nil
+}
+
+func (b *backend) propfindCalendar(propfind *internal.Propfind, cal *Calendar) (*internal.Response, error) {
+	props := map[xml.Name]internal.PropfindFunc{
+		internal.ResourceTypeName: func(*internal.RawXMLValue) (interface{}, error) {
+			return internal.NewResourceType(internal.CollectionName, calendarName), nil
+		},
+		internal.DisplayNameName: func(*internal.RawXMLValue) (interface{}, error) {
+			return &internal.DisplayName{Name: cal.Name}, nil
+		},
+		supportedCalendarDataName: func(*internal.RawXMLValue) (interface{}, error) {
+			return &supportedCalendarData{
+				Types: []calendarDataType{
+					{ContentType: ical.MIMEType, Version: "2.0"},
+				},
+			}, nil
+		},
+		supportedCalendarComponentSetName: func(*internal.RawXMLValue) (interface{}, error) {
+			return &supportedCalendarComponentSet{
+				Comp: []comp{
+					{Name: ical.CompEvent},
+				},
+			}, nil
+		},
+		// TODO: this is a principal property
+		calendarHomeSetName: func(*internal.RawXMLValue) (interface{}, error) {
+			return &calendarHomeSet{Href: internal.Href{Path: "/"}}, nil
+		},
+		// TODO: this should be set on all resources
+		internal.CurrentUserPrincipalName: func(*internal.RawXMLValue) (interface{}, error) {
+			return &internal.CurrentUserPrincipal{Href: internal.Href{Path: "/"}}, nil
+		},
+	}
+
+	if cal.Description != "" {
+		props[calendarDescriptionName] = func(*internal.RawXMLValue) (interface{}, error) {
+			return &calendarDescription{Description: cal.Description}, nil
+		}
+	}
+
+	if cal.MaxResourceSize > 0 {
+		props[maxResourceSizeName] = func(*internal.RawXMLValue) (interface{}, error) {
+			return &maxResourceSize{Size: cal.MaxResourceSize}, nil
+		}
+	}
+
+	// TODO: CALDAV:calendar-timezone, CALDAV:supported-calendar-component-set, CALDAV:min-date-time, CALDAV:max-date-time, CALDAV:max-instances, CALDAV:max-attendees-per-instance
+
+	return internal.NewPropfindResponse("/", propfind, props)
+}
+
+func (b *backend) propfindCalendarObject(propfind *internal.Propfind, co *CalendarObject) (*internal.Response, error) {
+	panic("TODO")
+}
+
+func (b *backend) Proppatch(r *http.Request, update *internal.Propertyupdate) (*internal.Response, error) {
+	panic("TODO")
+}
+
+func (b *backend) Put(r *http.Request) (*internal.Href, error) {
+	panic("TODO")
+}
+
+func (b *backend) Delete(r *http.Request) error {
+	panic("TODO")
+}
+
+func (b *backend) Mkcol(r *http.Request) error {
+	panic("TODO")
+}
+
+func (b *backend) Copy(r *http.Request, dest *internal.Href, recursive, overwrite bool) (created bool, err error) {
+	panic("TODO")
+}
+
+func (b *backend) Move(r *http.Request, dest *internal.Href, overwrite bool) (created bool, err error) {
+	panic("TODO")
+}