From 08155ead7bf80308b4cb67063cc91e3e3679ce16 Mon Sep 17 00:00:00 2001 From: Calvin Morrison Date: Sat, 22 Aug 2026 14:04:17 -0400 Subject: pim: a caldav backend, and a partstat that refuses to lie caldav/fs is the second backend, and it cost ~330 lines: discovery, a report for the window, ETags to decide whether anything moved. The event model, recurrence expansion, the tree, ctl, query, alarm and changed all came from lib/cal untouched, which is what the split was for. go-webdav hands back *ical.Calendar from the same library lib/cal parses with, so FromCalendars takes it straight in. Two interfaces, both optional. Identity says whose calendar this is, because in iTIP your identity is the mailto: in your own ATTENDEE line and nothing else can tell which attendee is you. RSVPer says the backend can answer an invitation -- meaning both halves of it, updating your copy and telling the organiser. A backend that can only do one should not implement it, so partstat is 0444 on a published .ics and writing to it fails rather than half-working. Two bugs worth naming. go-webdav resolves paths with path.Join, which drops a trailing slash: pointed at /dav/ it asks about /dav, and Cyrus answers 405 for that spelling and 207 for the other, so the first PROPFIND is done by hand. And an absolute DAV href replaces the endpoint's path rather than extending it; appending gave /dav/dav/calendars/..., a 404, and a probe reading 404 as "no" hid calendar-auto-schedule, which fastmail does in fact offer. pimup brings mail and the calendars up and mounts them; riostart runs it before opening any window, since a mount only exists in the namespace that made it. rio does not run riostart by itself: it is the argument to -i. Co-Authored-By: Claude Opus 5 --- pim/cmd/caldavfs/discover.go | 130 +++++++++++++++++++++++ pim/cmd/caldavfs/http.go | 14 +++ pim/cmd/caldavfs/main.go | 239 ++++++++++++++++++++++++++++++++++++++++++ pim/cmd/caldavfs/principal.go | 66 ++++++++++++ 4 files changed, 449 insertions(+) create mode 100644 pim/cmd/caldavfs/discover.go create mode 100644 pim/cmd/caldavfs/http.go create mode 100644 pim/cmd/caldavfs/main.go create mode 100644 pim/cmd/caldavfs/principal.go (limited to 'pim/cmd/caldavfs') diff --git a/pim/cmd/caldavfs/discover.go b/pim/cmd/caldavfs/discover.go new file mode 100644 index 0000000..2b5fb23 --- /dev/null +++ b/pim/cmd/caldavfs/discover.go @@ -0,0 +1,130 @@ +package main + +import ( + "context" + "fmt" + "net/url" + "os" + "strings" + "time" + + "github.com/emersion/go-webdav" + + "github.com/emersion/go-webdav/caldav" + "pim/lib/cal" +) + +// dial builds an authenticated client and finds the calendar to serve. +// +// The walk is the one CalDAV prescribes: the endpoint tells you your +// principal, the principal tells you where your calendars live, and +// that collection lists them. Naming a calendar by its display name +// beats hardcoding a path, which servers are free to change. +func dial(endpoint, user, pass, want string) (*caldav.Client, caldav.Calendar, bool, error) { + var zero caldav.Calendar + + hc := webdav.HTTPClientWithBasicAuth(nil, user, pass) + c, err := caldav.NewClient(hc, endpoint) + if err != nil { + return nil, zero, false, err + } + + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute) + defer cancel() + + principal, err := findPrincipal(endpoint, user, pass) + if err != nil { + return nil, zero, false, fmt.Errorf("principal: %v", err) + } + home, err := c.FindCalendarHomeSet(ctx, principal) + if err != nil { + return nil, zero, false, fmt.Errorf("home set: %v", err) + } + cals, err := c.FindCalendars(ctx, home) + if err != nil { + return nil, zero, false, fmt.Errorf("calendars: %v", err) + } + if len(cals) == 0 { + return nil, zero, false, fmt.Errorf("no calendars under %s", home) + } + + sched := autoSchedule(endpoint, user, pass, home) + cal.Warnf("home %s, auto-schedule %v", home, sched) + + if want == "" { + // No choice made: list them and refuse, rather than pick one + // and have it silently be the wrong calendar. + var names []string + for _, cl := range cals { + names = append(names, cl.Name) + } + return nil, zero, sched, fmt.Errorf("which calendar? -C one of: %s", + strings.Join(names, ", ")) + } + for _, cl := range cals { + if cl.Name == want || cl.Path == want { + return c, cl, sched, nil + } + } + return nil, zero, sched, fmt.Errorf("no calendar named %q", want) +} + +// autoSchedule asks whether the server sends iMIP on our behalf. A +// server that does means writing a PARTSTAT both updates our copy and +// tells the organiser; a server that does not means we must send the +// mail ourselves. +func autoSchedule(endpoint, user, pass, path string) bool { + req, err := newRequest("OPTIONS", endpoint, path) + if err != nil { + return false + } + req.SetBasicAuth(user, pass) + resp, err := httpDo(req) + if err != nil { + return false + } + defer resp.Body.Close() + for _, v := range resp.Header.Values("DAV") { + for _, f := range strings.Split(v, ",") { + if strings.TrimSpace(f) == "calendar-auto-schedule" { + return true + } + } + } + return false +} + +// urlJoin resolves a DAV href against the endpoint. +// +// An href from the server is absolute on that server: it replaces the +// endpoint's path rather than extending it. Appending it instead gives +// /dav/dav/calendars/... which answers 404, and a probe that reads a +// 404 as "no" reports a capability the server actually has. +func urlJoin(endpoint, href string) string { + base, err := url.Parse(endpoint) + if err != nil { + return href + } + ref, err := url.Parse(href) + if err != nil { + return href + } + return base.ResolveReference(ref).String() +} + +// readSecret reads a password from a file, so it stays out of argv where +// ps(1) would show it. +func readSecret(path string) (string, error) { + b, err := os.ReadFile(path) + if err != nil { + return "", err + } + for _, line := range strings.Split(string(b), "\n") { + line = strings.TrimSpace(line) + if line == "" || strings.HasPrefix(line, "#") { + continue + } + return strings.Trim(line, `"'`), nil + } + return "", fmt.Errorf("%s: empty", path) +} diff --git a/pim/cmd/caldavfs/http.go b/pim/cmd/caldavfs/http.go new file mode 100644 index 0000000..a49baf8 --- /dev/null +++ b/pim/cmd/caldavfs/http.go @@ -0,0 +1,14 @@ +package main + +import ( + "net/http" + "time" +) + +var client = &http.Client{Timeout: 2 * time.Minute} + +func newRequest(method, endpoint, path string) (*http.Request, error) { + return http.NewRequest(method, urlJoin(endpoint, path), nil) +} + +func httpDo(req *http.Request) (*http.Response, error) { return client.Do(req) } diff --git a/pim/cmd/caldavfs/main.go b/pim/cmd/caldavfs/main.go new file mode 100644 index 0000000..c3306de --- /dev/null +++ b/pim/cmd/caldavfs/main.go @@ -0,0 +1,239 @@ +// caldav/fs serves a CalDAV calendar as a 9p file system. +// +// It is a backend behind pim/lib/cal, which owns the tree, so everything +// above it -- events/date, events/uuid, ctl, query, alarm, changed -- is +// the same as any other calendar. Only fetching differs, and unlike a +// published .ics this one is a conversation: discovery, then a report +// for the window we care about. +// +// A CalDAV server that advertises calendar-auto-schedule (RFC 6638) +// sends the iMIP for you: writing your PARTSTAT back both updates your +// copy and tells the organiser. That is the whole reason this backend +// can honestly offer rsvp where ical/fs cannot. +package main + +import ( + "context" + "flag" + "fmt" + "os" + "strings" + "sync" + "time" + + "github.com/emersion/go-ical" + "github.com/emersion/go-webdav/caldav" + + "pim/lib/cal" +) + +func fatal(format string, a ...interface{}) { + cal.Warnf(format, a...) + os.Exit(1) +} + +type backend struct { + name string + client *caldav.Client + path string // the calendar collection + window time.Duration + refresh time.Duration + sched bool // server does the scheduling for us + + mu sync.Mutex + evs []*cal.Event + sig string + last time.Time + err string +} + +func (b *backend) Name() string { return b.name } + +// autoschedule is reported so a dry run shows it; it decides whether +// writing a PARTSTAT is enough or whether we must send the iMIP too. +func (b *backend) Sched() bool { return b.sched } + +func (b *backend) Caps() string { + // Writing is not implemented yet, so say so rather than promise it. + // When it is: "read write rsvp" plus "schedule" when the server + // advertises calendar-auto-schedule. + return "read" +} + +func (b *backend) Refresh() time.Duration { return b.refresh } + +func (b *backend) Status() (time.Time, string) { + b.mu.Lock() + defer b.mu.Unlock() + return b.last, b.err +} + +func (b *backend) Describe() string { + s := fmt.Sprintf("collection %s\n", b.path) + s += fmt.Sprintf("autoschedule %v\n", b.sched) + return s +} + +// Sync asks for every event in the window and reports whether the set +// changed. ETags make that cheap to decide: if every object still has +// the etag we saw last time, nothing has moved. +func (b *backend) Sync() (bool, error) { + ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute) + defer cancel() + + now := time.Now() + q := &caldav.CalendarQuery{ + CompRequest: caldav.CalendarCompRequest{ + Name: "VCALENDAR", + Props: []string{"VERSION"}, + Comps: []caldav.CalendarCompRequest{{ + Name: "VEVENT", + Props: []string{ + "SUMMARY", "UID", "DTSTART", "DTEND", "DURATION", + "RRULE", "RDATE", "EXDATE", "RECURRENCE-ID", + "LOCATION", "DESCRIPTION", "STATUS", "SEQUENCE", + "ORGANIZER", "ATTENDEE", + }, + }}, + }, + CompFilter: caldav.CompFilter{ + Name: "VCALENDAR", + Comps: []caldav.CompFilter{{ + Name: "VEVENT", + Start: now.Add(-b.window), + End: now.Add(b.window), + }}, + }, + } + objs, err := b.client.QueryCalendar(ctx, b.path, q) + b.note(time.Now(), err) + if err != nil { + return false, err + } + + sig := etagsig(objs) + b.mu.Lock() + same := sig == b.sig && b.evs != nil + b.mu.Unlock() + if same { + return false, nil + } + + cals := make([]*ical.Calendar, 0, len(objs)) + for _, o := range objs { + if o.Data != nil { + cals = append(cals, o.Data) + } + } + evs := cal.FromCalendars(cals) + + b.mu.Lock() + b.evs, b.sig = evs, sig + b.mu.Unlock() + cal.Warnf("%s: %d objects", b.name, len(objs)) + return true, nil +} + +func (b *backend) Events() ([]*cal.Event, error) { + b.mu.Lock() + defer b.mu.Unlock() + return b.evs, nil +} + +func (b *backend) note(t time.Time, err error) { + b.mu.Lock() + defer b.mu.Unlock() + b.last = t + if err != nil { + b.err = err.Error() + } else { + b.err = "" + } +} + +// etagsig summarises the collection: path and etag per object. If the +// server changes nothing, this does not change either. +func etagsig(objs []caldav.CalendarObject) string { + s := make([]string, 0, len(objs)) + for _, o := range objs { + s = append(s, o.Path+" "+o.ETag) + } + // QueryCalendar makes no promise about order + sortStrings(s) + return strings.Join(s, "\n") +} + +func sortStrings(s []string) { + for i := 1; i < len(s); i++ { + for j := i; j > 0 && s[j] < s[j-1]; j-- { + s[j], s[j-1] = s[j-1], s[j] + } + } +} + +func main() { + cal.Argv0 = "caldav/fs" + var ( + endpoint = flag.String("e", "", "caldav endpoint, e.g. https://caldav.fastmail.com/dav/") + user = flag.String("u", "", "account name") + pwfile = flag.String("p", "", "file holding the password (keeps it out of ps)") + which = flag.String("C", "", "which calendar to serve, by display name") + name = flag.String("N", "", "name to report in ctl (default: the display name)") + srv = flag.String("s", "", "service name to post in /srv (default caldav.$user.$pid)") + days = flag.Int("w", 400, "expansion window in days") + poll = flag.Duration("r", 15*time.Minute, "how often to re-query") + dry = flag.Bool("n", false, "load and report, do not serve") + ) + flag.Usage = func() { + fmt.Fprintf(os.Stderr, + "usage: caldav/fs -e endpoint -u user -p pwfile [-C calendar] [-N name] [-s srv] [-w days] [-r poll] [-n]\n") + os.Exit(2) + } + flag.Parse() + + if *endpoint == "" || *user == "" || *pwfile == "" { + flag.Usage() + } + pass, err := readSecret(*pwfile) + if err != nil { + fatal("%v", err) + } + + client, coll, sched, err := dial(*endpoint, *user, pass, *which) + if err != nil { + fatal("%v", err) + } + + who := os.Getenv("user") + if who == "" { + who = "glenda" + } + if *srv == "" { + // as rio(1) and plumb(1) name theirs, so several may run at once + *srv = fmt.Sprintf("caldav.%s.%d", who, os.Getpid()) + } + label := *name + if label == "" { + label = coll.Name + } + + be := &backend{ + name: label, client: client, path: coll.Path, sched: sched, + window: time.Duration(*days) * 24 * time.Hour, + refresh: *poll, + } + + s := cal.New(be, cal.Config{ + User: who, Srv: *srv, Conf: *pwfile, + Window: time.Duration(*days) * 24 * time.Hour, + }) + if *dry { + if err := s.Report(); err != nil { + fatal("%v", err) + } + return + } + if err := s.Serve(); err != nil { + fatal("%v", err) + } +} diff --git a/pim/cmd/caldavfs/principal.go b/pim/cmd/caldavfs/principal.go new file mode 100644 index 0000000..b5d6558 --- /dev/null +++ b/pim/cmd/caldavfs/principal.go @@ -0,0 +1,66 @@ +package main + +import ( + "encoding/xml" + "fmt" + "net/http" + "strings" +) + +// findPrincipal asks the endpoint who we are. +// +// go-webdav does this too, but it resolves the request path with +// path.Join, which drops a trailing slash: a client pointed at /dav/ +// ends up asking about /dav, and Cyrus answers 405 for that exact +// spelling while answering 207 for /dav/. Deeper paths tolerate either, +// so only this first request needs doing by hand. +func findPrincipal(endpoint, user, pass string) (string, error) { + body := `` + + `` + + req, err := http.NewRequest("PROPFIND", endpoint, strings.NewReader(body)) + if err != nil { + return "", err + } + req.Header.Set("Depth", "0") + req.Header.Set("Content-Type", "application/xml; charset=utf-8") + req.SetBasicAuth(user, pass) + + resp, err := client.Do(req) + if err != nil { + return "", err + } + defer resp.Body.Close() + if resp.StatusCode != http.StatusMultiStatus { + return "", fmt.Errorf("%s: %s", endpoint, resp.Status) + } + + // Spelled out rather than using encoding/xml's "a>b" path + // shorthand, which does not carry namespaces through. + type href struct { + Href string `xml:"DAV: href"` + } + type prop struct { + Principal href `xml:"DAV: current-user-principal"` + } + type propstat struct { + Prop prop `xml:"DAV: prop"` + } + type response struct { + Propstats []propstat `xml:"DAV: propstat"` + } + var ms struct { + Responses []response `xml:"DAV: response"` + } + if err := xml.NewDecoder(resp.Body).Decode(&ms); err != nil { + return "", err + } + for _, r := range ms.Responses { + for _, ps := range r.Propstats { + if h := strings.TrimSpace(ps.Prop.Principal.Href); h != "" { + return h, nil + } + } + } + return "", fmt.Errorf("%s: no current-user-principal", endpoint) +} -- cgit v1.2.3