Initial commit

CalDAV and CardDAV checkers sharing a single Go module. Discovery follows
RFC 6764 (/.well-known + SRV/TXT), authenticated probes cover principal,
home-set, collections and a minimal REPORT query on top of go-webdav.
Common shape in internal/dav/; CalDAV adds a scheduling rule.

Surfaces its context URL (and each secure-SRV target) as TLS endpoints via
the EndpointDiscoverer interface, so the dedicated TLS checker can pick
them up without re-parsing observations.

HTML report foregrounds common misconfigs (well-known returning 200,
missing SRV, plaintext-only SRV, missing DAV capability, skipped auth
phase) as action-item callouts before the full phase breakdown.

caldav/collect.go

@@ -0,0 +1,142 @@
+package caldav
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"git.happydns.org/checker-dav/internal/dav"
+	sdk "git.happydns.org/checker-sdk-go/checker"
+	webdav "github.com/emersion/go-webdav"
+	"github.com/emersion/go-webdav/caldav"
+)
+
+// Collect is intentionally resilient: each phase records its outcome and we
+// keep going as long as the next phase has something to work with. Rules
+// later turn the captured state into CheckStates.
+func (p *caldavProvider) Collect(ctx context.Context, opts sdk.CheckerOptions) (any, error) {
+	domain, _ := sdk.GetOption[string](opts, "domain_name")
+	user, _ := sdk.GetOption[string](opts, "username")
+	pass, _ := sdk.GetOption[string](opts, "password")
+	explicit, _ := sdk.GetOption[string](opts, "context_url")
+	timeoutSec := sdk.GetFloatOption(opts, "timeout_seconds", 10)
+
+	timeout := time.Duration(timeoutSec * float64(time.Second))
+	if timeout <= 0 {
+		timeout = 10 * time.Second
+	}
+
+	obs := &dav.Observation{
+		Kind:           dav.KindCalDAV,
+		Domain:         domain,
+		HasCredentials: user != "" && pass != "",
+		CollectedAt:    time.Now(),
+		Scheduling:     &dav.SchedulingResult{},
+	}
+
+	anonClient := dav.NewHTTPClient(timeout)
+
+	// Phase 1: Discovery
+	obs.Discovery = dav.Discover(ctx, anonClient, dav.KindCalDAV, domain, explicit)
+	if obs.Discovery.ContextURL == "" {
+		return obs, nil
+	}
+
+	// Phase 2: Transport + OPTIONS (no auth required)
+	optsRes, err := dav.ProbeOptions(ctx, anonClient, obs.Discovery.ContextURL)
+	obs.Options = optsRes
+	if err != nil {
+		obs.Transport = dav.TransportResult{Error: err.Error()}
+		return obs, nil
+	}
+	obs.Transport = dav.TransportResult{Reached: true}
+	obs.Scheduling.Advertised = optsRes.HasCapability("calendar-schedule")
+
+	// Phase 3: Authenticated probes
+	if !obs.HasCredentials {
+		obs.Principal.Skipped = true
+		obs.HomeSet.Skipped = true
+		obs.Collections.Skipped = true
+		obs.Report.Skipped = true
+		return obs, nil
+	}
+
+	authClient := dav.WithBasicAuth(anonClient, obs.Discovery.ContextURL, user, pass)
+
+	principal, err := dav.FindPrincipal(ctx, authClient, obs.Discovery.ContextURL)
+	if err != nil {
+		obs.Principal.Error = err.Error()
+		obs.HomeSet.Skipped = true
+		obs.Collections.Skipped = true
+		obs.Report.Skipped = true
+		return obs, nil
+	}
+	obs.Principal.URL = principal
+
+	cal, err := caldav.NewClient(asHTTPClient(authClient), obs.Discovery.ContextURL)
+	if err != nil {
+		obs.HomeSet.Error = err.Error()
+		obs.Collections.Skipped = true
+		obs.Report.Skipped = true
+		return obs, nil
+	}
+	home, err := cal.FindCalendarHomeSet(ctx, principal)
+	if err != nil {
+		obs.HomeSet.Error = err.Error()
+		obs.Collections.Skipped = true
+		obs.Report.Skipped = true
+		return obs, nil
+	}
+	obs.HomeSet.URL = home
+
+	calendars, err := cal.FindCalendars(ctx, home)
+	if err != nil {
+		obs.Collections.Error = err.Error()
+		obs.Report.Skipped = true
+	} else {
+		for _, c := range calendars {
+			obs.Collections.Items = append(obs.Collections.Items, dav.CollectionInfo{
+				Path:                  c.Path,
+				Name:                  c.Name,
+				Description:           c.Description,
+				MaxResourceSize:       c.MaxResourceSize,
+				SupportedComponentSet: c.SupportedComponentSet,
+			})
+		}
+	}
+
+	// Empty calendar-query against the first calendar: cheapest probe that
+	// still exercises the REPORT pipeline end-to-end.
+	if len(obs.Collections.Items) > 0 {
+		first := obs.Collections.Items[0].Path
+		obs.Report.ProbePath = first
+		q := &caldav.CalendarQuery{
+			CompRequest: caldav.CalendarCompRequest{
+				Name: "VCALENDAR",
+				Comps: []caldav.CalendarCompRequest{
+					{Name: "VEVENT"},
+				},
+			},
+		}
+		if _, err := cal.QueryCalendar(ctx, first, q); err != nil {
+			obs.Report.Error = err.Error()
+		} else {
+			obs.Report.QueryOK = true
+		}
+	} else {
+		obs.Report.Skipped = true
+	}
+
+	if obs.Scheduling.Advertised {
+		inbox, outbox, err := dav.FindScheduleURLs(ctx, authClient, principal)
+		if err != nil {
+			obs.Scheduling.Error = err.Error()
+		}
+		obs.Scheduling.InboxURL = inbox
+		obs.Scheduling.OutboxURL = outbox
+	}
+
+	return obs, nil
+}
+
+func asHTTPClient(c *http.Client) webdav.HTTPClient { return c }