Rename FS queue package to internal (#997)

federationsender/internal/perform/join.go

@@ -0,0 +1,70 @@
+package perform
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+// This file contains helpers for the PerformJoin function.
+
+type joinContext struct {
+	federation *gomatrixserverlib.FederationClient
+	keyRing    *gomatrixserverlib.KeyRing
+}
+
+// Returns a new join context.
+func JoinContext(f *gomatrixserverlib.FederationClient, k *gomatrixserverlib.KeyRing) *joinContext {
+	return &joinContext{
+		federation: f,
+		keyRing:    k,
+	}
+}
+
+// checkSendJoinResponse checks that all of the signatures are correct
+// and that the join is allowed by the supplied state.
+func (r joinContext) CheckSendJoinResponse(
+	ctx context.Context,
+	event gomatrixserverlib.Event,
+	server gomatrixserverlib.ServerName,
+	respMakeJoin gomatrixserverlib.RespMakeJoin,
+	respSendJoin gomatrixserverlib.RespSendJoin,
+) error {
+	// A list of events that we have retried, if they were not included in
+	// the auth events supplied in the send_join.
+	retries := map[string]bool{}
+
+retryCheck:
+	// TODO: Can we expand Check here to return a list of missing auth
+	// events rather than failing one at a time?
+	if err := respSendJoin.Check(ctx, r.keyRing, event); err != nil {
+		switch e := err.(type) {
+		case gomatrixserverlib.MissingAuthEventError:
+			// Check that we haven't already retried for this event, prevents
+			// us from ending up in endless loops
+			if !retries[e.AuthEventID] {
+				// Ask the server that we're talking to right now for the event
+				tx, txerr := r.federation.GetEvent(ctx, server, e.AuthEventID)
+				if txerr != nil {
+					return fmt.Errorf("r.federation.GetEvent: %w", txerr)
+				}
+				// For each event returned, add it to the auth events.
+				for _, pdu := range tx.PDUs {
+					ev, everr := gomatrixserverlib.NewEventFromUntrustedJSON(pdu, respMakeJoin.RoomVersion)
+					if everr != nil {
+						return fmt.Errorf("gomatrixserverlib.NewEventFromUntrustedJSON: %w", everr)
+					}
+					respSendJoin.AuthEvents = append(respSendJoin.AuthEvents, ev)
+				}
+				// Mark the event as retried and then give the check another go.
+				retries[e.AuthEventID] = true
+				goto retryCheck
+			}
+			return fmt.Errorf("respSendJoin (after retries): %w", e)
+		default:
+			return fmt.Errorf("respSendJoin: %w", err)
+		}
+	}
+	return nil
+}