package internal import ( "context" "crypto/ed25519" "fmt" "time" "github.com/matrix-org/dendrite/serverkeyapi/api" "github.com/matrix-org/gomatrixserverlib" "github.com/sirupsen/logrus" ) type ServerKeyAPI struct { api.ServerKeyInternalAPI ServerName gomatrixserverlib.ServerName ServerPublicKey ed25519.PublicKey ServerKeyID gomatrixserverlib.KeyID ServerKeyValidity time.Duration OurKeyRing gomatrixserverlib.KeyRing FedClient gomatrixserverlib.KeyClient } func (s *ServerKeyAPI) KeyRing() *gomatrixserverlib.KeyRing { // Return a keyring that forces requests to be proxied through the // below functions. That way we can enforce things like validity // and keeping the cache up-to-date. return &gomatrixserverlib.KeyRing{ KeyDatabase: s, KeyFetchers: []gomatrixserverlib.KeyFetcher{}, } } func (s *ServerKeyAPI) StoreKeys( _ context.Context, results map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult, ) error { // Run in a background context - we don't want to stop this work just // because the caller gives up waiting. ctx := context.Background() // Store any keys that we were given in our database. return s.OurKeyRing.KeyDatabase.StoreKeys(ctx, results) } func (s *ServerKeyAPI) FetchKeys( _ context.Context, requests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp, ) (map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult, error) { // Run in a background context - we don't want to stop this work just // because the caller gives up waiting. ctx := context.Background() now := gomatrixserverlib.AsTimestamp(time.Now()) results := map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult{} origRequests := map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp{} for k, v := range requests { origRequests[k] = v } // First, check if any of these key checks are for our own keys. If // they are then we will satisfy them directly. s.handleLocalKeys(ctx, requests, results) // Then consult our local database and see if we have the requested // keys. These might come from a cache, depending on the database // implementation used. if err := s.handleDatabaseKeys(ctx, now, requests, results); err != nil { return nil, err } // For any key requests that we still have outstanding, next try to // fetch them directly. We'll go through each of the key fetchers to // ask for the remaining keys for _, fetcher := range s.OurKeyRing.KeyFetchers { // If there are no more keys to look up then stop. if len(requests) == 0 { break } // Ask the fetcher to look up our keys. if err := s.handleFetcherKeys(ctx, now, fetcher, requests, results); err != nil { logrus.WithError(err).WithFields(logrus.Fields{ "fetcher_name": fetcher.FetcherName(), }).Errorf("Failed to retrieve %d key(s)", len(requests)) continue } } // Check that we've actually satisfied all of the key requests that we // were given. We should report an error if we didn't. for req := range origRequests { if _, ok := results[req]; !ok { // The results don't contain anything for this specific request, so // we've failed to satisfy it from local keys, database keys or from // all of the fetchers. Report an error. logrus.Warnf("Failed to retrieve key %q for server %q", req.KeyID, req.ServerName) return results, fmt.Errorf( "server key API failed to satisfy key request for server %q key ID %q", req.ServerName, req.KeyID, ) } } // Return the keys. return results, nil } func (s *ServerKeyAPI) FetcherName() string { return fmt.Sprintf("ServerKeyAPI (wrapping %q)", s.OurKeyRing.KeyDatabase.FetcherName()) } // handleLocalKeys handles cases where the key request contains // a request for our own server keys. func (s *ServerKeyAPI) handleLocalKeys( _ context.Context, requests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp, results map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult, ) { for req := range requests { if req.ServerName == s.ServerName { // We found a key request that is supposed to be for our own // keys. Remove it from the request list so we don't hit the // database or the fetchers for it. delete(requests, req) // Insert our own key into the response. results[req] = gomatrixserverlib.PublicKeyLookupResult{ VerifyKey: gomatrixserverlib.VerifyKey{ Key: gomatrixserverlib.Base64Bytes(s.ServerPublicKey), }, ExpiredTS: gomatrixserverlib.PublicKeyNotExpired, ValidUntilTS: gomatrixserverlib.AsTimestamp(time.Now().Add(s.ServerKeyValidity)), } } } } // handleDatabaseKeys handles cases where the key requests can be // satisfied from our local database/cache. func (s *ServerKeyAPI) handleDatabaseKeys( ctx context.Context, now gomatrixserverlib.Timestamp, requests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp, results map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult, ) error { // Ask the database/cache for the keys. dbResults, err := s.OurKeyRing.KeyDatabase.FetchKeys(ctx, requests) if err != nil { return err } // We successfully got some keys. Add them to the results. for req, res := range dbResults { // The key we've retrieved from the database/cache might // have passed its validity period, but right now, it's // the best thing we've got, and it might be sufficient to // verify a past event. results[req] = res // If the key is valid right now then we can also remove it // from the request list as we don't need to fetch it again // in that case. If the key isn't valid right now, then by // leaving it in the 'requests' map, we'll try to update the // key using the fetchers in handleFetcherKeys. if res.WasValidAt(now, true) { delete(requests, req) } } return nil } // handleFetcherKeys handles cases where a fetcher can satisfy // the remaining requests. func (s *ServerKeyAPI) handleFetcherKeys( ctx context.Context, now gomatrixserverlib.Timestamp, fetcher gomatrixserverlib.KeyFetcher, requests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp, results map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult, ) error { logrus.WithFields(logrus.Fields{ "fetcher_name": fetcher.FetcherName(), }).Infof("Fetching %d key(s)", len(requests)) // Create a context that limits our requests to 30 seconds. fetcherCtx, fetcherCancel := context.WithTimeout(ctx, time.Second*30) defer fetcherCancel() // Try to fetch the keys. fetcherResults, err := fetcher.FetchKeys(fetcherCtx, requests) if err != nil { return fmt.Errorf("fetcher.FetchKeys: %w", err) } // Build a map of the results that we want to commit to the // database. We do this in a separate map because otherwise we // might end up trying to rewrite database entries. storeResults := map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.PublicKeyLookupResult{} // Now let's look at the results that we got from this fetcher. for req, res := range fetcherResults { if req.ServerName == s.ServerName { continue } if prev, ok := results[req]; ok { // We've already got a previous entry for this request // so let's see if the newly retrieved one contains a more // up-to-date validity period. if res.ValidUntilTS > prev.ValidUntilTS { // This key is newer than the one we had so let's store // it in the database. storeResults[req] = res } } else { // We didn't already have a previous entry for this request // so store it in the database anyway for now. storeResults[req] = res } // Update the results map with this new result. If nothing // else, we can try verifying against this key. results[req] = res // Remove it from the request list so we won't re-fetch it. delete(requests, req) } // Store the keys from our store map. if err = s.OurKeyRing.KeyDatabase.StoreKeys(context.Background(), storeResults); err != nil { logrus.WithError(err).WithFields(logrus.Fields{ "fetcher_name": fetcher.FetcherName(), "database_name": s.OurKeyRing.KeyDatabase.FetcherName(), }).Errorf("Failed to store keys in the database") return fmt.Errorf("server key API failed to store retrieved keys: %w", err) } if len(storeResults) > 0 { logrus.WithFields(logrus.Fields{ "fetcher_name": fetcher.FetcherName(), }).Infof("Updated %d of %d key(s) in database (%d keys remaining)", len(storeResults), len(results), len(requests)) } return nil }