dendrite/signingkeyserver/internal/api.go

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package internal
import (
"context"
"crypto/ed25519"
"fmt"
"time"
"github.com/matrix-org/dendrite/setup/config"
"github.com/matrix-org/dendrite/signingkeyserver/api"
"github.com/matrix-org/gomatrixserverlib"
"github.com/sirupsen/logrus"
)
type ServerKeyAPI struct {
api.SigningKeyServerAPI
ServerName gomatrixserverlib.ServerName
ServerPublicKey ed25519.PublicKey
ServerKeyID gomatrixserverlib.KeyID
ServerKeyValidity time.Duration
OldServerKeys []config.OldVerifyKeys
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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,
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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()
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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 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, either current or old.
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 {
continue
}
if req.KeyID == s.ServerKeyID {
// 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)),
}
} else {
// The key request doesn't match our current key. Let's see
// if it matches any of our old verify keys.
for _, oldVerifyKey := range s.OldServerKeys {
if req.KeyID == oldVerifyKey.KeyID {
// We found a key request that is supposed to be an expired
// key.
delete(requests, req)
// Insert our own key into the response.
results[req] = gomatrixserverlib.PublicKeyLookupResult{
VerifyKey: gomatrixserverlib.VerifyKey{
Key: gomatrixserverlib.Base64Bytes(oldVerifyKey.PrivateKey.Public().(ed25519.PublicKey)),
},
ExpiredTS: oldVerifyKey.ExpiredAt,
ValidUntilTS: gomatrixserverlib.PublicKeyNotValid,
}
// No need to look at the other keys.
break
}
}
}
}
}
// 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,
_ 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 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.
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storeResults[req] = res
}
} else {
// We didn't already have a previous entry for this request
// so store it in the database anyway for now.
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storeResults[req] = res
}
// Update the results map with this new result. If nothing
// else, we can try verifying against this key.
results[req] = res
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// Remove it from the request list so we won't re-fetch it.
delete(requests, req)
}
// Store the keys from our store map.
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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(),
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}).Infof("Updated %d of %d key(s) in database (%d keys remaining)", len(storeResults), len(results), len(requests))
}
return nil
}