From 4802216752289efb0cf6fc0a47c16e9ed11fda18 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 29 Jul 2021 15:29:16 +0100
Subject: [PATCH] Initial signature upload support maybe

---
 keyserver/internal/cross_signing.go | 66 +++++++++++++++++++++++++++++
 keyserver/storage/interface.go      |  2 +
 keyserver/storage/shared/storage.go | 15 +++++++
 3 files changed, 83 insertions(+)

diff --git a/keyserver/internal/cross_signing.go b/keyserver/internal/cross_signing.go
index b08a6e45..ffdcfb4d 100644
--- a/keyserver/internal/cross_signing.go
+++ b/keyserver/internal/cross_signing.go
@@ -160,6 +160,72 @@ func (a *KeyInternalAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.P
 }
 
 func (a *KeyInternalAPI) PerformUploadDeviceSignatures(ctx context.Context, req *api.PerformUploadDeviceSignaturesRequest, res *api.PerformUploadDeviceSignaturesResponse) {
+	for targetUserID, forTarget := range req.CrossSigningSignatures {
+		for targetID, signable := range forTarget {
+			switch obj := signable.(type) {
+			case *gomatrixserverlib.CrossSigningKey: // signing a key
+				// Check to see if we know about the target user ID and key ID. If we
+				// don't then we'll just drop the signatures.
+				keys, err := a.DB.CrossSigningKeysForUser(ctx, targetUserID)
+				if err != nil {
+					continue
+				}
+				foundMatchingKey := false
+				for _, key := range keys {
+					if key.Encode() == targetID {
+						foundMatchingKey = true
+					}
+				}
+				if !foundMatchingKey {
+					continue
+				}
+
+				/*
+					keyJSON, err := json.Marshal(obj)
+					if err != nil {
+						res.Error = &api.KeyError{
+							Err: fmt.Sprintf("The JSON of the signable object is invalid: %s", err.Error()),
+						}
+						return
+					}
+				*/
+
+				for originUserID, forOriginUserID := range obj.Signatures {
+					for originKeyID, signature := range forOriginUserID {
+						// TODO: sig checking
+						/*
+							if err := gomatrixserverlib.VerifyJSON(originUserID, originKeyID, ed25519.PublicKey(masterKey), keyJSON); err != nil {
+								res.Error = &api.KeyError{
+									Err:                fmt.Sprintf("The %q sub-key failed master key signature verification: %s", purpose, err.Error()),
+									IsInvalidSignature: true,
+								}
+								return
+							}
+						*/
+
+						err := a.DB.StoreCrossSigningSigsForTarget(ctx, originUserID, originKeyID, targetUserID, gomatrixserverlib.KeyID(targetID), signature)
+						if err != nil {
+							res.Error = &api.KeyError{
+								Err: "Failed to store cross-signing keys for target: " + err.Error(),
+							}
+							return
+						}
+					}
+				}
+
+			case *gomatrixserverlib.CrossSigningSignature: // signing a device
+				// TODO: signatures for devices
+				continue
+
+			default:
+				res.Error = &api.KeyError{
+					Err: "Found an unexpected item type",
+				}
+				return
+			}
+		}
+	}
+
 	res.Error = &api.KeyError{
 		Err: "Not supported yet",
 	}
diff --git a/keyserver/storage/interface.go b/keyserver/storage/interface.go
index e0eeefcf..e46afc44 100644
--- a/keyserver/storage/interface.go
+++ b/keyserver/storage/interface.go
@@ -79,5 +79,7 @@ type Database interface {
 
 	CrossSigningKeysForUser(ctx context.Context, userID string) (api.CrossSigningKeyMap, error)
 	CrossSigningSigsForTarget(ctx context.Context, targetUserID string, targetKeyID gomatrixserverlib.KeyID) (api.CrossSigningSigMap, error)
+
 	StoreCrossSigningKeysForUser(ctx context.Context, userID string, keyMap api.CrossSigningKeyMap, streamID int64) error
+	StoreCrossSigningSigsForTarget(ctx context.Context, originUserID string, originKeyID gomatrixserverlib.KeyID, targetUserID string, targetKeyID gomatrixserverlib.KeyID, signature gomatrixserverlib.Base64Bytes) error
 }
diff --git a/keyserver/storage/shared/storage.go b/keyserver/storage/shared/storage.go
index 6a63f3c2..0ae4f6f5 100644
--- a/keyserver/storage/shared/storage.go
+++ b/keyserver/storage/shared/storage.go
@@ -179,3 +179,18 @@ func (d *Database) StoreCrossSigningKeysForUser(ctx context.Context, userID stri
 		return nil
 	})
 }
+
+// StoreCrossSigningSigsForTarget stores a signature for a target user ID and key/dvice.
+func (d *Database) StoreCrossSigningSigsForTarget(
+	ctx context.Context,
+	originUserID string, originKeyID gomatrixserverlib.KeyID,
+	targetUserID string, targetKeyID gomatrixserverlib.KeyID,
+	signature gomatrixserverlib.Base64Bytes,
+) error {
+	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
+		if err := d.CrossSigningSigsTable.InsertCrossSigningSigsForTarget(ctx, nil, originUserID, originKeyID, targetUserID, targetKeyID, signature); err != nil {
+			return fmt.Errorf("d.CrossSigningSigsTable.InsertCrossSigningSigsForTarget: %w", err)
+		}
+		return nil
+	})
+}