[chore] Try to parse public key as both Actor + bare key (#2710)

* [chore] Try to parse public key as both Actor + bare key

* fix weird test fail

2 files changed, 168 insertions, 48 deletions

diff --git a/internal/ap/extract.go b/internal/ap/extract.go
index d9288c162..e0c90c5d7 100644
--- a/internal/ap/extract.go
+++ b/internal/ap/extract.go
@@ -515,9 +515,9 @@ func ExtractURL(i WithURL) (*url.URL, error) {
 	return nil, gtserror.New("no valid URL property found")
 }
 
-// ExtractPublicKey extracts the public key, public key ID, and public
+// ExtractPubKeyFromActor extracts the public key, public key ID, and public
 // key owner ID from an interface, or an error if something goes wrong.
-func ExtractPublicKey(i WithPublicKey) (
+func ExtractPubKeyFromActor(i WithPublicKey) (
 	*rsa.PublicKey, // pubkey
 	*url.URL, // pubkey ID
 	*url.URL, // pubkey owner
@@ -528,6 +528,7 @@ func ExtractPublicKey(i WithPublicKey) (
 		return nil, nil, nil, gtserror.New("public key property was nil")
 	}
 
+	// Take the first public key we can find.
 	for iter := pubKeyProp.Begin(); iter != pubKeyProp.End(); iter = iter.Next() {
 		if !iter.IsW3IDSecurityV1PublicKey() {
 			continue
@@ -538,63 +539,74 @@ func ExtractPublicKey(i WithPublicKey) (
 			continue
 		}
 
-		pubKeyID, err := pub.GetId(pkey)
-		if err != nil {
-			continue
-		}
+		return ExtractPubKeyFromKey(pkey)
+	}
 
-		pubKeyOwnerProp := pkey.GetW3IDSecurityV1Owner()
-		if pubKeyOwnerProp == nil {
-			continue
-		}
+	return nil, nil, nil, gtserror.New("couldn't find valid public key")
+}
 
-		pubKeyOwner := pubKeyOwnerProp.GetIRI()
-		if pubKeyOwner == nil {
-			continue
-		}
+// ExtractPubKeyFromActor extracts the public key, public key ID, and public
+// key owner ID from an interface, or an error if something goes wrong.
+func ExtractPubKeyFromKey(pkey vocab.W3IDSecurityV1PublicKey) (
+	*rsa.PublicKey, // pubkey
+	*url.URL, // pubkey ID
+	*url.URL, // pubkey owner
+	error,
+) {
+	pubKeyID, err := pub.GetId(pkey)
+	if err != nil {
+		return nil, nil, nil, errors.New("no id set on public key")
+	}
 
-		pubKeyPemProp := pkey.GetW3IDSecurityV1PublicKeyPem()
-		if pubKeyPemProp == nil {
-			continue
-		}
+	pubKeyOwnerProp := pkey.GetW3IDSecurityV1Owner()
+	if pubKeyOwnerProp == nil {
+		return nil, nil, nil, errors.New("nil pubKeyOwnerProp")
+	}
 
-		pkeyPem := pubKeyPemProp.Get()
-		if pkeyPem == "" {
-			continue
-		}
+	pubKeyOwner := pubKeyOwnerProp.GetIRI()
+	if pubKeyOwner == nil {
+		return nil, nil, nil, errors.New("nil iri on pubKeyOwnerProp")
+	}
 
-		block, _ := pem.Decode([]byte(pkeyPem))
-		if block == nil {
-			continue
-		}
+	pubKeyPemProp := pkey.GetW3IDSecurityV1PublicKeyPem()
+	if pubKeyPemProp == nil {
+		return nil, nil, nil, errors.New("nil pubKeyPemProp")
+	}
 
-		var p crypto.PublicKey
-		switch block.Type {
-		case "PUBLIC KEY":
-			p, err = x509.ParsePKIXPublicKey(block.Bytes)
-		case "RSA PUBLIC KEY":
-			p, err = x509.ParsePKCS1PublicKey(block.Bytes)
-		default:
-			err = fmt.Errorf("unknown block type: %q", block.Type)
-		}
-		if err != nil {
-			err = gtserror.Newf("could not parse public key from block bytes: %w", err)
-			return nil, nil, nil, err
-		}
+	pkeyPem := pubKeyPemProp.Get()
+	if pkeyPem == "" {
+		return nil, nil, nil, errors.New("empty pubKeyPemProp")
+	}
 
-		if p == nil {
-			return nil, nil, nil, gtserror.New("returned public key was empty")
-		}
+	block, _ := pem.Decode([]byte(pkeyPem))
+	if block == nil {
+		return nil, nil, nil, errors.New("nil pubKeyPem")
+	}
 
-		pubKey, ok := p.(*rsa.PublicKey)
-		if !ok {
-			continue
-		}
+	var p crypto.PublicKey
+	switch block.Type {
+	case "PUBLIC KEY":
+		p, err = x509.ParsePKIXPublicKey(block.Bytes)
+	case "RSA PUBLIC KEY":
+		p, err = x509.ParsePKCS1PublicKey(block.Bytes)
+	default:
+		err = fmt.Errorf("unknown block type: %q", block.Type)
+	}
+	if err != nil {
+		err = fmt.Errorf("could not parse public key from block bytes: %w", err)
+		return nil, nil, nil, err
+	}
 
-		return pubKey, pubKeyID, pubKeyOwner, nil
+	if p == nil {
+		return nil, nil, nil, fmt.Errorf("returned public key was empty")
+	}
+
+	pubKey, ok := p.(*rsa.PublicKey)
+	if !ok {
+		return nil, nil, nil, fmt.Errorf("could not type pubKey to *rsa.PublicKey")
 	}
 
-	return nil, nil, nil, gtserror.New("couldn't find public key")
+	return pubKey, pubKeyID, pubKeyOwner, nil
 }
 
 // ExtractContent returns an intermediary representation of
diff --git a/internal/ap/extractpubkey_test.go b/internal/ap/extractpubkey_test.go
new file mode 100644
index 000000000..f7218f8b1
--- /dev/null
+++ b/internal/ap/extractpubkey_test.go
@@ -0,0 +1,108 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package ap_test
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/activity/streams"
+	typepublickey "github.com/superseriousbusiness/activity/streams/impl/w3idsecurityv1/type_publickey"
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+)
+
+const (
+	stubActor = `{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1"
+  ],
+  "id": "https://gts.superseriousbusiness.org/users/dumpsterqueer",
+  "preferredUsername": "dumpsterqueer",
+  "publicKey": {
+    "id": "https://gts.superseriousbusiness.org/users/dumpsterqueer/main-key",
+    "owner": "https://gts.superseriousbusiness.org/users/dumpsterqueer",
+    "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAt7cDz2XfTJXbmmmVXZ3o\nQGB1zu1yP+2/QZZFbLCeM0bMm5cfjJ/olli6kpdcGLh1lFpSgyLE0PlAVNYdSke9\nzcxDao6N16wavFx/bOYhh8HJPPXzlFpNeQQ+EBQ1ivzuLQyzIFTMV4TyZzOREoG9\nizuXuuKDaH/ENDE6qlIDuqtICIjnURjpxnBLldPUxfUvuSO3zY+jTidsxhjUjqkK\nC7RtEVi/D6/CzktVevz5bE/gcAYgKmK0dmkJ9HH6LzOlvkM4Wrq5h/hrM+H1z5e5\nPpdJsl3KlRT4wusuM1Z5xqLQ0oIP4mX/Kd3ypCe150i+jaoCsqBk8OPtl/zKMw1a\nYQIDAQAB\n-----END PUBLIC KEY-----\n"
+  },
+  "type": "Person"
+}`
+
+	key = `{
+  "@context": "https://w3id.org/security/v1",
+  "id": "https://gts.superseriousbusiness.org/users/dumpsterqueer/main-key",
+  "owner": "https://gts.superseriousbusiness.org/users/dumpsterqueer",
+  "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAt7cDz2XfTJXbmmmVXZ3o\nQGB1zu1yP+2/QZZFbLCeM0bMm5cfjJ/olli6kpdcGLh1lFpSgyLE0PlAVNYdSke9\nzcxDao6N16wavFx/bOYhh8HJPPXzlFpNeQQ+EBQ1ivzuLQyzIFTMV4TyZzOREoG9\nizuXuuKDaH/ENDE6qlIDuqtICIjnURjpxnBLldPUxfUvuSO3zY+jTidsxhjUjqkK\nC7RtEVi/D6/CzktVevz5bE/gcAYgKmK0dmkJ9HH6LzOlvkM4Wrq5h/hrM+H1z5e5\nPpdJsl3KlRT4wusuM1Z5xqLQ0oIP4mX/Kd3ypCe150i+jaoCsqBk8OPtl/zKMw1a\nYQIDAQAB\n-----END PUBLIC KEY-----\n"
+}`
+)
+
+type ExtractPubKeyTestSuite struct {
+	APTestSuite
+}
+
+func (suite *ExtractPubKeyTestSuite) TestExtractPubKeyFromStub() {
+	m := make(map[string]interface{})
+	if err := json.Unmarshal([]byte(stubActor), &m); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	t, err := streams.ToType(context.Background(), m)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	wpk, ok := t.(ap.WithPublicKey)
+	if !ok {
+		suite.FailNow("", "could not parse %T as WithPublicKey", t)
+	}
+
+	pubKey, pubKeyID, ownerURI, err := ap.ExtractPubKeyFromActor(wpk)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	suite.NotNil(pubKey)
+	suite.Equal("https://gts.superseriousbusiness.org/users/dumpsterqueer/main-key", pubKeyID.String())
+	suite.Equal("https://gts.superseriousbusiness.org/users/dumpsterqueer", ownerURI.String())
+}
+
+func (suite *ExtractPubKeyTestSuite) TestExtractPubKeyFromKey() {
+	m := make(map[string]interface{})
+	if err := json.Unmarshal([]byte(key), &m); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	pk, err := typepublickey.DeserializePublicKey(m, nil)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	pubKey, pubKeyID, ownerURI, err := ap.ExtractPubKeyFromKey(pk)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	suite.NotNil(pubKey)
+	suite.Equal("https://gts.superseriousbusiness.org/users/dumpsterqueer/main-key", pubKeyID.String())
+	suite.Equal("https://gts.superseriousbusiness.org/users/dumpsterqueer", ownerURI.String())
+}
+
+func TestExtractPubKeyTestSuite(t *testing.T) {
+	suite.Run(t, &ExtractPubKeyTestSuite{})
+}