3 files changed, 114 insertions, 35 deletions

diff --git a/internal/processing/fedi/accept.go b/internal/processing/fedi/accept.go
index e63b460db..97e36fbb3 100644
--- a/internal/processing/fedi/accept.go
+++ b/internal/processing/fedi/accept.go
@@ -19,10 +19,8 @@ package fedi
 
 import (
 	"context"
-	"errors"
 
 	"code.superseriousbusiness.org/gotosocial/internal/ap"
-	"code.superseriousbusiness.org/gotosocial/internal/db"
 	"code.superseriousbusiness.org/gotosocial/internal/gtserror"
 )
 
@@ -34,44 +32,18 @@ import (
 func (p *Processor) AcceptGet(
 	ctx context.Context,
 	requestedUser string,
-	reqID string,
-) (interface{}, gtserror.WithCode) {
-	// Authenticate incoming request, getting related accounts.
-	auth, errWithCode := p.authenticate(ctx, requestedUser)
+	intReqID string,
+) (any, gtserror.WithCode) {
+	// Ensure valid request, intReq exists, etc.
+	intReq, errWithCode := p.validateIntReqRequest(ctx, requestedUser, intReqID)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
-	if auth.handshakingURI != nil {
-		// We're currently handshaking, which means
-		// we don't know this account yet. This should
-		// be a very rare race condition.
-		err := gtserror.Newf("network race handshaking %s", auth.handshakingURI)
-		return nil, gtserror.NewErrorInternalError(err)
-	}
-
-	receivingAcct := auth.receivingAcct
-
-	req, err := p.state.DB.GetInteractionRequestByID(ctx, reqID)
-	if err != nil && !errors.Is(err, db.ErrNoEntries) {
-		err := gtserror.Newf("db error getting interaction request %s: %w", reqID, err)
-		return nil, gtserror.NewErrorInternalError(err)
-	}
-
-	if req == nil || !req.IsAccepted() {
-		// Request doesn't exist or hasn't been accepted.
-		err := gtserror.Newf("interaction request %s not found", reqID)
-		return nil, gtserror.NewErrorNotFound(err)
-	}
-
-	if req.TargetAccountID != receivingAcct.ID {
-		const text = "interaction request does not belong to receiving account"
-		return nil, gtserror.NewErrorNotFound(errors.New(text))
-	}
-
-	accept, err := p.converter.InteractionReqToASAccept(ctx, req)
+	// Convert + serialize the Accept.
+	accept, err := p.converter.InteractionReqToASAccept(ctx, intReq)
 	if err != nil {
-		err := gtserror.Newf("error converting accept: %w", err)
+		err := gtserror.Newf("error converting to accept: %w", err)
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
diff --git a/internal/processing/fedi/authorization.go b/internal/processing/fedi/authorization.go
new file mode 100644
index 000000000..bbba6a2d8
--- /dev/null
+++ b/internal/processing/fedi/authorization.go
@@ -0,0 +1,57 @@
+// 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 fedi
+
+import (
+	"context"
+
+	"code.superseriousbusiness.org/gotosocial/internal/ap"
+	"code.superseriousbusiness.org/gotosocial/internal/gtserror"
+)
+
+// AuthorizationGet handles the getting of a fedi/activitypub
+// representation of a local interaction authorization.
+//
+// It performs appropriate authentication before
+// returning a JSON serializable interface.
+func (p *Processor) AuthorizationGet(
+	ctx context.Context,
+	requestedUser string,
+	intReqID string,
+) (any, gtserror.WithCode) {
+	// Ensure valid request, intReq exists, etc.
+	intReq, errWithCode := p.validateIntReqRequest(ctx, requestedUser, intReqID)
+	if errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	// Convert + serialize the Authorization.
+	authorization, err := p.converter.InteractionReqToASAuthorization(ctx, intReq)
+	if err != nil {
+		err := gtserror.Newf("error converting to authorization: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	data, err := ap.Serialize(authorization)
+	if err != nil {
+		err := gtserror.Newf("error serializing accept: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return data, nil
+}
diff --git a/internal/processing/fedi/common.go b/internal/processing/fedi/common.go
index 9059aef39..fc783f93e 100644
--- a/internal/processing/fedi/common.go
+++ b/internal/processing/fedi/common.go
@@ -20,6 +20,7 @@ package fedi
 import (
 	"context"
 	"errors"
+	"fmt"
 	"net/url"
 
 	"code.superseriousbusiness.org/gotosocial/internal/db"
@@ -81,3 +82,52 @@ func (p *Processor) authenticate(ctx context.Context, requestedUser string) (*co
 		receivingAcct:  receiver,
 	}, nil
 }
+
+// validateIntReqRequest is a shortcut function
+// for returning an accepted interaction request
+// targeting `requestedUser`.
+func (p *Processor) validateIntReqRequest(
+	ctx context.Context,
+	requestedUser string,
+	intReqID string,
+) (*gtsmodel.InteractionRequest, gtserror.WithCode) {
+	// Authenticate incoming request, getting related accounts.
+	auth, errWithCode := p.authenticate(ctx, requestedUser)
+	if errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	if auth.handshakingURI != nil {
+		// We're currently handshaking, which means we don't know
+		// this account yet. This should be a very rare race condition.
+		err := gtserror.Newf("network race handshaking %s", auth.handshakingURI)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Fetch interaction request with the given ID.
+	req, err := p.state.DB.GetInteractionRequestByID(ctx, intReqID)
+	if err != nil && !errors.Is(err, db.ErrNoEntries) {
+		err := gtserror.Newf("db error getting interaction request %s: %w", intReqID, err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Ensure that this is an existing
+	// and *accepted* interaction request.
+	if req == nil || !req.IsAccepted() {
+		const text = "interaction request not found"
+		return nil, gtserror.NewErrorNotFound(errors.New(text))
+	}
+
+	// Ensure interaction request was accepted
+	// by the account in the request path.
+	if req.TargetAccountID != auth.receivingAcct.ID {
+		text := fmt.Sprintf(
+			"account %s is not targeted by interaction request %s and therefore can't accept it",
+			requestedUser, intReqID,
+		)
+		return nil, gtserror.NewErrorNotFound(errors.New(text))
+	}
+
+	// All fine.
+	return req, nil
+}