fix: assorted ActivityPub code only refactors (#8708)

Fix parts of issue #8221 and part of PR #4767 Is linked to https://codeberg.org/forgejo/forgejo/pulls/8274 The commit 555f6e57ad fixes timeout forgejo/forgejo#8274 (Kommentar) Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8708 Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org> Co-authored-by: Michael Jerger <michael.jerger@meissa-gmbh.de> Co-committed-by: Michael Jerger <michael.jerger@meissa-gmbh.de>
2025-08-08 04:06:44 +02:00 · 2025-07-28 15:17:29 +02:00 · 2025-07-28 15:17:29 +02:00 · 388e4eb44b
commit 388e4eb44b
parent 106707b40f
20 changed files with 744 additions and 69 deletions
--- a/.deadcode-out
+++ b/.deadcode-out
@ -246,7 +246,10 @@ forgejo.org/services/context
 	GetPrivateContext

 forgejo.org/services/federation
+	NewErrInternalf
+	ErrInternal.Error
 	Init
+	NewServiceResultWithBytes

 forgejo.org/services/repository
 	IsErrForkAlreadyExist
--- a/models/repo/repo_repository.go
+++ b/models/repo/repo_repository.go
@ -38,18 +38,18 @@ func StoreFollowingRepos(ctx context.Context, localRepoID int64, followingRepoLi
 	}

 	// Begin transaction
-	ctx, committer, err := db.TxContext((ctx))
+	dbCtx, committer, err := db.TxContext((ctx))
 	if err != nil {
 		return err
 	}
 	defer committer.Close()

-	_, err = db.GetEngine(ctx).Where("repo_id=?", localRepoID).Delete(FollowingRepo{})
+	_, err = db.GetEngine(dbCtx).Where("repo_id=?", localRepoID).Delete(FollowingRepo{})
 	if err != nil {
 		return err
 	}
 	for _, followingRepo := range followingRepoList {
-		_, err = db.GetEngine(ctx).Insert(followingRepo)
+		_, err = db.GetEngine(dbCtx).Insert(followingRepo)
 		if err != nil {
 			return err
 		}
--- a/models/user/follow.go
+++ b/models/user/follow.go
@ -39,21 +39,21 @@ func FollowUser(ctx context.Context, userID, followID int64) (err error) {
 		return ErrBlockedByUser
 	}

-	ctx, committer, err := db.TxContext(ctx)
+	dbCtx, committer, err := db.TxContext(ctx)
 	if err != nil {
 		return err
 	}
 	defer committer.Close()

-	if err = db.Insert(ctx, &Follow{UserID: userID, FollowID: followID}); err != nil {
+	if err = db.Insert(dbCtx, &Follow{UserID: userID, FollowID: followID}); err != nil {
 		return err
 	}

-	if _, err = db.Exec(ctx, "UPDATE `user` SET num_followers = num_followers + 1 WHERE id = ?", followID); err != nil {
+	if _, err = db.Exec(dbCtx, "UPDATE `user` SET num_followers = num_followers + 1 WHERE id = ?", followID); err != nil {
 		return err
 	}

-	if _, err = db.Exec(ctx, "UPDATE `user` SET num_following = num_following + 1 WHERE id = ?", userID); err != nil {
+	if _, err = db.Exec(dbCtx, "UPDATE `user` SET num_following = num_following + 1 WHERE id = ?", userID); err != nil {
 		return err
 	}
 	return committer.Commit()
@ -65,21 +65,21 @@ func UnfollowUser(ctx context.Context, userID, followID int64) (err error) {
 		return nil
 	}

-	ctx, committer, err := db.TxContext(ctx)
+	dbCtx, committer, err := db.TxContext(ctx)
 	if err != nil {
 		return err
 	}
 	defer committer.Close()

-	if _, err = db.DeleteByBean(ctx, &Follow{UserID: userID, FollowID: followID}); err != nil {
+	if _, err = db.DeleteByBean(dbCtx, &Follow{UserID: userID, FollowID: followID}); err != nil {
 		return err
 	}

-	if _, err = db.Exec(ctx, "UPDATE `user` SET num_followers = num_followers - 1 WHERE id = ?", followID); err != nil {
+	if _, err = db.Exec(dbCtx, "UPDATE `user` SET num_followers = num_followers - 1 WHERE id = ?", followID); err != nil {
 		return err
 	}

-	if _, err = db.Exec(ctx, "UPDATE `user` SET num_following = num_following - 1 WHERE id = ?", userID); err != nil {
+	if _, err = db.Exec(dbCtx, "UPDATE `user` SET num_following = num_following - 1 WHERE id = ?", userID); err != nil {
 		return err
 	}
 	return committer.Commit()
--- a/models/user/user_repository.go
+++ b/models/user/user_repository.go
@ -28,7 +28,7 @@ func CreateFederatedUser(ctx context.Context, user *User, federatedUser *Federat
 	}

 	// Begin transaction
-	ctx, committer, err := db.TxContext((ctx))
+	txCtx, committer, err := db.TxContext(ctx)
 	if err != nil {
 		return err
 	}
@ -39,7 +39,7 @@ func CreateFederatedUser(ctx context.Context, user *User, federatedUser *Federat
 		}
 	}()

-	if err := CreateUser(ctx, user, &overwrite); err != nil {
+	if err := CreateUser(txCtx, user, &overwrite); err != nil {
 		return err
 	}

@ -48,7 +48,7 @@ func CreateFederatedUser(ctx context.Context, user *User, federatedUser *Federat
 		return err
 	}

-	_, err = db.GetEngine(ctx).Insert(federatedUser)
+	_, err = db.GetEngine(txCtx).Insert(federatedUser)
 	if err != nil {
 		return err
 	}
@ -70,7 +70,7 @@ func FindFederatedUser(ctx context.Context, externalID string, federationHostID
 	if err != nil {
 		return nil, nil, err
 	} else if !has {
-		return nil, nil, fmt.Errorf("User %v for federated user is missing", federatedUser.UserID)
+		return nil, nil, fmt.Errorf("FederatedUser table contains entry for user ID %v, but no user with this ID exists", federatedUser.UserID)
 	}

 	if res, err := validation.IsValid(*user); !res {
@ -87,7 +87,7 @@ func GetFederatedUser(ctx context.Context, externalID string, federationHostID i
 	if err != nil {
 		return nil, nil, err
 	} else if federatedUser == nil {
-		return nil, nil, fmt.Errorf("FederatedUser for externalId = %v and federationHostId = %v does not exist", externalID, federationHostID)
+		return nil, nil, fmt.Errorf("FederatedUser not found (given externalId: %v, federationHostId: %v)", externalID, federationHostID)
 	}
 	return user, federatedUser, nil
 }
@ -99,13 +99,13 @@ func GetFederatedUserByUserID(ctx context.Context, userID int64) (*User, *Federa
 	if err != nil {
 		return nil, nil, err
 	} else if !has {
-		return nil, nil, fmt.Errorf("Federated user %v does not exist", federatedUser.UserID)
+		return nil, nil, fmt.Errorf("FederatedUser table does not contain entry for user ID: %v", federatedUser.UserID)
 	}
 	has, err = db.GetEngine(ctx).ID(federatedUser.UserID).Get(user)
 	if err != nil {
 		return nil, nil, err
 	} else if !has {
-		return nil, nil, fmt.Errorf("User %v for federated user is missing", federatedUser.UserID)
+		return nil, nil, fmt.Errorf("FederatedUser table contains entry for user ID %v, but no user with this ID exists", federatedUser.UserID)
 	}

 	if res, err := validation.IsValid(*user); !res {
@ -130,7 +130,7 @@ func FindFederatedUserByKeyID(ctx context.Context, keyID string) (*User, *Federa
 	if err != nil {
 		return nil, nil, err
 	} else if !has {
-		return nil, nil, fmt.Errorf("User %v for federated user is missing", federatedUser.UserID)
+		return nil, nil, fmt.Errorf("FederatedUser table contains entry for user ID %v, but no user with this ID exists", federatedUser.UserID)
 	}

 	if res, err := validation.IsValid(*user); !res {
--- a/modules/activitypub/client.go
+++ b/modules/activitypub/client.go
@ -66,6 +66,11 @@ type ClientFactory struct {

 // NewClient function
 func NewClientFactory() (c *ClientFactory, err error) {
+	return NewClientFactoryWithTimeout(5 * time.Second)
+}
+
+// NewClient function
+func NewClientFactoryWithTimeout(timeout time.Duration) (c *ClientFactory, err error) {
 	if err = containsRequiredHTTPHeaders(http.MethodGet, setting.Federation.GetHeaders); err != nil {
 		return nil, err
 	} else if err = containsRequiredHTTPHeaders(http.MethodPost, setting.Federation.PostHeaders); err != nil {
@ -77,7 +82,7 @@ func NewClientFactory() (c *ClientFactory, err error) {
 			Transport: &http.Transport{
 				Proxy: proxy.Proxy(),
 			},
-			Timeout: 5 * time.Second,
+			Timeout: timeout,
 		},
 		algs:        setting.HttpsigAlgs,
 		digestAlg:   httpsig.DigestAlgorithm(setting.Federation.DigestAlgorithm),
--- a/routers/api/v1/activitypub/repository.go
+++ b/routers/api/v1/activitypub/repository.go
@ -71,10 +71,11 @@ func RepositoryInbox(ctx *context.APIContext) {
 	repository := ctx.Repo.Repository
 	log.Info("RepositoryInbox: repo: %v", repository)
 	form := web.GetForm(ctx)
-	// TODO: Decide between like/undo{like} activity
-	httpStatus, title, err := federation.ProcessLikeActivity(ctx, form, repository.ID)
+	activity := form.(*ap.Activity)
+	result, err := federation.ProcessRepositoryInbox(ctx, activity, repository.ID)
 	if err != nil {
-		ctx.Error(httpStatus, title, err)
+		ctx.Error(federation.HTTPStatus(err), "Processing Repository Inbox failed", result)
+		return
 	}
-	ctx.Status(http.StatusNoContent)
+	responseServiceResult(ctx, result)
 }
--- a/routers/api/v1/activitypub/reqsignature.go
+++ b/routers/api/v1/activitypub/reqsignature.go
@ -8,13 +8,13 @@ import (

 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
-	gitea_context "forgejo.org/services/context"
+	services_context "forgejo.org/services/context"
 	"forgejo.org/services/federation"

 	"github.com/42wim/httpsig"
 )

-func verifyHTTPUserOrInstanceSignature(ctx *gitea_context.APIContext) (authenticated bool, err error) {
+func verifyHTTPUserOrInstanceSignature(ctx services_context.APIContext) (authenticated bool, err error) {
 	if !setting.Federation.SignatureEnforced {
 		return true, nil
 	}
@ -28,9 +28,9 @@ func verifyHTTPUserOrInstanceSignature(ctx *gitea_context.APIContext) (authentic
 	}

 	signatureAlgorithm := httpsig.Algorithm(setting.Federation.SignatureAlgorithms[0])
-	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx.Base, v.KeyId())
+	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx, v.KeyId())
 	if err != nil || pubKey == nil {
-		pubKey, err = federation.FindOrCreateFederationHostKey(ctx.Base, v.KeyId())
+		pubKey, err = federation.FindOrCreateFederationHostKey(ctx, v.KeyId())
 		if err != nil {
 			return false, err
 		}
@ -43,7 +43,7 @@ func verifyHTTPUserOrInstanceSignature(ctx *gitea_context.APIContext) (authentic
 	return true, nil
 }

-func verifyHTTPUserSignature(ctx *gitea_context.APIContext) (authenticated bool, err error) {
+func verifyHTTPUserSignature(ctx services_context.APIContext) (authenticated bool, err error) {
 	if !setting.Federation.SignatureEnforced {
 		return true, nil
 	}
@ -57,7 +57,7 @@ func verifyHTTPUserSignature(ctx *gitea_context.APIContext) (authenticated bool,
 	}

 	signatureAlgorithm := httpsig.Algorithm(setting.Federation.SignatureAlgorithms[0])
-	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx.Base, v.KeyId())
+	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx, v.KeyId())
 	if err != nil {
 		return false, err
 	}
@ -70,9 +70,9 @@ func verifyHTTPUserSignature(ctx *gitea_context.APIContext) (authenticated bool,
 }

 // ReqHTTPSignature function
-func ReqHTTPUserOrInstanceSignature() func(ctx *gitea_context.APIContext) {
-	return func(ctx *gitea_context.APIContext) {
-		if authenticated, err := verifyHTTPUserOrInstanceSignature(ctx); err != nil {
+func ReqHTTPUserOrInstanceSignature() func(ctx *services_context.APIContext) {
+	return func(ctx *services_context.APIContext) {
+		if authenticated, err := verifyHTTPUserOrInstanceSignature(*ctx); err != nil {
 			log.Warn("verifyHttpSignatures failed: %v", err)
 			ctx.Error(http.StatusBadRequest, "reqSignature", "request signature verification failed")
 		} else if !authenticated {
@ -81,10 +81,10 @@ func ReqHTTPUserOrInstanceSignature() func(ctx *gitea_context.APIContext) {
 	}
 }

-// ReqHTTPSignature function
-func ReqHTTPUserSignature() func(ctx *gitea_context.APIContext) {
-	return func(ctx *gitea_context.APIContext) {
-		if authenticated, err := verifyHTTPUserSignature(ctx); err != nil {
+// ReqHTTPUserSignature function
+func ReqHTTPUserSignature() func(ctx *services_context.APIContext) {
+	return func(ctx *services_context.APIContext) {
+		if authenticated, err := verifyHTTPUserSignature(*ctx); err != nil {
 			log.Warn("verifyHttpSignatures failed: %v", err)
 			ctx.Error(http.StatusBadRequest, "reqSignature", "request signature verification failed")
 		} else if !authenticated {
--- a/routers/api/v1/activitypub/response.go
+++ b/routers/api/v1/activitypub/response.go
@ -10,12 +10,46 @@ import (
 	"forgejo.org/modules/forgefed"
 	"forgejo.org/modules/log"
 	"forgejo.org/services/context"
+	"forgejo.org/services/federation"

 	ap "github.com/go-ap/activitypub"
 	"github.com/go-ap/jsonld"
 )

 // Respond with an ActivityStreams object
+func responseServiceResult(ctx *context.APIContext, result federation.ServiceResult) {
+	ctx.Resp.Header().Add("Content-Type", activitypub.ActivityStreamsContentType)
+
+	switch {
+	case result.StatusOnly():
+		ctx.Resp.WriteHeader(result.HTTPStatus)
+		return
+	case result.WithBytes():
+		ctx.Resp.WriteHeader(result.HTTPStatus)
+		if _, err := ctx.Resp.Write(result.Bytes); err != nil {
+			log.Error("Error writing a response: %v", err)
+			ctx.Error(http.StatusInternalServerError, "Error writing a response", err)
+			return
+		}
+	case result.WithActivity():
+		binary, err := jsonld.WithContext(
+			jsonld.IRI(ap.ActivityBaseURI),
+			jsonld.IRI(ap.SecurityContextURI),
+			jsonld.IRI(forgefed.ForgeFedNamespaceURI),
+		).Marshal(result.Activity)
+		if err != nil {
+			ctx.ServerError("Marshal", err)
+			return
+		}
+		ctx.Resp.WriteHeader(result.HTTPStatus)
+		if _, err = ctx.Resp.Write(binary); err != nil {
+			log.Error("write to resp err: %v", err)
+		}
+	}
+}
+
+// Respond with an ActivityStreams object
+// Deprecated
 func response(ctx *context.APIContext, v any) {
 	binary, err := jsonld.WithContext(
 		jsonld.IRI(ap.ActivityBaseURI),
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@ -81,7 +81,6 @@ import (
 	repo_model "forgejo.org/models/repo"
 	"forgejo.org/models/unit"
 	user_model "forgejo.org/models/user"
-	"forgejo.org/modules/forgefed"
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
 	api "forgejo.org/modules/structs"
@ -853,7 +852,7 @@ func Routes() *web.Route {
 				m.Group("/repository-id/{repository-id}", func() {
 					m.Get("", activitypub.ReqHTTPUserSignature(), activitypub.Repository)
 					m.Post("/inbox",
-						bind(forgefed.ForgeLike{}),
+						bind(ap.Activity{}),
 						activitypub.ReqHTTPUserSignature(),
 						activitypub.RepositoryInbox)
 				}, context.RepositoryIDAssignmentAPI())
--- a/services/federation/error.go
+++ b/services/federation/error.go
@ -0,0 +1,44 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package federation
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type ErrNotAcceptable struct {
+	Message string
+}
+
+func NewErrNotAcceptablef(format string, a ...any) ErrNotAcceptable {
+	message := fmt.Sprintf(format, a...)
+	return ErrNotAcceptable{Message: message}
+}
+
+func (err ErrNotAcceptable) Error() string {
+	return fmt.Sprintf("NotAcceptable: %v", err.Message)
+}
+
+type ErrInternal struct {
+	Message string
+}
+
+func NewErrInternalf(format string, a ...any) ErrInternal {
+	message := fmt.Sprintf(format, a...)
+	return ErrInternal{Message: message}
+}
+
+func (err ErrInternal) Error() string {
+	return fmt.Sprintf("InternalServerError: %v", err.Message)
+}
+
+func HTTPStatus(err error) int {
+	switch err.(type) {
+	case ErrNotAcceptable:
+		return http.StatusNotAcceptable
+	default:
+		return http.StatusInternalServerError
+	}
+}
--- a/services/federation/federation_service.go
+++ b/services/federation/federation_service.go
@ -18,7 +18,6 @@ import (
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
 	"forgejo.org/modules/validation"
-	context_service "forgejo.org/services/context"

 	"github.com/google/uuid"
 )
@ -27,7 +26,7 @@ func Init() error {
 	return nil
 }

-func FindOrCreateFederationHost(ctx *context_service.Base, actorURI string) (*forgefed.FederationHost, error) {
+func FindOrCreateFederationHost(ctx context.Context, actorURI string) (*forgefed.FederationHost, error) {
 	rawActorID, err := fm.NewActorID(actorURI)
 	if err != nil {
 		return nil, err
@ -46,7 +45,7 @@ func FindOrCreateFederationHost(ctx *context_service.Base, actorURI string) (*fo
 	return federationHost, nil
 }

-func FindOrCreateFederatedUser(ctx *context_service.Base, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
+func FindOrCreateFederatedUser(ctx context.Context, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
 	user, federatedUser, federationHost, err := findFederatedUser(ctx, actorURI)
 	if err != nil {
 		return nil, nil, nil, err
@ -57,20 +56,21 @@ func FindOrCreateFederatedUser(ctx *context_service.Base, actorURI string) (*use
 	}

 	if user != nil {
-		log.Trace("Found local federatedUser: %#v", user)
+		log.Trace("Local ActivityPub user found (actorURI: %#v, user: %#v)", actorURI, user)
 	} else {
+		log.Trace("Attempting to create new user and federatedUser for actorURI: %#v", actorURI)
 		user, federatedUser, err = createUserFromAP(ctx, personID, federationHost.ID)
 		if err != nil {
 			return nil, nil, nil, err
 		}
-		log.Trace("Created federatedUser from ap: %#v", user)
+		log.Trace("Created user %#v with federatedUser %#v from distant server", user, federatedUser)
 	}
 	log.Trace("Got user: %v", user.Name)

 	return user, federatedUser, federationHost, nil
 }

-func findFederatedUser(ctx *context_service.Base, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
+func findFederatedUser(ctx context.Context, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
 	federationHost, err := FindOrCreateFederationHost(ctx, actorURI)
 	if err != nil {
 		return nil, nil, nil, err
@ -90,6 +90,7 @@ func findFederatedUser(ctx *context_service.Base, actorURI string) (*user.User,

 func createFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forgefed.FederationHost, error) {
 	actionsUser := user.NewAPServerActor()
+
 	clientFactory, err := activitypub.GetClientFactory(ctx)
 	if err != nil {
 		return nil, err
@ -161,7 +162,7 @@ func fetchUserFromAP(ctx context.Context, personID fm.PersonID, federationHostID
 		return nil, nil, err
 	}

-	log.Info("Fetched valid person:%q", person)
+	log.Info("Fetched valid person from distant server: %q", person)

 	localFqdn, err := url.ParseRequestURI(setting.AppURL)
 	if err != nil {
@ -220,7 +221,7 @@ func fetchUserFromAP(ctx context.Context, personID fm.PersonID, federationHostID
 		},
 	}

-	log.Info("Fetch federatedUser:%q", federatedUser)
+	log.Info("Fetched person's %q federatedUser from distant server: %q", person, federatedUser)
 	return &newUser, &federatedUser, nil
 }

@ -234,6 +235,6 @@ func createUserFromAP(ctx context.Context, personID fm.PersonID, federationHostI
 		return nil, nil, err
 	}

-	log.Info("Created federatedUser:%q", federatedUser)
+	log.Info("Created federatedUser: %q", federatedUser)
 	return newUser, federatedUser, nil
 }
--- a/services/federation/repository_inbox_like.go
+++ b/services/federation/repository_inbox_like.go
@ -5,7 +5,6 @@ package federation

 import (
 	"context"
-	"errors"
 	"fmt"
 	"net/http"
 	"time"
@ -18,6 +17,8 @@ import (
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/validation"
 	context_service "forgejo.org/services/context"
+
+	ap "github.com/go-ap/activitypub"
 )

 // ProcessLikeActivity receives a ForgeLike activity and does the following:
@ -27,32 +28,32 @@ import (
 // Validation of incoming RepositoryID against Local RepositoryID
 // Star the repo if it wasn't already stared
 // Do some mitigation against out of order attacks
-func ProcessLikeActivity(ctx *context_service.APIContext, form any, repositoryID int64) (int, string, error) {
-	activity := form.(*fm.ForgeLike)
-	if res, err := validation.IsValid(activity); !res {
-		return http.StatusNotAcceptable, "Invalid activity", err
+func ProcessLikeActivity(ctx context.Context, activity *ap.Activity, repositoryID int64) (ServiceResult, error) {
+	constructorLikeActivity, _ := fm.NewForgeLike(activity.Actor.GetLink().String(), activity.Object.GetLink().String(), activity.StartTime)
+	if res, err := validation.IsValid(constructorLikeActivity); !res {
+		return ServiceResult{}, NewErrNotAcceptablef("Invalid activity: %v", err)
 	}
 	log.Trace("Activity validated: %#v", activity)

 	// parse actorID (person)
 	actorURI := activity.Actor.GetID().String()
-	user, _, federationHost, err := FindOrCreateFederatedUser(ctx.Base, actorURI)
+	user, _, federationHost, err := FindOrCreateFederatedUser(ctx, actorURI)
 	if err != nil {
-		ctx.Error(http.StatusNotAcceptable, "Federated user not found", err)
-		return http.StatusInternalServerError, "FindOrCreateFederatedUser", err
+		log.Error("Federated user not found (%s): %v", actorURI, err)
+		return ServiceResult{}, NewErrNotAcceptablef("FindOrCreateFederatedUser failed: %v", err)
 	}

-	if !activity.IsNewer(federationHost.LatestActivity) {
-		return http.StatusNotAcceptable, "Activity out of order.", errors.New("Activity already processed")
+	if !constructorLikeActivity.IsNewer(federationHost.LatestActivity) {
+		return ServiceResult{}, NewErrNotAcceptablef("LatestActivity: activity already processed: %v", err)
 	}

 	// parse objectID (repository)
-	objectID, err := fm.NewRepositoryID(activity.Object.GetID().String(), string(forgefed.ForgejoSourceType))
+	objectID, err := fm.NewRepositoryID(constructorLikeActivity.Object.GetID().String(), string(forgefed.ForgejoSourceType))
 	if err != nil {
-		return http.StatusNotAcceptable, "Invalid objectId", err
+		return ServiceResult{}, NewErrNotAcceptablef("Parsing repo objectID failed: %v", err)
 	}
 	if objectID.ID != fmt.Sprint(repositoryID) {
-		return http.StatusNotAcceptable, "Invalid objectId", err
+		return ServiceResult{}, NewErrNotAcceptablef("Invalid repoId: %v", err)
 	}
 	log.Trace("Object accepted: %#v", objectID)

@ -61,16 +62,16 @@ func ProcessLikeActivity(ctx *context_service.APIContext, form any, repositoryID
 	if !alreadyStared {
 		err = repo.StarRepo(ctx, user.ID, repositoryID, true)
 		if err != nil {
-			return http.StatusNotAcceptable, "Error staring", err
+			return ServiceResult{}, NewErrNotAcceptablef("Staring failed: %v", err)
 		}
 	}
 	federationHost.LatestActivity = activity.StartTime
 	err = forgefed.UpdateFederationHost(ctx, federationHost)
 	if err != nil {
-		return http.StatusNotAcceptable, "Error updating federatedHost", err
+		return ServiceResult{}, NewErrNotAcceptablef("Updating federatedHost failed: %v", err)
 	}

-	return 0, "", nil
+	return NewServiceResultStatusOnly(http.StatusNoContent), nil
 }

 // Create or update a list of FollowingRepo structs
--- a/services/federation/repository_service.go
+++ b/services/federation/repository_service.go
@ -0,0 +1,19 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package federation
+
+import (
+	"context"
+
+	ap "github.com/go-ap/activitypub"
+)
+
+func ProcessRepositoryInbox(ctx context.Context, activity *ap.Activity, repositoryID int64) (ServiceResult, error) {
+	switch activity.Type {
+	case ap.LikeType:
+		return ProcessLikeActivity(ctx, activity, repositoryID)
+	default:
+		return ServiceResult{}, NewErrNotAcceptablef("Not a like activity: %v", activity.Type)
+	}
+}
--- a/services/federation/result.go
+++ b/services/federation/result.go
@ -0,0 +1,35 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package federation
+
+import "github.com/go-ap/activitypub"
+
+type ServiceResult struct {
+	HTTPStatus   int
+	Bytes        []byte
+	Activity     activitypub.Activity
+	withBytes    bool
+	withActivity bool
+	statusOnly   bool
+}
+
+func NewServiceResultStatusOnly(status int) ServiceResult {
+	return ServiceResult{HTTPStatus: status, statusOnly: true}
+}
+
+func NewServiceResultWithBytes(status int, bytes []byte) ServiceResult {
+	return ServiceResult{HTTPStatus: status, Bytes: bytes, withBytes: true}
+}
+
+func (serviceResult ServiceResult) WithBytes() bool {
+	return serviceResult.withBytes
+}
+
+func (serviceResult ServiceResult) WithActivity() bool {
+	return serviceResult.withActivity
+}
+
+func (serviceResult ServiceResult) StatusOnly() bool {
+	return serviceResult.statusOnly
+}
--- a/services/federation/signature_service.go
+++ b/services/federation/signature_service.go
@ -4,6 +4,7 @@
 package federation

 import (
+	"context"
 	"crypto/x509"
 	"database/sql"
 	"encoding/pem"
@ -15,13 +16,12 @@ import (
 	"forgejo.org/models/user"
 	"forgejo.org/modules/activitypub"
 	fm "forgejo.org/modules/forgefed"
-	context_service "forgejo.org/services/context"

 	ap "github.com/go-ap/activitypub"
 )

 // Factory function for ActorID. Created struct is asserted to be valid
-func NewActorIDFromKeyID(ctx *context_service.Base, uri string) (fm.ActorID, error) {
+func NewActorIDFromKeyID(ctx context.Context, uri string) (fm.ActorID, error) {
 	parsedURI, err := url.Parse(uri)
 	parsedURI.Fragment = ""
 	if err != nil {
@ -54,7 +54,7 @@ func NewActorIDFromKeyID(ctx *context_service.Base, uri string) (fm.ActorID, err
 	return result, err
 }

-func FindOrCreateFederatedUserKey(ctx *context_service.Base, keyID string) (pubKey any, err error) {
+func FindOrCreateFederatedUserKey(ctx context.Context, keyID string) (pubKey any, err error) {
 	var federatedUser *user.FederatedUser
 	var keyURL *url.URL

@ -122,7 +122,7 @@ func FindOrCreateFederatedUserKey(ctx *context_service.Base, keyID string) (pubK
 	return nil, nil
 }

-func FindOrCreateFederationHostKey(ctx *context_service.Base, keyID string) (pubKey any, err error) {
+func FindOrCreateFederationHostKey(ctx context.Context, keyID string) (pubKey any, err error) {
 	keyURL, err := url.Parse(keyID)
 	if err != nil {
 		return nil, err
@ -183,8 +183,9 @@ func FindOrCreateFederationHostKey(ctx *context_service.Base, keyID string) (pub
 	return nil, nil
 }

-func fetchKeyFromAp(ctx *context_service.Base, keyURL url.URL) (pubKey any, pubKeyBytes []byte, apPerson *ap.Person, err error) {
+func fetchKeyFromAp(ctx context.Context, keyURL url.URL) (pubKey any, pubKeyBytes []byte, apPerson *ap.Person, err error) {
 	actionsUser := user.NewAPServerActor()
+
 	clientFactory, err := activitypub.GetClientFactory(ctx)
 	if err != nil {
 		return nil, nil, nil, err
--- a/tests/integration/api_activitypub_actor_test.go
+++ b/tests/integration/api_activitypub_actor_test.go
@ -0,0 +1,77 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strconv"
+	"testing"
+
+	"forgejo.org/modules/forgefed"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+	"forgejo.org/routers"
+	"forgejo.org/services/contexttest"
+	"forgejo.org/services/federation"
+	"forgejo.org/tests"
+
+	ap "github.com/go-ap/activitypub"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestActivityPubActor(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+	defer tests.PrepareTestEnv(t)()
+
+	req := NewRequest(t, "GET", "/api/v1/activitypub/actor")
+	resp := MakeRequest(t, req, http.StatusOK)
+	assert.Contains(t, resp.Body.String(), "@context")
+
+	var actor ap.Actor
+	err := actor.UnmarshalJSON(resp.Body.Bytes())
+	require.NoError(t, err)
+
+	assert.Equal(t, ap.ApplicationType, actor.Type)
+	assert.Equal(t, "ghost", actor.PreferredUsername.String())
+	keyID := actor.GetID().String()
+	assert.Regexp(t, "activitypub/actor$", keyID)
+	assert.Regexp(t, "activitypub/actor/inbox$", actor.Inbox.GetID().String())
+
+	pubKey := actor.PublicKey
+	assert.NotNil(t, pubKey)
+	publicKeyID := keyID + "#main-key"
+	assert.Equal(t, pubKey.ID.String(), publicKeyID)
+
+	pubKeyPem := pubKey.PublicKeyPem
+	assert.NotNil(t, pubKeyPem)
+	assert.Regexp(t, "^-----BEGIN PUBLIC KEY-----", pubKeyPem)
+}
+
+func TestActorNewFromKeyId(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		ctx, _ := contexttest.MockAPIContext(t, "/api/v1/activitypub/actor")
+		sut, err := federation.NewActorIDFromKeyID(ctx.Base, fmt.Sprintf("%sapi/v1/activitypub/actor#main-key", u))
+		require.NoError(t, err)
+
+		port, err := strconv.ParseUint(u.Port(), 10, 16)
+		require.NoError(t, err)
+
+		assert.Equal(t, forgefed.ActorID{
+			ID:                 "actor",
+			HostSchema:         "http",
+			Path:               "api/v1/activitypub",
+			Host:               setting.Domain,
+			HostPort:           uint16(port),
+			UnvalidatedInput:   fmt.Sprintf("http://%s:%d/api/v1/activitypub/actor", setting.Domain, port),
+			IsPortSupplemented: false,
+		}, sut)
+	})
+}
--- a/tests/integration/api_activitypub_person_test.go
+++ b/tests/integration/api_activitypub_person_test.go
@ -0,0 +1,113 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+	"time"
+
+	"forgejo.org/models/unittest"
+	user_model "forgejo.org/models/user"
+	"forgejo.org/modules/activitypub"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+	"forgejo.org/routers"
+	"forgejo.org/services/contexttest"
+	"forgejo.org/tests"
+
+	ap "github.com/go-ap/activitypub"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestActivityPubPerson(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
+
+	onGiteaRun(t, func(t *testing.T, localUrl *url.URL) {
+		defer test.MockVariableValue(&setting.AppURL, localUrl.String())()
+
+		localUserID := 2
+		localUserName := "user2"
+		localUserURL := fmt.Sprintf("%sapi/v1/activitypub/user-id/%d", localUrl, localUserID)
+
+		// distantURL := federatedSrv.URL
+		// distantUser15URL := fmt.Sprintf("%s/api/v1/activitypub/user-id/15", distantURL)
+
+		// Unsigned request
+		t.Run("UnsignedRequest", func(t *testing.T) {
+			req := NewRequest(t, "GET", localUserURL)
+			MakeRequest(t, req, http.StatusBadRequest)
+		})
+
+		// Signed request
+		t.Run("SignedRequestValidation", func(t *testing.T) {
+			ctx, _ := contexttest.MockAPIContext(t, localUserURL)
+			cf, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+			require.NoError(t, err)
+
+			c, err := cf.WithKeysDirect(ctx, mock.Persons[0].PrivKey,
+				mock.Persons[0].KeyID(federatedSrv.URL))
+			require.NoError(t, err)
+
+			resp, err := c.GetBody(localUserURL)
+			require.NoError(t, err)
+
+			var person ap.Person
+			err = person.UnmarshalJSON(resp)
+			require.NoError(t, err)
+
+			assert.Equal(t, ap.PersonType, person.Type)
+			assert.Equal(t, localUserName, person.PreferredUsername.String())
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d$", localUserID), person.GetID())
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d/inbox$", localUserID), person.Inbox.GetID().String())
+
+			assert.NotNil(t, person.PublicKey)
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d#main-key$", localUserID), person.PublicKey.ID)
+
+			assert.NotNil(t, person.PublicKey.PublicKeyPem)
+			assert.Regexp(t, "^-----BEGIN PUBLIC KEY-----", person.PublicKey.PublicKeyPem)
+		})
+	})
+}
+
+func TestActivityPubMissingPerson(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	req := NewRequest(t, "GET", "/api/v1/activitypub/user-id/999999999")
+	resp := MakeRequest(t, req, http.StatusNotFound)
+	assert.Contains(t, resp.Body.String(), "user does not exist")
+}
+
+func TestActivityPubPersonInbox(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		defer test.MockVariableValue(&setting.AppURL, u.String())()
+		user1 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+
+		user1url := u.JoinPath("/api/v1/activitypub/user-id/1").String() + "#main-key"
+		user2inboxurl := u.JoinPath("/api/v1/activitypub/user-id/2/inbox").String()
+		ctx, _ := contexttest.MockAPIContext(t, user2inboxurl)
+		cf, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+		require.NoError(t, err)
+		c, err := cf.WithKeys(ctx, user1, user1url)
+		require.NoError(t, err)
+
+		// Signed request "succeeds"
+		resp, err := c.Post([]byte{}, user2inboxurl)
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode)
+	})
+}
--- a/tests/integration/api_activitypub_repository_test.go
+++ b/tests/integration/api_activitypub_repository_test.go
@ -0,0 +1,176 @@
+// Copyright 2024, 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+	"time"
+
+	"forgejo.org/models/forgefed"
+	"forgejo.org/models/unittest"
+	"forgejo.org/models/user"
+	"forgejo.org/modules/activitypub"
+	forgefed_modules "forgejo.org/modules/forgefed"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+	"forgejo.org/routers"
+	"forgejo.org/services/contexttest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestActivityPubRepository(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		repositoryID := 2
+
+		localRepository := fmt.Sprintf("%sapi/v1/activitypub/repository-id/%d", u, repositoryID)
+
+		ctx, _ := contexttest.MockAPIContext(t, localRepository)
+		cf, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+		require.NoError(t, err)
+
+		c, err := cf.WithKeysDirect(ctx, mock.Persons[0].PrivKey,
+			mock.Persons[0].KeyID(federatedSrv.URL))
+		require.NoError(t, err)
+
+		resp, err := c.GetBody(localRepository)
+		require.NoError(t, err)
+		assert.Contains(t, string(resp), "@context")
+
+		var repository forgefed_modules.Repository
+		err = repository.UnmarshalJSON(resp)
+		require.NoError(t, err)
+
+		assert.Regexp(t, fmt.Sprintf("activitypub/repository-id/%d$", repositoryID), repository.GetID().String())
+	})
+}
+
+func TestActivityPubMissingRepository(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&setting.Federation.SignatureEnforced, false)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	repositoryID := 9999999
+	req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/activitypub/repository-id/%d", repositoryID))
+	resp := MakeRequest(t, req, http.StatusNotFound)
+	assert.Contains(t, resp.Body.String(), "repository does not exist")
+}
+
+func TestActivityPubRepositoryInboxValid(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		repositoryID := 2
+		timeNow := time.Now().UTC()
+		localRepoInbox := u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d/inbox", repositoryID)).String()
+
+		ctx, _ := contexttest.MockAPIContext(t, localRepoInbox)
+		cf, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+		require.NoError(t, err)
+
+		c, err := cf.WithKeysDirect(ctx, mock.Persons[0].PrivKey,
+			mock.Persons[0].KeyID(federatedSrv.URL))
+		require.NoError(t, err)
+
+		activity1 := []byte(fmt.Sprintf(
+			`{"type":"Like",`+
+				`"startTime":"%s",`+
+				`"actor":"%s/api/v1/activitypub/user-id/15",`+
+				`"object":"%s"}`,
+			timeNow.Format(time.RFC3339),
+			federatedSrv.URL, u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d", repositoryID)).String()))
+		t.Logf("activity: %s", activity1)
+		resp, err := c.Post(activity1, localRepoInbox)
+
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode)
+
+		federationHost := unittest.AssertExistsAndLoadBean(t, &forgefed.FederationHost{HostFqdn: "127.0.0.1"})
+		federatedUser := unittest.AssertExistsAndLoadBean(t, &user.FederatedUser{ExternalID: "15", FederationHostID: federationHost.ID})
+		unittest.AssertExistsAndLoadBean(t, &user.User{ID: federatedUser.UserID})
+
+		// A like activity by a different user of the same federated host.
+		activity2 := []byte(fmt.Sprintf(
+			`{"type":"Like",`+
+				`"startTime":"%s",`+
+				`"actor":"%s/api/v1/activitypub/user-id/30",`+
+				`"object":"%s"}`,
+			// Make sure this activity happens later then the one before
+			timeNow.Add(time.Second).Format(time.RFC3339),
+			federatedSrv.URL, u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d", repositoryID)).String()))
+		t.Logf("activity: %s", activity2)
+		resp, err = c.Post(activity2, localRepoInbox)
+
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode)
+
+		federatedUser = unittest.AssertExistsAndLoadBean(t, &user.FederatedUser{ExternalID: "30", FederationHostID: federationHost.ID})
+		unittest.AssertExistsAndLoadBean(t, &user.User{ID: federatedUser.UserID})
+
+		// The same user sends another like activity
+		otherRepositoryID := 3
+		otherRepoInboxURL := u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d/inbox", otherRepositoryID)).String()
+		activity3 := []byte(fmt.Sprintf(
+			`{"type":"Like",`+
+				`"startTime":"%s",`+
+				`"actor":"%s/api/v1/activitypub/user-id/30",`+
+				`"object":"%s"}`,
+			// Make sure this activity happens later then the ones before
+			timeNow.Add(time.Second*2).Format(time.RFC3339),
+			federatedSrv.URL, u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d", otherRepositoryID)).String()))
+		t.Logf("activity: %s", activity3)
+		resp, err = c.Post(activity3, otherRepoInboxURL)
+
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode)
+
+		federatedUser = unittest.AssertExistsAndLoadBean(t, &user.FederatedUser{ExternalID: "30", FederationHostID: federationHost.ID})
+		unittest.AssertExistsAndLoadBean(t, &user.User{ID: federatedUser.UserID})
+
+		// Replay activity2.
+		resp, err = c.Post(activity2, localRepoInbox)
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNotAcceptable, resp.StatusCode)
+	})
+}
+
+func TestActivityPubRepositoryInboxInvalid(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&setting.Federation.SignatureEnforced, false)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		apServerActor := user.NewAPServerActor()
+		repositoryID := 2
+		localRepo2Inbox := u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d/inbox", repositoryID)).String()
+
+		ctx, _ := contexttest.MockAPIContext(t, localRepo2Inbox)
+		cf, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+		require.NoError(t, err)
+
+		c, err := cf.WithKeys(ctx, apServerActor, apServerActor.KeyID())
+		require.NoError(t, err)
+
+		activity := []byte(`{"type":"Wrong"}`)
+		resp, err := c.Post(activity, localRepo2Inbox)
+		require.NoError(t, err)
+		assert.Equal(t, http.StatusNotAcceptable, resp.StatusCode)
+	})
+}
--- a/tests/integration/api_federation_httpsig_test.go
+++ b/tests/integration/api_federation_httpsig_test.go
@ -0,0 +1,85 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+	"time"
+
+	"forgejo.org/models/db"
+	"forgejo.org/models/forgefed"
+	"forgejo.org/models/unittest"
+	"forgejo.org/models/user"
+	"forgejo.org/modules/activitypub"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+	"forgejo.org/routers"
+	"forgejo.org/services/contexttest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFederationHttpSigValidation(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		userID := 2
+		userURL := fmt.Sprintf("%sapi/v1/activitypub/user-id/%d", u, userID)
+
+		user1 := unittest.AssertExistsAndLoadBean(t, &user.User{ID: 1})
+
+		ctx, _ := contexttest.MockAPIContext(t, userURL)
+		clientFactory, err := activitypub.NewClientFactoryWithTimeout(60 * time.Second)
+		require.NoError(t, err)
+
+		apClient, err := clientFactory.WithKeys(ctx, user1, user1.KeyID())
+		require.NoError(t, err)
+
+		// Unsigned request
+		t.Run("UnsignedRequest", func(t *testing.T) {
+			req := NewRequest(t, "GET", userURL)
+			MakeRequest(t, req, http.StatusBadRequest)
+		})
+
+		// Signed request
+		t.Run("SignedRequest", func(t *testing.T) {
+			resp, err := apClient.Get(userURL)
+			require.NoError(t, err)
+			assert.Equal(t, http.StatusOK, resp.StatusCode)
+		})
+
+		// HACK HACK HACK: the host part of the URL gets set to which IP forgejo is
+		// listening on, NOT localhost, which is the Domain given to forgejo which
+		// is then used for eg. the keyID all requests
+		applicationKeyID := fmt.Sprintf("%sapi/v1/activitypub/actor#main-key", setting.AppURL)
+		actorKeyID := fmt.Sprintf("%sapi/v1/activitypub/user-id/1#main-key", setting.AppURL)
+
+		// Check for cached public keys
+		t.Run("ValidateCaches", func(t *testing.T) {
+			host, err := forgefed.FindFederationHostByKeyID(db.DefaultContext, applicationKeyID)
+			require.NoError(t, err)
+			assert.NotNil(t, host)
+			assert.True(t, host.PublicKey.Valid)
+
+			_, user, err := user.FindFederatedUserByKeyID(db.DefaultContext, actorKeyID)
+			require.NoError(t, err)
+			assert.NotNil(t, user)
+			assert.True(t, user.PublicKey.Valid)
+		})
+
+		// Disable signature validation
+		defer test.MockVariableValue(&setting.Federation.SignatureEnforced, false)()
+
+		// Unsigned request
+		t.Run("SignatureValidationDisabled", func(t *testing.T) {
+			req := NewRequest(t, "GET", userURL)
+			MakeRequest(t, req, http.StatusOK)
+		})
+	})
+}
--- a/tests/integration/repo_star_federation_test.go
+++ b/tests/integration/repo_star_federation_test.go
@ -0,0 +1,81 @@
+// Copyright 2024 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"testing"
+
+	"forgejo.org/models/forgefed"
+	repo_model "forgejo.org/models/repo"
+	"forgejo.org/models/unittest"
+	user_model "forgejo.org/models/user"
+	fm "forgejo.org/modules/forgefed"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+	"forgejo.org/modules/validation"
+	"forgejo.org/tests"
+)
+
+func TestActivityPubRepoFollowing(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1, OwnerID: user.ID})
+	session := loginUser(t, user.Name)
+
+	t.Run("Add a following repo", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		link := fmt.Sprintf("/%s/settings", repo.FullName())
+
+		req := NewRequestWithValues(t, "POST", link, map[string]string{
+			"_csrf":           GetCSRF(t, session, link),
+			"action":          "federation",
+			"following_repos": fmt.Sprintf("%s/api/v1/activitypub/repository-id/1", federatedSrv.URL),
+		})
+		session.MakeRequest(t, req, http.StatusSeeOther)
+
+		// Verify it was added.
+		federationHost := unittest.AssertExistsAndLoadBean(t, &forgefed.FederationHost{HostFqdn: "127.0.0.1"})
+		unittest.AssertExistsAndLoadBean(t, &repo_model.FollowingRepo{
+			ExternalID:       "1",
+			FederationHostID: federationHost.ID,
+		})
+	})
+
+	t.Run("Star a repo having a following repo", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		repoLink := fmt.Sprintf("/%s", repo.FullName())
+		link := fmt.Sprintf("%s/action/star", repoLink)
+		req := NewRequestWithValues(t, "POST", link, map[string]string{
+			"_csrf": GetCSRF(t, session, repoLink),
+		})
+
+		session.MakeRequest(t, req, http.StatusOK)
+
+		// Verify distant server received a like activity
+		like := fm.ForgeLike{}
+		err := like.UnmarshalJSON([]byte(mock.LastPost))
+		if err != nil {
+			t.Errorf("Error unmarshalling ForgeLike: %q", err)
+		}
+		if isValid, err := validation.IsValid(like); !isValid {
+			t.Errorf("ForgeLike is not valid: %q", err)
+		}
+		activityType := like.Type
+		object := like.Object.GetLink().String()
+		isLikeType := activityType == "Like"
+		isCorrectObject := strings.HasSuffix(object, "/api/v1/activitypub/repository-id/1")
+		if !isLikeType || !isCorrectObject {
+			t.Error("Activity is not a like for this repo")
+		}
+	})
+}