forgejo/services/federation/federation_service.go

// Copyright 2024 The Forgejo Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package federation

import (
	"context"
	"fmt"
	"net/http"

	"code.gitea.io/gitea/models/forgefed"
	"code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/activitypub"
	fm "code.gitea.io/gitea/modules/forgefed"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/validation"
)

// ProcessLikeActivity receives a ForgeLike activity and does the following:
// Validation of the activity
// Creation of a (remote) federationHost if not existing
// Creation of a forgefed Person if not existing
// 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.Context, form any, repositoryID int64) (int, string, error) {
	activity := form.(*fm.ForgeLike)
	if res, err := validation.IsValid(activity); !res {
		return http.StatusNotAcceptable, "Invalid activity", err
	}
	log.Info("Activity validated:%v", activity)

	// parse actorID (person)
	actorURI := activity.Actor.GetID().String()
	log.Info("actorURI was: %v", actorURI)
	federationHost, err := GetFederationHostForURI(ctx, actorURI)
	if err != nil {
		return http.StatusInternalServerError, "Wrong FederationHost", err
	}
	if !activity.IsNewer(federationHost.LatestActivity) {
		return http.StatusNotAcceptable, "Activity out of order.", fmt.Errorf("Activity already processed")
	}

	return 0, "", nil
}

func CreateFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forgefed.FederationHost, error) {
	actionsUser := user.NewActionsUser()
	client, err := activitypub.NewClient(ctx, actionsUser, "no idea where to get key material.")
	if err != nil {
		return nil, err
	}
	body, err := client.GetBody(actorID.AsWellKnownNodeInfoURI())
	if err != nil {
		return nil, err
	}
	nodeInfoWellKnown, err := forgefed.NewNodeInfoWellKnown(body)
	if err != nil {
		return nil, err
	}
	body, err = client.GetBody(nodeInfoWellKnown.Href)
	if err != nil {
		return nil, err
	}
	nodeInfo, err := forgefed.NewNodeInfo(body)
	if err != nil {
		return nil, err
	}
	result, err := forgefed.NewFederationHost(nodeInfo, actorID.Host)
	if err != nil {
		return nil, err
	}
	err = forgefed.CreateFederationHost(ctx, &result)
	if err != nil {
		return nil, err
	}
	return &result, nil
}

func GetFederationHostForURI(ctx context.Context, actorURI string) (*forgefed.FederationHost, error) {
	log.Info("Input was: %v", actorURI)
	rawActorID, err := fm.NewActorID(actorURI)
	if err != nil {
		return nil, err
	}
	federationHost, err := forgefed.FindFederationHostByFqdn(ctx, rawActorID.Host)
	if err != nil {
		return nil, err
	}
	if federationHost == nil {
		result, err := CreateFederationHostFromAP(ctx, rawActorID)
		if err != nil {
			return nil, err
		}
		federationHost = result
	}
	return federationHost, nil
}