Remote instance dereferencing (#70)

Remote instances are now dereferenced when they post to an inbox on a GtS instance.

    Dereferencing will be done first by checking the /api/v1/instance endpoint of an instance.
    If that doesn't work, /.well-known/nodeinfo will be checked.
    If that doesn't work, only a minimal representation of the instance will be stored.

A new field was added to the Instance database model. To create it:

alter table instances add column contact_account_username text;

1 files changed, 0 insertions, 365 deletions

diff --git a/internal/federation/util.go b/internal/federation/util.go
deleted file mode 100644
index 9ec0770f6..000000000
--- a/internal/federation/util.go
+++ /dev/null
@@ -1,365 +0,0 @@
-/*
-   GoToSocial
-   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
-
-   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 federation
-
-import (
-	"context"
-	"crypto/x509"
-	"encoding/json"
-	"encoding/pem"
-	"errors"
-	"fmt"
-	"net/http"
-	"net/url"
-	"strings"
-
-	"github.com/go-fed/activity/pub"
-	"github.com/go-fed/activity/streams"
-	"github.com/go-fed/activity/streams/vocab"
-	"github.com/go-fed/httpsig"
-	"github.com/superseriousbusiness/gotosocial/internal/db"
-	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
-	"github.com/superseriousbusiness/gotosocial/internal/transport"
-	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
-)
-
-/*
-	publicKeyer is BORROWED DIRECTLY FROM https://github.com/go-fed/apcore/blob/master/ap/util.go
-	Thank you @cj@mastodon.technology ! <3
-*/
-type publicKeyer interface {
-	GetW3IDSecurityV1PublicKey() vocab.W3IDSecurityV1PublicKeyProperty
-}
-
-/*
-	getPublicKeyFromResponse is adapted from https://github.com/go-fed/apcore/blob/master/ap/util.go
-	Thank you @cj@mastodon.technology ! <3
-*/
-func getPublicKeyFromResponse(c context.Context, b []byte, keyID *url.URL) (vocab.W3IDSecurityV1PublicKey, error) {
-	m := make(map[string]interface{})
-	if err := json.Unmarshal(b, &m); err != nil {
-		return nil, err
-	}
-
-	t, err := streams.ToType(c, m)
-	if err != nil {
-		return nil, err
-	}
-
-	pker, ok := t.(publicKeyer)
-	if !ok {
-		return nil, fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %T", t)
-	}
-
-	pkp := pker.GetW3IDSecurityV1PublicKey()
-	if pkp == nil {
-		return nil, errors.New("publicKey property is not provided")
-	}
-
-	var pkpFound vocab.W3IDSecurityV1PublicKey
-	for pkpIter := pkp.Begin(); pkpIter != pkp.End(); pkpIter = pkpIter.Next() {
-		if !pkpIter.IsW3IDSecurityV1PublicKey() {
-			continue
-		}
-		pkValue := pkpIter.Get()
-		var pkID *url.URL
-		pkID, err = pub.GetId(pkValue)
-		if err != nil {
-			return nil, err
-		}
-		if pkID.String() != keyID.String() {
-			continue
-		}
-		pkpFound = pkValue
-		break
-	}
-
-	if pkpFound == nil {
-		return nil, fmt.Errorf("cannot find publicKey with id: %s", keyID)
-	}
-
-	return pkpFound, nil
-}
-
-// AuthenticateFederatedRequest authenticates any kind of incoming federated request from a remote server. This includes things like
-// GET requests for dereferencing our users or statuses etc, and POST requests for delivering new Activities. The function returns
-// the URL of the owner of the public key used in the http signature.
-//
-// Authenticate in this case is defined as just making sure that the http request is actually signed by whoever claims
-// to have signed it, by fetching the public key from the signature and checking it against the remote public key. This function
-// *does not* check whether the request is authorized, only whether it's authentic.
-//
-// The provided username will be used to generate a transport for making remote requests/derefencing the public key ID of the request signature.
-// Ideally you should pass in the username of the user *being requested*, so that the remote server can decide how to handle the request based on who's making it.
-// Ie., if the request on this server is for https://example.org/users/some_username then you should pass in the username 'some_username'.
-// The remote server will then know that this is the user making the dereferencing request, and they can decide to allow or deny the request depending on their settings.
-//
-// Note that it is also valid to pass in an empty string here, in which case the keys of the instance account will be used.
-//
-// Also note that this function *does not* dereference the remote account that the signature key is associated with.
-// Other functions should use the returned URL to dereference the remote account, if required.
-func (f *federator) AuthenticateFederatedRequest(username string, r *http.Request) (*url.URL, error) {
-	// set this extra field for signature validation
-	r.Header.Set("host", f.config.Host)
-
-	verifier, err := httpsig.NewVerifier(r)
-	if err != nil {
-		return nil, fmt.Errorf("could not create http sig verifier: %s", err)
-	}
-
-	// The key ID should be given in the signature so that we know where to fetch it from the remote server.
-	// This will be something like https://example.org/users/whatever_requesting_user#main-key
-	requestingPublicKeyID, err := url.Parse(verifier.KeyId())
-	if err != nil {
-		return nil, fmt.Errorf("could not parse key id into a url: %s", err)
-	}
-
-	var publicKey interface{}
-	var pkOwnerURI *url.URL
-	requestingRemoteAccount := &gtsmodel.Account{}
-	requestingLocalAccount := &gtsmodel.Account{}
-	if strings.EqualFold(requestingPublicKeyID.Host, f.config.Host) {
-		// LOCAL ACCOUNT REQUEST
-		// the request is coming from INSIDE THE HOUSE so skip the remote dereferencing
-		if err := f.db.GetWhere([]db.Where{{Key: "public_key_uri", Value: requestingPublicKeyID.String()}}, requestingLocalAccount); err != nil {
-			return nil, fmt.Errorf("couldn't get local account with public key uri %s from the database: %s", requestingPublicKeyID.String(), err)
-		}
-		publicKey = requestingLocalAccount.PublicKey
-		pkOwnerURI, err = url.Parse(requestingLocalAccount.URI)
-		if err != nil {
-			return nil, fmt.Errorf("error parsing url %s: %s", requestingLocalAccount.URI, err)
-		}
-	} else if err := f.db.GetWhere([]db.Where{{Key: "public_key_uri", Value: requestingPublicKeyID.String()}}, requestingRemoteAccount); err == nil {
-		// REMOTE ACCOUNT REQUEST WITH KEY CACHED LOCALLY
-		// this is a remote account and we already have the public key for it so use that
-		publicKey = requestingRemoteAccount.PublicKey
-		pkOwnerURI, err = url.Parse(requestingRemoteAccount.URI)
-		if err != nil {
-			return nil, fmt.Errorf("error parsing url %s: %s", requestingRemoteAccount.URI, err)
-		}
-	} else {
-		// REMOTE ACCOUNT REQUEST WITHOUT KEY CACHED LOCALLY
-		// the request is remote and we don't have the public key yet,
-		// so we need to authenticate the request properly by dereferencing the remote key
-		transport, err := f.GetTransportForUser(username)
-		if err != nil {
-			return nil, fmt.Errorf("transport err: %s", err)
-		}
-
-		// The actual http call to the remote server is made right here in the Dereference function.
-		b, err := transport.Dereference(context.Background(), requestingPublicKeyID)
-		if err != nil {
-			return nil, fmt.Errorf("error deferencing key %s: %s", requestingPublicKeyID.String(), err)
-		}
-
-		// if the key isn't in the response, we can't authenticate the request
-		requestingPublicKey, err := getPublicKeyFromResponse(context.Background(), b, requestingPublicKeyID)
-		if err != nil {
-			return nil, fmt.Errorf("error getting key %s from response %s: %s", requestingPublicKeyID.String(), string(b), err)
-		}
-
-		// we should be able to get the actual key embedded in the vocab.W3IDSecurityV1PublicKey
-		pkPemProp := requestingPublicKey.GetW3IDSecurityV1PublicKeyPem()
-		if pkPemProp == nil || !pkPemProp.IsXMLSchemaString() {
-			return nil, errors.New("publicKeyPem property is not provided or it is not embedded as a value")
-		}
-
-		// and decode the PEM so that we can parse it as a golang public key
-		pubKeyPem := pkPemProp.Get()
-		block, _ := pem.Decode([]byte(pubKeyPem))
-		if block == nil || block.Type != "PUBLIC KEY" {
-			return nil, errors.New("could not decode publicKeyPem to PUBLIC KEY pem block type")
-		}
-
-		publicKey, err = x509.ParsePKIXPublicKey(block.Bytes)
-		if err != nil {
-			return nil, fmt.Errorf("could not parse public key from block bytes: %s", err)
-		}
-
-		// all good! we just need the URI of the key owner to return
-		pkOwnerProp := requestingPublicKey.GetW3IDSecurityV1Owner()
-		if pkOwnerProp == nil || !pkOwnerProp.IsIRI() {
-			return nil, errors.New("publicKeyOwner property is not provided or it is not embedded as a value")
-		}
-		pkOwnerURI = pkOwnerProp.GetIRI()
-	}
-	if publicKey == nil {
-		return nil, errors.New("returned public key was empty")
-	}
-
-	// do the actual authentication here!
-	algo := httpsig.RSA_SHA256 // TODO: make this more robust
-	if err := verifier.Verify(publicKey, algo); err != nil {
-		return nil, fmt.Errorf("error verifying key %s: %s", requestingPublicKeyID.String(), err)
-	}
-
-	return pkOwnerURI, nil
-}
-
-func (f *federator) DereferenceRemoteAccount(username string, remoteAccountID *url.URL) (typeutils.Accountable, error) {
-	f.startHandshake(username, remoteAccountID)
-	defer f.stopHandshake(username, remoteAccountID)
-
-	transport, err := f.GetTransportForUser(username)
-	if err != nil {
-		return nil, fmt.Errorf("transport err: %s", err)
-	}
-
-	b, err := transport.Dereference(context.Background(), remoteAccountID)
-	if err != nil {
-		return nil, fmt.Errorf("error deferencing %s: %s", remoteAccountID.String(), err)
-	}
-
-	m := make(map[string]interface{})
-	if err := json.Unmarshal(b, &m); err != nil {
-		return nil, fmt.Errorf("error unmarshalling bytes into json: %s", err)
-	}
-
-	t, err := streams.ToType(context.Background(), m)
-	if err != nil {
-		return nil, fmt.Errorf("error resolving json into ap vocab type: %s", err)
-	}
-
-	switch t.GetTypeName() {
-	case string(gtsmodel.ActivityStreamsPerson):
-		p, ok := t.(vocab.ActivityStreamsPerson)
-		if !ok {
-			return nil, errors.New("error resolving type as activitystreams person")
-		}
-		return p, nil
-	case string(gtsmodel.ActivityStreamsApplication):
-		p, ok := t.(vocab.ActivityStreamsApplication)
-		if !ok {
-			return nil, errors.New("error resolving type as activitystreams application")
-		}
-		return p, nil
-	case string(gtsmodel.ActivityStreamsService):
-		p, ok := t.(vocab.ActivityStreamsService)
-		if !ok {
-			return nil, errors.New("error resolving type as activitystreams service")
-		}
-		return p, nil
-	}
-
-	return nil, fmt.Errorf("type name %s not supported", t.GetTypeName())
-}
-
-func (f *federator) DereferenceRemoteStatus(username string, remoteStatusID *url.URL) (typeutils.Statusable, error) {
-	transport, err := f.GetTransportForUser(username)
-	if err != nil {
-		return nil, fmt.Errorf("transport err: %s", err)
-	}
-
-	b, err := transport.Dereference(context.Background(), remoteStatusID)
-	if err != nil {
-		return nil, fmt.Errorf("error deferencing %s: %s", remoteStatusID.String(), err)
-	}
-
-	m := make(map[string]interface{})
-	if err := json.Unmarshal(b, &m); err != nil {
-		return nil, fmt.Errorf("error unmarshalling bytes into json: %s", err)
-	}
-
-	t, err := streams.ToType(context.Background(), m)
-	if err != nil {
-		return nil, fmt.Errorf("error resolving json into ap vocab type: %s", err)
-	}
-
-	// Article, Document, Image, Video, Note, Page, Event, Place, Mention, Profile
-	switch t.GetTypeName() {
-	case gtsmodel.ActivityStreamsArticle:
-		p, ok := t.(vocab.ActivityStreamsArticle)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsArticle")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsDocument:
-		p, ok := t.(vocab.ActivityStreamsDocument)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsDocument")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsImage:
-		p, ok := t.(vocab.ActivityStreamsImage)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsImage")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsVideo:
-		p, ok := t.(vocab.ActivityStreamsVideo)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsVideo")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsNote:
-		p, ok := t.(vocab.ActivityStreamsNote)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsNote")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsPage:
-		p, ok := t.(vocab.ActivityStreamsPage)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsPage")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsEvent:
-		p, ok := t.(vocab.ActivityStreamsEvent)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsEvent")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsPlace:
-		p, ok := t.(vocab.ActivityStreamsPlace)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsPlace")
-		}
-		return p, nil
-	case gtsmodel.ActivityStreamsProfile:
-		p, ok := t.(vocab.ActivityStreamsProfile)
-		if !ok {
-			return nil, errors.New("error resolving type as ActivityStreamsProfile")
-		}
-		return p, nil
-	}
-
-	return nil, fmt.Errorf("type name %s not supported", t.GetTypeName())
-}
-
-func (f *federator) GetTransportForUser(username string) (transport.Transport, error) {
-	// We need an account to use to create a transport for dereferecing the signature.
-	// If a username has been given, we can fetch the account with that username and use it.
-	// Otherwise, we can take the instance account and use those credentials to make the request.
-	ourAccount := &gtsmodel.Account{}
-	var u string
-	if username == "" {
-		u = f.config.Host
-	} else {
-		u = username
-	}
-	if err := f.db.GetLocalAccountByUsername(u, ourAccount); err != nil {
-		return nil, fmt.Errorf("error getting account %s from db: %s", username, err)
-	}
-
-	transport, err := f.transportController.NewTransport(ourAccount.PublicKeyURI, ourAccount.PrivateKey)
-	if err != nil {
-		return nil, fmt.Errorf("error creating transport for user %s: %s", username, err)
-	}
-	return transport, nil
-}