start adding remote instance dereference

internal/federation/federatingprotocol.go

@@ -125,6 +125,18 @@ func (f *federator) AuthenticatePostInbox(ctx context.Context, w http.ResponseWr
 		return ctx, false, fmt.Errorf("not authenticated: %s", err)
 	}
 
+	// authentication has passed, so add an instance entry for this instance if it hasn't been done already
+	i := &gtsmodel.Instance{}
+	if err := f.db.GetWhere([]db.Where{{Key: "domain", Value: publicKeyOwnerURI.Host, CaseInsensitive: true}}, i); err != nil {
+		if _, ok := err.(db.ErrNoEntries); !ok {
+			// there's been an actual error
+			return ctx, false, fmt.Errorf("error getting requesting account with public key id %s: %s", publicKeyOwnerURI.String(), err)
+		}
+		// we don't have an entry for this instance yet so create it
+		var err error
+		i, err := f.DereferenceRemoteInstance()
+	}
+
 	requestingAccount := &gtsmodel.Account{}
 	if err := f.db.GetWhere([]db.Where{{Key: "uri", Value: publicKeyOwnerURI.String()}}, requestingAccount); err != nil {
 		// there's been a proper error so return it

internal/federation/federator.go

@@ -24,6 +24,7 @@ import (
 
 	"github.com/go-fed/activity/pub"
 	"github.com/sirupsen/logrus"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/federation/federatingdb"
@@ -49,6 +50,8 @@ type Federator interface {
 	// DereferenceRemoteStatus can be used to get the representation of a remote status, based on its ID (which is a URI).
 	// The given username will be used to create a transport for making outgoing requests. See the implementation for more detailed comments.
 	DereferenceRemoteStatus(username string, remoteStatusID *url.URL) (typeutils.Statusable, error)
+	// DereferenceRemoteInstance
+	DereferenceRemoteInstance(username string, remoteInstanceURI *url.URL) (*apimodel.Instance, error)
 	// GetTransportForUser returns a new transport initialized with the key credentials belonging to the given username.
 	// This can be used for making signed http requests.
 	//

internal/federation/util.go

@@ -37,6 +37,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/transport"
 	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 )
 
 /*
@@ -134,7 +135,8 @@ func (f *federator) AuthenticateFederatedRequest(username string, r *http.Reques
 	var pkOwnerURI *url.URL
 	requestingRemoteAccount := &gtsmodel.Account{}
 	requestingLocalAccount := &gtsmodel.Account{}
-	if strings.EqualFold(requestingPublicKeyID.Host, f.config.Host) {
+	requestingHost := requestingPublicKeyID.Host
+	if strings.EqualFold(requestingHost, 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 {
@@ -340,6 +342,15 @@ func (f *federator) DereferenceRemoteStatus(username string, remoteStatusID *url
 	return nil, fmt.Errorf("type name %s not supported", t.GetTypeName())
 }
 
+func (f *federator) DereferenceRemoteInstance(username string, remoteInstanceURI *url.URL) (*apimodel.Instance, error) {
+	transport, err := f.GetTransportForUser(username)
+	if err != nil {
+		return nil, fmt.Errorf("transport err: %s", err)
+	}
+
+	return transport.DereferenceInstance(context.Background(), remoteInstanceURI)
+}
+
 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.

internal/transport/transport.go

@@ -3,6 +3,8 @@ package transport
 import (
 	"context"
 	"crypto"
+	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -12,13 +14,17 @@ import (
 	"github.com/go-fed/activity/pub"
 	"github.com/go-fed/httpsig"
 	"github.com/sirupsen/logrus"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 )
 
 // Transport wraps the pub.Transport interface with some additional
 // functionality for fetching remote media.
 type Transport interface {
 	pub.Transport
+	// DereferenceMedia fetches the bytes of the given media attachment IRI, with the expectedContentType.
 	DereferenceMedia(c context.Context, iri *url.URL, expectedContentType string) ([]byte, error)
+	// DereferenceInstance dereferences remote instance information, first by checking /api/v1/instance, and then by checking /.well-known/nodeinfo.
+	DereferenceInstance(c context.Context, iri *url.URL) (*apimodel.Instance, error)
 	// Finger performs a webfinger request with the given username and domain, and returns the bytes from the response body.
 	Finger(c context.Context, targetUsername string, targetDomains string) ([]byte, error)
 }
@@ -124,3 +130,85 @@ func (t *transport) Finger(c context.Context, targetUsername string, targetDomai
 	}
 	return ioutil.ReadAll(resp.Body)
 }
+
+func (t *transport) DereferenceInstance(c context.Context, iri *url.URL) (*apimodel.Instance, error) {
+	l := t.log.WithField("func", "DereferenceInstance")
+
+	var i *apimodel.Instance
+	var err error
+
+	// First try to dereference using /api/v1/instance.
+	// This will provide the most complete picture of an instance, and avoid unnecessary api calls.
+	//
+	// This will only work with Mastodon-api compatible instances: Mastodon, some Pleroma instances, GoToSocial.
+	l.Debugf("trying to dereference instance %s by /api/v1/instance", iri.Host)
+	i, err = dereferenceByAPIV1Instance(t, c, iri)
+	if err == nil {
+		l.Debugf("successfully dereferenced instance using /api/v1/instance")
+		return i, nil
+	}
+	l.Debugf("couldn't dereference instance using /api/v1/instance: %s", err)
+
+	// If that doesn't work, try to dereference using /.well-known/nodeinfo.
+	// This will involve two API calls and return less info overall, but should be more widely compatible.
+	l.Debugf("trying to dereference instance %s by /.well-known/nodeinfo", iri.Host)
+	i, err = dereferenceByNodeInfo(t, c, iri)
+	if err == nil {
+		l.Debugf("successfully dereferenced instance using /.well-known/nodeinfo")
+		return i, nil
+	}
+	l.Debugf("couldn't dereference instance using /.well-known/nodeinfo: %s", err)
+
+	return nil, fmt.Errorf("couldn't dereference instance %s using either /api/v1/instance or /.well-known/nodeinfo", iri.Host)
+}
+
+func dereferenceByAPIV1Instance(t *transport, c context.Context, iri *url.URL) (*apimodel.Instance, error) {
+	l := t.log.WithField("func", "dereferenceByAPIV1Instance")
+
+	cleanIRI := &url.URL{
+		Scheme: iri.Scheme,
+		Host:   iri.Host,
+		Path:   "api/v1/instance",
+	}
+
+	l.Debugf("performing GET to %s", cleanIRI.String())
+	req, err := http.NewRequest("GET", cleanIRI.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	req = req.WithContext(c)
+	req.Header.Add("Accept", "application/json")
+	req.Header.Add("Date", t.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
+	req.Header.Add("User-Agent", fmt.Sprintf("%s %s", t.appAgent, t.gofedAgent))
+	req.Header.Set("Host", cleanIRI.Host)
+	t.getSignerMu.Lock()
+	err = t.getSigner.SignRequest(t.privkey, t.pubKeyID, req, nil)
+	t.getSignerMu.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET request to %s failed (%d): %s", cleanIRI.String(), resp.StatusCode, resp.Status)
+	}
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	// try to parse the returned bytes directly into an Instance model
+	i := &apimodel.Instance{}
+	if err := json.Unmarshal(b, i); err != nil {
+		return nil, err
+	}
+
+	return i, nil
+}
+
+func dereferenceByNodeInfo(t *transport, c context.Context, iri *url.URL) (*apimodel.Instance, error) {
+	return nil, errors.New("not yet implemented")
+}