Roomserver perform join (#1001)

* Add PerformJoin template

* Try roomserver perform join

* Send correct server name to FS API

* Pass through content, try to handle multiple server names

* Fix local server checks

* Don't refer to non-existent error

* Add directory lookups of aliases

* Remove unneeded parameters

* Don't repeat join events into the roomserver

* Unmarshal the content, that would help

* Check if the user is already in the room in the fedeationapi too

* Return incompatible room version error

* Use Membership, don't try more servers than needed

* Review comments, make FS API take list of servernames, dedupe them, break out of loop properly on success

* Tweaks

federationsender/api/api.go

@@ -8,6 +8,12 @@ import (
 
 // FederationSenderInternalAPI is used to query information from the federation sender.
 type FederationSenderInternalAPI interface {
+	// PerformDirectoryLookup looks up a remote room ID from a room alias.
+	PerformDirectoryLookup(
+		ctx context.Context,
+		request *PerformDirectoryLookupRequest,
+		response *PerformDirectoryLookupResponse,
+	) error
 	// Query the joined hosts and the membership events accounting for their participation in a room.
 	// Note that if a server has multiple users in the room, it will have multiple entries in the returned slice.
 	// See `QueryJoinedHostServerNamesInRoom` for a de-duplicated version.

federationsender/api/perform.go

@@ -4,11 +4,15 @@ import (
 	"context"
 
 	commonHTTP "github.com/matrix-org/dendrite/common/http"
+	"github.com/matrix-org/dendrite/federationsender/types"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/opentracing/opentracing-go"
 )
 
 const (
+	// FederationSenderPerformJoinRequestPath is the HTTP path for the PerformJoinRequest API.
+	FederationSenderPerformDirectoryLookupRequestPath = "/api/federationsender/performDirectoryLookup"
+
 	// FederationSenderPerformJoinRequestPath is the HTTP path for the PerformJoinRequest API.
 	FederationSenderPerformJoinRequestPath = "/api/federationsender/performJoinRequest"
 
@@ -16,11 +20,34 @@ const (
 	FederationSenderPerformLeaveRequestPath = "/api/federationsender/performLeaveRequest"
 )
 
-type PerformJoinRequest struct {
-	RoomID     string                       `json:"room_id"`
-	UserID     string                       `json:"user_id"`
+type PerformDirectoryLookupRequest struct {
+	RoomAlias  string                       `json:"room_alias"`
 	ServerName gomatrixserverlib.ServerName `json:"server_name"`
-	Content    map[string]interface{}       `json:"content"`
+}
+
+type PerformDirectoryLookupResponse struct {
+	RoomID      string                         `json:"room_id"`
+	ServerNames []gomatrixserverlib.ServerName `json:"server_names"`
+}
+
+// Handle an instruction to make_join & send_join with a remote server.
+func (h *httpFederationSenderInternalAPI) PerformDirectoryLookup(
+	ctx context.Context,
+	request *PerformDirectoryLookupRequest,
+	response *PerformDirectoryLookupResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "PerformDirectoryLookup")
+	defer span.Finish()
+
+	apiURL := h.federationSenderURL + FederationSenderPerformDirectoryLookupRequestPath
+	return commonHTTP.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
+
+type PerformJoinRequest struct {
+	RoomID      string                 `json:"room_id"`
+	UserID      string                 `json:"user_id"`
+	ServerNames types.ServerNames      `json:"server_names"`
+	Content     map[string]interface{} `json:"content"`
 }
 
 type PerformJoinResponse struct {