From b836243a24b7928d9986c97d0ae66be57f71ab42 Mon Sep 17 00:00:00 2001
From: Jonathan Bartlett <34320158+Jonnobrow@users.noreply.github.com>
Date: Mon, 25 Jul 2022 10:39:57 +0100
Subject: [PATCH] Add .well-known/matrix/client to clientapi (#2551)

Signed-off-by: Jonathan Bartlett <jonathan@jonnobrow.co.uk>

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
---
 clientapi/clientapi.go        |  1 +
 clientapi/routing/routing.go  | 22 +++++++++++++++++++++-
 dendrite-sample.monolith.yaml |  4 ++++
 dendrite-sample.polylith.yaml |  4 ++++
 setup/config/config_global.go |  3 +++
 setup/config/config_test.go   |  1 +
 6 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/clientapi/clientapi.go b/clientapi/clientapi.go
index f550c29b..55735560 100644
--- a/clientapi/clientapi.go
+++ b/clientapi/clientapi.go
@@ -59,6 +59,7 @@ func AddPublicRoutes(
 
 	routing.Setup(
 		base.PublicClientAPIMux,
+		base.PublicWellKnownAPIMux,
 		base.SynapseAdminMux,
 		base.DendriteAdminMux,
 		cfg, rsAPI, asAPI,
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 0460850e..ced4fdbc 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -48,7 +48,7 @@ import (
 // applied:
 // nolint: gocyclo
 func Setup(
-	publicAPIMux, synapseAdminRouter, dendriteAdminRouter *mux.Router,
+	publicAPIMux, wkMux, synapseAdminRouter, dendriteAdminRouter *mux.Router,
 	cfg *config.ClientAPI,
 	rsAPI roomserverAPI.ClientRoomserverAPI,
 	asAPI appserviceAPI.AppServiceInternalAPI,
@@ -74,6 +74,26 @@ func Setup(
 		unstableFeatures["org.matrix."+msc] = true
 	}
 
+	if cfg.Matrix.WellKnownClientName != "" {
+		logrus.Infof("Setting m.homeserver base_url as %s at /.well-known/matrix/client", cfg.Matrix.WellKnownClientName)
+		wkMux.Handle("/client", httputil.MakeExternalAPI("wellknown", func(r *http.Request) util.JSONResponse {
+			return util.JSONResponse{
+				Code: http.StatusOK,
+				JSON: struct {
+					HomeserverName struct {
+						BaseUrl string `json:"base_url"`
+					} `json:"m.homeserver"`
+				}{
+					HomeserverName: struct {
+						BaseUrl string `json:"base_url"`
+					}{
+						BaseUrl: cfg.Matrix.WellKnownClientName,
+					},
+				},
+			}
+		})).Methods(http.MethodGet, http.MethodOptions)
+	}
+
 	publicAPIMux.Handle("/versions",
 		httputil.MakeExternalAPI("versions", func(req *http.Request) util.JSONResponse {
 			return util.JSONResponse{
diff --git a/dendrite-sample.monolith.yaml b/dendrite-sample.monolith.yaml
index c6050e40..cc6c173e 100644
--- a/dendrite-sample.monolith.yaml
+++ b/dendrite-sample.monolith.yaml
@@ -64,6 +64,10 @@ global:
   # e.g. localhost:443
   well_known_server_name: ""
 
+  # The server name to delegate client-server communications to, with optional port
+  # e.g. localhost:443
+  well_known_client_name: ""
+
   # Lists of domains that the server will trust as identity servers to verify third
   # party identifiers such as phone numbers and email addresses.
   trusted_third_party_id_servers:
diff --git a/dendrite-sample.polylith.yaml b/dendrite-sample.polylith.yaml
index 723547f5..92cab19b 100644
--- a/dendrite-sample.polylith.yaml
+++ b/dendrite-sample.polylith.yaml
@@ -54,6 +54,10 @@ global:
   # e.g. localhost:443
   well_known_server_name: ""
 
+  # The server name to delegate client-server communications to, with optional port
+  # e.g. localhost:443
+  well_known_client_name: ""
+
   # Lists of domains that the server will trust as identity servers to verify third
   # party identifiers such as phone numbers and email addresses.
   trusted_third_party_id_servers:
diff --git a/setup/config/config_global.go b/setup/config/config_global.go
index 10827bb2..d4e54e20 100644
--- a/setup/config/config_global.go
+++ b/setup/config/config_global.go
@@ -46,6 +46,9 @@ type Global struct {
 	// The server name to delegate server-server communications to, with optional port
 	WellKnownServerName string `yaml:"well_known_server_name"`
 
+	// The server name to delegate client-server communications to, with optional port
+	WellKnownClientName string `yaml:"well_known_client_name"`
+
 	// Disables federation. Dendrite will not be able to make any outbound HTTP requests
 	// to other servers and the federation API will not be exposed.
 	DisableFederation bool `yaml:"disable_federation"`
diff --git a/setup/config/config_test.go b/setup/config/config_test.go
index b9b1e7bb..ee7e7389 100644
--- a/setup/config/config_test.go
+++ b/setup/config/config_test.go
@@ -42,6 +42,7 @@ global:
   key_id: ed25519:auto
   key_validity_period: 168h0m0s
   well_known_server_name: "localhost:443"
+  well_known_client_name: "localhost:443"
   trusted_third_party_id_servers:
   - matrix.org
   - vector.im