From b6ee34918c79cbd82ab9320660fb9387d90ee758 Mon Sep 17 00:00:00 2001
From: Till Faelligen <tfaelligen@gmail.com>
Date: Mon, 14 Feb 2022 13:41:21 +0100
Subject: [PATCH] Add consent tracking endpoint

---
 clientapi/clientapi.go                |  3 +-
 clientapi/routing/consent_tracking.go | 47 +++++++++++++++++++++++++++
 clientapi/routing/routing.go          |  5 ++-
 3 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 clientapi/routing/consent_tracking.go

diff --git a/clientapi/clientapi.go b/clientapi/clientapi.go
index d678ada96..a6b811300 100644
--- a/clientapi/clientapi.go
+++ b/clientapi/clientapi.go
@@ -36,6 +36,7 @@ import (
 func AddPublicRoutes(
 	router *mux.Router,
 	synapseAdminRouter *mux.Router,
+	consentAPIMux *mux.Router,
 	cfg *config.ClientAPI,
 	accountsDB accounts.Database,
 	federation *gomatrixserverlib.FederationClient,
@@ -57,7 +58,7 @@ func AddPublicRoutes(
 	}
 
 	routing.Setup(
-		router, synapseAdminRouter, cfg, eduInputAPI, rsAPI, asAPI,
+		router, synapseAdminRouter, consentAPIMux, cfg, eduInputAPI, rsAPI, asAPI,
 		accountsDB, userAPI, federation,
 		syncProducer, transactionsCache, fsAPI, keyAPI, extRoomsProvider, mscCfg,
 	)
diff --git a/clientapi/routing/consent_tracking.go b/clientapi/routing/consent_tracking.go
new file mode 100644
index 000000000..5947855d4
--- /dev/null
+++ b/clientapi/routing/consent_tracking.go
@@ -0,0 +1,47 @@
+package routing
+
+import (
+	"net/http"
+
+	"github.com/matrix-org/dendrite/setup/config"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/sirupsen/logrus"
+)
+
+// The data used to populate the /consent request
+type constentTemplateData struct {
+	User          string
+	Version       string
+	UserHMAC      string
+	HasConsented  bool
+	PublicVersion bool
+}
+
+func consent(userAPI userapi.UserInternalAPI, cfg *config.ClientAPI) http.HandlerFunc {
+	consentCfg := cfg.Matrix.UserConsentOptions
+	return func(writer http.ResponseWriter, req *http.Request) {
+		if !consentCfg.Enabled() {
+			writer.WriteHeader(http.StatusBadRequest)
+			_, _ = writer.Write([]byte("consent tracking is disabled"))
+			return
+		}
+		switch req.Method {
+		case http.MethodGet:
+			// The data used to populate the /consent request
+			data := constentTemplateData{
+				User:     req.FormValue("u"),
+				Version:  req.FormValue("v"),
+				UserHMAC: req.FormValue("h"),
+			}
+			// display the privacy policy without a form
+			data.PublicVersion = data.User == "" || data.UserHMAC == "" || data.Version == ""
+
+			err := consentCfg.Templates.ExecuteTemplate(writer, consentCfg.Version+".gohtml", data)
+			if err != nil {
+				logrus.WithError(err).Error("unable to print consent template")
+			}
+		case http.MethodPost:
+
+		}
+	}
+}
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 732066166..d10817d1b 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -47,7 +47,7 @@ import (
 // applied:
 // nolint: gocyclo
 func Setup(
-	publicAPIMux, synapseAdminRouter *mux.Router, cfg *config.ClientAPI,
+	publicAPIMux, synapseAdminRouter, consentAPIMux *mux.Router, cfg *config.ClientAPI,
 	eduAPI eduServerAPI.EDUServerInputAPI,
 	rsAPI roomserverAPI.RoomserverInternalAPI,
 	asAPI appserviceAPI.AppServiceQueryAPI,
@@ -117,6 +117,9 @@ func Setup(
 		).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 	}
 
+	// unspecced consent tracking
+	consentAPIMux.HandleFunc("/consent", consent(userAPI, cfg)).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
+
 	r0mux := publicAPIMux.PathPrefix("/r0").Subrouter()
 	unstableMux := publicAPIMux.PathPrefix("/unstable").Subrouter()