From aa36166766cb896840d4ab9c2c4080b413bb4214 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erikj@matrix.org>
Date: Thu, 5 Oct 2017 15:47:29 +0100
Subject: [PATCH] Generate new devices for each new /login

---
 .../matrix-org/dendrite/clientapi/auth/auth.go       | 12 ++++++++++++
 .../matrix-org/dendrite/clientapi/readers/login.go   | 12 +++++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/github.com/matrix-org/dendrite/clientapi/auth/auth.go b/src/github.com/matrix-org/dendrite/clientapi/auth/auth.go
index b0bbe2bbb..668bab5f3 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/auth/auth.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/auth/auth.go
@@ -86,6 +86,18 @@ func GenerateAccessToken() (string, error) {
 	return base64.RawURLEncoding.EncodeToString(b), nil
 }
 
+// GenerateDeviceID creates a new device id. Returns an error if failed to generate
+// random bytes.
+func GenerateDeviceID() (string, error) {
+	b := make([]byte, tokenByteLength)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+	// url-safe no padding
+	return base64.RawURLEncoding.EncodeToString(b), nil
+}
+
 // extractAccessToken from a request, or return an error detailing what went wrong. The
 // error message MUST be human-readable and comprehensible to the client.
 func extractAccessToken(req *http.Request) (string, error) {
diff --git a/src/github.com/matrix-org/dendrite/clientapi/readers/login.go b/src/github.com/matrix-org/dendrite/clientapi/readers/login.go
index de6ecf5c6..329791fd1 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/readers/login.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/readers/login.go
@@ -113,15 +113,17 @@ func Login(
 
 		token, err := auth.GenerateAccessToken()
 		if err != nil {
-			return util.JSONResponse{
-				Code: 500,
-				JSON: jsonerror.Unknown("Failed to generate access token"),
-			}
+			httputil.LogThenError(req, err)
+		}
+
+		deviceID, err := auth.GenerateDeviceID()
+		if err != nil {
+			httputil.LogThenError(req, err)
 		}
 
 		// TODO: Use the device ID in the request
 		dev, err := deviceDB.CreateDevice(
-			req.Context(), acc.Localpart, auth.UnknownDeviceID, token,
+			req.Context(), acc.Localpart, deviceID, token,
 		)
 		if err != nil {
 			return util.JSONResponse{