From 369195caa5f52fc67c2496507fc99fccf4b0ede8 Mon Sep 17 00:00:00 2001
From: Luke Barnard <lukeb@openmarket.com>
Date: Wed, 10 May 2017 17:17:12 +0100
Subject: [PATCH 1/2] Modify register/available to be GET with query param

- GET is now the method for register/available
- a query parameter "username" is now used

Also, empty usernames are now handled with an error message on registration or via register/available: `User ID cannot be empty`
---
 synapse/handlers/register.py             | 7 +++++++
 synapse/rest/client/v2_alpha/register.py | 9 ++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 03c6a85fc6f0..dd84c5f5e9ba 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -54,6 +54,13 @@ def check_username(self, localpart, guest_access_token=None,
                 Codes.INVALID_USERNAME
             )
 
+        if len(localpart) == 0:
+            raise SynapseError(
+                400,
+                "User ID cannot be empty",
+                Codes.INVALID_USERNAME
+            )
+
         if localpart[0] == '_':
             raise SynapseError(
                 400,
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 6a7cd96ea560..1421c18152e7 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -21,7 +21,7 @@
 from synapse.api.constants import LoginType
 from synapse.api.errors import SynapseError, Codes, UnrecognizedRequestError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, assert_params_in_request
+    RestServlet, parse_json_object_from_request, assert_params_in_request, parse_string
 )
 from synapse.util.msisdn import phone_number_to_msisdn
 
@@ -142,15 +142,14 @@ def __init__(self, hs):
         )
 
     @defer.inlineCallbacks
-    def on_POST(self, request):
+    def on_GET(self, request):
         ip = self.hs.get_ip_from_request(request)
         with self.ratelimiter.ratelimit(ip) as wait_deferred:
             yield wait_deferred
 
-            body = parse_json_object_from_request(request)
-            assert_params_in_request(body, ['username'])
+            username = parse_string(request, "username", required=True)
 
-            yield self.registration_handler.check_username(body['username'])
+            yield self.registration_handler.check_username(username)
 
             defer.returnValue((200, {"available": True}))
 

From ccad2ed824f1601d2cc29aafe5dff6ef46668f5e Mon Sep 17 00:00:00 2001
From: Luke Barnard <lukeb@openmarket.com>
Date: Wed, 10 May 2017 17:34:30 +0100
Subject: [PATCH 2/2] Modify condition on empty localpart

---
 synapse/handlers/register.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index dd84c5f5e9ba..ee3a2269a847 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -54,7 +54,7 @@ def check_username(self, localpart, guest_access_token=None,
                 Codes.INVALID_USERNAME
             )
 
-        if len(localpart) == 0:
+        if not localpart:
             raise SynapseError(
                 400,
                 "User ID cannot be empty",