From e8d1ec0e92da96a01b6c723fcdb4eac27f801e87 Mon Sep 17 00:00:00 2001
From: Will Hunt <will@half-shot.uk>
Date: Wed, 27 Apr 2022 13:57:53 +0100
Subject: [PATCH] Add option to enable token registration without requiring
 3pids (#12526)

---
 changelog.d/12526.feature            | 1 +
 docs/sample_config.yaml              | 6 ++++++
 synapse/config/registration.py       | 9 +++++++++
 synapse/handlers/ui_auth/checkers.py | 4 +++-
 synapse/rest/client/register.py      | 7 ++++++-
 5 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 changelog.d/12526.feature

diff --git a/changelog.d/12526.feature b/changelog.d/12526.feature
new file mode 100644
index 0000000000..c01596282c
--- /dev/null
+++ b/changelog.d/12526.feature
@@ -0,0 +1 @@
+Add new `enable_registration_token_3pid_bypass` configuration option to allow registrations via token as an alternative to verifying a 3pid.
\ No newline at end of file
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index b8d8c0dbf0..67184c6b1a 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1323,6 +1323,12 @@ oembed:
 #
 #registration_requires_token: true
 
+# Allow users to submit a token during registration to bypass any required 3pid
+# steps configured in `registrations_require_3pid`.
+# Defaults to false, requiring that registration tokens (if enabled) complete a 3pid flow.
+#
+#enable_registration_token_3pid_bypass: false
+
 # If set, allows registration of standard or admin accounts by anyone who
 # has the shared secret, even if registration is otherwise disabled.
 #
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 39e9acb62a..70eb7e6a97 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -43,6 +43,9 @@ class RegistrationConfig(Config):
         self.registration_requires_token = config.get(
             "registration_requires_token", False
         )
+        self.enable_registration_token_3pid_bypasss = config.get(
+            "enable_registration_token_3pid_bypasss", False
+        )
         self.registration_shared_secret = config.get("registration_shared_secret")
 
         self.bcrypt_rounds = config.get("bcrypt_rounds", 12)
@@ -309,6 +312,12 @@ class RegistrationConfig(Config):
         #
         #registration_requires_token: true
 
+        # Allow users to submit a token during registration to bypass any required 3pid
+        # steps configured in `registrations_require_3pid`.
+        # Defaults to false, requiring that registration tokens (if enabled) complete a 3pid flow.
+        #
+        #enable_registration_token_3pid_bypass: false
+
         # If set, allows registration of standard or admin accounts by anyone who
         # has the shared secret, even if registration is otherwise disabled.
         #
diff --git a/synapse/handlers/ui_auth/checkers.py b/synapse/handlers/ui_auth/checkers.py
index 472b029af3..e2a441066d 100644
--- a/synapse/handlers/ui_auth/checkers.py
+++ b/synapse/handlers/ui_auth/checkers.py
@@ -256,7 +256,9 @@ class RegistrationTokenAuthChecker(UserInteractiveAuthChecker):
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         self.hs = hs
-        self._enabled = bool(hs.config.registration.registration_requires_token)
+        self._enabled = bool(
+            hs.config.registration.registration_requires_token
+        ) or bool(hs.config.registration.enable_registration_token_3pid_bypasss)
         self.store = hs.get_datastores().main
 
     def is_enabled(self) -> bool:
diff --git a/synapse/rest/client/register.py b/synapse/rest/client/register.py
index 70baf50fa4..13ef6b35a0 100644
--- a/synapse/rest/client/register.py
+++ b/synapse/rest/client/register.py
@@ -929,6 +929,10 @@ def _calculate_registration_flows(
         # always let users provide both MSISDN & email
         flows.append([LoginType.MSISDN, LoginType.EMAIL_IDENTITY])
 
+    # Add a flow that doesn't require any 3pids, if the config requests it.
+    if config.registration.enable_registration_token_3pid_bypasss:
+        flows.append([LoginType.REGISTRATION_TOKEN])
+
     # Prepend m.login.terms to all flows if we're requiring consent
     if config.consent.user_consent_at_registration:
         for flow in flows:
@@ -942,7 +946,8 @@ def _calculate_registration_flows(
     # Prepend registration token to all flows if we're requiring a token
     if config.registration.registration_requires_token:
         for flow in flows:
-            flow.insert(0, LoginType.REGISTRATION_TOKEN)
+            if LoginType.REGISTRATION_TOKEN not in flow:
+                flow.insert(0, LoginType.REGISTRATION_TOKEN)
 
     return flows