Revert "Drop support for delegating email validation (#13192)" (#13406)

Reverts commit fa71bb18b527d1a3e2629b48640ea67fff2f8c59, and tweaks documentation.

Signed-off-by: 3nprob <git@3n.anonaddy.com>

3 files changed, 117 insertions, 56 deletions

diff --git a/synapse/rest/client/account.py b/synapse/rest/client/account.py
index 0cc87a4001..50edc6b7d3 100644
--- a/synapse/rest/client/account.py
+++ b/synapse/rest/client/account.py
@@ -28,6 +28,7 @@ from synapse.api.errors import (
     SynapseError,
     ThreepidValidationError,
 )
+from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.handlers.ui_auth import UIAuthSessionDataConstants
 from synapse.http.server import HttpServer, finish_request, respond_with_html
 from synapse.http.servlet import (
@@ -63,7 +64,7 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
         self.config = hs.config
         self.identity_handler = hs.get_identity_handler()
 
-        if self.config.email.can_verify_email:
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
             self.mailer = Mailer(
                 hs=self.hs,
                 app_name=self.config.email.email_app_name,
@@ -72,10 +73,11 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
             )
 
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        if not self.config.email.can_verify_email:
-            logger.warning(
-                "User password resets have been disabled due to lack of email config"
-            )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
+            if self.config.email.local_threepid_handling_disabled_due_to_email_config:
+                logger.warning(
+                    "User password resets have been disabled due to lack of email config"
+                )
             raise SynapseError(
                 400, "Email-based password resets have been disabled on this server"
             )
@@ -127,21 +129,35 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
 
             raise SynapseError(400, "Email not found", Codes.THREEPID_NOT_FOUND)
 
-        # Send password reset emails from Synapse
-        sid = await self.identity_handler.send_threepid_validation(
-            email,
-            client_secret,
-            send_attempt,
-            self.mailer.send_password_reset_mail,
-            next_link,
-        )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+            assert self.hs.config.registration.account_threepid_delegate_email
+
+            # Have the configured identity server handle the request
+            ret = await self.identity_handler.request_email_token(
+                self.hs.config.registration.account_threepid_delegate_email,
+                email,
+                client_secret,
+                send_attempt,
+                next_link,
+            )
+        else:
+            # Send password reset emails from Synapse
+            sid = await self.identity_handler.send_threepid_validation(
+                email,
+                client_secret,
+                send_attempt,
+                self.mailer.send_password_reset_mail,
+                next_link,
+            )
+
+            # Wrap the session id in a JSON object
+            ret = {"sid": sid}
 
         threepid_send_requests.labels(type="email", reason="password_reset").observe(
             send_attempt
         )
 
-        # Wrap the session id in a JSON object
-        return 200, {"sid": sid}
+        return 200, ret
 
 
 class PasswordRestServlet(RestServlet):
@@ -333,7 +349,7 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
         self.identity_handler = hs.get_identity_handler()
         self.store = self.hs.get_datastores().main
 
-        if self.config.email.can_verify_email:
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
             self.mailer = Mailer(
                 hs=self.hs,
                 app_name=self.config.email.email_app_name,
@@ -342,10 +358,11 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
             )
 
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        if not self.config.email.can_verify_email:
-            logger.warning(
-                "Adding emails have been disabled due to lack of an email config"
-            )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
+            if self.config.email.local_threepid_handling_disabled_due_to_email_config:
+                logger.warning(
+                    "Adding emails have been disabled due to lack of an email config"
+                )
             raise SynapseError(
                 400, "Adding an email to your account is disabled on this server"
             )
@@ -396,20 +413,35 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
 
             raise SynapseError(400, "Email is already in use", Codes.THREEPID_IN_USE)
 
-        sid = await self.identity_handler.send_threepid_validation(
-            email,
-            client_secret,
-            send_attempt,
-            self.mailer.send_add_threepid_mail,
-            next_link,
-        )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+            assert self.hs.config.registration.account_threepid_delegate_email
+
+            # Have the configured identity server handle the request
+            ret = await self.identity_handler.request_email_token(
+                self.hs.config.registration.account_threepid_delegate_email,
+                email,
+                client_secret,
+                send_attempt,
+                next_link,
+            )
+        else:
+            # Send threepid validation emails from Synapse
+            sid = await self.identity_handler.send_threepid_validation(
+                email,
+                client_secret,
+                send_attempt,
+                self.mailer.send_add_threepid_mail,
+                next_link,
+            )
+
+            # Wrap the session id in a JSON object
+            ret = {"sid": sid}
 
         threepid_send_requests.labels(type="email", reason="add_threepid").observe(
             send_attempt
         )
 
-        # Wrap the session id in a JSON object
-        return 200, {"sid": sid}
+        return 200, ret
 
 
 class MsisdnThreepidRequestTokenRestServlet(RestServlet):
@@ -502,19 +534,25 @@ class AddThreepidEmailSubmitTokenServlet(RestServlet):
         self.config = hs.config
         self.clock = hs.get_clock()
         self.store = hs.get_datastores().main
-        if self.config.email.can_verify_email:
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
             self._failure_email_template = (
                 self.config.email.email_add_threepid_template_failure_html
             )
 
     async def on_GET(self, request: Request) -> None:
-        if not self.config.email.can_verify_email:
-            logger.warning(
-                "Adding emails have been disabled due to lack of an email config"
-            )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
+            if self.config.email.local_threepid_handling_disabled_due_to_email_config:
+                logger.warning(
+                    "Adding emails have been disabled due to lack of an email config"
+                )
             raise SynapseError(
                 400, "Adding an email to your account is disabled on this server"
             )
+        elif self.config.email.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+            raise SynapseError(
+                400,
+                "This homeserver is not validating threepids.",
+            )
 
         sid = parse_string(request, "sid", required=True)
         token = parse_string(request, "token", required=True)
diff --git a/synapse/rest/client/register.py b/synapse/rest/client/register.py
index a8402cdb3a..b7ab090bbd 100644
--- a/synapse/rest/client/register.py
+++ b/synapse/rest/client/register.py
@@ -31,6 +31,7 @@ from synapse.api.errors import (
 )
 from synapse.api.ratelimiting import Ratelimiter
 from synapse.config import ConfigError
+from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.config.homeserver import HomeServerConfig
 from synapse.config.ratelimiting import FederationRateLimitConfig
 from synapse.config.server import is_threepid_reserved
@@ -73,7 +74,7 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
         self.identity_handler = hs.get_identity_handler()
         self.config = hs.config
 
-        if self.hs.config.email.can_verify_email:
+        if self.hs.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
             self.mailer = Mailer(
                 hs=self.hs,
                 app_name=self.config.email.email_app_name,
@@ -82,10 +83,13 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
             )
 
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        if not self.hs.config.email.can_verify_email:
-            logger.warning(
-                "Email registration has been disabled due to lack of email config"
-            )
+        if self.hs.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
+            if (
+                self.hs.config.email.local_threepid_handling_disabled_due_to_email_config
+            ):
+                logger.warning(
+                    "Email registration has been disabled due to lack of email config"
+                )
             raise SynapseError(
                 400, "Email-based registration has been disabled on this server"
             )
@@ -134,21 +138,35 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
 
             raise SynapseError(400, "Email is already in use", Codes.THREEPID_IN_USE)
 
-        # Send registration emails from Synapse
-        sid = await self.identity_handler.send_threepid_validation(
-            email,
-            client_secret,
-            send_attempt,
-            self.mailer.send_registration_mail,
-            next_link,
-        )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+            assert self.hs.config.registration.account_threepid_delegate_email
+
+            # Have the configured identity server handle the request
+            ret = await self.identity_handler.request_email_token(
+                self.hs.config.registration.account_threepid_delegate_email,
+                email,
+                client_secret,
+                send_attempt,
+                next_link,
+            )
+        else:
+            # Send registration emails from Synapse,
+            # wrapping the session id in a JSON object.
+            ret = {
+                "sid": await self.identity_handler.send_threepid_validation(
+                    email,
+                    client_secret,
+                    send_attempt,
+                    self.mailer.send_registration_mail,
+                    next_link,
+                )
+            }
 
         threepid_send_requests.labels(type="email", reason="register").observe(
             send_attempt
         )
 
-        # Wrap the session id in a JSON object
-        return 200, {"sid": sid}
+        return 200, ret
 
 
 class MsisdnRegisterRequestTokenRestServlet(RestServlet):
@@ -242,7 +260,7 @@ class RegistrationSubmitTokenServlet(RestServlet):
         self.clock = hs.get_clock()
         self.store = hs.get_datastores().main
 
-        if self.config.email.can_verify_email:
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
             self._failure_email_template = (
                 self.config.email.email_registration_template_failure_html
             )
@@ -252,10 +270,11 @@ class RegistrationSubmitTokenServlet(RestServlet):
             raise SynapseError(
                 400, "This medium is currently not supported for registration"
             )
-        if not self.config.email.can_verify_email:
-            logger.warning(
-                "User registration via email has been disabled due to lack of email config"
-            )
+        if self.config.email.threepid_behaviour_email == ThreepidBehaviour.OFF:
+            if self.config.email.local_threepid_handling_disabled_due_to_email_config:
+                logger.warning(
+                    "User registration via email has been disabled due to lack of email config"
+                )
             raise SynapseError(
                 400, "Email-based registration is disabled on this server"
             )
diff --git a/synapse/rest/synapse/client/password_reset.py b/synapse/rest/synapse/client/password_reset.py
index b9402cfb75..6ac9dbc7c9 100644
--- a/synapse/rest/synapse/client/password_reset.py
+++ b/synapse/rest/synapse/client/password_reset.py
@@ -17,6 +17,7 @@ from typing import TYPE_CHECKING, Tuple
 from twisted.web.server import Request
 
 from synapse.api.errors import ThreepidValidationError
+from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.http.server import DirectServeHtmlResource
 from synapse.http.servlet import parse_string
 from synapse.util.stringutils import assert_valid_client_secret
@@ -45,6 +46,9 @@ class PasswordResetSubmitTokenResource(DirectServeHtmlResource):
         self.clock = hs.get_clock()
         self.store = hs.get_datastores().main
 
+        self._local_threepid_handling_disabled_due_to_email_config = (
+            hs.config.email.local_threepid_handling_disabled_due_to_email_config
+        )
         self._confirmation_email_template = (
             hs.config.email.email_password_reset_template_confirmation_html
         )
@@ -55,8 +59,8 @@ class PasswordResetSubmitTokenResource(DirectServeHtmlResource):
             hs.config.email.email_password_reset_template_failure_html
         )
 
-        # This resource should only be mounted if email validation is enabled
-        assert hs.config.email.can_verify_email
+        # This resource should not be mounted if threepid behaviour is not LOCAL
+        assert hs.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL
 
     async def _async_render_GET(self, request: Request) -> Tuple[int, bytes]:
         sid = parse_string(request, "sid", required=True)