Add lt-cred-mech authentication mechanism to Coturn

All homeserver implementations have been updated to support this as
well.

It's just Jitsi that possibly doesn't work with anything other than `auth-secret`.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3191

docs/configuring-playbook-turn.md

@@ -34,6 +34,21 @@ If your server has multiple external IP addresses, the Coturn role offers a diff
 matrix_coturn_turn_external_ip_addresses: ['1.2.3.4', '4.5.6.7']
 ```
 
+## Changing the authentication mechanism
+
+The playbook uses the [`auth-secret` authentication method](https://github.com/coturn/coturn/blob/873cabd6a2e5edd7e9cc5662cac3ffe47fe87a8e/README.turnserver#L186-L199) by default, but you may switch to the [`lt-cred-mech` method](https://github.com/coturn/coturn/blob/873cabd6a2e5edd7e9cc5662cac3ffe47fe87a8e/README.turnserver#L178) which [some report](https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3191) to be working better.
+
+To do so, add this override to your configuration:
+
+```yml
+matrix_coturn_authentication_method: lt-cred-mech
+```
+
+Regardless of the selected authentication method, the playbook generates secrets automatically and passes them to the homeserver and Coturn.
+
+If you're using [Jitsi](./configuring-playbook-jitsi.md), note that switching to `lt-cred-mech` will remove the integration between Jitsi and your own Coturn server, because Jitsi only seems to support the `auth-secret` authentication method.
+
+
 ## Using your own external Coturn server
 
 If you'd like to use another TURN server (be it Coturn or some other one), you can configure the playbook like this:

group_vars/matrix_servers

@@ -2723,7 +2723,10 @@ matrix_coturn_container_image_self_build: "{{ matrix_architecture not in ['amd64
 # to allow auto-detection (via an EchoIP service) to happen at runtime.
 matrix_coturn_turn_external_ip_address: "{{ ansible_host }}"
 
-matrix_coturn_turn_static_auth_secret: "{{ '%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'coturn.sas', rounds=655555) | to_uuid }}"
+matrix_coturn_turn_static_auth_secret: "{{ ('%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'coturn.sas', rounds=655555) | to_uuid) if matrix_coturn_authentication_method == 'auth-secret' else '' }}"
+
+matrix_coturn_lt_cred_mech_username: "{{ ('%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'coturn.user', rounds=655555) | to_uuid) if matrix_coturn_authentication_method == 'lt-cred-mech' else '' }}"
+matrix_coturn_lt_cred_mech_password: "{{ ('%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'coturn.pass', rounds=655555) | to_uuid) if matrix_coturn_authentication_method == 'lt-cred-mech' else '' }}"
 
 matrix_coturn_tls_enabled: "{{ matrix_playbook_ssl_enabled }}"
 
@@ -3007,7 +3010,9 @@ jitsi_web_stun_servers: |
 # The Jitsi instance installed by this playbook is meant for embedding into Matrix clients, so framing is allowed.
 jitsi_web_framing_enabled: true
 
-jitsi_turn_credentials: "{{ matrix_coturn_turn_static_auth_secret if matrix_coturn_enabled else '' }}"
+# Jitsi (Prosody) only seems to support authenticating with Coturn using `auth-secret`, not `lt-cred-mech`.
+# See: https://prosody.im/doc/coturn
+jitsi_turn_credentials: "{{ matrix_coturn_turn_static_auth_secret if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'auth-secret') else '' }}"
 jitsi_turn_host: "{{ ('turn.' + matrix_server_fqn_matrix) if matrix_coturn_enabled else '' }}"
 jitsi_turns_host: "{{ ('turn.' + matrix_server_fqn_matrix) if matrix_coturn_enabled else '' }}"
 jitsi_turn_port: "{{ matrix_coturn_container_stun_plain_host_bind_port if matrix_coturn_enabled else '' }}"
@@ -3972,7 +3977,9 @@ matrix_synapse_turn_uris: |
     ] if matrix_coturn_enabled else [])
   }}
 
-matrix_synapse_turn_shared_secret: "{{ matrix_coturn_turn_static_auth_secret if matrix_coturn_enabled else '' }}"
+matrix_synapse_turn_shared_secret: "{{ matrix_coturn_turn_static_auth_secret if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'auth-secret') else '' }}"
+matrix_synapse_turn_username: "{{ matrix_coturn_lt_cred_mech_username if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
+matrix_synapse_turn_password: "{{ matrix_coturn_lt_cred_mech_password if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
 
 matrix_synapse_self_check_validate_certificates: "{{ matrix_playbook_ssl_enabled }}"
 
@@ -4639,7 +4646,9 @@ matrix_dendrite_client_api_turn_uris: |
     else []
   }}
 
-matrix_dendrite_client_api_turn_shared_secret: "{{ matrix_coturn_turn_static_auth_secret if matrix_coturn_enabled else '' }}"
+matrix_dendrite_client_api_turn_shared_secret: "{{ matrix_coturn_turn_static_auth_secret if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'auth-secret') else '' }}"
+matrix_dendrite_client_api_turn_username: "{{ matrix_coturn_lt_cred_mech_username if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
+matrix_dendrite_client_api_turn_password: "{{ matrix_coturn_lt_cred_mech_password if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
 
 matrix_dendrite_disable_tls_validation: "{{ not matrix_playbook_ssl_enabled }}"
 
@@ -4717,7 +4726,9 @@ matrix_conduit_turn_uris: |
     ] if matrix_coturn_enabled else [])
   }}
 
-matrix_conduit_turn_secret: "{{ matrix_coturn_turn_static_auth_secret if matrix_coturn_enabled else '' }}"
+matrix_conduit_turn_secret: "{{ matrix_coturn_turn_static_auth_secret if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'auth-secret') else '' }}"
+matrix_conduit_turn_username: "{{ matrix_coturn_lt_cred_mech_username if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
+matrix_conduit_turn_password: "{{ matrix_coturn_lt_cred_mech_password if (matrix_coturn_enabled and matrix_coturn_authentication_method == 'lt-cred-mech') else '' }}"
 
 ######################################################################
 #

roles/custom/matrix-coturn/defaults/main.yml

@@ -73,10 +73,26 @@ matrix_coturn_container_turn_range_listen_interface: "{{ '' if matrix_coturn_con
 matrix_coturn_turn_udp_min_port: 49152
 matrix_coturn_turn_udp_max_port: 49172
 
-# A shared secret (between Synapse and Coturn) used for authentication.
+# Controls which authentication method to enable.
+#
+# lt-cred-mech likely provides better compatibility,
+# as described here: https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3191
+# but those claims are unverified.
+#
+# For now, we still default to `auth-secret` like we've always done.
+#
+# Known values: auth-secret, lt-cred-mech
+matrix_coturn_authentication_method: auth-secret
+
+# A shared secret used for authentication when `matrix_coturn_authentication_method` is `auth-secret`.
 # You can put any string here, but generating a strong one is preferred (e.g. `pwgen -s 64 1`).
 matrix_coturn_turn_static_auth_secret: ""
 
+# A username used authentication when `matrix_coturn_authentication_method` is `lt-cred-mech`.
+matrix_coturn_lt_cred_mech_username: ""
+# A password used authentication when `matrix_coturn_authentication_method` is `lt-cred-mech`.
+matrix_coturn_lt_cred_mech_password: ""
+
 # The external IP address of the machine where Coturn is.
 # If do not define an IP address here or in `matrix_coturn_turn_external_ip_addresses`, auto-detection via an EchoIP service will be done.
 # See `matrix_coturn_turn_external_ip_address_auto_detection_enabled`

roles/custom/matrix-coturn/tasks/validate_config.yml

@@ -9,10 +9,18 @@
   with_items:
     - {'old': 'matrix_coturn_docker_network', 'new': 'matrix_coturn_container_network'}
 
+- name: Fail if matrix_coturn_authentication_method is invalid
+  ansible.builtin.fail:
+    msg: >-
+      Invalid authentication method specified in `matrix_coturn_authentication_method`
+  when: "matrix_coturn_authentication_method not in ['auth-secret', 'lt-cred-mech']"
+
 - name: Fail if required Coturn settings not defined
   ansible.builtin.fail:
     msg: >-
-      You need to define a required configuration setting (`{{ item }}`) for using Coturn.
-  when: "vars[item] == ''"
+      You need to define a required configuration setting (`{{ item.name }}`).
+  when: "item.when | bool and vars[item.name] == ''"
   with_items:
-    - "matrix_coturn_turn_static_auth_secret"
+    - {'name': 'matrix_coturn_turn_static_auth_secret', when: "{{ matrix_coturn_authentication_method == 'auth-secret' }}"}
+    - {'name': 'matrix_coturn_lt_cred_mech_username', when: "{{ matrix_coturn_authentication_method == 'lt-cred-mech' }}"}
+    - {'name': 'matrix_coturn_lt_cred_mech_password', when: "{{ matrix_coturn_authentication_method == 'lt-cred-mech' }}"}

roles/custom/matrix-coturn/templates/turnserver.conf.j2

@@ -1,17 +1,27 @@
 #jinja2: lstrip_blocks: "True"
+
+{% if matrix_coturn_authentication_method == 'auth-secret' %}
 use-auth-secret
 static-auth-secret={{ matrix_coturn_turn_static_auth_secret }}
+userdb=/var/tmp/turnserver.db
+{% endif %}
+
+{% if matrix_coturn_authentication_method == 'lt-cred-mech' %}
+lt-cred-mech
+user={{ matrix_coturn_lt_cred_mech_username }}:{{ matrix_coturn_lt_cred_mech_password }}
+{% endif %}
+
 realm=turn.{{ matrix_server_fqn_matrix }}
 
 min-port={{ matrix_coturn_turn_udp_min_port }}
 max-port={{ matrix_coturn_turn_udp_max_port }}
+
 {% for ip in matrix_coturn_turn_external_ip_addresses %}
 external-ip={{ ip }}
 {% endfor %}
 
 log-file=stdout
 pidfile=/var/tmp/turnserver.pid
-userdb=/var/tmp/turnserver.db
 
 no-cli
 

roles/custom/matrix-dendrite/defaults/main.yml

@@ -283,6 +283,8 @@ matrix_dendrite_mscs_database: "dendrite_mscs"
 
 matrix_dendrite_client_api_turn_uris: []
 matrix_dendrite_client_api_turn_shared_secret: ""
+matrix_dendrite_client_api_turn_username: ""
+matrix_dendrite_client_api_turn_password: ""
 matrix_dendrite_client_api_turn_allow_guests: false
 
 matrix_dendrite_disable_tls_validation: false

roles/custom/matrix-dendrite/templates/dendrite.yaml.j2

@@ -202,8 +202,8 @@ client_api:
     turn_user_lifetime: ""
     turn_uris: {{ matrix_dendrite_client_api_turn_uris | to_json }}
     turn_shared_secret: {{ matrix_dendrite_client_api_turn_shared_secret | to_json }}
-    turn_username: ""
-    turn_password: ""
+    turn_username: {{ matrix_dendrite_client_api_turn_username | to_json }}
+    turn_password: {{ matrix_dendrite_client_api_turn_password | to_json }}
 
   # Settings for rate-limited endpoints. Rate limiting will kick in after the
   # threshold number of "slots" have been taken by requests from a specific

roles/custom/matrix-synapse/defaults/main.yml

@@ -1063,6 +1063,8 @@ matrix_synapse_database_database: "synapse"
 
 matrix_synapse_turn_uris: []
 matrix_synapse_turn_shared_secret: ""
+matrix_synapse_turn_username: ""
+matrix_synapse_turn_password: ""
 matrix_synapse_turn_allow_guests: false
 
 matrix_synapse_email_enabled: false

roles/custom/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -1263,13 +1263,13 @@ turn_uris: {{ matrix_synapse_turn_uris|to_json }}
 
 # The shared secret used to compute passwords for the TURN server
 #
-turn_shared_secret: {{ matrix_synapse_turn_shared_secret | string|to_json }}
+turn_shared_secret: {{ matrix_synapse_turn_shared_secret | string | to_json }}
 
 # The Username and password if the TURN server needs them and
 # does not use a token
 #
-#turn_username: "TURNSERVER_USERNAME"
-#turn_password: "TURNSERVER_PASSWORD"
+turn_username: {{ matrix_synapse_turn_username | string  | to_json }}
+turn_password: {{ matrix_synapse_turn_password | string  | to_json }}
 
 # How long generated TURN credentials last
 #