chore: News fragments

changelog.d/+1608cdcb.feature.md

@@ -0,0 +1 @@
+Users will now be prevented from removing their email if the server is configured to require an email when registering an account.

changelog.d/+e82957a7.bugfix.md

@@ -0,0 +1 @@
+Fixed a situation where multiple email addresses could be associated with one user when that user changes their email address.

conduwuit-example.toml

@@ -2104,6 +2104,9 @@
 # Whether to require that users provide an email address when they
 # register.
 #
+# If either this option or `require_email_for_token_registration` are set,
+# users will not be allowed to remove their email address.
+#
 #require_email_for_registration = false
 
 # Whether to require that users who register with a registration token

src/api/client/account/threepid.rs

@@ -53,6 +53,10 @@ pub(crate) async fn request_3pid_management_token_via_email_route(
 	State(services): State<crate::State>,
 	body: Ruma<request_3pid_management_token_via_email::v3::Request>,
 ) -> Result<request_3pid_management_token_via_email::v3::Response> {
+	if !services.threepid.email_requirement().may_change() {
+		return Err!(Request(Forbidden("You may not change your email address.")));
+	}
+
 	let Ok(email) = Address::try_from(body.email.clone()) else {
 		return Err!(Request(InvalidParam("Invalid email address.")));
 	};
@@ -105,6 +109,10 @@ pub(crate) async fn add_3pid_route(
 ) -> Result<add_3pid::v3::Response> {
 	let sender_user = body.sender_user();
 
+	if !services.threepid.email_requirement().may_change() {
+		return Err!(Request(Forbidden("You may not change your email address.")));
+	}
+
 	// Require password auth to add an email
 	let _ = services
 		.uiaa
@@ -138,6 +146,10 @@ pub(crate) async fn delete_3pid_route(
 		});
 	}
 
+	if !services.threepid.email_requirement().may_remove() {
+		return Err!(Request(Forbidden("You may not remove your email address.")));
+	}
+
 	if services
 		.threepid
 		.disassociate_localpart_email(sender_user.localpart())

src/api/client/capabilities.rs

@@ -32,7 +32,7 @@ pub(crate) async fn get_capabilities_route(
 
 	// Only allow 3pid changes if SMTP is configured
 	capabilities.thirdparty_id_changes = ThirdPartyIdChangesCapability {
-		enabled: services.mailer.mailer().is_some(),
+		enabled: services.threepid.email_requirement().may_change(),
 	};
 
 	capabilities.get_login_token = GetLoginTokenCapability {

src/core/config/mod.rs

@@ -2516,6 +2516,9 @@ pub struct SmtpConfig {
 	/// Whether to require that users provide an email address when they
 	/// register.
 	///
+	/// If either this option or `require_email_for_token_registration` are set,
+	/// users will not be allowed to remove their email address.
+	///
 	/// default: false
 	#[serde(default)]
 	pub require_email_for_registration: bool,

src/service/threepid/mod.rs

@@ -25,6 +25,23 @@ pub struct Service {
 	ratelimiter: DefaultKeyedRateLimiter<Address>,
 }
 
+pub enum EmailRequirement {
+	/// Users may change their email, but cannot remove it entirely.
+	Required,
+	/// Users may change or remove their email.
+	Optional,
+	/// Users may not change their email at all.
+	Unavailable,
+}
+
+impl EmailRequirement {
+	#[must_use]
+	pub fn may_change(&self) -> bool { matches!(self, Self::Required | Self::Optional) }
+
+	#[must_use]
+	pub fn may_remove(&self) -> bool { matches!(self, Self::Optional) }
+}
+
 struct Data {
 	localpart_email: Arc<Map>,
 	email_localpart: Arc<Map>,
@@ -64,6 +81,19 @@ impl Service {
 		Quota::per_minute(nonzero!(10_u32)).allow_burst(nonzero!(2_u32));
 	const VALIDATION_URL_PATH: &str = "/_continuwuity/3pid/email/validate";
 
+	/// Check if users are required to have an email address.
+	pub fn email_requirement(&self) -> EmailRequirement {
+		if let Some(smtp) = &self.services.config.smtp {
+			if smtp.require_email_for_registration || smtp.require_email_for_token_registration {
+				EmailRequirement::Required
+			} else {
+				EmailRequirement::Optional
+			}
+		} else {
+			EmailRequirement::Unavailable
+		}
+	}
+
 	/// Send a validation message to an email address.
 	///
 	/// Returns the validation session ID on success.
@@ -234,6 +264,9 @@ pub async fn associate_localpart_email(
 			| None => {
 				// The supplied email is not already in use.
 
+				// Remove the user's existing email first.
+				let _ = self.disassociate_localpart_email(localpart).await;
+
 				let email: &str = email.as_ref();
 				self.db.localpart_email.insert(localpart, email);
 				self.db.email_localpart.insert(email, localpart);