Taking the legacy listeners away, and putting them back

LP-1 and LP-5, the registry half. close() removes every listener object the policy closes, saving each one whole first; reopen() puts them back. The switch removes the listener objects, not just their sockets. A stopped socket returns on the next restart, which would reopen every port the operator had just closed, and the operator would have no way to know. A removed object stays removed, and a server that boots with the switch on never spawns those listeners at all -- so there is no boot-time special case to write or to forget. LP-3 is decided here, on the object rather than the running socket, and sees every address a listener binds: a submission listener that also binds 25 is inbound and stays. lmtp and http are never candidates. A listener that cannot be put back does not stop the others; it comes back with its reason and stays saved for another try (LP-5). A delete the registry declines is reported as not removed, so the policy never claims a port is closed while it is still accepting. Stopping the running socket is still a separate step in common, which owns the listener registry. Nothing calls any of this yet.
2026-09-20 15:19:08 -07:00
parent c35b24b123
commit f04dbc3417
2 changed files with 296 additions and 0 deletions
@@ -0,0 +1,295 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Taking the legacy listeners away and putting them back (legacy-protocols
+//! spec, LP-1 and LP-5).
+//!
+//! The switch removes the listener **objects**, not just their sockets. A
+//! stopped socket comes back on the next restart, which would reopen every
+//! port the operator just closed; a removed object does not. It also means a
+//! server that boots with the switch on never spawns them in the first place,
+//! with no boot-time special case.
+//!
+//! Each removed object is kept whole in the policy so LP-5 can put it back
+//! exactly as it was. Closing the running socket is a separate step, and lives
+//! in `common`, which owns the listener registry: this crate sits below it.
+//!
+//! None of this touches the host's firewall or any port-forward (LP-20).
+
+use crate::security::protocol_policy::{ProtocolPolicy, SavedListener};
+use registry::schema::{
+    enums::NetworkListenerProtocol,
+    prelude::Object,
+    structs::NetworkListener,
+};
+use store::{
+    RegistryStore,
+    registry::write::{RegistryWrite, RegistryWriteResult},
+};
+use trc::AddContext;
+
+/// How the registry schema spells a listener's protocol. These are the strings
+/// [`ProtocolPolicy::closes`] matches on.
+pub fn protocol_name(protocol: NetworkListenerProtocol) -> &'static str {
+    match protocol {
+        NetworkListenerProtocol::Smtp => "smtp",
+        NetworkListenerProtocol::Lmtp => "lmtp",
+        NetworkListenerProtocol::Http => "http",
+        NetworkListenerProtocol::Imap => "imap",
+        NetworkListenerProtocol::Pop3 => "pop3",
+        NetworkListenerProtocol::ManageSieve => "manageSieve",
+    }
+}
+
+/// Every port a listener binds. A listener may bind several, and one of them
+/// being 25 makes the whole listener inbound (LP-3).
+pub fn ports(listener: &NetworkListener) -> Vec<u16> {
+    listener.bind.iter().map(|addr| addr.0.port()).collect()
+}
+
+/// Whether the policy closes this listener.
+pub fn closes(policy: &ProtocolPolicy, listener: &NetworkListener) -> bool {
+    policy.closes(protocol_name(listener.protocol), &ports(listener))
+}
+
+/// Saves a listener whole, ready to be put back (LP-5).
+fn save(listener: &NetworkListener) -> trc::Result<SavedListener> {
+    Ok(SavedListener {
+        id: listener.name.clone(),
+        protocol: protocol_name(listener.protocol).to_string(),
+        ports: ports(listener),
+        object: serde_json::to_value(listener).map_err(|err| {
+            trc::StoreEvent::UnexpectedError
+                .caused_by(trc::location!())
+                .reason(err)
+        })?,
+    })
+}
+
+/// Removes every listener the policy closes, saving each one whole first
+/// (LP-1). Returns what was removed, in the order the registry listed it.
+///
+/// The caller then stops the matching running sockets, by the `id` of each
+/// returned listener — which is the listener's name, the same key the runtime
+/// registry uses.
+pub async fn close(
+    registry: &RegistryStore,
+    policy: &ProtocolPolicy,
+) -> trc::Result<Vec<SavedListener>> {
+    let mut removed = Vec::new();
+
+    for listener in registry
+        .list::<NetworkListener>()
+        .await
+        .caused_by(trc::location!())?
+    {
+        if !closes(policy, &listener.object) {
+            continue;
+        }
+
+        let saved = save(&listener.object)?;
+        match registry
+            .write(RegistryWrite::delete(listener.id))
+            .await
+            .caused_by(trc::location!())?
+        {
+            RegistryWriteResult::Success(_) | RegistryWriteResult::NotFound { .. } => {
+                removed.push(saved);
+            }
+            // Anything else means the registry declined the delete. Leave the
+            // listener alone and say nothing was removed, so the policy does
+            // not claim a port is closed while it is still accepting.
+            _ => {}
+        }
+    }
+
+    Ok(removed)
+}
+
+/// Puts back every saved listener (LP-5).
+///
+/// Returns the ones restored and the ones that could not be, each with the
+/// reason. A listener that cannot come back — its port taken in the meantime,
+/// say — does not stop the others, and stays saved for another try.
+pub async fn reopen(
+    registry: &RegistryStore,
+    saved: &[SavedListener],
+) -> trc::Result<(Vec<SavedListener>, Vec<(SavedListener, String)>)> {
+    let mut restored = Vec::new();
+    let mut failed = Vec::new();
+
+    for listener in saved {
+        let object: NetworkListener = match serde_json::from_value(listener.object.clone()) {
+            Ok(object) => object,
+            Err(err) => {
+                failed.push((listener.clone(), format!("saved listener unreadable: {err}")));
+                continue;
+            }
+        };
+
+        let object: Object = object.into();
+        match registry
+            .write(RegistryWrite::insert(&object))
+            .await
+            .caused_by(trc::location!())?
+        {
+            RegistryWriteResult::Success(_) => restored.push(listener.clone()),
+            other => failed.push((listener.clone(), format!("{other:?}"))),
+        }
+    }
+
+    Ok((restored, failed))
+}
+
+/// The listener objects that exist right now, as `(name, protocol, ports)`.
+/// The confirmation (LP-16) lists exactly what will close, before anything
+/// happens.
+pub async fn would_close(
+    registry: &RegistryStore,
+    policy: &ProtocolPolicy,
+) -> trc::Result<Vec<SavedListener>> {
+    let mut out = Vec::new();
+    for listener in registry
+        .list::<NetworkListener>()
+        .await
+        .caused_by(trc::location!())?
+    {
+        if closes(policy, &listener.object) {
+            out.push(save(&listener.object)?);
+        }
+    }
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::security::protocol_policy::LegacyProtocols;
+    use registry::{schema::prelude::SocketAddr, types::map::Map};
+    use std::str::FromStr;
+
+    fn listener(name: &str, protocol: NetworkListenerProtocol, binds: &[&str]) -> NetworkListener {
+        NetworkListener {
+            name: name.to_string(),
+            protocol,
+            bind: Map::new(
+                binds
+                    .iter()
+                    .map(|addr| SocketAddr::from_str(addr).unwrap())
+                    .collect::<Vec<_>>(),
+            ),
+            ..Default::default()
+        }
+    }
+
+    fn disabled() -> ProtocolPolicy {
+        ProtocolPolicy {
+            legacy_protocols: LegacyProtocols::Disabled,
+            ..Default::default()
+        }
+    }
+
+    /// The protocol names match what the policy matches on.
+    #[test]
+    fn protocol_names_are_the_schema_spelling() {
+        assert_eq!(protocol_name(NetworkListenerProtocol::Imap), "imap");
+        assert_eq!(protocol_name(NetworkListenerProtocol::Pop3), "pop3");
+        assert_eq!(
+            protocol_name(NetworkListenerProtocol::ManageSieve),
+            "manageSieve"
+        );
+        assert_eq!(protocol_name(NetworkListenerProtocol::Smtp), "smtp");
+    }
+
+    /// Every bound port is seen, so a listener that also binds 25 is caught.
+    #[test]
+    fn every_bound_port_is_seen() {
+        let l = listener(
+            "mixed",
+            NetworkListenerProtocol::Smtp,
+            &["[::]:465", "0.0.0.0:25"],
+        );
+        let mut p = ports(&l);
+        p.sort();
+        assert_eq!(p, vec![25, 465]);
+    }
+
+    /// The mail-app listeners close; inbound and JMAP do not (LP-1, LP-3).
+    #[test]
+    fn the_right_listeners_close() {
+        let policy = disabled();
+
+        for (name, protocol, binds) in [
+            ("imaps", NetworkListenerProtocol::Imap, &["[::]:993"][..]),
+            ("pop3s", NetworkListenerProtocol::Pop3, &["[::]:995"][..]),
+            (
+                "sieve",
+                NetworkListenerProtocol::ManageSieve,
+                &["[::]:4190"][..],
+            ),
+            (
+                "submissions",
+                NetworkListenerProtocol::Smtp,
+                &["[::]:465"][..],
+            ),
+        ] {
+            assert!(
+                closes(&policy, &listener(name, protocol, binds)),
+                "{name} should close"
+            );
+        }
+
+        for (name, protocol, binds) in [
+            ("smtp", NetworkListenerProtocol::Smtp, &["[::]:25"][..]),
+            ("https", NetworkListenerProtocol::Http, &["[::]:443"][..]),
+            ("lmtp", NetworkListenerProtocol::Lmtp, &["[::]:11200"][..]),
+        ] {
+            assert!(
+                !closes(&policy, &listener(name, protocol, binds)),
+                "{name} must stay"
+            );
+        }
+    }
+
+    /// A submission listener that also binds 25 is inbound, and stays (LP-3).
+    #[test]
+    fn a_listener_that_also_binds_25_stays() {
+        let policy = disabled();
+        let l = listener(
+            "mixed",
+            NetworkListenerProtocol::Smtp,
+            &["[::]:465", "[::]:25"],
+        );
+        assert!(!closes(&policy, &l));
+    }
+
+    /// A saved listener keeps every field, including ones this code never
+    /// reads, and comes back as the same object (LP-5).
+    #[test]
+    fn a_saved_listener_round_trips() {
+        let mut original = listener("imaps", NetworkListenerProtocol::Imap, &["[::]:993"]);
+        original.socket_no_delay = true;
+        original.socket_backlog = Some(2048);
+
+        let saved = save(&original).unwrap();
+        assert_eq!(saved.id, "imaps");
+        assert_eq!(saved.protocol, "imap");
+        assert_eq!(saved.ports, vec![993]);
+
+        let back: NetworkListener = serde_json::from_value(saved.object).unwrap();
+        assert_eq!(back, original);
+    }
+
+    /// While the switch is off, nothing closes.
+    #[test]
+    fn enabled_closes_nothing() {
+        let policy = ProtocolPolicy::default();
+        assert!(!closes(
+            &policy,
+            &listener("imaps", NetworkListenerProtocol::Imap, &["[::]:993"])
+        ));
+    }
+}
@@ -10,4 +10,5 @@
 //! ships. The legacy-protocols switch is INBUXA's own design, specified in
 //! `legacy-protocols.md`.

+pub mod listeners;
 pub mod protocol_policy;