Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1175 insertions, 0 deletions

diff --git a/third_party/rust/tabs/src/sync/bridge.rs b/third_party/rust/tabs/src/sync/bridge.rs
new file mode 100644
index 0000000000..33f686026c
--- /dev/null
+++ b/third_party/rust/tabs/src/sync/bridge.rs
@@ -0,0 +1,457 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::sync::{Arc, Mutex};
+
+use crate::error::{ApiResult, Result, TabsApiError};
+use crate::sync::engine::TabsSyncImpl;
+use crate::TabsStore;
+use error_support::handle_error;
+use sync15::bso::{IncomingBso, OutgoingBso};
+use sync15::engine::{ApplyResults, BridgedEngine, CollSyncIds, EngineSyncAssociation};
+use sync15::{ClientData, ServerTimestamp};
+use sync_guid::Guid as SyncGuid;
+
+impl TabsStore {
+    // Returns a bridged sync engine for Desktop for this store.
+    pub fn bridged_engine(self: Arc<Self>) -> Arc<TabsBridgedEngine> {
+        let bridge_impl = crate::sync::bridge::BridgedEngineImpl::new(&self);
+        // This is a concrete struct exposed via uniffi.
+        let concrete = TabsBridgedEngine::new(bridge_impl);
+        Arc::new(concrete)
+    }
+}
+
+/// A bridged engine implements all the methods needed to make the
+/// `storage.sync` store work with Desktop's Sync implementation.
+/// Conceptually it's very similar to our SyncEngine, and once we have SyncEngine
+/// and BridgedEngine using the same types we can probably combine them (or at least
+/// implement this bridged engine purely in terms of SyncEngine)
+/// See also #2841 and #5139
+pub struct BridgedEngineImpl {
+    sync_impl: Mutex<TabsSyncImpl>,
+    incoming: Mutex<Vec<IncomingBso>>,
+}
+
+impl BridgedEngineImpl {
+    /// Creates a bridged engine for syncing.
+    pub fn new(store: &Arc<TabsStore>) -> Self {
+        Self {
+            sync_impl: Mutex::new(TabsSyncImpl::new(store.clone())),
+            incoming: Mutex::default(),
+        }
+    }
+}
+
+impl BridgedEngine for BridgedEngineImpl {
+    type Error = TabsApiError;
+
+    fn last_sync(&self) -> ApiResult<i64> {
+        handle_error! {
+            Ok(self
+                .sync_impl
+                .lock()
+                .unwrap()
+                .last_sync
+                .unwrap_or_default()
+                .as_millis())
+        }
+    }
+
+    fn set_last_sync(&self, last_sync_millis: i64) -> ApiResult<()> {
+        handle_error! {
+            self.sync_impl.lock().unwrap().last_sync =
+                Some(ServerTimestamp::from_millis(last_sync_millis));
+            Ok(())
+        }
+    }
+
+    fn sync_id(&self) -> ApiResult<Option<String>> {
+        handle_error! {
+            Ok(match self.sync_impl.lock().unwrap().get_sync_assoc() {
+                EngineSyncAssociation::Connected(id) => Some(id.coll.to_string()),
+                EngineSyncAssociation::Disconnected => None,
+            })
+        }
+    }
+
+    fn reset_sync_id(&self) -> ApiResult<String> {
+        handle_error! {
+            let new_id = SyncGuid::random().to_string();
+            let new_coll_ids = CollSyncIds {
+                global: SyncGuid::empty(),
+                coll: new_id.clone().into(),
+            };
+            self.sync_impl
+                .lock()
+                .unwrap()
+                .reset(EngineSyncAssociation::Connected(new_coll_ids))?;
+            Ok(new_id)
+        }
+    }
+
+    fn ensure_current_sync_id(&self, sync_id: &str) -> ApiResult<String> {
+        handle_error! {
+            let mut sync_impl = self.sync_impl.lock().unwrap();
+            let assoc = sync_impl.get_sync_assoc();
+            if matches!(assoc, EngineSyncAssociation::Connected(c) if c.coll == sync_id) {
+                log::debug!("ensure_current_sync_id is current");
+            } else {
+                let new_coll_ids = CollSyncIds {
+                    global: SyncGuid::empty(),
+                    coll: sync_id.into(),
+                };
+                sync_impl.reset(EngineSyncAssociation::Connected(new_coll_ids))?;
+            }
+            Ok(sync_id.to_string()) // this is a bit odd, why the result?
+        }
+    }
+
+    fn prepare_for_sync(&self, client_data: &str) -> ApiResult<()> {
+        handle_error! {
+            let data: ClientData = serde_json::from_str(client_data)?;
+            self.sync_impl.lock().unwrap().prepare_for_sync(data)
+        }
+    }
+
+    fn sync_started(&self) -> ApiResult<()> {
+        // This is a no-op for the Tabs Engine
+        Ok(())
+    }
+
+    fn store_incoming(&self, incoming: Vec<IncomingBso>) -> ApiResult<()> {
+        handle_error! {
+            // Store the incoming payload in memory so we can use it in apply
+            *(self.incoming.lock().unwrap()) = incoming;
+            Ok(())
+        }
+    }
+
+    fn apply(&self) -> ApiResult<ApplyResults> {
+        handle_error! {
+            let mut incoming = self.incoming.lock().unwrap();
+            // We've a reference to a Vec<> but it's owned by the mutex - swap the mutex owned
+            // value for an empty vec so we can consume the original.
+            let mut records = Vec::new();
+            std::mem::swap(&mut records, &mut *incoming);
+            let mut telem = sync15::telemetry::Engine::new("tabs");
+
+            let mut sync_impl = self.sync_impl.lock().unwrap();
+            let outgoing = sync_impl.apply_incoming(records, &mut telem)?;
+
+            Ok(ApplyResults {
+                records: outgoing,
+                num_reconciled: Some(0),
+            })
+        }
+    }
+
+    fn set_uploaded(&self, server_modified_millis: i64, ids: &[SyncGuid]) -> ApiResult<()> {
+        handle_error! {
+            self
+                .sync_impl
+                .lock()
+                .unwrap()
+                .sync_finished(ServerTimestamp::from_millis(server_modified_millis), ids)
+        }
+    }
+
+    fn sync_finished(&self) -> ApiResult<()> {
+        handle_error! {
+            *(self.incoming.lock().unwrap()) = Vec::default();
+            Ok(())
+        }
+    }
+
+    fn reset(&self) -> ApiResult<()> {
+        handle_error! {
+            self.sync_impl
+                .lock()
+                .unwrap()
+                .reset(EngineSyncAssociation::Disconnected)?;
+            Ok(())
+        }
+    }
+
+    fn wipe(&self) -> ApiResult<()> {
+        handle_error! {
+            self.sync_impl.lock().unwrap().wipe()?;
+            Ok(())
+        }
+    }
+}
+
+// This is for uniffi to expose, and does nothing than delegate back to the trait.
+pub struct TabsBridgedEngine {
+    bridge_impl: BridgedEngineImpl,
+}
+
+impl TabsBridgedEngine {
+    pub fn new(bridge_impl: BridgedEngineImpl) -> Self {
+        Self { bridge_impl }
+    }
+
+    pub fn last_sync(&self) -> ApiResult<i64> {
+        self.bridge_impl.last_sync()
+    }
+
+    pub fn set_last_sync(&self, last_sync: i64) -> ApiResult<()> {
+        self.bridge_impl.set_last_sync(last_sync)
+    }
+
+    pub fn sync_id(&self) -> ApiResult<Option<String>> {
+        self.bridge_impl.sync_id()
+    }
+
+    pub fn reset_sync_id(&self) -> ApiResult<String> {
+        self.bridge_impl.reset_sync_id()
+    }
+
+    pub fn ensure_current_sync_id(&self, sync_id: &str) -> ApiResult<String> {
+        self.bridge_impl.ensure_current_sync_id(sync_id)
+    }
+
+    pub fn prepare_for_sync(&self, client_data: &str) -> ApiResult<()> {
+        self.bridge_impl.prepare_for_sync(client_data)
+    }
+
+    pub fn sync_started(&self) -> ApiResult<()> {
+        self.bridge_impl.sync_started()
+    }
+
+    // Decode the JSON-encoded IncomingBso's that UniFFI passes to us
+    fn convert_incoming_bsos(&self, incoming: Vec<String>) -> ApiResult<Vec<IncomingBso>> {
+        handle_error! {
+            let mut bsos = Vec::with_capacity(incoming.len());
+            for inc in incoming {
+                bsos.push(serde_json::from_str::<IncomingBso>(&inc)?);
+            }
+            Ok(bsos)
+        }
+    }
+
+    // Encode OutgoingBso's into JSON for UniFFI
+    fn convert_outgoing_bsos(&self, outgoing: Vec<OutgoingBso>) -> ApiResult<Vec<String>> {
+        handle_error! {
+            let mut bsos = Vec::with_capacity(outgoing.len());
+            for e in outgoing {
+                bsos.push(serde_json::to_string(&e)?);
+            }
+            Ok(bsos)
+        }
+    }
+
+    pub fn store_incoming(&self, incoming: Vec<String>) -> ApiResult<()> {
+        self.bridge_impl
+            .store_incoming(self.convert_incoming_bsos(incoming)?)
+    }
+
+    pub fn apply(&self) -> ApiResult<Vec<String>> {
+        let apply_results = self.bridge_impl.apply()?;
+        self.convert_outgoing_bsos(apply_results.records)
+    }
+
+    pub fn set_uploaded(&self, server_modified_millis: i64, guids: Vec<SyncGuid>) -> ApiResult<()> {
+        self.bridge_impl
+            .set_uploaded(server_modified_millis, &guids)
+    }
+
+    pub fn sync_finished(&self) -> ApiResult<()> {
+        self.bridge_impl.sync_finished()
+    }
+
+    pub fn reset(&self) -> ApiResult<()> {
+        self.bridge_impl.reset()
+    }
+
+    pub fn wipe(&self) -> ApiResult<()> {
+        self.bridge_impl.wipe()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::storage::RemoteTab;
+    use crate::sync::record::TabsRecordTab;
+    use serde_json::json;
+    use std::collections::HashMap;
+    use sync15::{ClientData, RemoteClient};
+
+    const TTL_1_YEAR: u32 = 31_622_400;
+
+    // A copy of the normal "engine" tests but which go via the bridge
+    #[test]
+    fn test_sync_via_bridge() {
+        env_logger::try_init().ok();
+
+        let store = Arc::new(TabsStore::new_with_mem_path("test-bridge_incoming"));
+
+        // Set some local tabs for our device.
+        let my_tabs = vec![
+            RemoteTab {
+                title: "my first tab".to_string(),
+                url_history: vec!["http://1.com".to_string()],
+                icon: None,
+                last_used: 0,
+            },
+            RemoteTab {
+                title: "my second tab".to_string(),
+                url_history: vec!["http://2.com".to_string()],
+                icon: None,
+                last_used: 1,
+            },
+        ];
+        store.set_local_tabs(my_tabs.clone());
+
+        let bridge = store.bridged_engine();
+
+        let client_data = ClientData {
+            local_client_id: "my-device".to_string(),
+            recent_clients: HashMap::from([
+                (
+                    "my-device".to_string(),
+                    RemoteClient {
+                        fxa_device_id: None,
+                        device_name: "my device".to_string(),
+                        device_type: None,
+                    },
+                ),
+                (
+                    "device-no-tabs".to_string(),
+                    RemoteClient {
+                        fxa_device_id: None,
+                        device_name: "device with no tabs".to_string(),
+                        device_type: None,
+                    },
+                ),
+                (
+                    "device-with-a-tab".to_string(),
+                    RemoteClient {
+                        fxa_device_id: None,
+                        device_name: "device with a tab".to_string(),
+                        device_type: None,
+                    },
+                ),
+            ]),
+        };
+        bridge
+            .prepare_for_sync(&serde_json::to_string(&client_data).unwrap())
+            .expect("should work");
+
+        let records = vec![
+            // my-device should be ignored by sync - here it is acting as what our engine last
+            // wrote, but the actual tabs in our store we set above are what should be used.
+            json!({
+                "id": "my-device",
+                "clientName": "my device",
+                "tabs": [{
+                    "title": "the title",
+                    "urlHistory": [
+                        "https://mozilla.org/"
+                    ],
+                    "icon": "https://mozilla.org/icon",
+                    "lastUsed": 1643764207
+                }]
+            }),
+            json!({
+                "id": "device-no-tabs",
+                "clientName": "device with no tabs",
+                "tabs": [],
+            }),
+            json!({
+                "id": "device-with-a-tab",
+                "clientName": "device with a tab",
+                "tabs": [{
+                    "title": "the title",
+                    "urlHistory": [
+                        "https://mozilla.org/"
+                    ],
+                    "icon": "https://mozilla.org/icon",
+                    "lastUsed": 1643764207
+                }]
+            }),
+            // This has the main payload as OK but the tabs part invalid.
+            json!({
+                "id": "device-with-invalid-tab",
+                "clientName": "device with a tab",
+                "tabs": [{
+                    "foo": "bar",
+                }]
+            }),
+            // We want this to be a valid payload but an invalid tab - so it needs an ID.
+            json!({
+                "id": "invalid-tab",
+                "foo": "bar"
+            }),
+        ];
+
+        let mut incoming = Vec::new();
+        for record in records {
+            // Annoyingly we can't use `IncomingEnvelope` directly as it intentionally doesn't
+            // support Serialize - so need to use explicit json.
+            let envelope = json!({
+                "id": record.get("id"),
+                "modified": 0,
+                "payload": serde_json::to_string(&record).unwrap(),
+            });
+            incoming.push(serde_json::to_string(&envelope).unwrap());
+        }
+
+        bridge.store_incoming(incoming).expect("should store");
+
+        let out = bridge.apply().expect("should apply");
+
+        assert_eq!(out.len(), 1);
+        let ours = serde_json::from_str::<serde_json::Value>(&out[0]).unwrap();
+        // As above, can't use `OutgoingEnvelope` as it doesn't Deserialize.
+        // First, convert my_tabs from the local `RemoteTab` to the Sync specific `TabsRecord`
+        let expected_tabs: Vec<TabsRecordTab> =
+            my_tabs.into_iter().map(|t| t.to_record_tab()).collect();
+        let expected = json!({
+            "id": "my-device".to_string(),
+            "payload": json!({
+                "id": "my-device".to_string(),
+                "clientName": "my device",
+                "tabs": serde_json::to_value(expected_tabs).unwrap(),
+            }).to_string(),
+            "ttl": TTL_1_YEAR,
+        });
+
+        assert_eq!(ours, expected);
+        bridge.set_uploaded(1234, vec![]).unwrap();
+        assert_eq!(bridge.last_sync().unwrap(), 1234);
+    }
+
+    #[test]
+    fn test_sync_meta() {
+        env_logger::try_init().ok();
+
+        let store = Arc::new(TabsStore::new_with_mem_path("test-meta"));
+        let bridge = store.bridged_engine();
+
+        bridge.set_last_sync(3).unwrap();
+        assert_eq!(bridge.last_sync().unwrap(), 3);
+
+        assert!(bridge.sync_id().unwrap().is_none());
+
+        bridge.ensure_current_sync_id("some_guid").unwrap();
+        assert_eq!(bridge.sync_id().unwrap(), Some("some_guid".to_string()));
+        // changing the sync ID should reset the timestamp
+        assert_eq!(bridge.last_sync().unwrap(), 0);
+        bridge.set_last_sync(3).unwrap();
+
+        bridge.reset_sync_id().unwrap();
+        // should now be a random guid.
+        assert_ne!(bridge.sync_id().unwrap(), Some("some_guid".to_string()));
+        // should have reset the last sync timestamp.
+        assert_eq!(bridge.last_sync().unwrap(), 0);
+        bridge.set_last_sync(3).unwrap();
+
+        // `reset` clears the guid and the timestamp
+        bridge.reset().unwrap();
+        assert_eq!(bridge.last_sync().unwrap(), 0);
+        assert!(bridge.sync_id().unwrap().is_none());
+    }
+}
diff --git a/third_party/rust/tabs/src/sync/engine.rs b/third_party/rust/tabs/src/sync/engine.rs
new file mode 100644
index 0000000000..6ffa5274df
--- /dev/null
+++ b/third_party/rust/tabs/src/sync/engine.rs
@@ -0,0 +1,515 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::storage::{ClientRemoteTabs, RemoteTab};
+use crate::store::TabsStore;
+use crate::sync::record::{TabsRecord, TabsRecordTab};
+use crate::Result;
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex, Weak};
+use sync15::bso::{IncomingBso, OutgoingBso, OutgoingEnvelope};
+use sync15::engine::{
+    CollectionRequest, EngineSyncAssociation, IncomingChangeset, OutgoingChangeset, SyncEngine,
+    SyncEngineId,
+};
+use sync15::{telemetry, ClientData, DeviceType, RemoteClient, ServerTimestamp};
+use sync_guid::Guid;
+
+const TTL_1_YEAR: u32 = 31_622_400;
+
+// Our "sync manager" will use whatever is stashed here.
+lazy_static::lazy_static! {
+    // Mutex: just taken long enough to update the inner stuff
+    static ref STORE_FOR_MANAGER: Mutex<Weak<TabsStore>> = Mutex::new(Weak::new());
+}
+
+/// Called by the sync manager to get a sync engine via the store previously
+/// registered with the sync manager.
+pub fn get_registered_sync_engine(engine_id: &SyncEngineId) -> Option<Box<dyn SyncEngine>> {
+    let weak = STORE_FOR_MANAGER.lock().unwrap();
+    match weak.upgrade() {
+        None => None,
+        Some(store) => match engine_id {
+            SyncEngineId::Tabs => Some(Box::new(TabsEngine::new(Arc::clone(&store)))),
+            // panicing here seems reasonable - it's a static error if this
+            // it hit, not something that runtime conditions can influence.
+            _ => unreachable!("can't provide unknown engine: {}", engine_id),
+        },
+    }
+}
+
+impl ClientRemoteTabs {
+    fn from_record_with_remote_client(
+        client_id: String,
+        last_modified: ServerTimestamp,
+        remote_client: &RemoteClient,
+        record: TabsRecord,
+    ) -> Self {
+        Self {
+            client_id,
+            client_name: remote_client.device_name.clone(),
+            device_type: remote_client.device_type.unwrap_or(DeviceType::Unknown),
+            last_modified: last_modified.as_millis(),
+            remote_tabs: record.tabs.iter().map(RemoteTab::from_record_tab).collect(),
+        }
+    }
+
+    fn from_record(client_id: String, last_modified: ServerTimestamp, record: TabsRecord) -> Self {
+        Self {
+            client_id,
+            client_name: record.client_name,
+            device_type: DeviceType::Unknown,
+            last_modified: last_modified.as_millis(),
+            remote_tabs: record.tabs.iter().map(RemoteTab::from_record_tab).collect(),
+        }
+    }
+    fn to_record(&self) -> TabsRecord {
+        TabsRecord {
+            id: self.client_id.clone(),
+            client_name: self.client_name.clone(),
+            tabs: self
+                .remote_tabs
+                .iter()
+                .map(RemoteTab::to_record_tab)
+                .collect(),
+        }
+    }
+}
+
+impl RemoteTab {
+    fn from_record_tab(tab: &TabsRecordTab) -> Self {
+        Self {
+            title: tab.title.clone(),
+            url_history: tab.url_history.clone(),
+            icon: tab.icon.clone(),
+            last_used: tab.last_used.checked_mul(1000).unwrap_or_default(),
+        }
+    }
+    pub(super) fn to_record_tab(&self) -> TabsRecordTab {
+        TabsRecordTab {
+            title: self.title.clone(),
+            url_history: self.url_history.clone(),
+            icon: self.icon.clone(),
+            last_used: self.last_used.checked_div(1000).unwrap_or_default(),
+        }
+    }
+}
+
+// This is the implementation of syncing, which is used by the 2 different "sync engines"
+// (We hope to get these 2 engines even closer in the future, but for now, we suck this up)
+pub struct TabsSyncImpl {
+    pub(super) store: Arc<TabsStore>,
+    remote_clients: HashMap<String, RemoteClient>,
+    pub(super) last_sync: Option<ServerTimestamp>,
+    sync_store_assoc: EngineSyncAssociation,
+    pub(super) local_id: String,
+}
+
+impl TabsSyncImpl {
+    pub fn new(store: Arc<TabsStore>) -> Self {
+        Self {
+            store,
+            remote_clients: HashMap::new(),
+            last_sync: None,
+            sync_store_assoc: EngineSyncAssociation::Disconnected,
+            local_id: Default::default(),
+        }
+    }
+
+    pub fn prepare_for_sync(&mut self, client_data: ClientData) -> Result<()> {
+        self.remote_clients = client_data.recent_clients;
+        self.local_id = client_data.local_client_id;
+        Ok(())
+    }
+
+    pub fn apply_incoming(
+        &mut self,
+        inbound: Vec<IncomingBso>,
+        telem: &mut telemetry::Engine,
+    ) -> Result<Vec<OutgoingBso>> {
+        let local_id = self.local_id.clone();
+        let mut remote_tabs = Vec::with_capacity(inbound.len());
+        let mut incoming_telemetry = telemetry::EngineIncoming::new();
+
+        for incoming in inbound {
+            if incoming.envelope.id == local_id {
+                // That's our own record, ignore it.
+                continue;
+            }
+            let modified = incoming.envelope.modified;
+            let record = match incoming.into_content::<TabsRecord>().content() {
+                Some(record) => record,
+                None => {
+                    // Invalid record or a "tombstone" which tabs don't have.
+                    log::warn!("Ignoring incoming invalid tab");
+                    incoming_telemetry.failed(1);
+                    continue;
+                }
+            };
+            let id = record.id.clone();
+            let crt = if let Some(remote_client) = self.remote_clients.get(&id) {
+                ClientRemoteTabs::from_record_with_remote_client(
+                    remote_client
+                        .fxa_device_id
+                        .as_ref()
+                        .unwrap_or(&id)
+                        .to_owned(),
+                    modified,
+                    remote_client,
+                    record,
+                )
+            } else {
+                // A record with a device that's not in our remote clients seems unlikely, but
+                // could happen - in most cases though, it will be due to a disconnected client -
+                // so we really should consider just dropping it? (Sadly though, it does seem
+                // possible it's actually a very recently connected client, so we keep it)
+
+                // XXX - this is actually a foot-gun, particularly for desktop. If we don't know
+                // the device, we assume the device ID is the fxa-device-id, which may not be the
+                // case.
+                // So we should drop these records! But we can't do this now because stand alone
+                // syncing (ie, store.sync()) doesn't allow us to pass the device list in, so
+                // we'd get no rows!
+                // See also: https://github.com/mozilla/application-services/issues/5199
+                log::info!(
+                    "Storing tabs from a client that doesn't appear in the devices list: {}",
+                    id,
+                );
+                ClientRemoteTabs::from_record(id, modified, record)
+            };
+            remote_tabs.push(crt);
+        }
+
+        // We want to keep the mutex for as short as possible
+        let local_tabs = {
+            let mut storage = self.store.storage.lock().unwrap();
+            // In desktop we might end up here with zero records when doing a quick-write, in
+            // which case we don't want to wipe the DB.
+            if !remote_tabs.is_empty() {
+                storage.replace_remote_tabs(remote_tabs)?;
+            }
+            storage.prepare_local_tabs_for_upload()
+        };
+        let outgoing = if let Some(local_tabs) = local_tabs {
+            let (client_name, device_type) = self
+                .remote_clients
+                .get(&local_id)
+                .map(|client| {
+                    (
+                        client.device_name.clone(),
+                        client.device_type.unwrap_or(DeviceType::Unknown),
+                    )
+                })
+                .unwrap_or_else(|| (String::new(), DeviceType::Unknown));
+            let local_record = ClientRemoteTabs {
+                client_id: local_id.clone(),
+                client_name,
+                device_type,
+                last_modified: 0, // ignored for outgoing records.
+                remote_tabs: local_tabs.to_vec(),
+            };
+            log::trace!("outgoing {:?}", local_record);
+            let envelope = OutgoingEnvelope {
+                id: local_id.into(),
+                ttl: Some(TTL_1_YEAR),
+                ..Default::default()
+            };
+            vec![OutgoingBso::from_content(
+                envelope,
+                local_record.to_record(),
+            )?]
+        } else {
+            vec![]
+        };
+        telem.incoming(incoming_telemetry);
+        Ok(outgoing)
+    }
+
+    pub fn sync_finished(
+        &mut self,
+        new_timestamp: ServerTimestamp,
+        records_synced: &[Guid],
+    ) -> Result<()> {
+        log::info!(
+            "sync completed after uploading {} records",
+            records_synced.len()
+        );
+        self.last_sync = Some(new_timestamp);
+        Ok(())
+    }
+
+    pub fn reset(&mut self, assoc: EngineSyncAssociation) -> Result<()> {
+        self.remote_clients.clear();
+        self.sync_store_assoc = assoc;
+        self.last_sync = None;
+        self.store.storage.lock().unwrap().wipe_remote_tabs()?;
+        Ok(())
+    }
+
+    pub fn wipe(&mut self) -> Result<()> {
+        self.reset(EngineSyncAssociation::Disconnected)?;
+        // not clear why we need to wipe the local tabs - the app is just going
+        // to re-add them?
+        self.store.storage.lock().unwrap().wipe_local_tabs();
+        Ok(())
+    }
+
+    pub fn get_sync_assoc(&self) -> &EngineSyncAssociation {
+        &self.sync_store_assoc
+    }
+}
+
+// This is the "SyncEngine" used when syncing via the Sync Manager.
+pub struct TabsEngine {
+    pub sync_impl: Mutex<TabsSyncImpl>,
+}
+
+impl TabsEngine {
+    pub fn new(store: Arc<TabsStore>) -> Self {
+        Self {
+            sync_impl: Mutex::new(TabsSyncImpl::new(store)),
+        }
+    }
+}
+
+impl SyncEngine for TabsEngine {
+    fn collection_name(&self) -> std::borrow::Cow<'static, str> {
+        "tabs".into()
+    }
+
+    fn prepare_for_sync(&self, get_client_data: &dyn Fn() -> ClientData) -> anyhow::Result<()> {
+        Ok(self
+            .sync_impl
+            .lock()
+            .unwrap()
+            .prepare_for_sync(get_client_data())?)
+    }
+
+    fn apply_incoming(
+        &self,
+        inbound: Vec<IncomingChangeset>,
+        telem: &mut telemetry::Engine,
+    ) -> anyhow::Result<OutgoingChangeset> {
+        assert_eq!(inbound.len(), 1, "only requested one set of records");
+        let inbound = inbound.into_iter().next().unwrap();
+        let outgoing_records = self
+            .sync_impl
+            .lock()
+            .unwrap()
+            .apply_incoming(inbound.changes, telem)?;
+
+        Ok(OutgoingChangeset::new_with_changes(
+            "tabs",
+            inbound.timestamp,
+            outgoing_records,
+        ))
+    }
+
+    fn sync_finished(
+        &self,
+        new_timestamp: ServerTimestamp,
+        records_synced: Vec<Guid>,
+    ) -> anyhow::Result<()> {
+        Ok(self
+            .sync_impl
+            .lock()
+            .unwrap()
+            .sync_finished(new_timestamp, &records_synced)?)
+    }
+
+    fn get_collection_requests(
+        &self,
+        server_timestamp: ServerTimestamp,
+    ) -> anyhow::Result<Vec<CollectionRequest>> {
+        let since = self.sync_impl.lock().unwrap().last_sync.unwrap_or_default();
+        Ok(if since == server_timestamp {
+            vec![]
+        } else {
+            vec![CollectionRequest::new("tabs").full().newer_than(since)]
+        })
+    }
+
+    fn get_sync_assoc(&self) -> anyhow::Result<EngineSyncAssociation> {
+        Ok(self.sync_impl.lock().unwrap().get_sync_assoc().clone())
+    }
+
+    fn reset(&self, assoc: &EngineSyncAssociation) -> anyhow::Result<()> {
+        Ok(self.sync_impl.lock().unwrap().reset(assoc.clone())?)
+    }
+
+    fn wipe(&self) -> anyhow::Result<()> {
+        Ok(self.sync_impl.lock().unwrap().wipe()?)
+    }
+}
+
+impl crate::TabsStore {
+    // This allows the embedding app to say "make this instance available to
+    // the sync manager". The implementation is more like "offer to sync mgr"
+    // (thereby avoiding us needing to link with the sync manager) but
+    // `register_with_sync_manager()` is logically what's happening so that's
+    // the name it gets.
+    pub fn register_with_sync_manager(self: Arc<Self>) {
+        let mut state = STORE_FOR_MANAGER.lock().unwrap();
+        *state = Arc::downgrade(&self);
+    }
+}
+
+#[cfg(test)]
+pub mod test {
+    use super::*;
+    use serde_json::json;
+    use sync15::bso::IncomingBso;
+
+    #[test]
+    fn test_incoming_tabs() {
+        env_logger::try_init().ok();
+
+        let engine = TabsEngine::new(Arc::new(TabsStore::new_with_mem_path("test-incoming")));
+
+        let records = vec![
+            json!({
+                "id": "device-no-tabs",
+                "clientName": "device with no tabs",
+                "tabs": [],
+            }),
+            json!({
+                "id": "device-with-a-tab",
+                "clientName": "device with a tab",
+                "tabs": [{
+                    "title": "the title",
+                    "urlHistory": [
+                        "https://mozilla.org/"
+                    ],
+                    "icon": "https://mozilla.org/icon",
+                    "lastUsed": 1643764207
+                }]
+            }),
+            // This has the main payload as OK but the tabs part invalid.
+            json!({
+                "id": "device-with-invalid-tab",
+                "clientName": "device with a tab",
+                "tabs": [{
+                    "foo": "bar",
+                }]
+            }),
+            // We want this to be a valid payload but an invalid tab - so it needs an ID.
+            json!({
+                "id": "invalid-tab",
+                "foo": "bar"
+            }),
+        ];
+
+        let incoming = IncomingChangeset::new_with_changes(
+            engine.collection_name(),
+            ServerTimestamp(0),
+            records
+                .into_iter()
+                .map(IncomingBso::from_test_content)
+                .collect(),
+        );
+        let outgoing = engine
+            .apply_incoming(vec![incoming], &mut telemetry::Engine::new("tabs"))
+            .expect("Should apply incoming and stage outgoing records");
+
+        assert!(outgoing.changes.is_empty());
+
+        // now check the store has what we think it has.
+        let sync_impl = engine.sync_impl.lock().unwrap();
+        let mut storage = sync_impl.store.storage.lock().unwrap();
+        let mut crts = storage.get_remote_tabs().expect("should work");
+        crts.sort_by(|a, b| a.client_name.partial_cmp(&b.client_name).unwrap());
+        assert_eq!(crts.len(), 2, "we currently include devices with no tabs");
+        let crt = &crts[0];
+        assert_eq!(crt.client_name, "device with a tab");
+        assert_eq!(crt.device_type, DeviceType::Unknown);
+        assert_eq!(crt.remote_tabs.len(), 1);
+        assert_eq!(crt.remote_tabs[0].title, "the title");
+
+        let crt = &crts[1];
+        assert_eq!(crt.client_name, "device with no tabs");
+        assert_eq!(crt.device_type, DeviceType::Unknown);
+        assert_eq!(crt.remote_tabs.len(), 0);
+    }
+
+    #[test]
+    fn test_no_incoming_doesnt_write() {
+        env_logger::try_init().ok();
+
+        let engine = TabsEngine::new(Arc::new(TabsStore::new_with_mem_path(
+            "test_no_incoming_doesnt_write",
+        )));
+
+        let records = vec![json!({
+            "id": "device-with-a-tab",
+            "clientName": "device with a tab",
+            "tabs": [{
+                "title": "the title",
+                "urlHistory": [
+                    "https://mozilla.org/"
+                ],
+                "icon": "https://mozilla.org/icon",
+                "lastUsed": 1643764207
+            }]
+        })];
+
+        let incoming = IncomingChangeset::new_with_changes(
+            engine.collection_name(),
+            ServerTimestamp(0),
+            records
+                .into_iter()
+                .map(IncomingBso::from_test_content)
+                .collect(),
+        );
+        engine
+            .apply_incoming(vec![incoming], &mut telemetry::Engine::new("tabs"))
+            .expect("Should apply incoming and stage outgoing records");
+
+        // now check the store has what we think it has.
+        {
+            let sync_impl = engine.sync_impl.lock().unwrap();
+            let mut storage = sync_impl.store.storage.lock().unwrap();
+            assert_eq!(storage.get_remote_tabs().expect("should work").len(), 1);
+        }
+
+        // Now another sync with zero incoming records, should still be able to get back
+        // our one client.
+        let incoming = IncomingChangeset::new_with_changes(
+            engine.collection_name(),
+            ServerTimestamp(0),
+            vec![],
+        );
+        engine
+            .apply_incoming(vec![incoming], &mut telemetry::Engine::new("tabs"))
+            .expect("Should succeed applying zero records");
+
+        {
+            let sync_impl = engine.sync_impl.lock().unwrap();
+            let mut storage = sync_impl.store.storage.lock().unwrap();
+            assert_eq!(storage.get_remote_tabs().expect("should work").len(), 1);
+        }
+    }
+
+    #[test]
+    fn test_sync_manager_registration() {
+        let store = Arc::new(TabsStore::new_with_mem_path("test-registration"));
+        assert_eq!(Arc::strong_count(&store), 1);
+        assert_eq!(Arc::weak_count(&store), 0);
+        Arc::clone(&store).register_with_sync_manager();
+        assert_eq!(Arc::strong_count(&store), 1);
+        assert_eq!(Arc::weak_count(&store), 1);
+        let registered = STORE_FOR_MANAGER
+            .lock()
+            .unwrap()
+            .upgrade()
+            .expect("should upgrade");
+        assert!(Arc::ptr_eq(&store, &registered));
+        drop(registered);
+        // should be no new references
+        assert_eq!(Arc::strong_count(&store), 1);
+        assert_eq!(Arc::weak_count(&store), 1);
+        // dropping the registered object should drop the registration.
+        drop(store);
+        assert!(STORE_FOR_MANAGER.lock().unwrap().upgrade().is_none());
+    }
+}
diff --git a/third_party/rust/tabs/src/sync/full_sync.rs b/third_party/rust/tabs/src/sync/full_sync.rs
new file mode 100644
index 0000000000..defd4b473b
--- /dev/null
+++ b/third_party/rust/tabs/src/sync/full_sync.rs
@@ -0,0 +1,72 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::{sync::engine::TabsSyncImpl, ApiResult, Result, TabsEngine, TabsStore};
+use error_support::handle_error;
+use interrupt_support::NeverInterrupts;
+use std::sync::Arc;
+use sync15::client::{sync_multiple, MemoryCachedState, Sync15StorageClientInit};
+use sync15::engine::EngineSyncAssociation;
+use sync15::KeyBundle;
+
+impl TabsStore {
+    pub fn reset(self: Arc<Self>) -> ApiResult<()> {
+        handle_error! {
+            let mut sync_impl = TabsSyncImpl::new(Arc::clone(&self));
+            sync_impl.reset(EngineSyncAssociation::Disconnected)?;
+            Ok(())
+        }
+    }
+
+    /// A convenience wrapper around sync_multiple.
+    pub fn sync(
+        self: Arc<Self>,
+        key_id: String,
+        access_token: String,
+        sync_key: String,
+        tokenserver_url: String,
+        local_id: String,
+    ) -> ApiResult<String> {
+        handle_error! {
+            let mut mem_cached_state = MemoryCachedState::default();
+            let engine = TabsEngine::new(Arc::clone(&self));
+
+            // Since we are syncing without the sync manager, there's no
+            // command processor, therefore no clients engine, and in
+            // consequence `TabsStore::prepare_for_sync` is never called
+            // which means our `local_id` will never be set.
+            // Do it here.
+            engine.sync_impl.lock().unwrap().local_id = local_id;
+
+            let storage_init = &Sync15StorageClientInit {
+                key_id,
+                access_token,
+                tokenserver_url: url::Url::parse(tokenserver_url.as_str())?,
+            };
+            let root_sync_key = &KeyBundle::from_ksync_base64(sync_key.as_str())?;
+
+            let mut result = sync_multiple(
+                &[&engine],
+                &mut None,
+                &mut mem_cached_state,
+                storage_init,
+                root_sync_key,
+                &NeverInterrupts,
+                None,
+            );
+
+            // for b/w compat reasons, we do some dances with the result.
+            // XXX - note that this means telemetry isn't going to be reported back
+            // to the app - we need to check with lockwise about whether they really
+            // need these failures to be reported or whether we can loosen this.
+            if let Err(e) = result.result {
+                return Err(e.into());
+            }
+            match result.engine_results.remove("tabs") {
+                None | Some(Ok(())) => Ok(serde_json::to_string(&result.telemetry)?),
+                Some(Err(e)) => Err(e.into()),
+            }
+        }
+    }
+}
diff --git a/third_party/rust/tabs/src/sync/mod.rs b/third_party/rust/tabs/src/sync/mod.rs
new file mode 100644
index 0000000000..0fccbb2aae
--- /dev/null
+++ b/third_party/rust/tabs/src/sync/mod.rs
@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+pub(crate) mod bridge;
+pub(crate) mod engine;
+mod record;
+
+#[cfg(feature = "full-sync")]
+pub mod full_sync;
+
+// When full-sync isn't enabled we need stub versions for these UDL exposed functions.
+#[cfg(not(feature = "full-sync"))]
+impl crate::TabsStore {
+    pub fn reset(self: std::sync::Arc<Self>) -> crate::error::ApiResult<()> {
+        log::warn!("reset: feature not enabled");
+        Err(crate::error::TabsApiError::SyncError {
+            reason: "reset".to_string(),
+        })
+    }
+
+    pub fn sync(
+        self: std::sync::Arc<Self>,
+        _key_id: String,
+        _access_token: String,
+        _sync_key: String,
+        _tokenserver_url: String,
+        _local_id: String,
+    ) -> crate::error::ApiResult<String> {
+        log::warn!("sync: feature not enabled");
+        Err(crate::error::TabsApiError::SyncError {
+            reason: "sync".to_string(),
+        })
+    }
+}
diff --git a/third_party/rust/tabs/src/sync/record.rs b/third_party/rust/tabs/src/sync/record.rs
new file mode 100644
index 0000000000..61e99e7316
--- /dev/null
+++ b/third_party/rust/tabs/src/sync/record.rs
@@ -0,0 +1,96 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use serde_derive::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "camelCase")]
+pub struct TabsRecordTab {
+    pub title: String,
+    pub url_history: Vec<String>,
+    pub icon: Option<String>,
+    pub last_used: i64, // Seconds since epoch!
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct TabsRecord {
+    // `String` instead of `SyncGuid` because some IDs are FxA device ID (XXX - that doesn't
+    // matter though - this could easily be a Guid!)
+    pub id: String,
+    pub client_name: String,
+    pub tabs: Vec<TabsRecordTab>,
+}
+
+#[cfg(test)]
+pub mod test {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn test_payload() {
+        let payload = json!({
+            "id": "JkeBPC50ZI0m",
+            "clientName": "client name",
+            "tabs": [{
+                "title": "the title",
+                "urlHistory": [
+                    "https://mozilla.org/"
+                ],
+                "icon": "https://mozilla.org/icon",
+                "lastUsed": 1643764207
+            }]
+        });
+        let record: TabsRecord = serde_json::from_value(payload).expect("should work");
+        assert_eq!(record.id, "JkeBPC50ZI0m");
+        assert_eq!(record.client_name, "client name");
+        assert_eq!(record.tabs.len(), 1);
+        let tab = &record.tabs[0];
+        assert_eq!(tab.title, "the title");
+        assert_eq!(tab.icon, Some("https://mozilla.org/icon".to_string()));
+        assert_eq!(tab.last_used, 1643764207);
+    }
+
+    #[test]
+    fn test_roundtrip() {
+        let tab = TabsRecord {
+            id: "JkeBPC50ZI0m".into(),
+            client_name: "client name".into(),
+            tabs: vec![TabsRecordTab {
+                title: "the title".into(),
+                url_history: vec!["https://mozilla.org/".into()],
+                icon: Some("https://mozilla.org/icon".into()),
+                last_used: 1643764207,
+            }],
+        };
+        let round_tripped =
+            serde_json::from_value(serde_json::to_value(tab.clone()).unwrap()).unwrap();
+        assert_eq!(tab, round_tripped);
+    }
+
+    #[test]
+    fn test_extra_fields() {
+        let payload = json!({
+            "id": "JkeBPC50ZI0m",
+            // Let's say we agree on new tabs to record, we want old versions to
+            // ignore them!
+            "ignoredField": "??",
+            "clientName": "client name",
+            "tabs": [{
+                "title": "the title",
+                "urlHistory": [
+                    "https://mozilla.org/"
+                ],
+                "icon": "https://mozilla.org/icon",
+                "lastUsed": 1643764207,
+                // Ditto - make sure we ignore unexpected fields in each tab.
+                "ignoredField": "??",
+            }]
+        });
+        let record: TabsRecord = serde_json::from_value(payload).unwrap();
+        // The point of this test is really just to ensure the deser worked, so
+        // just check the ID.
+        assert_eq!(record.id, "JkeBPC50ZI0m");
+    }
+}