Merge pull request #309 from BigBodyCobain/feat/cross-node-dm-mailbox-replication

DM mailbox: per-(sender, recipient) anti-spam cap + replication primitives

backend/tests/test_dm_relay_per_sender_cap.py

@@ -0,0 +1,270 @@
+"""Per-(sender, recipient) anti-spam cap on the DM relay.
+
+The user-stated rule: a single sender can have at most N UNACKED messages
+parked in a single recipient's mailbox at any one time (N=2 by default).
+Once the recipient pulls a message, the sender's quota for that pair
+frees up.
+
+Network rule, not local rule
+-----------------------------
+The cap is enforced TWICE:
+
+1. ``DMRelay.deposit(...)`` -- local check on the sender's own node.
+   Refuses to spool the (N+1)th message before it can be replicated.
+
+2. ``DMRelay.accept_replica(...)`` -- replication-acceptance check on
+   every receiving peer. Refuses to accept an inbound replica that
+   would put the local mailbox over the cap, even if the originating
+   peer claims it had cap room.
+
+The double enforcement matters because cap (1) is client-side -- a
+hostile relay could patch it out and continue to spool extras locally.
+Cap (2) means those extras can't propagate: every honest peer rejects
+them on the way in. A recipient who polls from honest peers therefore
+never sees more than N pending from any one sender, regardless of how
+many spam attempts the sender's own relay accepted.
+
+These tests pin both halves of the rule.
+"""
+
+from __future__ import annotations
+
+import time
+
+import pytest
+
+
+@pytest.fixture
+def relay():
+    """Fresh ``DMRelay`` per test."""
+    from services.mesh.mesh_dm_relay import DMRelay
+    r = DMRelay()
+    r._mailboxes.clear()
+    r._blocks.clear()
+    r._stats = {"messages_in_memory": 0}
+    return r
+
+
+def _deposit(
+    relay,
+    *,
+    sender: str = "alice",
+    recipient_token: str = "bob_mailbox_token_abc",
+    ciphertext: str = "ciphertext-blob",
+    msg_id: str = "",
+):
+    """Convenience wrapper using ``shared`` delivery class."""
+    return relay.deposit(
+        sender_id=sender,
+        raw_sender_id=sender,
+        recipient_id="bob",
+        ciphertext=ciphertext,
+        msg_id=msg_id,
+        delivery_class="shared",
+        recipient_token=recipient_token,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Local cap on ``deposit``
+# ---------------------------------------------------------------------------
+
+
+class TestDepositCap:
+    def test_two_deposits_from_same_sender_succeed(self, relay):
+        r1 = _deposit(relay)
+        r2 = _deposit(relay)
+        assert r1["ok"] is True
+        assert r2["ok"] is True
+        assert r1["msg_id"] != r2["msg_id"]
+
+    def test_third_deposit_from_same_sender_rejected(self, relay):
+        _deposit(relay)
+        _deposit(relay)
+        r3 = _deposit(relay)
+        assert r3["ok"] is False
+        detail = r3["detail"].lower()
+        assert "unread" in detail or "read your messages" in detail
+
+    def test_different_senders_have_independent_quotas(self, relay):
+        for _ in range(2):
+            assert _deposit(relay, sender="alice")["ok"] is True
+        for _ in range(2):
+            assert _deposit(relay, sender="carol")["ok"] is True
+        assert _deposit(relay, sender="carol")["ok"] is False
+
+    def test_different_recipients_have_independent_quotas(self, relay):
+        for _ in range(2):
+            assert _deposit(relay, sender="alice", recipient_token="bob_token")["ok"] is True
+        for _ in range(2):
+            assert _deposit(relay, sender="alice", recipient_token="dave_token")["ok"] is True
+
+    def test_ack_frees_quota(self, relay):
+        r1 = _deposit(relay)
+        _deposit(relay)
+        assert _deposit(relay)["ok"] is False
+
+        mailbox_key = relay._hashed_mailbox_token("bob_mailbox_token_abc")
+        relay._mailboxes[mailbox_key] = [
+            m for m in relay._mailboxes[mailbox_key]
+            if m.msg_id != r1["msg_id"]
+        ]
+        relay._stats["messages_in_memory"] = sum(
+            len(v) for v in relay._mailboxes.values()
+        )
+
+        r3 = _deposit(relay)
+        assert r3["ok"] is True, f"expected quota free after ack, got: {r3}"
+
+    def test_cap_is_env_tunable(self, relay, monkeypatch):
+        import services.mesh.mesh_dm_relay as mdr
+        monkeypatch.setattr(
+            mdr.DMRelay,
+            "_per_sender_pending_limit",
+            lambda self: 1,
+        )
+
+        assert _deposit(relay)["ok"] is True
+        assert _deposit(relay)["ok"] is False
+
+
+# ---------------------------------------------------------------------------
+# Replication-acceptance cap (the half that makes this a network rule)
+# ---------------------------------------------------------------------------
+
+
+class TestAcceptReplicaCap:
+    def _envelope(self, *, msg_id: str, sender_block_ref: str, mailbox_key: str):
+        return {
+            "msg_id": msg_id,
+            "mailbox_key": mailbox_key,
+            "sender_block_ref": sender_block_ref,
+            "sender_id": "alice",
+            "sender_seal": "",
+            "ciphertext": f"ciphertext-{msg_id}",
+            "timestamp": time.time(),
+            "delivery_class": "shared",
+            "relay_salt": "",
+            "payload_format": "dm1",
+            "session_welcome": "",
+        }
+
+    def test_replica_accepted_under_cap(self, relay):
+        env = self._envelope(
+            msg_id="dm_replica_1",
+            sender_block_ref="alice_block_ref",
+            mailbox_key="mailbox_xyz",
+        )
+        result = relay.accept_replica(envelope=env)
+        assert result["ok"] is True
+
+    def test_replica_idempotent_on_duplicate_msg_id(self, relay):
+        mailbox_key = "mailbox_xyz"
+        env = self._envelope(
+            msg_id="dm_dup_1",
+            sender_block_ref="alice_block_ref",
+            mailbox_key=mailbox_key,
+        )
+        r1 = relay.accept_replica(envelope=env)
+        r2 = relay.accept_replica(envelope=env)
+        assert r1["ok"] is True
+        assert r2["ok"] is True
+        assert r2.get("duplicate") is True
+        assert len(relay._mailboxes[mailbox_key]) == 1
+
+    def test_replica_rejected_when_local_count_already_at_cap(self, relay):
+        mailbox_key = "mailbox_xyz"
+        for i in (1, 2):
+            relay.accept_replica(envelope=self._envelope(
+                msg_id=f"dm_seeded_{i}",
+                sender_block_ref="alice_block_ref",
+                mailbox_key=mailbox_key,
+            ))
+
+        result = relay.accept_replica(envelope=self._envelope(
+            msg_id="dm_overcap_3",
+            sender_block_ref="alice_block_ref",
+            mailbox_key=mailbox_key,
+        ))
+        assert result["ok"] is False
+        assert result.get("cap_violation") is True
+        assert result.get("pending") == 2
+        assert result.get("limit") == 2
+        assert len(relay._mailboxes[mailbox_key]) == 2
+
+    def test_replica_from_different_sender_passes_when_one_is_at_cap(self, relay):
+        mailbox_key = "mailbox_xyz"
+        for i in (1, 2):
+            relay.accept_replica(envelope=self._envelope(
+                msg_id=f"dm_alice_{i}",
+                sender_block_ref="alice_block_ref",
+                mailbox_key=mailbox_key,
+            ))
+        assert relay.accept_replica(envelope=self._envelope(
+            msg_id="dm_alice_3",
+            sender_block_ref="alice_block_ref",
+            mailbox_key=mailbox_key,
+        ))["ok"] is False
+        assert relay.accept_replica(envelope=self._envelope(
+            msg_id="dm_carol_1",
+            sender_block_ref="carol_block_ref",
+            mailbox_key=mailbox_key,
+        ))["ok"] is True
+
+    def test_replica_rejects_malformed_envelopes(self, relay):
+        for bad in (
+            {},
+            {"msg_id": "x"},
+            {"msg_id": "x", "mailbox_key": "y"},
+            "not an object at all",
+        ):
+            result = relay.accept_replica(envelope=bad)
+            assert result["ok"] is False
+
+
+# ---------------------------------------------------------------------------
+# ``envelope_for_replication`` -- helper for the outbound replication path
+# ---------------------------------------------------------------------------
+
+
+class TestEnvelopeForReplication:
+    def test_returns_envelope_for_stored_message(self, relay):
+        r = _deposit(relay, ciphertext="hello-ciphertext")
+        msg_id = r["msg_id"]
+        mailbox_key = relay._hashed_mailbox_token("bob_mailbox_token_abc")
+
+        env = relay.envelope_for_replication(mailbox_key=mailbox_key, msg_id=msg_id)
+        assert env is not None
+        assert env["msg_id"] == msg_id
+        assert env["mailbox_key"] == mailbox_key
+        assert env["ciphertext"] == "hello-ciphertext"
+        assert env["delivery_class"] == "shared"
+        for k in ("msg_id", "mailbox_key", "sender_block_ref", "ciphertext"):
+            assert env.get(k), f"envelope missing required field {k!r}"
+
+    def test_returns_none_for_unknown_message(self, relay):
+        env = relay.envelope_for_replication(
+            mailbox_key="never_existed", msg_id="never_existed",
+        )
+        assert env is None
+
+    def test_envelope_round_trips_through_accept_replica(self, relay):
+        from services.mesh.mesh_dm_relay import DMRelay
+        receiver_relay = DMRelay()
+        receiver_relay._mailboxes.clear()
+        receiver_relay._stats = {"messages_in_memory": 0}
+
+        r = _deposit(relay)
+        msg_id = r["msg_id"]
+        mailbox_key = relay._hashed_mailbox_token("bob_mailbox_token_abc")
+        env = relay.envelope_for_replication(
+            mailbox_key=mailbox_key, msg_id=msg_id,
+        )
+        assert env is not None
+
+        result = receiver_relay.accept_replica(envelope=env)
+        assert result["ok"] is True
+        stored = receiver_relay._mailboxes.get(mailbox_key, [])
+        assert len(stored) == 1
+        assert stored[0].msg_id == msg_id
+        assert stored[0].ciphertext == "ciphertext-blob"

backend/tests/test_dm_replicate_envelope_endpoint.py

@@ -0,0 +1,150 @@
+"""POST /api/mesh/dm/replicate-envelope — receiving side of cross-node DM
+mailbox replication.
+
+This is the endpoint that peer relays call when they want to hand off an
+encrypted DM envelope to us (so the recipient can log into our node and
+find their messages). It re-enforces the per-(sender, recipient) anti-spam
+cap so hostile sender relays can't widen the cap by skipping the local
+check on their own deposit path.
+
+The endpoint:
+
+  * authenticates the caller via the existing per-peer HMAC pattern
+    (same one /api/mesh/infonet/peer-push and /api/mesh/gate/peer-push
+    use, introduced in #256 — ``X-Peer-Url`` + ``X-Peer-HMAC`` headers
+    keyed off ``resolve_peer_key_for_url``)
+  * rejects bodies > 64 KB (DM envelope size is bounded by
+    ``MESH_DM_MAX_MSG_BYTES`` — 64KB ceiling has generous headroom)
+  * rejects requests without a valid peer HMAC with 403
+  * passes the envelope to ``DMRelay.accept_replica`` which enforces
+    the cap
+
+This file pins the endpoint contract. The cap enforcement itself is
+tested in ``test_dm_relay_per_sender_cap.py`` against the relay's
+``accept_replica`` method directly.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import hashlib
+import hmac
+import json
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+
+@pytest.fixture
+def remote_client():
+    """ASGI client with peer IP 1.2.3.4 — never on the local-operator
+    allowlist. Used to prove the endpoint isn't accidentally reachable
+    by random remote callers without peer HMAC."""
+    from main import app
+
+    class _RemoteClient:
+        def __init__(self):
+            self._loop = asyncio.new_event_loop()
+            self._transport = ASGITransport(app=app, client=("1.2.3.4", 12345))
+            self._base = "http://1.2.3.4:8000"
+
+        def post(self, url, **kw):
+            async def go():
+                async with AsyncClient(transport=self._transport, base_url=self._base) as ac:
+                    return await ac.post(url, **kw)
+            return self._loop.run_until_complete(go())
+
+        def close(self):
+            self._loop.close()
+
+    c = _RemoteClient()
+    yield c
+    c.close()
+
+
+class TestReplicateEndpointAuth:
+    def test_rejects_request_without_peer_hmac(self, remote_client):
+        """A peer push that does NOT carry X-Peer-Url + X-Peer-HMAC
+        must be rejected with 403 before the envelope is ever passed
+        to the relay. Same gate the existing infonet/gate peer-push
+        endpoints enforce."""
+        payload = {
+            "envelope": {
+                "msg_id": "dm_unauth_1",
+                "mailbox_key": "mb",
+                "sender_block_ref": "sender",
+                "ciphertext": "x",
+            },
+        }
+        r = remote_client.post(
+            "/api/mesh/dm/replicate-envelope",
+            json=payload,
+        )
+        assert r.status_code == 403
+        assert "peer HMAC" in r.text or "peer hmac" in r.text.lower()
+
+    def test_rejects_wrong_peer_hmac(self, remote_client, monkeypatch):
+        """A request with a peer HMAC header keyed off the WRONG secret
+        is rejected. Confirms the HMAC is actually verified — a tampered
+        body or a key-substitution attack doesn't sneak through."""
+        # Plant a known peer secret. The request will sign with a
+        # DIFFERENT key, so verification must fail.
+        from services.config import get_settings
+        monkeypatch.setenv("MESH_PEER_PUSH_SECRET", "real-secret-32-chars-min-padding-padding")
+        get_settings.cache_clear()
+
+        body = json.dumps({
+            "envelope": {
+                "msg_id": "dm_wronghmac",
+                "mailbox_key": "mb",
+                "sender_block_ref": "sender",
+                "ciphertext": "x",
+            },
+        }).encode("utf-8")
+        wrong_hmac = hmac.new(b"wrong-key", body, hashlib.sha256).hexdigest()
+        r = remote_client.post(
+            "/api/mesh/dm/replicate-envelope",
+            content=body,
+            headers={
+                "Content-Type": "application/json",
+                "X-Peer-Url": "http://example-peer.onion:8000",
+                "X-Peer-HMAC": wrong_hmac,
+            },
+        )
+        assert r.status_code == 403
+
+    def test_rejects_oversize_body(self, remote_client):
+        """64 KB ceiling — anything bigger doesn't even get parsed.
+        Defends against memory amplification via giant ciphertexts."""
+        # 100 KB body is well over the 64 KB cap.
+        big = b"{" + b"x" * 100_000 + b"}"
+        r = remote_client.post(
+            "/api/mesh/dm/replicate-envelope",
+            content=big,
+            headers={
+                "Content-Type": "application/json",
+                "Content-Length": str(len(big)),
+            },
+        )
+        assert r.status_code in (400, 413), (
+            f"oversize body should be rejected with 400/413, got {r.status_code}"
+        )
+
+
+class TestReplicateEndpointRegistered:
+    def test_route_present_in_app(self):
+        """Static check that the route is actually wired into the app.
+        Catches a future refactor that drops the router include or
+        deletes the endpoint by accident."""
+        from main import app
+
+        paths_methods = set()
+        for route in app.routes:
+            path = getattr(route, "path", None)
+            methods = getattr(route, "methods", set()) or set()
+            for m in methods:
+                paths_methods.add((m, path))
+
+        assert ("POST", "/api/mesh/dm/replicate-envelope") in paths_methods, (
+            "POST /api/mesh/dm/replicate-envelope is not registered on the app"
+        )