fix(bitcoind): guard block-sub handlers against errored RPC replies

Same #277 root cause in the block-subscription path: Bitcoin Core 28+
uses strict JSON-RPC 2.0, so an errored getblock/getbestblockhash reply
has no 'result' key. handle_block_sub and handle_block_sub_redis accessed
r['result'] unguarded, so a transient RPC error would raise
KeyError: 'result' and kill the block stream / block-update task.

Skip and log the block when the reply has no result instead of crashing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/bitcoind/service.py

@@ -162,6 +162,11 @@ async def handle_block_sub(request: Request, verbosity: int = 1) -> str:
         hash = binascii.hexlify(body).decode("utf-8")
         r = await bitcoin_rpc_async("getblock", [hash, verbosity])
 
+        # strict JSON-RPC 2.0: an errored reply has no "result" key
+        if "result" not in r or r.get("error") is not None:
+            logger.error(f"getblock failed, skipping block: {r.get('error')}")
+            continue
+
         yield json.dumps(r["result"])
 
 
@@ -180,6 +185,11 @@ async def handle_block_sub_redis(verbosity: int = 1) -> str:
             hash = binascii.hexlify(body).decode("utf-8")
         elif bitcoin_config.zmq_block_rpc == BlockRpcFunc.RAWBLOCK:
             r1 = await bitcoin_rpc_async("getbestblockhash", [])
+            if "result" not in r1 or r1.get("error") is not None:
+                logger.error(
+                    f"getbestblockhash failed, skipping block: {r1.get('error')}"
+                )
+                continue
             hash = r1["result"]
         else:
             raise NotImplementedError(
@@ -187,6 +197,11 @@ async def handle_block_sub_redis(verbosity: int = 1) -> str:
             )
 
         r = await bitcoin_rpc_async("getblock", [hash, verbosity])
+        # strict JSON-RPC 2.0: an errored reply has no "result" key
+        if "result" not in r or r.get("error") is not None:
+            logger.error(f"getblock failed, skipping block: {r.get('error')}")
+            continue
+
         await broadcast_sse_msg(SSE.BTC_NEW_BLOC, r["result"])
 
 

tests/test_block_sub_error.py

@@ -0,0 +1,79 @@
+"""
+Regression test for the same #277 root cause in the block-subscription path.
+
+Bitcoin Core 28+ returns strict JSON-RPC 2.0, so an errored getblock reply
+has no "result" key. handle_block_sub did `yield json.dumps(r["result"])`
+unguarded, which would crash the block stream with KeyError: 'result'.
+"""
+
+import json
+
+from app.bitcoind import service
+
+
+class _FakeSocket:
+    def setsockopt(self, *args):
+        pass
+
+    def setsockopt_string(self, *args):
+        pass
+
+    def connect(self, *args):
+        pass
+
+    async def recv_multipart(self):
+        # 32-byte block hash body -> a valid 64 char hex hash
+        return (b"hashblock", b"\x11" * 32, b"\x00")
+
+
+class _FakeCtx:
+    def socket(self, *args):
+        return _FakeSocket()
+
+    def destroy(self):
+        pass
+
+
+class _FakeRequest:
+    """is_disconnected() returns False for the first `process` checks, then
+    True to break the loop."""
+
+    def __init__(self, process: int):
+        self._calls = 0
+        self._process = process
+
+    async def is_disconnected(self):
+        self._calls += 1
+        return self._calls > self._process
+
+
+def _patch_zmq(monkeypatch):
+    monkeypatch.setattr(service.zmq.asyncio, "Context", lambda: _FakeCtx())
+
+
+async def test_handle_block_sub_skips_errored_getblock(monkeypatch):
+    _patch_zmq(monkeypatch)
+
+    async def fake_rpc(method, params=[]):
+        # strict JSON-RPC 2.0 error: no "result" key
+        return {"error": "some transient RPC error", "status": 500}
+
+    monkeypatch.setattr(service, "bitcoin_rpc_async", fake_rpc)
+
+    items = [item async for item in service.handle_block_sub(_FakeRequest(1))]
+
+    assert items == []  # error skipped, nothing yielded, no KeyError
+
+
+async def test_handle_block_sub_yields_on_success(monkeypatch):
+    _patch_zmq(monkeypatch)
+
+    async def fake_rpc(method, params=[]):
+        return {"result": {"height": 5}, "error": None}
+
+    monkeypatch.setattr(service, "bitcoin_rpc_async", fake_rpc)
+
+    items = [item async for item in service.handle_block_sub(_FakeRequest(1))]
+
+    assert len(items) == 1
+    assert json.loads(items[0]) == {"height": 5}