ipc mining: pass missing context to BlockTemplate methods (incompatible schema change)
What the developer wrote
Authored by Sjors Provoost
ipc mining: pass missing context to BlockTemplate methods (incompatible schema change)
Adding a context parameter ensures that these methods are run in
their own thread and don't block other calls. They were missing
for:
- createNewBlock()
- checkBlock()
The missing parameters were first pointed out by plebhash in
https://github.com/bitcoin/bitcoin/issues/33575#issuecomment-3383290115 and
adding them should prevent possible performance problems and lockups,
especially with #34184 which can make the createNewBlock method block for a
long time before returning. It would be straightforward to make this change in
a backward compatible way
(https://github.com/bitcoin/bitcoin/pull/34184#discussion_r2770232149) but nice
to not need to go through the trouble.
Warning: This is an intermediate, review-only commit. Binaries built from it
should not be distributed or used to connect to other clients or servers. It
makes incompatible changes to the `mining.capnp` schema without updating the
`Init.makeMining` version, causing binaries to advertise support for a schema
they do not actually implement. Mixed versions may therefore exchange garbage
requests/responses instead of producing clear errors. The final commit in this
series bumps the mining interface number to ensure mismatches are detected.
git-bisect-skip: yes
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
What changed, and why it matters
This is a Bitcoin Core internal-only commit that changes the inter-process communication (IPC) schema used between the main node and external mining components. It adds a missing 'context' parameter to two mining methods so they run in their own thread and don't block other calls. The commit itself explicitly warns it is an intermediate, review-only change that should not be distributed, because it makes incompatible schema changes without bumping the version number, which could cause mismatched binaries to exchange garbage data instead of clean errors. The actual security risk is low and self-contained: it is a known, temporary incompatibility during development, not a vulnerability in shipped code.
Do not build, distribute, or run binaries from this isolated commit in production or on any network. Treat it as a review-only intermediate change. Ensure the final commit in the series that bumps the mining interface version is included before any release or deployment. Reviewers should verify that the version bump in Init.makeMining is present in the subsequent commit and that functional tests cover both old and new interface behavior if backward compatibility is desired.
Security signals we found
Incompatible IPC schema change without version bump
Explicit developer warning against distributing or connecting binaries built from this commit
Risk of garbage request/response exchange between mismatched versions rather than clean errors
Intended fix for performance/lockup issues in mining IPC methods
Marked git-bisect-skip indicating unstable intermediate state
Evidence from the diff
The commit modifies src/ipc/capnp/mining.capnp to add a Proxy.Context parameter to createNewBlock() and checkBlock() in the Mining interface, and updates Python functional tests to pass the new context argument. The stated purpose is to ensure these long-running methods execute on their own thread via the IPC proxy framework, preventing them from blocking other calls. The commit message explicitly labels this as an intermediate, review-only commit with an incompatible schema change that does not update Init.makeMining version, meaning binaries built from this commit would advertise a mining interface version they do not implement. The commit is marked git-bisect-skip and warns against distributing or connecting such binaries. The final commit in the series is expected to bump the interface version to restore proper mismatch detection.
Changed components
src/ipc/capnp/mining.capnptest/functional/interface_ipc_mining.pytest/functional/test_framework/ipc_util.pyBitcoin Core IPC mining interfaceInspect captured patch +8 / −8
diff --git a/src/ipc/capnp/mining.capnp b/src/ipc/capnp/mining.capnp
index 0727fcc0..47cd242b 100644
--- a/src/ipc/capnp/mining.capnp
+++ b/src/ipc/capnp/mining.capnp
@@ -22,8 +22,8 @@ interface Mining $Proxy.wrap("interfaces::Mining") {
isInitialBlockDownload @1 (context :Proxy.Context) -> (result: Bool);
getTip @2 (context :Proxy.Context) -> (result: Common.BlockRef, hasResult: Bool);
waitTipChanged @3 (context :Proxy.Context, currentTip: Data, timeout: Float64 = .maxDouble) -> (result: Common.BlockRef);
- createNewBlock @4 (options: BlockCreateOptions) -> (result: BlockTemplate);
- checkBlock @5 (block: Data, options: BlockCheckOptions) -> (reason: Text, debug: Text, result: Bool);
+ createNewBlock @4 (context :Proxy.Context, options: BlockCreateOptions) -> (result: BlockTemplate);
+ checkBlock @5 (context :Proxy.Context, block: Data, options: BlockCheckOptions) -> (reason: Text, debug: Text, result: Bool);
}
interface BlockTemplate $Proxy.wrap("interfaces::BlockTemplate") {
diff --git a/test/functional/interface_ipc_mining.py b/test/functional/interface_ipc_mining.py
index 0a530827..2221d462 100755
--- a/test/functional/interface_ipc_mining.py
+++ b/test/functional/interface_ipc_mining.py
@@ -242,7 +242,7 @@ class IPCMiningTest(BitcoinTestFramework):
self.log.debug("Enforce minimum reserved weight for IPC clients too")
opts.blockReservedWeight = 0
try:
- await mining.createNewBlock(opts)
+ await mining.createNewBlock(ctx, opts)
raise AssertionError("createNewBlock unexpectedly succeeded")
except capnp.lib.capnp.KjException as e:
if e.type == "DISCONNECTED":
@@ -269,7 +269,7 @@ class IPCMiningTest(BitcoinTestFramework):
current_block_height = self.nodes[0].getchaintips()[0]["height"]
check_opts = self.capnp_modules['mining'].BlockCheckOptions()
- async with destroying((await mining.createNewBlock(self.default_block_create_options)).result, ctx) as template:
+ async with destroying((await mining.createNewBlock(ctx, self.default_block_create_options)).result, ctx) as template:
block = await mining_get_block(template, ctx)
balance = self.miniwallet.get_balance()
coinbase = await self.build_coinbase_test(template, ctx, self.miniwallet)
@@ -282,7 +282,7 @@ class IPCMiningTest(BitcoinTestFramework):
self.log.debug("Submit a block with a bad version")
block.nVersion = 0
block.solve()
- check = await mining.checkBlock(block.serialize(), check_opts)
+ check = await mining.checkBlock(ctx, block.serialize(), check_opts)
assert_equal(check.result, False)
assert_equal(check.reason, "bad-version(0x00000000)")
submitted = (await template.submitSolution(ctx, block.nVersion, block.nTime, block.nNonce, coinbase.serialize())).result
@@ -292,7 +292,7 @@ class IPCMiningTest(BitcoinTestFramework):
block.solve()
self.log.debug("First call checkBlock()")
- block_valid = (await mining.checkBlock(block.serialize(), check_opts)).result
+ block_valid = (await mining.checkBlock(ctx, block.serialize(), check_opts)).result
assert_equal(block_valid, True)
# The remote template block will be mutated, capture the original:
@@ -324,7 +324,7 @@ class IPCMiningTest(BitcoinTestFramework):
self.miniwallet.rescan_utxos()
assert_equal(self.miniwallet.get_balance(), balance + 1)
self.log.debug("Check block should fail now, since it is a duplicate")
- check = await mining.checkBlock(block.serialize(), check_opts)
+ check = await mining.checkBlock(ctx, block.serialize(), check_opts)
assert_equal(check.result, False)
assert_equal(check.reason, "inconclusive-not-best-prevblk")
diff --git a/test/functional/test_framework/ipc_util.py b/test/functional/test_framework/ipc_util.py
index 2ab74aba..11497463 100644
--- a/test/functional/test_framework/ipc_util.py
+++ b/test/functional/test_framework/ipc_util.py
@@ -108,7 +108,7 @@ async def make_capnp_init_ctx(self):
async def mining_create_block_template(mining, stack, ctx, opts):
"""Call mining.createNewBlock() and return template, then call template.destroy() when stack exits."""
- response = await mining.createNewBlock(opts)
+ response = await mining.createNewBlock(ctx, opts)
if not response._has("result"):
return None
return await stack.enter_async_context(destroying(response.result, ctx))
Why this scored 25/100
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