ipc mining: provide default option values (incompatible schema change)
What the developer wrote
Authored by Ryan Ofsky
ipc mining: provide default option values (incompatible schema change)
This change copies default option values from the C++ mining interface to the
Cap'n Proto interface. Currently, no capnp default values are set, so they are
implicitly all false or 0, which is inconvenient for the rust and python
clients and inconsistent with the C++ client.
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
What changed, and why it matters
This is a Bitcoin Core internal commit that adds default values to an inter-process communication (IPC) schema used by experimental mining interfaces. The commit itself warns it is an intermediate, review-only change that should not be used in production because it makes an incompatible schema change without bumping the version number. If someone ignored that warning and ran mismatched binaries, the two sides could misunderstand each other's messages and exchange garbage data instead of clean errors. There is no direct evidence this is exploitable as a security vulnerability; the risk is primarily operational and self-disclosed by the developers.
Treat this commit as the developers label it: review-only, do not ship binaries from it, and ensure the follow-up commit that bumps Init.makeMining is included before any release or deployment. No security patch is required; normal code-review and version-bump verification is sufficient.
Security signals we found
Incompatible schema change without version bump (self-disclosed by commit message)
Risk of garbage requests/responses between mismatched IPC peers if binaries are built from this intermediate commit
No input validation, memory corruption, or cryptographic weakness introduced in the diff
Change is isolated to experimental IPC mining interfaces, not P2P or consensus code
Evidence from the diff
The patch updates src/ipc/capnp/mining.capnp to supply Cap’n Proto default values (true, .maxDouble, .defaultBlockReservedWeight, etc.) for fields in BlockCreateOptions, BlockWaitOptions, BlockCheckOptions, and the waitTipChanged timeout. It also removes explicit default assignments in the Python functional test now that the schema provides them. The commit message explicitly states this is an intermediate, incompatible schema change that does not update Init.makeMining, so mixed-version IPC peers would not detect the mismatch and could exchange malformed requests/responses. The change is not a memory-safety bug, cryptographic flaw, or consensus issue; it is a schema-versioning hazard in an opt-in/experimental IPC subsystem.
Changed components
src/ipc/capnp/mining.capnptest/functional/interface_ipc_mining.pyExperimental IPC mining interface (Cap'n Proto wrapper)Inspect captured patch +9 / −17
diff --git a/src/ipc/capnp/mining.capnp b/src/ipc/capnp/mining.capnp
index 7e5cced6..1811716f 100644
--- a/src/ipc/capnp/mining.capnp
+++ b/src/ipc/capnp/mining.capnp
@@ -21,7 +21,7 @@ interface Mining $Proxy.wrap("interfaces::Mining") {
isTestChain @0 (context :Proxy.Context) -> (result: Bool);
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) -> (result: Common.BlockRef);
+ 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);
}
@@ -43,19 +43,19 @@ interface BlockTemplate $Proxy.wrap("interfaces::BlockTemplate") {
}
struct BlockCreateOptions $Proxy.wrap("node::BlockCreateOptions") {
- useMempool @0 :Bool $Proxy.name("use_mempool");
- blockReservedWeight @1 :UInt64 $Proxy.name("block_reserved_weight");
- coinbaseOutputMaxAdditionalSigops @2 :UInt64 $Proxy.name("coinbase_output_max_additional_sigops");
+ useMempool @0 :Bool = true $Proxy.name("use_mempool");
+ blockReservedWeight @1 :UInt64 = .defaultBlockReservedWeight $Proxy.name("block_reserved_weight");
+ coinbaseOutputMaxAdditionalSigops @2 :UInt64 = .defaultCoinbaseOutputMaxAdditionalSigops $Proxy.name("coinbase_output_max_additional_sigops");
}
struct BlockWaitOptions $Proxy.wrap("node::BlockWaitOptions") {
- timeout @0 : Float64 $Proxy.name("timeout");
- feeThreshold @1 : Int64 $Proxy.name("fee_threshold");
+ timeout @0 : Float64 = .maxDouble $Proxy.name("timeout");
+ feeThreshold @1 : Int64 = .maxMoney $Proxy.name("fee_threshold");
}
struct BlockCheckOptions $Proxy.wrap("node::BlockCheckOptions") {
- checkMerkleRoot @0 :Bool $Proxy.name("check_merkle_root");
- checkPow @1 :Bool $Proxy.name("check_pow");
+ checkMerkleRoot @0 :Bool = true $Proxy.name("check_merkle_root");
+ checkPow @1 :Bool = true $Proxy.name("check_pow");
}
struct CoinbaseTx $Proxy.wrap("node::CoinbaseTx") {
diff --git a/test/functional/interface_ipc_mining.py b/test/functional/interface_ipc_mining.py
index d4a0d87e..a02727bb 100755
--- a/test/functional/interface_ipc_mining.py
+++ b/test/functional/interface_ipc_mining.py
@@ -243,9 +243,6 @@ class IPCMiningTest(BitcoinTestFramework):
async with AsyncExitStack() as stack:
opts = self.capnp_modules['mining'].BlockCreateOptions()
- opts.useMempool = True
- opts.blockReservedWeight = 4000
- opts.coinbaseOutputMaxAdditionalSigops = 0
template = await mining_create_block_template(mining, stack, ctx, opts)
assert template is not None
block = await mining_get_block(template, ctx)
@@ -351,12 +348,7 @@ class IPCMiningTest(BitcoinTestFramework):
def run_test(self):
self.miniwallet = MiniWallet(self.nodes[0])
- self.default_block_create_options = self.capnp_modules['mining'].BlockCreateOptions(
- useMempool=True,
- blockReservedWeight=4000,
- coinbaseOutputMaxAdditionalSigops=0
- )
-
+ self.default_block_create_options = self.capnp_modules['mining'].BlockCreateOptions()
self.run_mining_interface_test()
self.run_block_template_test()
self.run_coinbase_and_submission_test()
Why this scored 19/100
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