Merge bitcoin/bitcoin#27609: rpc: allow submitpackage to be called outside of regtest

5b878be742dbfcd232d949d2df1fff4743aec3d8 [doc] add release note for submitpackage (glozow)
7a9bb2a2a59ba49f80519c8435229abec2432486 [rpc] allow submitpackage to be called outside of regtest (glozow)
5b9087a9a7da2602485e85e0b163dc3cbd2daf31 [rpc] require package to be a tree in submitpackage (glozow)
e32ba1599c599e75b1da3393f71f633de860505f [txpackages] IsChildWithParentsTree() (glozow)
b4f28cc345ef9c5261c4a8d743654a44784c7802 [doc] parent pay for child in aggregate CheckFeeRate (glozow)

Pull request description:

  Permit (restricted topology) submitpackage RPC outside of regtest. Suggested in https://github.com/bitcoin/bitcoin/pull/26933#issuecomment-1510851570

  This RPC should be safe but still experimental - interface may change, not all features (e.g. package RBF) are implemented, etc. If a miner wants to expose this to people, they can effectively use "package relay" before the p2p changes are implemented. However, please note **this is not package relay**; transactions submitted this way will not relay to other nodes if the feerates are below their mempool min fee. Users should put this behind some kind of rate limit or permissions.

ACKs for top commit:
  instagibbs:
    ACK 5b878be742dbfcd232d949d2df1fff4743aec3d8
  achow101:
    ACK 5b878be742dbfcd232d949d2df1fff4743aec3d8
  dergoegge:
    Code review ACK 5b878be742dbfcd232d949d2df1fff4743aec3d8
  ajtowns:
    ACK 5b878be742dbfcd232d949d2df1fff4743aec3d8
  ariard:
    Code Review ACK  5b878be742. Though didn’t manually test the PR.

Tree-SHA512: 610365c0b2ffcccd55dedd1151879c82de1027e3319712bcb11d54f2467afaae4d05dca5f4b25f03354c80845fef538d3938b958174dda8b14c10670537a6524

2 files changed, 19 insertions, 0 deletions

diff --git a/src/policy/packages.cpp b/src/policy/packages.cpp
index fd272a2642..47a9274a31 100644
--- a/src/policy/packages.cpp
+++ b/src/policy/packages.cpp
@@ -88,3 +88,18 @@ bool IsChildWithParents(const Package& package)
     return std::all_of(package.cbegin(), package.cend() - 1,
                        [&input_txids](const auto& ptx) { return input_txids.count(ptx->GetHash()) > 0; });
 }
+
+bool IsChildWithParentsTree(const Package& package)
+{
+    if (!IsChildWithParents(package)) return false;
+    std::unordered_set<uint256, SaltedTxidHasher> parent_txids;
+    std::transform(package.cbegin(), package.cend() - 1, std::inserter(parent_txids, parent_txids.end()),
+                   [](const auto& ptx) { return ptx->GetHash(); });
+    // Each parent must not have an input who is one of the other parents.
+    return std::all_of(package.cbegin(), package.cend() - 1, [&](const auto& ptx) {
+        for (const auto& input : ptx->vin) {
+            if (parent_txids.count(input.prevout.hash) > 0) return false;
+        }
+        return true;
+    });
+}
diff --git a/src/policy/packages.h b/src/policy/packages.h
index 702667b8ad..cf37857e4b 100644
--- a/src/policy/packages.h
+++ b/src/policy/packages.h
@@ -63,4 +63,8 @@ bool CheckPackage(const Package& txns, PackageValidationState& state);
  */
 bool IsChildWithParents(const Package& package);
 
+/** Context-free check that a package IsChildWithParents() and none of the parents depend on each
+ * other (the package is a "tree").
+ */
+bool IsChildWithParentsTree(const Package& package);
 #endif // BITCOIN_POLICY_PACKAGES_H