Require callers of AcceptBlockHeader() to perform anti-dos checks

In order to prevent memory DoS, we must ensure that we don't accept a new
header into memory until we've performed anti-DoS checks, such as verifying
that the header is part of a sufficiently high work chain. This commit adds a
new argument to AcceptBlockHeader() so that we can ensure that all call-sites
which might cause a new header to be accepted into memory have to grapple with
the question of whether the header is safe to accept, or needs further
validation.

This patch also fixes two places where low-difficulty-headers could have been
processed without such validation (processing an unrequested block from the
network, and processing a compact block).

Credit to Niklas Gögge for noticing this issue, and thanks to Sjors Provoost
for test code.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/test/blockfilter_index_tests.cpp b/src/test/blockfilter_index_tests.cpp
index 1a182209b8..2798e998af 100644
--- a/src/test/blockfilter_index_tests.cpp
+++ b/src/test/blockfilter_index_tests.cpp
@@ -101,7 +101,7 @@ bool BuildChainTestingSetup::BuildChain(const CBlockIndex* pindex,
         CBlockHeader header = block->GetBlockHeader();
 
         BlockValidationState state;
-        if (!Assert(m_node.chainman)->ProcessNewBlockHeaders({header}, state, &pindex)) {
+        if (!Assert(m_node.chainman)->ProcessNewBlockHeaders({header}, true, state, &pindex)) {
             return false;
         }
     }
@@ -178,7 +178,7 @@ BOOST_FIXTURE_TEST_CASE(blockfilter_index_initial_sync, BuildChainTestingSetup)
     uint256 chainA_last_header = last_header;
     for (size_t i = 0; i < 2; i++) {
         const auto& block = chainA[i];
-        BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, nullptr));
+        BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, true, nullptr));
     }
     for (size_t i = 0; i < 2; i++) {
         const auto& block = chainA[i];
@@ -196,7 +196,7 @@ BOOST_FIXTURE_TEST_CASE(blockfilter_index_initial_sync, BuildChainTestingSetup)
     uint256 chainB_last_header = last_header;
     for (size_t i = 0; i < 3; i++) {
         const auto& block = chainB[i];
-        BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, nullptr));
+        BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, true, nullptr));
     }
     for (size_t i = 0; i < 3; i++) {
         const auto& block = chainB[i];
@@ -227,7 +227,7 @@ BOOST_FIXTURE_TEST_CASE(blockfilter_index_initial_sync, BuildChainTestingSetup)
     // Reorg back to chain A.
      for (size_t i = 2; i < 4; i++) {
          const auto& block = chainA[i];
-         BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, nullptr));
+         BOOST_REQUIRE(Assert(m_node.chainman)->ProcessNewBlock(block, true, true, nullptr));
      }
 
      // Check that chain A and B blocks can be retrieved.