Tests: Edit bloated varint test and add option for 'barely expensive' tests

qa/rpc-tests/p2p-fullblocktest.py

@@ -65,6 +65,10 @@ class FullBlockTest(ComparisonTestFramework):
         self.tip = None
         self.blocks = {}
 
+    def add_options(self, parser):
+        super().add_options(parser)
+        parser.add_option("--runbarelyexpensive", dest="runbarelyexpensive", default=True)
+
     def run_test(self):
         self.test = TestManager(self, self.options.tmpdir)
         self.test.add_all_connections(self.nodes)
@@ -875,10 +879,13 @@ class FullBlockTest(ComparisonTestFramework):
         yield rejected(RejectResult(16, b'bad-txns-nonfinal'))
 
 
-        #  This checks that a block with a bloated VARINT between the block_header and the array of tx is rejected
-        #  (previous behavior was that it was accepted.)  It also checks that if you subsequently send that block
-        #  with correct encoding, it should be accepted (i.e., the receiving node should not reject it on the
-        #  basis that it's the same as an already-rejected block, which would be a DoS vulnerability.)
+        #  This checks that a block with a bloated VARINT between the block_header and the array of tx such that
+        #  the block is > MAX_BLOCK_SIZE with the bloated varint, but <= MAX_BLOCK_SIZE without the bloated varint,
+        #  does not cause a subsequent, identical block with canonical encoding to be rejected.  The test does not
+        #  care whether the bloated block is accepted or rejected; it only cares that the second block is accepted.
+        #
+        #  What matters is that the receiving node should not reject the bloated block, and then reject the canonical
+        #  block on the basis that it's the same as an already-rejected block (which would be a consensus failure.)
         #
         #  -> b39 (11) -> b42 (12) -> b43 (13) -> b53 (14) -> b55 (15) -> b57 (16) -> b60 (17) -> b64 (18)
         #                                                                                        \
@@ -903,7 +910,7 @@ class FullBlockTest(ComparisonTestFramework):
         tx.vin.append(CTxIn(COutPoint(b64a.vtx[1].sha256, 0)))
         b64a = update_block("64a", [tx])
         assert_equal(len(b64a.serialize()), MAX_BLOCK_SIZE + 8)
-        yield rejected()
+        yield TestInstance([[self.tip, None]])
 
         # comptool workaround: to make sure b64 is delivered, manually erase b64a from blockstore
         self.test.block_store.erase(b64a.sha256)
@@ -941,7 +948,6 @@ class FullBlockTest(ComparisonTestFramework):
         update_block(66, [tx2, tx1])
         yield rejected(RejectResult(16, b'bad-txns-inputs-missingorspent'))
 
-
         # Attempt to double-spend a transaction created in a block
         #
         # -> b43 (13) -> b53 (14) -> b55 (15) -> b57 (16) -> b60 (17) -> b64 (18) -> b65 (19)
@@ -1239,6 +1245,7 @@ class FullBlockTest(ComparisonTestFramework):
         #  Test re-org of a week's worth of blocks (1088 blocks)
         #  This test takes a minute or two and can be accomplished in memory
         #
+        if self.options.runbarelyexpensive:
             tip(88)
             LARGE_REORG_SIZE = 1088
             test1 = TestInstance(sync_every_block=False)
@@ -1281,5 +1288,6 @@ class FullBlockTest(ComparisonTestFramework):
             chain1_tip += 2
 
 
+
 if __name__ == '__main__':
     FullBlockTest().main()