test: p2p block malleability #33172

1. 
   musaHaruna commented at 3:45 pm on August 11, 2025: none

   This PR adds a functional test to repeat the existing malleability check for oversized coinbase witness nonce size using a block that is small enough to be relayed over the P2P network.

   This addresses the TODO in test_block_malleability by ensuring behavior is consistent between submitblock RPC and P2P relay.

2. DrahtBot added the label Tests on Aug 11, 2025
3. 
   DrahtBot commented at 3:45 pm on August 11, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33172.

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   ACK	bc1cindy

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4. test: repeat block malleability test with relayable block over P2P

   Adds a functional test that repeats the existing witness nonce size
   malleability check using a block under MAX_BLOCK_WEIGHT so it can be
   relayed over the P2P network, addressing the TODO in test_block_malleability.
   
   Includes rejection check for 'bad-witness-nonce-size' and confirmation
   that a corrected block is accepted.

   19c5dba8ca
5. musaHaruna force-pushed on Aug 11, 2025
6. 
   bc1cindy commented at 0:17 am on August 12, 2025: none

   ACK 19c5dba

   Tested on macOS, completed successfully in ~64 seconds.

   The implementation properly addresses the TODO comment by adding P2P test coverage for block malleability. Uses 100KB witness data - large enough to trigger bad-witness-nonce-size but small enough to stay under MAX_BLOCK_WEIGHT. Follows existing patterns and tests both rejection and acceptance paths consistently.

   Good addition to test coverage.

Contributors
musaHaruna DrahtBot bc1cindy

Labels
Tests