Bisq’s bitcoinj tor/onion changes audit

[oscarguindzberg]

Overview

• Changes done on bisq's bitcoinj just support onion v2 addresses.
• Most of the code needed to support tor/onion services is in https://github.com/bisq-network/bisq (out of scope of this audit)
• Upstream tor support in bitcoinj was removed because it was not well maintained and caused problems and there were no volunteers to maintain it (Remove Orchid forked subproject and support for connecting via Tor. bitcoinj/bitcoinj#1314)
• Tor support could be re-enabled upstream by contributing changes done on bisq's bitcoinj and on https://github.com/bisq-network/bisq
• Tor support upstream could provide
  • Connect to peers running behind an onion address
  • Resolve DNS over tor
  • Connect via tor to clearnet peers
  • A mechanism to start a local tor client (orchid or another tor client)

Commit review

• PeerGroup.addAddress(): don't increase max connections if address already exist 011fe40
  • No changes suggested.
  • Created PR upstream PeerGroup.addAddress(): don't increase max connections if address alr… bitcoinj/bitcoinj#1741
• Catch PeerDiscoveryException during getPeers call. avoids stack trace when all DNS lookups timeout 834f57a
  • No changes suggested.
  • Created PR upstream Don't stop peer discovery if one peer discoverer throws an exception. bitcoinj/bitcoinj#1742
• PeerAddress hashCode() and equals(): add hostname and refactor 0988148
  • No changes suggested.
• Changes to support connecting to .onion addresses 9f09a89
  • See Tor/Onion code review changes #24