Merge #19569: Enable fetching of orphan parents from wtxid peers

10b7a6d532148f880568c529e61a6d7edc7c91a9 refactor: make txmempool interface use GenTxid (Pieter Wuille)
5c124e17407a5b5824fec062b73a03a1030fa28c refactor: make FindTxForGetData use GenTxid (Pieter Wuille)
a2bfac893549e2d62708d8cda7071b4fe9750a2d refactor: use GenTxid in tx request functions (Pieter Wuille)
e65d115b725640eefb3bfa09786447816f7ca9cc test: request parents of orphan from wtxid relay peer (Anthony Towns)
900d7f6c075fd78e63503f31d267dbc16b3983d9 p2p: enable fetching of orphans from wtxid peers (Pieter Wuille)
9efd86a908cf09d9ddbadd3195f202635117d505 refactor: add GenTxid (=txid or wtxid) type and use it for tx request logic (Pieter Wuille)
d362f19355b36531a4a82094e0259f7f3db500a7 doc: list support for BIP 339 in doc/bips.md (Pieter Wuille)

Pull request description:

  This is based on https://github.com/bitcoin/bitcoin/pull/18044#discussion_r450687076.

  A new type `GenTxid` is added to protocol.h, which represents a tagged txid-or-wtxid. The tx request logic is updated to use these instead of uint256s, permitting per-announcement distinguishing of txid/wtxid (instead of assuming that everything we want to request from a wtxid peer is wtx). Then the restriction of orphan-parent requesting to non-wtxid peers is lifted.

  Also document BIP339 in doc/bips.md.

ACKs for top commit:
  jnewbery:
    Code review ACK 10b7a6d532148f880568c529e61a6d7edc7c91a9
  jonatack:
    ACK 10b7a6d532148f880568c529e61a6d7edc7c91a9
  ajtowns:
    ACK 10b7a6d532148f880568c529e61a6d7edc7c91a9 -- code review. Using gtxid to replace the is_txid_or_wtxid flag for the mempool functions is nice.
  naumenkogs:
    utACK 10b7a6d

Tree-SHA512: d518d13ffd71f8d2b3c175dc905362a7259689e6022a97a0b4f14f1f9fdd87475cf5af70cb12338d1e5d31b52c12e4faaea436114056a2ae9669cb506240758b

1 files changed, 15 insertions, 0 deletions

diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 4514db578a..544bab6d9b 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -12,6 +12,8 @@
 #include <serialize.h>
 #include <uint256.h>
 
+#include <tuple>
+
 static const int SERIALIZE_TRANSACTION_NO_WITNESS = 0x40000000;
 
 /** An outpoint - a combination of a transaction hash and an index n into its vout */
@@ -388,4 +390,17 @@ typedef std::shared_ptr<const CTransaction> CTransactionRef;
 static inline CTransactionRef MakeTransactionRef() { return std::make_shared<const CTransaction>(); }
 template <typename Tx> static inline CTransactionRef MakeTransactionRef(Tx&& txIn) { return std::make_shared<const CTransaction>(std::forward<Tx>(txIn)); }
 
+/** A generic txid reference (txid or wtxid). */
+class GenTxid
+{
+    const bool m_is_wtxid;
+    const uint256 m_hash;
+public:
+    GenTxid(bool is_wtxid, const uint256& hash) : m_is_wtxid(is_wtxid), m_hash(hash) {}
+    bool IsWtxid() const { return m_is_wtxid; }
+    const uint256& GetHash() const { return m_hash; }
+    friend bool operator==(const GenTxid& a, const GenTxid& b) { return a.m_is_wtxid == b.m_is_wtxid && a.m_hash == b.m_hash; }
+    friend bool operator<(const GenTxid& a, const GenTxid& b) { return std::tie(a.m_is_wtxid, a.m_hash) < std::tie(b.m_is_wtxid, b.m_hash); }
+};
+
 #endif // BITCOIN_PRIMITIVES_TRANSACTION_H