Merge #19776: net, rpc: expose high bandwidth mode state via getpeerinfo

343dc4760f test: add test for high-bandwidth mode states in getpeerinfo (Sebastian Falbesoner)
dab6583307 doc: release note for new getpeerinfo fields "bip152_hb_{from,to}" (Sebastian Falbesoner)
a7ed00f8bb rpc: expose high-bandwidth mode states via getpeerinfo (Sebastian Falbesoner)
30bc8fab68 net: save high-bandwidth mode states in CNodeStats (Sebastian Falbesoner)

Pull request description:

  Fixes #19676, "_For every peer expose through getpeerinfo RPC whether or not we selected them as HB peers, and whether or not they selected us as HB peers._" See [BIP152](https://github.com/bitcoin/bips/blob/master/bip-0152.mediawiki), in particular the [protocol flow diagram](https://github.com/bitcoin/bips/raw/master/bip-0152/protocol-flow.png).  The newly introduced states are changed on the following places in the code:
  * on reception of a `SENDCMPCT` message with valid version, the field `m_highbandwidth_from` is changed depending on the first integer parameter in the message (1=high bandwidth, 0=low bandwidth), i.e. it just mirrors the field `CNodeState.fPreferHeaderAndIDs`.
  * after adding a `SENDCMPCT` message to the send queue, the field `m_highbandwidth_to` is changed depending on how the first integer parameter is set (same as above)

  Note that after receiving `VERACK`, the node also sends `SENDCMPCT`, but that is only to announce the preferred version and never selects high-bandwidth mode, hence there is no need to change the state variables there, which are initialized to `false` anyways.

ACKs for top commit:
  naumenkogs:
    reACK 343dc4760f
  jonatack:
    re-ACK 343dc4760f per `git range-diff 7ea6499 4df1d12 343dc47`

Tree-SHA512: f4999e6a935266812c2259a9b5dc459710037d3c9e938006d282557cc225e56128f72965faffb207fc60c6531fab1206db976dd8729a69e8ca29d4835317b99f

test/functional/p2p_compactblocks.py

@@ -764,6 +764,34 @@ class CompactBlocksTest(BitcoinTestFramework):
         stalling_peer.send_and_ping(msg)
         assert_equal(int(node.getbestblockhash(), 16), block.sha256)
 
+    def test_highbandwidth_mode_states_via_getpeerinfo(self):
+        # create new p2p connection for a fresh state w/o any prior sendcmpct messages sent
+        hb_test_node = self.nodes[0].add_p2p_connection(TestP2PConn(cmpct_version=2))
+
+        # assert the RPC getpeerinfo boolean fields `bip152_hb_{to, from}`
+        # match the given parameters for the last peer of a given node
+        def assert_highbandwidth_states(node, hb_to, hb_from):
+            peerinfo = node.getpeerinfo()[-1]
+            assert_equal(peerinfo['bip152_hb_to'], hb_to)
+            assert_equal(peerinfo['bip152_hb_from'], hb_from)
+
+        # initially, neither node has selected the other peer as high-bandwidth yet
+        assert_highbandwidth_states(self.nodes[0], hb_to=False, hb_from=False)
+
+        # peer requests high-bandwidth mode by sending sendcmpct(1)
+        hb_test_node.send_and_ping(msg_sendcmpct(announce=True, version=2))
+        assert_highbandwidth_states(self.nodes[0], hb_to=False, hb_from=True)
+
+        # peer generates a block and sends it to node, which should
+        # select the peer as high-bandwidth (up to 3 peers according to BIP 152)
+        block = self.build_block_on_tip(self.nodes[0])
+        hb_test_node.send_and_ping(msg_block(block))
+        assert_highbandwidth_states(self.nodes[0], hb_to=True, hb_from=True)
+
+        # peer requests low-bandwidth mode by sending sendcmpct(0)
+        hb_test_node.send_and_ping(msg_sendcmpct(announce=False, version=2))
+        assert_highbandwidth_states(self.nodes[0], hb_to=True, hb_from=False)
+
     def run_test(self):
         # Get the nodes out of IBD
         self.nodes[0].generate(1)
@@ -822,6 +850,9 @@ class CompactBlocksTest(BitcoinTestFramework):
         self.log.info("Testing invalid index in cmpctblock message...")
         self.test_invalid_cmpctblock_message()
 
+        self.log.info("Testing high-bandwidth mode states via getpeerinfo...")
+        self.test_highbandwidth_mode_states_via_getpeerinfo()
+
 
 if __name__ == '__main__':
     CompactBlocksTest().main()