net: Pass best block known height into CConnman

CConnman then passes the current best height into CNode at creation time.

This way CConnman/CNode have no dependency on main for height, and the signals
only move in one direction.

This also helps to prevent identity leakage a tiny bit. Before this change, an
attacker could theoretically make 2 connections on different interfaces. They
would connect fully on one, and only establish the initial connection on the
other. Once they receive a new block, they would relay it to your first
connection, and immediately commence the version handshake on the second. Since
the new block height is reflected immediately, they could attempt to learn
whether the two connections were correlated.

This is, of course, incredibly unlikely to work due to the small timings
involved and receipt from other senders. But it doesn't hurt to lock-in
nBestHeight at the time of connection, rather than letting the remote choose
the time.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index 1019b12c1c..bc9a98ab04 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -154,6 +154,7 @@ BOOST_AUTO_TEST_CASE(cnode_simple_test)
 {
     SOCKET hSocket = INVALID_SOCKET;
     NodeId id = 0;
+    int height = 0;
 
     in_addr ipv4Addr;
     ipv4Addr.s_addr = 0xa0b0c001;
@@ -163,12 +164,12 @@ BOOST_AUTO_TEST_CASE(cnode_simple_test)
     bool fInboundIn = false;
 
     // Test that fFeeler is false by default.
-    CNode* pnode1 = new CNode(id++, NODE_NETWORK, hSocket, addr, pszDest, fInboundIn);
+    CNode* pnode1 = new CNode(id++, NODE_NETWORK, height, hSocket, addr, pszDest, fInboundIn);
     BOOST_CHECK(pnode1->fInbound == false);
     BOOST_CHECK(pnode1->fFeeler == false);
 
     fInboundIn = true;
-    CNode* pnode2 = new CNode(id++, NODE_NETWORK, hSocket, addr, pszDest, fInboundIn);
+    CNode* pnode2 = new CNode(id++, NODE_NETWORK, height, hSocket, addr, pszDest, fInboundIn);
     BOOST_CHECK(pnode2->fInbound == true);
     BOOST_CHECK(pnode2->fFeeler == false);
 }