Ignore getaddr messages on Outbound connections.

The only time when a client sends a "getaddr" message is when he
esatblishes an Outbound connection (see ProcessMessage() in
src/main.cpp).  Another bitcoin client is expected to receive a
"getaddr" message only on Inbound connection. Ignoring "gettaddr"
requests on Outbound connections can resolve potential privacy issues
(and as was said such request normally do not happen anyway).

Rebased-From: dca799e1db
Github-Pull: #5442
This commit is contained in:
Ivan Pustogarov 2014-12-07 17:30:57 +01:00 committed by Wladimir J. van der Laan
parent d5d8998028
commit 200f29363b
No known key found for this signature in database
GPG Key ID: 74810B012346C9A6
1 changed files with 6 additions and 1 deletions

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@ -3976,7 +3976,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
}
else if (strCommand == "getaddr")
// This asymmetric behavior for inbound and outbound connections was introduced
// to prevent a fingerprinting attack: an attacker can send specific fake addresses
// to users' AddrMan and later request them by sending getaddr messages.
// Making users (which are behind NAT and can only make outgoing connections) ignore
// getaddr message mitigates the attack.
else if ((strCommand == "getaddr") && (pfrom->fInbound))
{
pfrom->vAddrToSend.clear();
vector<CAddress> vAddr = addrman.GetAddr();