From 5029698186445bf3cd69d0e720f019c472661bff Mon Sep 17 00:00:00 2001 From: kazcw Date: Wed, 16 Jul 2014 14:31:41 -0700 Subject: prevent peer flooding request queue for an inv mapAlreadyAskedFor does not keep track of which peer has a request queued for a particular tx. As a result, a peer can blind a node to a tx indefinitely by sending many invs for the same tx, and then never replying to getdatas for it. Each inv received will be placed 2 minutes farther back in mapAlreadyAskedFor, so a short message containing 10 invs would render that tx unavailable for 20 minutes. This is fixed by disallowing a peer from having more than one entry for a particular inv in mapAlreadyAskedFor at a time. --- src/net.cpp | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'src/net.cpp') diff --git a/src/net.cpp b/src/net.cpp index cff4c5450..04119e9dd 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -2410,6 +2410,10 @@ void CNode::AskFor(const CInv& inv) { if (mapAskFor.size() > MAPASKFOR_MAX_SZ) return; + // a peer may not occupy multiple positions in an inv's request queue + if (!setAskFor.insert(inv.hash).second) + return; + // We're using mapAskFor as a priority queue, // the key is the earliest time the request can be sent int64_t nRequestTime; -- cgit v1.2.3