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 cff4c54505..04119e9ddd 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 From ebb25f4c23adbcb55796c402bafd6064a136f16f Mon Sep 17 00:00:00 2001 From: Gregory Maxwell Date: Mon, 23 Nov 2015 01:54:23 +0000 Subject: Limit setAskFor and retire requested entries only when a getdata returns. The setAskFor duplicate elimination was too eager and removed entries when we still had no getdata response, allowing the peer to keep INVing and not responding. --- src/net.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/net.cpp') diff --git a/src/net.cpp b/src/net.cpp index 04119e9ddd..a8b6ca9c5b 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -2408,9 +2408,9 @@ CNode::~CNode() void CNode::AskFor(const CInv& inv) { - if (mapAskFor.size() > MAPASKFOR_MAX_SZ) + if (mapAskFor.size() > MAPASKFOR_MAX_SZ || setAskFor.size() > SETASKFOR_MAX_SZ) return; - // a peer may not occupy multiple positions in an inv's request queue + // a peer may not have multiple non-responded queue positions for a single inv item if (!setAskFor.insert(inv.hash).second) return; -- cgit v1.2.3