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Move handling of unconnecting headers into own function

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This commit is contained in:
Suhas Daftuar 2022-02-08 17:02:55 -05:00
parent 2111f32f2a
commit 7f2450871b
1 changed files with 63 additions and 28 deletions
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91
src/net_processing.cpp
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@ -560,6 +560,11 @@ private:
const std::vector<CBlockHeader>& headers,
bool via_compact_block)
EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
/** Various helpers for headers processing, invoked by ProcessHeadersMessage() */
/** Deal with state tracking and headers sync for peers that send the
* occasional non-connecting header (this can happen due to BIP 130 headers
* announcements for blocks interacting with the 2hr (MAX_FUTURE_BLOCK_TIME) rule). */
void HandleFewUnconnectingHeaders(CNode& pfrom, Peer& peer, const std::vector<CBlockHeader>& headers);
void SendBlockTransactions(CNode& pfrom, Peer& peer, const CBlock& block, const BlockTransactionsRequest& req);
@ -2194,6 +2199,48 @@ void PeerManagerImpl::SendBlockTransactions(CNode& pfrom, Peer& peer, const CBlo
m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::BLOCKTXN, resp));
}
/**
* Special handling for unconnecting headers that might be part of a block
* announcement.
*
* We'll send a getheaders message in response to try to connect the chain.
*
* The peer can send up to MAX_UNCONNECTING_HEADERS in a row that
* don't connect before given DoS points.
*
* Once a headers message is received that is valid and does connect,
* nUnconnectingHeaders gets reset back to 0.
*/
void PeerManagerImpl::HandleFewUnconnectingHeaders(CNode& pfrom, Peer& peer,
const std::vector<CBlockHeader>& headers)
{
const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());
LOCK(cs_main);
CNodeState *nodestate = State(pfrom.GetId());
nodestate->nUnconnectingHeaders++;
// Try to fill in the missing headers.
m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(m_chainman.m_best_header), uint256()));
LogPrint(BCLog::NET, "received header %s: missing prev block %s, sending getheaders (%d) to end (peer=%d, nUnconnectingHeaders=%d)\n",
headers[0].GetHash().ToString(),
headers[0].hashPrevBlock.ToString(),
m_chainman.m_best_header->nHeight,
pfrom.GetId(), nodestate->nUnconnectingHeaders);
// Set hashLastUnknownBlock for this peer, so that if we
// eventually get the headers - even from a different peer -
// we can use this peer to download.
UpdateBlockAvailability(pfrom.GetId(), headers.back().GetHash());
// The peer may just be broken, so periodically assign DoS points if this
// condition persists.
if (nodestate->nUnconnectingHeaders % MAX_UNCONNECTING_HEADERS == 0) {
Misbehaving(peer, 20, strprintf("%d non-connecting headers", nodestate->nUnconnectingHeaders));
}
}
void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
const std::vector<CBlockHeader>& headers,
bool via_compact_block)
@ -2208,36 +2255,24 @@ void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
bool received_new_header = false;
const CBlockIndex *pindexLast = nullptr;
// Do these headers connect to something in our block index?
bool headers_connect_blockindex{WITH_LOCK(::cs_main, return m_chainman.m_blockman.LookupBlockIndex(headers[0].hashPrevBlock) != nullptr)};
if (!headers_connect_blockindex) {
if (nCount <= MAX_BLOCKS_TO_ANNOUNCE) {
// If this looks like it could be a BIP 130 block announcement, use
// special logic for handling headers that don't connect, as this
// could be benign.
HandleFewUnconnectingHeaders(pfrom, peer, headers);
} else {
Misbehaving(peer, 10, "invalid header received");
}
return;
}
{
LOCK(cs_main);
CNodeState *nodestate = State(pfrom.GetId());
// If this looks like it could be a block announcement (nCount <=
// MAX_BLOCKS_TO_ANNOUNCE), use special logic for handling headers that
// don't connect:
// - Send a getheaders message in response to try to connect the chain.
// - The peer can send up to MAX_UNCONNECTING_HEADERS in a row that
// don't connect before giving DoS points
// - Once a headers message is received that is valid and does connect,
// nUnconnectingHeaders gets reset back to 0.
if (!m_chainman.m_blockman.LookupBlockIndex(headers[0].hashPrevBlock) && nCount <= MAX_BLOCKS_TO_ANNOUNCE) {
nodestate->nUnconnectingHeaders++;
m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(m_chainman.m_best_header), uint256()));
LogPrint(BCLog::NET, "received header %s: missing prev block %s, sending getheaders (%d) to end (peer=%d, nUnconnectingHeaders=%d)\n",
headers[0].GetHash().ToString(),
headers[0].hashPrevBlock.ToString(),
m_chainman.m_best_header->nHeight,
pfrom.GetId(), nodestate->nUnconnectingHeaders);
// Set hashLastUnknownBlock for this peer, so that if we
// eventually get the headers - even from a different peer -
// we can use this peer to download.
UpdateBlockAvailability(pfrom.GetId(), headers.back().GetHash());
if (nodestate->nUnconnectingHeaders % MAX_UNCONNECTING_HEADERS == 0) {
Misbehaving(peer, 20, strprintf("%d non-connecting headers", nodestate->nUnconnectingHeaders));
}
return;
}
uint256 hashLastBlock;
for (const CBlockHeader& header : headers) {