diff options
| -rw-r--r-- | src/net.cpp | 2 | ||||
| -rw-r--r-- | src/net.h | 17 |
2 files changed, 14 insertions, 5 deletions
diff --git a/src/net.cpp b/src/net.cpp index 3eac2235a5..7dec4abfb9 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -1811,7 +1811,7 @@ void CConnman::SetTryNewOutboundPeer(bool flag) // Return the number of peers we have over our outbound connection limit // Exclude peers that are marked for disconnect, or are going to be -// disconnected soon (eg one-shots and feelers) +// disconnected soon (eg ADDR_FETCH and FEELER) // Also exclude peers that haven't finished initial connection handshake yet // (so that we don't decide we're over our desired connection limit, and then // evict some peer that has finished the handshake) @@ -153,10 +153,19 @@ enum class ConnectionType { MANUAL, /** - * Feeler connections are short lived connections used to increase the - * number of connectable addresses in our AddrMan. Approximately every - * FEELER_INTERVAL, we attempt to connect to a random address from the new - * table. If successful, we add it to the tried table. + * Feeler connections are short-lived connections made to check that a node + * is alive. They can be useful for: + * - test-before-evict: if one of the peers is considered for eviction from + * our AddrMan because another peer is mapped to the same slot in the tried table, + * evict only if this longer-known peer is offline. + * - move node addresses from New to Tried table, so that we have more + * connectable addresses in our AddrMan. + * Note that in the literature ("Eclipse Attacks on Bitcoin’s Peer-to-Peer Network") + * only the latter feature is referred to as "feeler connections", + * although in our codebase feeler connections encompass test-before-evict as well. + * We make these connections approximately every FEELER_INTERVAL: + * first we resolve previously found collisions if they exist (test-before-evict), + * otherwise connect to a node from the new table. */ FEELER, |