Tests if addresses are online or offline by briefly connecting to them. These short lived connections are referred to as feeler connections. Feeler connections are designed to increase the number of fresh online addresses in tried by selecting and connecting to addresses in new. One feeler connection is attempted on average once every two minutes.
This change was suggested as Countermeasure 4 in
Eclipse Attacks on Bitcoin’s Peer-to-Peer Network, Ethan Heilman,
Alison Kendler, Aviv Zohar, Sharon Goldberg. ePrint Archive Report
2015/263. March 2015.
The `pickDataDirectory()` function was calling `exit(0)` to quit
the application when the user closes the dialog without choosing
a data directory.
This is a bad idea because a background thread is created (to
check free space on the drive of the currently selected datadir).
The thread is not stopped and unwound properly, resulting in a potential
race condition somewhere deep in Qt.
So replace the `exit()` by a boolean return value, and let the
stack unwind normally.
- Ignore GETBLOCKTXN requests for unknown blocks
Don't disconnect peers, or else we leak information that could be
used for fingerprinting.
- Ignore CMPCTBLOCK messages for pruned blocks
Also ignores CMPCTBLOCK announcements that have too little work. This is to
prevent disk-exhaustion DoS.
Github-Pull: #8408
Rebased-From: 1de2a466321d06e49834
When processing a headers message that looks like a block announcement,
send peer a getheaders if the headers message won't connect.
Apply DoS points after too many consecutive unconnecting headers messages.
Moves the IsStandard check to happen after the premature-witness check,
so that adding a witness to a transaction can't prevent mempool acceptance.
Note that this doesn't address the broader category of potential mempool DoS
issues that affect transactions after segwit activation.
Also cap the allocation for the leveldb-specific cache for the UTXO set
to 8MiB.
This avoids that the extra cache memory goes to the much less effective
leveldb cache instead of our application-level cache.
This reverts PR #4906, "Coinselection prunes extraneous inputs from
ApproximateBestSubset".
Apparently the previous behavior of slightly over-estimating the set of
inputs was useful in cleaning up UTXOs.
See also #7664, #7657, as well as 2016-07-01 discussion on #bitcoin-core-dev IRC.
Generate an (invalid) example address for in the bitcoin address
widgets, based on the network prefix, instead of hardcoding a mainnet
address.
- `1NS17iag9jJgTHD1VXjvLCEnZuQ3rJDE9L` for mainnet (same as now)
- `n2wxQmfexkjwEPgdD6iJA7T7RtzkmHxhFc` for testnet
Pieter Wuille