This change was suggested as Countermeasure 2 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.
Normally bitcoin core does not display any network originated strings without
sanitizing or hex encoding. This wasn't done for strcommand in many places.
This could be used to play havoc with a terminal displaying the logs,
especially with printtoconsole in use.
Thanks to Evil-Knievel for reporting this issue.
This avoids connecting to them again too soon in ThreadOpenConnections.
Make an exception for connection failures to the proxy as these
shouldn't affect the status of specific nodes.
This is a simplified re-do of closed pull #3088.
This patch eliminates the privacy and reliability problematic use
of centralized web services for discovering the node's addresses
for advertisement.
The Bitcoin protocol already allows your peers to tell you what
IP they think you have, but this data isn't trustworthy since
they could lie. So the challenge is using it without creating a
DOS vector.
To accomplish this we adopt an approach similar to the one used
by P2Pool: If we're announcing and don't have a better address
discovered (e.g. via UPNP) or configured we just announce to
each peer the address that peer told us. Since peers could
already replace, forge, or drop our address messages this cannot
create a new vulnerability... but if even one of our peers is
giving us a good address we'll eventually make a useful
advertisement.
We also may randomly use the peer-provided address for the
daily rebroadcast even if we otherwise have a seemingly routable
address, just in case we've been misconfigured (e.g. by UPNP).
To avoid privacy problems, we only do these things if discovery
is enabled.
Many changes:
* Do not use 'getblocks', but 'getheaders', and use it to build a headers tree.
* Blocks are fetched in parallel from all available outbound peers, using a
limited moving window. When one peer stalls the movement of the window, it is
disconnected.
* No more orphan blocks. At all. We only ever request a block for which we have
verified the headers, and store it to disk immediately. This means that a
disk-fill attack would require PoW.
* Require protocol version 31800 for every peer (released in december 2010).
* No more syncnode (we sync from everyone we can, though limited to 1 during
initial *headers* sync).
* Introduce some extra named constants, comments and asserts.
Avoids that SOCKS5 negotiation will hold up the shutdown process.
- Sockets can stay in non-blocking mode, no need to switch it on/off
anymore
- Adds a timeout (20 seconds) on SOCK5 negotiation. This should be
enough for even Tor to get a connection to a hidden service, and
avoids blocking the opencon thread indefinitely on a hanging proxy.
Fixes#2954.
Split up util.cpp/h into:
- string utilities (hex, base32, base64): no internal dependencies, no dependency on boost (apart from foreach)
- money utilities (parsesmoney, formatmoney)
- time utilities (gettime*, sleep, format date):
- and the rest (logging, argument parsing, config file parsing)
The latter is basically the environment and OS handling,
and is stripped of all utility functions, so we may want to
rename it to something else than util.cpp/h for clarity (Matt suggested
osinterface).
Breaks dependency of sha256.cpp on all the things pulled in by util.
- the call to CloseSocket() is placed after the WSAGetLastError(), because
a CloseSocket() can trigger an error also, which we don't want for the
logging in this two cases
Simpler alternative to #4348.
The current setup with closesocket() is strange. It poses
as a compatibility wrapper but adds functionality.
Rename it and make it a documented utility function in netbase.
Code movement only, zero effect on the functionality.
This adds a -whitelist option to specify subnet ranges from which peers
that connect are whitelisted. In addition, there is a -whitebind option
which works like -bind, except peers connecting to it are also
whitelisted (allowing a separate listen port for trusted connections).
Being whitelisted has two effects (for now):
* They are immune to DoS disconnection/banning.
* Transactions they broadcast (which are valid) are always relayed,
even if they were already in the mempool. This means that a node
can function as a gateway for a local network, and that rebroadcasts
from the local network will work as expected.
Whitelisting replaces the magic exemption localhost had for DoS
disconnection (local addresses are still never banned, though), which
implied hidden service connects (from a localhost Tor node) were
incorrectly immune to DoS disconnection as well. This old
behaviour is removed for that reason, but can be restored using
-whitelist=127.0.0.1 or -whitelist=::1 can be specified. -whitebind
is safer to use in case non-trusted localhost connections are expected
(like hidden services).
- add a small wrapper in util around RAND_bytes() and replace with
GetRandBytes() in the code to log errors from calling RAND_bytes()
- remove OpenSSL header rand.h where no longer needed
Ruben de Vries