Bitcoin will not make an outbound connection to a network group
(/16 for IPv4) that it is already connected to. This means that
if an attacker wants good odds of capturing all a nodes outbound
connections he must have hosts on a a large number of distinct
groups.
Previously both inbound and outbound connections were used to
feed this exclusion. The use of inbound connections, which can be
controlled by the attacker, actually has the potential of making
sibyl attacks _easier_: An attacker can start up hosts in groups
which house many honest nodes and make outbound connections to
the victim to exclude big swaths of honest nodes. Because the
attacker chooses to make the outbound connection he can always
beat out honest nodes for the consumption of inbound slots.
At _best_ the old behavior increases attacker costs by a single
group (e.g. one distinct group to use to fill up all your inbound
slots), but at worst it allows the attacker to select whole
networks you won't connect to.
This commit makes the nodes use only outbound links to exclude
network groups for outbound connections. Fancier things could
be done, like weaker exclusion for inbound groups... but
simplicity is good and I don't believe more complexity is
currently needed.
not process any already received messages.
The primary reason to do this is if a node spams hundreds of messages
and we ban them, we don't want to continue processing the rest of it.
* do not let vnThreadsRunning[1] go negative
* do not perform locking operations while vnThreadsRunning[1] is decreased
* check vnThreadsRunning[1] at exit
This fixes a potential bug where some NATs may replace the node's
interal IP with its external IP in version messages, causing
incorrect checksums when version messages begin being checksummed
on February 14, 2012.
Partial cherry pick of:
Compile with extra warnings turned on. And more makefile/code tidying up.
This turns on most gcc warnings, and removes some unused variables and other code that triggers warnings.
Exceptions are:
-Wno-sign-compare : triggered by lots of comparisons of signed integer to foo.size(), which is unsigned.
-Wno-char-subscripts : triggered by the convert-to-hex functions (I may fix this in a future commit).
Conflicts:
src/makefile.osx
src/makefile.unix
src/netbase.cpp
src/rpc.cpp
Made three critical blocks for cs_mapAddresses smaller, and moved
writing to the database out of them. This should also improve the
concurrency of the code.
Luke Dashjr