Commit Graph

28 Commits

Author SHA1 Message Date
Felix Lange c73b654fd1 p2p/discover: move bond logic from table to transport (#17048)
* p2p/discover: move bond logic from table to transport

This commit moves node endpoint verification (bonding) from the table to
the UDP transport implementation. Previously, adding a node to the table
entailed pinging the node if needed. With this change, the ping-back
logic is embedded in the packet handler at a lower level.

It is easy to verify that the basic protocol is unchanged: we still
require a valid pong reply from the node before findnode is accepted.

The node database tracked the time of last ping sent to the node and
time of last valid pong received from the node. Node endpoints are
considered verified when a valid pong is received and the time of last
pong was called 'bond time'. The time of last ping sent was unused. In
this commit, the last ping database entry is repurposed to mean last
ping _received_. This entry is now used to track whether the node needs
to be pinged back.

The other big change is how nodes are added to the table. We used to add
nodes in Table.bond, which ran when a remote node pinged us or when we
encountered the node in a neighbors reply. The transport now adds to the
table directly after the endpoint is verified through ping. To ensure
that the Table can't be filled just by pinging the node repeatedly, we
retain the isInitDone check. During init, only nodes from neighbors
replies are added.

* p2p/discover: reduce findnode failure counter on success

* p2p/discover: remove unused parameter of loadSeedNodes

* p2p/discover: improve ping-back check and comments

* p2p/discover: add neighbors reply nodes always, not just during init
2018-07-03 16:24:12 +03:00
kiel barry 864e80a48f p2p: fix some golint warnings (#16577) 2018-05-08 13:08:43 +02:00
Felix Lange 9123eceb0f p2p, p2p/discover: misc connectivity improvements (#16069)
* p2p: add DialRatio for configuration of inbound vs. dialed connections

* p2p: add connection flags to PeerInfo

* p2p/netutil: add SameNet, DistinctNetSet

* p2p/discover: improve revalidation and seeding

This changes node revalidation to be periodic instead of on-demand. This
should prevent issues where dead nodes get stuck in closer buckets
because no other node will ever come along to replace them.

Every 5 seconds (on average), the last node in a random bucket is
checked and moved to the front of the bucket if it is still responding.
If revalidation fails, the last node is replaced by an entry of the
'replacement list' containing recently-seen nodes.

Most close buckets are removed because it's very unlikely we'll ever
encounter a node that would fall into any of those buckets.

Table seeding is also improved: we now require a few minutes of table
membership before considering a node as a potential seed node. This
should make it less likely to store short-lived nodes as potential
seeds.

* p2p/discover: fix nits in UDP transport

We would skip sending neighbors replies if there were fewer than
maxNeighbors results and CheckRelayIP returned an error for the last
one. While here, also resolve a TODO about pong reply tokens.
2018-02-12 14:36:09 +02:00
Felix Lange 35a7dcb162 all: gofmt -w -s 2017-01-06 15:52:03 +01:00
Felix Lange a98d1d67d6 p2p/discover, p2p/discv5: prevent relay of invalid IPs and low ports
The discovery DHT contains a number of hosts with LAN and loopback IPs.
These get relayed because some implementations do not perform any checks
on the IP.

go-ethereum already prevented relay in most cases because it verifies
that the host actually exists before adding it to the local table. But
this verification causes other issues. We have received several reports
where people's VPSs got shut down by hosting providers because sending
packets to random LAN hosts is indistinguishable from a slow port scan.

The new check prevents sending random packets to LAN by discarding LAN
IPs sent by Internet hosts (and loopback IPs from LAN and Internet
hosts). The new check also blacklists almost all currently registered
special-purpose networks assigned by IANA to avoid inciting random
responses from services in the LAN.

As another precaution against abuse of the DHT, ports below 1024 are now
considered invalid.
2016-11-22 22:21:18 +01:00
Ricardo Catalinas Jiménez 436fc8d76a all: Rename crypto.Sha3{,Hash}() to crypto.Keccak256{,Hash}()
As we aren't really using the standarized SHA-3
2016-02-21 22:34:34 +00:00
Felix Lange d1f507b7f1 p2p/discover: support incomplete node URLs, add Resolve 2015-12-17 23:38:54 +01:00
Péter Szilágyi 9e1d9bff3b node: customizable protocol and service stacks 2015-11-27 11:06:12 +02:00
Felix Lange b4374436f3 p2p/discover: fix race involving the seed node iterator
nodeDB.querySeeds was not safe for concurrent use but could be called
concurrenty on multiple goroutines in the following case:

- the table was empty
- a timed refresh started
- a lookup was started and initiated refresh

These conditions are unlikely to coincide during normal use, but are
much more likely to occur all at once when the user's machine just woke
from sleep. The root cause of the issue is that querySeeds reused the
same leveldb iterator until it was exhausted.

This commit moves the refresh scheduling logic into its own goroutine
(so only one refresh is ever active) and changes querySeeds to not use
a persistent iterator. The seed node selection is now more random and
ignores nodes that have not been contacted in the last 5 days.
2015-09-30 16:23:03 +02:00
Felix Lange 01ed3fa1a9 p2p/discover: unlock the table during ping replacement
Table.mutex was being held while waiting for a reply packet, which
effectively made many parts of the whole stack block on that packet,
including the net_peerCount RPC call.
2015-08-11 11:42:17 +02:00
Felix Lange b23b4dbd79 p2p/discover: close Table during testing
Not closing the table used to be fine, but now the table has a database.
2015-08-06 12:27:59 +02:00
Felix Lange bfbcfbe4a9 all: fix license headers one more time
I forgot to update one instance of "go-ethereum" in commit 3f047be5a.
2015-07-23 18:35:11 +02:00
Felix Lange 3f047be5aa all: update license headers to distiguish GPL/LGPL
All code outside of cmd/ is licensed as LGPL. The headers
now reflect this by calling the whole work "the go-ethereum library".
2015-07-22 18:51:45 +02:00
Felix Lange ea54283b30 all: update license information 2015-07-07 14:12:44 +02:00
Felix Lange a8e4cb6dfe p2p/discover: use separate rand.Source instances in tests
rand.Source isn't safe for concurrent use.
2015-06-10 15:18:01 +02:00
Felix Lange 9f38ef5d97 p2p/discover: add ReadRandomNodes 2015-05-25 01:17:14 +02:00
Felix Lange 2adcc31bb4 p2p/discover: new distance metric based on sha3(id)
The previous metric was pubkey1^pubkey2, as specified in the Kademlia
paper. We missed that EC public keys are not uniformly distributed.
Using the hash of the public keys addresses that. It also makes it
a bit harder to generate node IDs that are close to a particular node.
2015-05-06 16:10:41 +02:00
Felix Lange 72ab6d3255 p2p/discover: track sha3(ID) in Node 2015-04-30 15:02:23 +02:00
Felix Lange fc747ef4a6 p2p/discover: new endpoint format
This commit changes the discovery protocol to use the new "v4" endpoint
format, which allows for separate UDP and TCP ports and makes it
possible to discover the UDP address after NAT.
2015-04-30 14:57:33 +02:00
Péter Szilágyi 8646365b42 cmd/bootnode, eth, p2p, p2p/discover: use a fancier db design 2015-04-24 18:04:41 +03:00
Péter Szilágyi 6def110c37 cmd/bootnode, eth, p2p, p2p/discover: clean up the seeder and mesh into eth. 2015-04-24 11:33:55 +03:00
Péter Szilágyi 971702e7a1 p2p/discovery: fix broken tests due to API update 2015-04-24 11:23:20 +03:00
Felix Lange a77c431e37 p2p/discover: fix off by one error causing buckets to contain duplicates 2015-04-01 17:00:12 +02:00
Felix Lange de7af720d6 p2p/discover: implement node bonding
This a fix for an attack vector where the discovery protocol could be
used to amplify traffic in a DDOS attack. A malicious actor would send a
findnode request with the IP address and UDP port of the target as the
source address. The recipient of the findnode packet would then send a
neighbors packet (which is 16x the size of findnode) to the victim.

Our solution is to require a 'bond' with the sender of findnode. If no
bond exists, the findnode packet is not processed. A bond between nodes
α and β is created when α replies to a ping from β.

This (initial) version of the bonding implementation might still be
vulnerable against replay attacks during the expiration time window.
We will add stricter source address validation later.
2015-04-01 17:00:12 +02:00
Felix Lange 9915d3c3be p2p/discover: deflake UDP tests 2015-02-09 11:02:32 +01:00
Felix Lange 8564eb9f7e p2p/discover: add node URL functions, distinguish TCP/UDP ports
The discovery RPC protocol does not yet distinguish TCP and UDP ports.
But it can't hurt to do so in our internal model.
2015-02-07 00:12:23 +01:00
Felix Lange 739066ec56 p2p/discover: add some helper functions 2015-02-06 00:00:36 +01:00
Felix Lange 12224c7f59 p2p/discover: new package implementing the Node Discovery Protocol 2015-02-06 00:00:36 +01:00