Commit Graph

58 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
thomasmodeneis ba1030b6b8 build: enable goimports and varcheck linters (#16446) 2018-04-18 00:53:50 +02:00
Felix Lange aeedec4078 p2p/discover: s/lastPong/bondTime/, update TestUDP_findnode
I forgot to change the check in udp.go when I changed Table.bond to be
based on lastPong instead of node presence in db. Rename lastPong to
bondTime and add hasBond so it's clearer what this DB key is used for
now.
2018-02-16 21:29:20 +01:00
Péter Szilágyi 32301a4d6b
p2p/discover: validate bond against lastpong, not db presence 2018-02-16 17:05:08 +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
Felföldi Zsolt 92580d69d3 p2p, p2p/discover, p2p/discv5: implement UDP port sharing (#15200)
This commit affects p2p/discv5 "topic discovery" by running it on
the same UDP port where the old discovery works. This is realized
by giving an "unhandled" packet channel to the old v4 discovery
packet handler where all invalid packets are sent. These packets
are then processed by v5. v5 packets are always invalid when
interpreted by v4 and vice versa. This is ensured by adding one
to the first byte of the packet hash in v5 packets.

DiscoveryV5Bootnodes is also changed to point to new bootnodes
that are implementing the changed packet format with modified
hash. Existing and new v5 bootnodes are both running on different
ports ATM.
2018-01-22 13:38:34 +01:00
Ali Hajimirza 33b158e0ed discover: Changed Logging from Debug to Info (#14485) 2017-05-20 13:10:59 +02:00
Felix Lange 96ae35e2ac p2p, p2p/discover, p2p/nat: rework logging using context keys 2017-02-28 10:20:29 +01:00
Péter Szilágyi d4fd06c3dc
all: blidly swap out glog to our log15, logs need rework 2017-02-23 12:16:44 +02:00
Péter Szilágyi 189dee26c6
p2p: remove trailing newlines from log messages 2017-02-23 12:00:04 +02:00
Felix Lange a47341cf96 p2p, p2p/discover, p2p/discv5: add IP network restriction feature
The p2p packages can now be configured to restrict all communication to
a certain subset of IP networks. This feature is meant to be used for
private networks.
2016-11-22 22:21:18 +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
Felix Lange ba2884f343 p2p/discover, p2p/discv5: use netutil.IsTemporaryError 2016-11-22 22:21:15 +01:00
Jeffrey Wilcke 483feb0d3f Merge pull request #2242 from jimenezrick/upstream-crypto
Closes #2241: Use Keccak-256 from golang.org/x/crypto/sha3 and mention explicitly
2016-02-24 12:57:57 +01:00
Péter Szilágyi ac954f48bd p2p/discover: emphasize warning, add 10 min cooldown 2016-02-24 12:16:28 +02:00
Péter Szilágyi b1908f6a16 psp/discovery: NTP sanity check clock drift in case of expirations 2016-02-24 12:14:15 +02:00
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 ee1debda53 p2p/discover: EIP-8 changes 2016-02-19 11:14:42 +01:00
Felix Lange 2871781f64 p2p/discover: fix Windows-specific issue for larger-than-buffer packets
On Windows, UDPConn.ReadFrom returns an error for packets larger
than the receive buffer. The error is not marked temporary, causing
our loop to exit when the first oversized packet arrived. The fix
is to treat this particular error as temporary.

Fixes: #1579, #2087
Updates: #2082
2016-01-22 23:44:25 +01:00
Felix Lange 04c6369a09 p2p, p2p/discover: track bootstrap state in p2p/discover
This change simplifies the dial scheduling logic because it
no longer needs to track whether the discovery table has been
bootstrapped.
2015-12-17 23:38:54 +01:00
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 32dda97602 p2p/discover: ignore packet version numbers
The strict matching can get in the way of protocol upgrades.
2015-09-30 16:23:03 +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
Jeffrey Wilcke e2d44814a5 Merge pull request #1694 from obscuren/hide-fdtrack
fdtrack: hide message
2015-08-19 13:50:54 -07:00
Jeffrey Wilcke 269c5c7107 Revert "fdtrack: temporary hack for tracking file descriptor usage"
This reverts commit 5c949d3b3b.
2015-08-19 21:46:01 +02:00
Felix Lange 7d5ff770e2 p2p/discover: continue reading after temporary errors
Might solve #1579
2015-08-19 14:38:55 +02:00
Felix Lange 590c99a98f p2p/discover: fix UDP reply packet timeout handling
If the timeout fired (even just nanoseconds) before the deadline of the
next pending reply, the timer was not rescheduled. The timer would've
been rescheduled anyway once the next packet was sent, but there were
cases where no next packet could ever be sent due to the locking issue
fixed in the previous commit.

As timing-related bugs go, this issue had been present for a long time
and I could never reproduce it. The test added in this commit did
reproduce the issue on about one out of 15 runs.
2015-08-11 11:42:17 +02:00
Felix Lange 5c949d3b3b fdtrack: temporary hack for tracking file descriptor usage
Package fdtrack logs statistics about open file descriptors.
This should help identify the source of #1549.
2015-08-04 03:10:27 +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 251846d65a p2p/discover: fix out-of-bounds slicing for chunked neighbors packets
The code assumed that Table.closest always returns at least 13 nodes.
This is not true for small tables (e.g. during bootstrap).
2015-05-13 21:49:04 +02:00
subtly a32693770c Manual send of multiple neighbours packets. Test receiving multiple neighbours packets. 2015-05-13 20:03:17 +02:00
subtly 7473c93668 UDP Interop. Limit datagrams to 1280bytes.
We don't have a UDP which specifies any messages that will be 4KB. Aside from being implemented for months and a necessity for encryption and piggy-backing packets, 1280bytes is ideal, and, means this TODO can be completed!

Why 1280 bytes?
* It's less than the default MTU for most WAN/LAN networks. That means fewer fragmented datagrams (esp on well-connected networks).
* Fragmented datagrams and dropped packets suck and add latency while OS waits for a dropped fragment to never arrive (blocking readLoop())
* Most of our packets are < 1280 bytes.
* 1280 bytes is minimum datagram size and MTU for IPv6 -- on IPv6, a datagram < 1280bytes will *never* be fragmented.

UDP datagrams are dropped. A lot! And fragmented datagrams are worse. If a datagram has a 30% chance of being dropped, then a fragmented datagram has a 60% chance of being dropped. More importantly, we have signed packets and can't do anything with a packet unless we receive the entire datagram because the signature can't be verified. The same is true when we have encrypted packets.

So the solution here to picking an ideal buffer size for receiving datagrams is a number under 1400bytes. And the lower-bound value for IPv6 of 1280 bytes make's it a non-decision. On IPv4 most ISPs and 3g/4g/let networks have an MTU just over 1400 -- and *never* over 1500. Never -- that means packets over 1500 (in reality: ~1450) bytes are fragmented. And probably dropped a lot.

Just to prove the point, here are pings sending non-fragmented packets over wifi/ISP, and a second set of pings via cell-phone tethering. It's important to note that, if *any* router between my system and the EC2 node has a lower MTU, the message would not go through:

On wifi w/normal ISP:
localhost:Debug $ ping -D -s 1450 52.6.250.242
PING 52.6.250.242 (52.6.250.242): 1450 data bytes
1458 bytes from 52.6.250.242: icmp_seq=0 ttl=42 time=104.831 ms
1458 bytes from 52.6.250.242: icmp_seq=1 ttl=42 time=119.004 ms
^C
--- 52.6.250.242 ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 104.831/111.918/119.004/7.087 ms
localhost:Debug $ ping -D -s 1480 52.6.250.242
PING 52.6.250.242 (52.6.250.242): 1480 data bytes
ping: sendto: Message too long
ping: sendto: Message too long
Request timeout for icmp_seq 0
ping: sendto: Message too long
Request timeout for icmp_seq 1


Tethering to O2:
localhost:Debug $ ping -D -s 1480 52.6.250.242
PING 52.6.250.242 (52.6.250.242): 1480 data bytes
ping: sendto: Message too long
ping: sendto: Message too long
Request timeout for icmp_seq 0
^C
--- 52.6.250.242 ping statistics ---
2 packets transmitted, 0 packets received, 100.0% packet loss
localhost:Debug $ ping -D -s 1450 52.6.250.242
PING 52.6.250.242 (52.6.250.242): 1450 data bytes
1458 bytes from 52.6.250.242: icmp_seq=0 ttl=42 time=107.844 ms
1458 bytes from 52.6.250.242: icmp_seq=1 ttl=42 time=105.127 ms
1458 bytes from 52.6.250.242: icmp_seq=2 ttl=42 time=120.483 ms
1458 bytes from 52.6.250.242: icmp_seq=3 ttl=42 time=102.136 ms
2015-05-13 19:03:00 +02:00
Felix Lange bcfd788661 p2p/discover: bump packet timeouts to 500ms 2015-05-06 22:59:00 +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 b34a8ef624 p2p, p2p/discover: protocol version 4 2015-04-30 14:57:34 +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 5f735d6fce cmd, eth, p2p, p2p/discover: init and clean up the seed cache 2015-04-24 11:23:20 +03:00
Felix Lange eedbb1ee9a p2p/discover: use rlp.DecodeBytes 2015-04-17 14:45:09 +02:00
Felix Lange 0217652d1b p2p/discover: improve timer handling for reply timeouts 2015-04-13 18:08:11 +02:00
Felix Lange 7be05b4b9d p2p/discover: don't log packet content 2015-04-10 13:26:27 +02:00
Felix Lange 9cd8c96157 p2p/discover: make packet processing less concurrent 2015-04-10 13:26:27 +02:00
obscuren 688d118c7e Updated logging 2015-04-07 14:57:04 +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 92928309b2 p2p/discover: add version number to ping packet
The primary motivation for doing this right now is that old PoC 8
nodes and newer PoC 9 nodes keep discovering each other, causing
handshake failures.
2015-04-01 15:53:04 +02:00