Commit Graph

36 Commits

Author SHA1 Message Date
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
Felix Lange
7ea131d4ff p2p/discover: fix pending replies iteration
Range expressions capture the length of the slice once before the first
iteration. A range expression cannot be used here since the loop
modifies the slice variable (including length changes).
2015-02-17 15:21:39 +01:00
Felix Lange
cf754b9483 p2p/discover: fix race in ListenUDP
udp.Table was assigned after the readLoop started, so
packets could arrive and be processed before the Table was there.
2015-02-13 15:06:47 +01:00
Felix Lange
170eb3ac68 p2p/discover: map listening port using configured mechanism 2015-02-13 11:39:32 +01:00
Felix Lange
82f0bd9009 p2p/discover: code review fixes 2015-02-13 11:39:31 +01:00
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