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p2p/discover: new distance metric based on sha3(id)

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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.
This commit is contained in:
Felix Lange
2015-04-27 00:50:18 +02:00
parent d457a1187d
commit 2adcc31bb4
6 changed files with 354 additions and 106 deletions
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16
p2p/discover/udp_test.go
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@ -16,6 +16,7 @@ import (
"testing"
"time"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/logger"
)
@ -26,7 +27,7 @@ func init() {
// shared test variables
var (
futureExp = uint64(time.Now().Add(10 * time.Hour).Unix())
testTarget = MustHexID("01010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101")
testTarget = NodeID{0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}
testRemote = rpcEndpoint{IP: net.ParseIP("1.1.1.1").To4(), UDP: 1, TCP: 2}
testLocalAnnounced = rpcEndpoint{IP: net.ParseIP("2.2.2.2").To4(), UDP: 3, TCP: 4}
testLocal = rpcEndpoint{IP: net.ParseIP("3.3.3.3").To4(), UDP: 5, TCP: 6}
@ -145,15 +146,10 @@ func TestUDP_findnode(t *testing.T) {
// put a few nodes into the table. their exact
// distribution shouldn't matter much, altough we need to
// take care not to overflow any bucket.
target := testTarget
nodes := &nodesByDistance{target: target}
targetHash := crypto.Sha3Hash(testTarget[:])
nodes := &nodesByDistance{target: targetHash}
for i := 0; i < bucketSize; i++ {
nodes.push(&Node{
IP: net.IP{1, 2, 3, byte(i)},
UDP: uint16(i + 2),
TCP: uint16(i + 3),
ID: randomID(test.table.self.ID, i+2),
}, bucketSize)
nodes.push(nodeAtDistance(test.table.self.sha, i+2), bucketSize)
}
test.table.add(nodes.entries)
@ -168,7 +164,7 @@ func TestUDP_findnode(t *testing.T) {
// check that closest neighbors are returned.
test.packetIn(nil, findnodePacket, &findnode{Target: testTarget, Expiration: futureExp})
test.waitPacketOut(func(p *neighbors) {
expected := test.table.closest(testTarget, bucketSize)
expected := test.table.closest(targetHash, bucketSize)
if len(p.Nodes) != bucketSize {
t.Errorf("wrong number of results: got %d, want %d", len(p.Nodes), bucketSize)
}