nwaku/waku/v2/waku_dnsdisc.nim

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when (NimMajor, NimMinor) < (1, 4):
{.push raises: [Defect].}
else:
{.push raises: [].}
## A set of utilities to integrate EIP-1459 DNS-based discovery
## for Waku v2 nodes.
##
## EIP-1459 is defined in https://eips.ethereum.org/EIPS/eip-1459
import
std/options,
stew/shims/net,
chronicles,
chronos,
metrics,
eth/keys,
eth/p2p/discoveryv5/enr,
libp2p/crypto/crypto,
libp2p/crypto/secp,
libp2p/multiaddress,
libp2p/peerid,
discovery/dnsdisc/client
import
./waku_core
export client
declarePublicGauge waku_dnsdisc_discovered, "number of nodes discovered"
declarePublicGauge waku_dnsdisc_errors, "number of waku dnsdisc errors", ["type"]
logScope:
topics = "waku dnsdisc"
type
WakuDnsDiscovery* = object
client*: Client
resolver*: Resolver
#####################
# DNS Discovery API #
#####################
proc emptyResolver*(domain: string): Future[string] {.async, gcsafe.} =
debug "Empty resolver called", domain=domain
return ""
proc findPeers*(wdd: var WakuDnsDiscovery): Result[seq[RemotePeerInfo], cstring] =
## Find peers to connect to using DNS based discovery
info "Finding peers using Waku DNS discovery"
# Synchronise client tree using configured resolver
var tree: Tree
try:
tree = wdd.client.getTree(wdd.resolver) # @TODO: this is currently a blocking operation to not violate memory safety
except Exception:
error "Failed to synchronise client tree"
waku_dnsdisc_errors.inc(labelValues = ["tree_sync_failure"])
return err("Node discovery failed")
let discoveredEnr = wdd.client.getNodeRecords()
if discoveredEnr.len > 0:
info "Successfully discovered ENR", count=discoveredEnr.len
else:
trace "No ENR retrieved from client tree"
var discoveredNodes: seq[RemotePeerInfo]
for enr in discoveredEnr:
# Convert discovered ENR to RemotePeerInfo and add to discovered nodes
let res = enr.toRemotePeerInfo()
if res.isOk():
discoveredNodes.add(res.get())
else:
error "Failed to convert ENR to peer info", enr= $enr, err=res.error()
waku_dnsdisc_errors.inc(labelValues = ["peer_info_failure"])
if discoveredNodes.len > 0:
info "Successfully discovered nodes", count=discoveredNodes.len
waku_dnsdisc_discovered.inc(discoveredNodes.len.int64)
return ok(discoveredNodes)
proc init*(T: type WakuDnsDiscovery,
locationUrl: string,
resolver: Resolver): Result[T, cstring] =
## Initialise Waku peer discovery via DNS
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debug "init WakuDnsDiscovery", locationUrl=locationUrl
let
client = ? Client.init(locationUrl)
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wakuDnsDisc = WakuDnsDiscovery(client: client, resolver: resolver)
debug "init success"
return ok(wakuDnsDisc)