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# Nim-LibP2P
# Copyright (c) 2022 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
## Base interface for pubsub protocols
##
## You can `subscribe<#subscribe%2CPubSub%2Cstring%2CTopicHandler>`_ to a topic,
## `publish<#publish.e%2CPubSub%2Cstring%2Cseq%5Bbyte%5D>`_ something on it,
## and eventually `unsubscribe<#unsubscribe%2CPubSub%2Cstring%2CTopicHandler>`_ from it.
{.push raises: [Defect].}
import std/[tables, sequtils, sets, strutils]
import chronos, chronicles, metrics
import ./errors as pubsub_errors,
./pubsubpeer,
./rpc/[message, messages, protobuf],
../../switch,
../protocol,
../../crypto/crypto,
../../stream/connection,
../../peerid,
../../peerinfo,
../../errors,
../../utility
import metrics
import stew/results
export results
export PubSubPeer
export PubSubObserver
export protocol
export pubsub_errors
logScope:
topics = "libp2p pubsub"
const
KnownLibP2PTopics* {.strdefine.} = ""
KnownLibP2PTopicsSeq* = KnownLibP2PTopics.toLowerAscii().split(",")
declareGauge(libp2p_pubsub_peers, "pubsub peer instances")
declareGauge(libp2p_pubsub_topics, "pubsub subscribed topics")
declareCounter(libp2p_pubsub_subscriptions, "pubsub subscription operations")
declareCounter(libp2p_pubsub_unsubscriptions, "pubsub unsubscription operations")
declareGauge(libp2p_pubsub_topic_handlers, "pubsub subscribed topics handlers count", labels = ["topic"])
declareCounter(libp2p_pubsub_validation_success, "pubsub successfully validated messages")
declareCounter(libp2p_pubsub_validation_failure, "pubsub failed validated messages")
declareCounter(libp2p_pubsub_validation_ignore, "pubsub ignore validated messages")
declarePublicCounter(libp2p_pubsub_messages_published, "published messages", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_messages_rebroadcasted, "re-broadcasted messages", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_subscriptions, "pubsub broadcast subscriptions", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_unsubscriptions, "pubsub broadcast unsubscriptions", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_messages, "pubsub broadcast messages", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_subscriptions, "pubsub received subscriptions", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_unsubscriptions, "pubsub received subscriptions", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_messages, "pubsub received messages", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_iwant, "pubsub broadcast iwant")
declarePublicCounter(libp2p_pubsub_broadcast_ihave, "pubsub broadcast ihave", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_graft, "pubsub broadcast graft", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_broadcast_prune, "pubsub broadcast prune", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_iwant, "pubsub broadcast iwant")
declarePublicCounter(libp2p_pubsub_received_ihave, "pubsub broadcast ihave", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_graft, "pubsub broadcast graft", labels = ["topic"])
declarePublicCounter(libp2p_pubsub_received_prune, "pubsub broadcast prune", labels = ["topic"])
type
InitializationError* = object of LPError
TopicHandler* {.public.} = proc(topic: string,
data: seq[byte]): Future[void] {.gcsafe, raises: [Defect].}
ValidatorHandler* {.public.} = proc(topic: string,
message: Message): Future[ValidationResult] {.gcsafe, raises: [Defect].}
TopicPair* = tuple[topic: string, handler: TopicHandler]
MsgIdProvider* {.public.} =
proc(m: Message): Result[MessageID, ValidationResult] {.noSideEffect, raises: [Defect], gcsafe.}
SubscriptionValidator* {.public.} =
proc(topic: string): bool {.raises: [Defect], gcsafe.}
## Every time a peer send us a subscription (even to an unknown topic),
## we have to store it, which may be an attack vector.
## This callback can be used to reject topic we're not interested in
PubSub* {.public.} = ref object of LPProtocol
switch*: Switch # the switch used to dial/connect to peers
peerInfo*: PeerInfo # this peer's info
topics*: Table[string, seq[TopicHandler]] # the topics that _we_ are interested in
peers*: Table[PeerId, PubSubPeer] #\
# Peers that we are interested to gossip with (but not necessarily
# yet connected to)
triggerSelf*: bool ## trigger own local handler on publish
verifySignature*: bool ## enable signature verification
sign*: bool ## enable message signing
validators*: Table[string, HashSet[ValidatorHandler]]
observers: ref seq[PubSubObserver] # ref as in smart_ptr
msgIdProvider*: MsgIdProvider ## Turn message into message id (not nil)
msgSeqno*: uint64
anonymize*: bool ## if we omit fromPeer and seqno from RPC messages we send
subscriptionValidator*: SubscriptionValidator # callback used to validate subscriptions
topicsHigh*: int ## the maximum number of topics a peer is allowed to subscribe to
maxMessageSize*: int ##\
## the maximum raw message size we'll globally allow
## for finer tuning, check message size on topic validator
##
## sending a big message to a peer with a lower size limit can
## lead to issues, from descoring to connection drops
##
## defaults to 1mB
rng*: ref HmacDrbgContext
knownTopics*: HashSet[string]
method unsubscribePeer*(p: PubSub, peerId: PeerId) {.base.} =
## handle peer disconnects
##
debug "unsubscribing pubsub peer", peerId
p.peers.del(peerId)
libp2p_pubsub_peers.set(p.peers.len.int64)
proc send*(p: PubSub, peer: PubSubPeer, msg: RPCMsg) {.raises: [Defect].} =
## Attempt to send `msg` to remote peer
##
trace "sending pubsub message to peer", peer, msg = shortLog(msg)
peer.send(msg, p.anonymize)
proc broadcast*(
p: PubSub,
sendPeers: auto, # Iteratble[PubSubPeer]
msg: RPCMsg) {.raises: [Defect].} =
## Attempt to send `msg` to the given peers
let npeers = sendPeers.len.int64
for sub in msg.subscriptions:
if sub.subscribe:
if p.knownTopics.contains(sub.topic):
libp2p_pubsub_broadcast_subscriptions.inc(npeers, labelValues = [sub.topic])
else:
libp2p_pubsub_broadcast_subscriptions.inc(npeers, labelValues = ["generic"])
else:
if p.knownTopics.contains(sub.topic):
libp2p_pubsub_broadcast_unsubscriptions.inc(npeers, labelValues = [sub.topic])
else:
libp2p_pubsub_broadcast_unsubscriptions.inc(npeers, labelValues = ["generic"])
for smsg in msg.messages:
for topic in smsg.topicIDs:
if p.knownTopics.contains(topic):
libp2p_pubsub_broadcast_messages.inc(npeers, labelValues = [topic])
else:
libp2p_pubsub_broadcast_messages.inc(npeers, labelValues = ["generic"])
if msg.control.isSome():
libp2p_pubsub_broadcast_iwant.inc(npeers * msg.control.get().iwant.len.int64)
let control = msg.control.get()
for ihave in control.ihave:
if p.knownTopics.contains(ihave.topicID):
libp2p_pubsub_broadcast_ihave.inc(npeers, labelValues = [ihave.topicID])
else:
libp2p_pubsub_broadcast_ihave.inc(npeers, labelValues = ["generic"])
for graft in control.graft:
if p.knownTopics.contains(graft.topicID):
libp2p_pubsub_broadcast_graft.inc(npeers, labelValues = [graft.topicID])
else:
libp2p_pubsub_broadcast_graft.inc(npeers, labelValues = ["generic"])
for prune in control.prune:
if p.knownTopics.contains(prune.topicID):
libp2p_pubsub_broadcast_prune.inc(npeers, labelValues = [prune.topicID])
else:
libp2p_pubsub_broadcast_prune.inc(npeers, labelValues = ["generic"])
trace "broadcasting messages to peers",
peers = sendPeers.len, msg = shortLog(msg)
if anyIt(sendPeers, it.hasObservers):
for peer in sendPeers:
p.send(peer, msg)
else:
# Fast path that only encodes message once
let encoded = encodeRpcMsg(msg, p.anonymize)
for peer in sendPeers:
peer.sendEncoded(encoded)
proc sendSubs*(p: PubSub,
peer: PubSubPeer,
topics: openArray[string],
subscribe: bool) =
## send subscriptions to remote peer
p.send(peer, RPCMsg.withSubs(topics, subscribe))
for topic in topics:
if subscribe:
if p.knownTopics.contains(topic):
libp2p_pubsub_broadcast_subscriptions.inc(labelValues = [topic])
else:
libp2p_pubsub_broadcast_subscriptions.inc(labelValues = ["generic"])
else:
if p.knownTopics.contains(topic):
libp2p_pubsub_broadcast_unsubscriptions.inc(labelValues = [topic])
else:
libp2p_pubsub_broadcast_unsubscriptions.inc(labelValues = ["generic"])
proc updateMetrics*(p: PubSub, rpcMsg: RPCMsg) =
for i in 0..<min(rpcMsg.subscriptions.len, p.topicsHigh):
template sub(): untyped = rpcMsg.subscriptions[i]
if sub.subscribe:
if p.knownTopics.contains(sub.topic):
libp2p_pubsub_received_subscriptions.inc(labelValues = [sub.topic])
else:
libp2p_pubsub_received_subscriptions.inc(labelValues = ["generic"])
else:
if p.knownTopics.contains(sub.topic):
libp2p_pubsub_received_unsubscriptions.inc(labelValues = [sub.topic])
else:
libp2p_pubsub_received_unsubscriptions.inc(labelValues = ["generic"])
for i in 0..<rpcMsg.messages.len():
template smsg: untyped = rpcMsg.messages[i]
for j in 0..<smsg.topicIDs.len():
template topic: untyped = smsg.topicIDs[j]
if p.knownTopics.contains(topic):
libp2p_pubsub_received_messages.inc(labelValues = [topic])
else:
libp2p_pubsub_received_messages.inc(labelValues = ["generic"])
if rpcMsg.control.isSome():
libp2p_pubsub_received_iwant.inc(rpcMsg.control.get().iwant.len.int64)
template control: untyped = rpcMsg.control.unsafeGet()
for ihave in control.ihave:
if p.knownTopics.contains(ihave.topicID):
libp2p_pubsub_received_ihave.inc(labelValues = [ihave.topicID])
else:
libp2p_pubsub_received_ihave.inc(labelValues = ["generic"])
for graft in control.graft:
if p.knownTopics.contains(graft.topicID):
libp2p_pubsub_received_graft.inc(labelValues = [graft.topicID])
else:
libp2p_pubsub_received_graft.inc(labelValues = ["generic"])
for prune in control.prune:
if p.knownTopics.contains(prune.topicID):
libp2p_pubsub_received_prune.inc(labelValues = [prune.topicID])
else:
libp2p_pubsub_received_prune.inc(labelValues = ["generic"])
method rpcHandler*(p: PubSub,
peer: PubSubPeer,
rpcMsg: RPCMsg): Future[void] {.base.} =
## Handler that must be overridden by concrete implementation
raiseAssert "Unimplemented"
method onNewPeer(p: PubSub, peer: PubSubPeer) {.base.} = discard
method onPubSubPeerEvent*(p: PubSub, peer: PubsubPeer, event: PubsubPeerEvent) {.base, gcsafe.} =
# Peer event is raised for the send connection in particular
case event.kind
of PubSubPeerEventKind.Connected:
if p.topics.len > 0:
p.sendSubs(peer, toSeq(p.topics.keys), true)
of PubSubPeerEventKind.Disconnected:
discard
proc getOrCreatePeer*(
p: PubSub,
peerId: PeerId,
protos: seq[string]): PubSubPeer =
p.peers.withValue(peerId, peer):
return peer[]
proc getConn(): Future[Connection] =
p.switch.dial(peerId, protos)
proc dropConn(peer: PubSubPeer) =
proc dropConnAsync(peer: PubsubPeer) {.async.} =
try:
await p.switch.disconnect(peer.peerId)
except CatchableError as exc: # never cancelled
trace "Failed to close connection", peer, error = exc.name, msg = exc.msg
asyncSpawn dropConnAsync(peer)
proc onEvent(peer: PubsubPeer, event: PubsubPeerEvent) {.gcsafe.} =
p.onPubSubPeerEvent(peer, event)
# create new pubsub peer
let pubSubPeer = PubSubPeer.new(peerId, getConn, dropConn, onEvent, protos[0], p.maxMessageSize)
debug "created new pubsub peer", peerId
p.peers[peerId] = pubSubPeer
pubSubPeer.observers = p.observers
onNewPeer(p, pubSubPeer)
# metrics
libp2p_pubsub_peers.set(p.peers.len.int64)
pubsubPeer.connect()
return pubSubPeer
proc handleData*(p: PubSub, topic: string, data: seq[byte]): Future[void] =
# Start work on all data handlers without copying data into closure like
# happens on {.async.} transformation
p.topics.withValue(topic, handlers) do:
var futs = newSeq[Future[void]]()
for handler in handlers[]:
if handler != nil: # allow nil handlers
let fut = handler(topic, data)
if not fut.completed(): # Fast path for successful sync handlers
futs.add(fut)
if futs.len() > 0:
proc waiter(): Future[void] {.async.} =
# slow path - we have to wait for the handlers to complete
try:
futs = await allFinished(futs)
except CancelledError:
# propagate cancellation
for fut in futs:
if not(fut.finished):
fut.cancel()
# check for errors in futures
for fut in futs:
if fut.failed:
let err = fut.readError()
warn "Error in topic handler", msg = err.msg
return waiter()
# Fast path - futures finished synchronously or nobody cared about data
var res = newFuture[void]()
res.complete()
return res
method handleConn*(p: PubSub,
conn: Connection,
proto: string) {.base, async.} =
## handle incoming connections
##
## this proc will:
## 1) register a new PubSubPeer for the connection
## 2) register a handler with the peer;
## this handler gets called on every rpc message
## that the peer receives
## 3) ask the peer to subscribe us to every topic
## that we're interested in
##
proc handler(peer: PubSubPeer, msg: RPCMsg): Future[void] =
# call pubsub rpc handler
p.rpcHandler(peer, msg)
let peer = p.getOrCreatePeer(conn.peerId, @[proto])
try:
peer.handler = handler
await peer.handle(conn) # spawn peer read loop
trace "pubsub peer handler ended", conn
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception ocurred in pubsub handle", exc = exc.msg, conn
finally:
await conn.closeWithEOF()
method subscribePeer*(p: PubSub, peer: PeerId) {.base.} =
## subscribe to remote peer to receive/send pubsub
## messages
##
discard p.getOrCreatePeer(peer, p.codecs)
proc updateTopicMetrics(p: PubSub, topic: string) =
# metrics
libp2p_pubsub_topics.set(p.topics.len.int64)
if p.knownTopics.contains(topic):
p.topics.withValue(topic, handlers) do:
libp2p_pubsub_topic_handlers.set(handlers[].len.int64, labelValues = [topic])
do:
libp2p_pubsub_topic_handlers.set(0, labelValues = [topic])
else:
var others: int64 = 0
for key, val in p.topics:
if key notin p.knownTopics: others += 1
libp2p_pubsub_topic_handlers.set(others, labelValues = ["other"])
method onTopicSubscription*(p: PubSub, topic: string, subscribed: bool) {.base.} =
# Called when subscribe is called the first time for a topic or unsubscribe
# removes the last handler
# Notify others that we are no longer interested in the topic
for _, peer in p.peers:
p.sendSubs(peer, [topic], subscribed)
if subscribed:
libp2p_pubsub_subscriptions.inc()
else:
libp2p_pubsub_unsubscriptions.inc()
proc unsubscribe*(p: PubSub,
topic: string,
handler: TopicHandler) {.public.} =
## unsubscribe from a ``topic`` string
##
p.topics.withValue(topic, handlers):
handlers[].keepItIf(it != handler)
if handlers[].len() == 0:
p.topics.del(topic)
p.onTopicSubscription(topic, false)
p.updateTopicMetrics(topic)
proc unsubscribe*(p: PubSub, topics: openArray[TopicPair]) {.public.} =
## unsubscribe from a list of ``topic`` handlers
for t in topics:
p.unsubscribe(t.topic, t.handler)
proc unsubscribeAll*(p: PubSub, topic: string) {.public.} =
## unsubscribe every `handler` from `topic`
if topic notin p.topics:
debug "unsubscribeAll called for an unknown topic", topic
else:
p.topics.del(topic)
p.onTopicSubscription(topic, false)
p.updateTopicMetrics(topic)
proc subscribe*(p: PubSub,
topic: string,
handler: TopicHandler) {.public.} =
## subscribe to a topic
##
## ``topic`` - a string topic to subscribe to
##
## ``handler`` - user provided proc that
## will be triggered on every
## received message
# Check that this is an allowed topic
if p.subscriptionValidator != nil and p.subscriptionValidator(topic) == false:
warn "Trying to subscribe to a topic not passing validation!", topic
return
p.topics.withValue(topic, handlers) do:
# Already subscribed, just adding another handler
handlers[].add(handler)
do:
trace "subscribing to topic", name = topic
p.topics[topic] = @[handler]
# Notify on first handler
p.onTopicSubscription(topic, true)
p.updateTopicMetrics(topic)
method publish*(p: PubSub,
topic: string,
data: seq[byte]): Future[int] {.base, async, public.} =
## publish to a ``topic``
##
## The return value is the number of neighbours that we attempted to send the
## message to, excluding self. Note that this is an optimistic number of
## attempts - the number of peers that actually receive the message might
## be lower.
if p.triggerSelf:
await handleData(p, topic, data)
return 0
method initPubSub*(p: PubSub)
{.base, raises: [Defect, InitializationError].} =
## perform pubsub initialization
p.observers = new(seq[PubSubObserver])
if p.msgIdProvider == nil:
p.msgIdProvider = defaultMsgIdProvider
method addValidator*(p: PubSub,
topic: varargs[string],
hook: ValidatorHandler) {.base, public.} =
## Add a validator to a `topic`. Each new message received in this
## will be sent to `hook`. `hook` can return either `Accept`,
## `Ignore` or `Reject` (which can descore the peer)
for t in topic:
trace "adding validator for topic", topicId = t
p.validators.mgetOrPut(t, HashSet[ValidatorHandler]()).incl(hook)
method removeValidator*(p: PubSub,
topic: varargs[string],
hook: ValidatorHandler) {.base, public.} =
for t in topic:
p.validators.withValue(t, validators):
validators[].excl(hook)
if validators[].len() == 0:
p.validators.del(t)
method validate*(p: PubSub, message: Message): Future[ValidationResult] {.async, base.} =
var pending: seq[Future[ValidationResult]]
trace "about to validate message"
for topic in message.topicIDs:
trace "looking for validators on topic", topicID = topic,
registered = toSeq(p.validators.keys)
if topic in p.validators:
trace "running validators for topic", topicID = topic
for validator in p.validators[topic]:
pending.add(validator(topic, message))
result = ValidationResult.Accept
let futs = await allFinished(pending)
for fut in futs:
if fut.failed:
result = ValidationResult.Reject
break
let res = fut.read()
if res != ValidationResult.Accept:
result = res
if res == ValidationResult.Reject:
break
case result
of ValidationResult.Accept:
libp2p_pubsub_validation_success.inc()
of ValidationResult.Reject:
libp2p_pubsub_validation_failure.inc()
of ValidationResult.Ignore:
libp2p_pubsub_validation_ignore.inc()
proc init*[PubParams: object | bool](
P: typedesc[PubSub],
switch: Switch,
triggerSelf: bool = false,
anonymize: bool = false,
verifySignature: bool = true,
sign: bool = true,
msgIdProvider: MsgIdProvider = defaultMsgIdProvider,
subscriptionValidator: SubscriptionValidator = nil,
maxMessageSize: int = 1024 * 1024,
rng: ref HmacDrbgContext = newRng(),
parameters: PubParams = false): P
{.raises: [Defect, InitializationError], public.} =
let pubsub =
when PubParams is bool:
P(switch: switch,
peerInfo: switch.peerInfo,
triggerSelf: triggerSelf,
anonymize: anonymize,
verifySignature: verifySignature,
sign: sign,
msgIdProvider: msgIdProvider,
subscriptionValidator: subscriptionValidator,
maxMessageSize: maxMessageSize,
rng: rng,
topicsHigh: int.high)
else:
P(switch: switch,
peerInfo: switch.peerInfo,
triggerSelf: triggerSelf,
anonymize: anonymize,
verifySignature: verifySignature,
sign: sign,
msgIdProvider: msgIdProvider,
subscriptionValidator: subscriptionValidator,
parameters: parameters,
maxMessageSize: maxMessageSize,
rng: rng,
topicsHigh: int.high)
proc peerEventHandler(peerId: PeerId, event: PeerEvent) {.async.} =
if event.kind == PeerEventKind.Joined:
pubsub.subscribePeer(peerId)
else:
pubsub.unsubscribePeer(peerId)
switch.addPeerEventHandler(peerEventHandler, PeerEventKind.Joined)
switch.addPeerEventHandler(peerEventHandler, PeerEventKind.Left)
pubsub.knownTopics = KnownLibP2PTopicsSeq.toHashSet()
pubsub.initPubSub()
return pubsub
proc addObserver*(p: PubSub; observer: PubSubObserver) {.public.} = p.observers[] &= observer
proc removeObserver*(p: PubSub; observer: PubSubObserver) {.public.} =
let idx = p.observers[].find(observer)
if idx != -1:
p.observers[].del(idx)
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