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Fix socket.infoHashes access error #208

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Merged
feross merged 3 commits into from
Feb 28, 2017
Merged

Fix socket.infoHashes access error #208

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b2c2b8f
do not access socket.infoHashes if socket is destroyed
feross Feb 21, 2017
fe11c69
do not close socket even when it's not in other swarms
feross Feb 21, 2017
ccb50a7
add one missing self.destroyed check
feross Feb 21, 2017
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12 changes: 2 additions & 10 deletions lib/server/swarm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -29,15 +29,7 @@ function Swarm (infoHash, server) {
peer_id: peer.peerId
}
self._onAnnounceStopped(params, peer, peer.peerId)

// When a websocket peer is evicted, and it's not in any other swarms, close
// the websocket to conserve server resources.
if (peer.socket && peer.socket.infoHashes.length === 0) {
try {
peer.socket.close()
peer.socket = null
} catch (err) {}
}
peer.socket = null
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@feross feross Feb 21, 2017

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This entire section isn't actually necessary, I realized. It is okay for a client to have a websocket open to the server but to not be in any swarms. Because they might join another swarm in the future.

When the client first connects, they are not in any swarms and we are okay with that. So, there's no reason to close it preemptively here. We always do cleanup once the client closes the socket.

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@DiegoRBaquero DiegoRBaquero Feb 21, 2017

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Why not use delete? I think we've discussed it before but I couldn't recall the reason.

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@feross feross Feb 21, 2017

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In this situation, either way works fine. The whole peer object is going to be garbage-collected once all the references to it are gone.

The situation you're referring to is when trying to remove a property from an instance of a class (i.e. something with a prototype). In that case, it's better to use object.prop = null since delete object.prop will cause a de-optimization because it changes the "shape" of the object in memory.

Using delete is fine on object literals {} though.

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@DiegoRBaquero DiegoRBaquero Feb 22, 2017

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Ah, alright, thanks!

So why even nullify?, it's been deleted from the lru, once this block runs it should be gc'd

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@feross feross Feb 28, 2017

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You make a good point. It's not necessary, but I think it doesn't hurt to be explicit where we can. We could also set any references to peer to null but we don't keep any of those, other than what's in the LRU cache.

})
}

Expand Down Expand Up @@ -102,7 +94,7 @@ Swarm.prototype._onAnnounceStopped = function (params, peer, id) {

// If it's a websocket, remove this swarm's infohash from the list of active
// swarms that this peer is participating in.
if (peer.socket) {
if (peer.socket && !peer.socket.destroyed) {
var index = peer.socket.infoHashes.indexOf(this.infoHash)
arrayRemove(peer.socket.infoHashes, index)
}
Expand Down
4 changes: 3 additions & 1 deletion server.js
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Original file line number Diff line number Diff line change
Expand Up @@ -491,7 +491,7 @@ Server.prototype._onWebSocketRequest = function (socket, opts, params) {
if (!socket.peerId) socket.peerId = params.peer_id // as hex

self._onRequest(params, function (err, response) {
if (self.destroyed) return
if (self.destroyed || socket.destroyed) return
if (err) {
socket.send(JSON.stringify({
action: params.action === common.ACTIONS.ANNOUNCE ? 'announce' : 'scrape',
Expand Down Expand Up @@ -545,6 +545,7 @@ Server.prototype._onWebSocketRequest = function (socket, opts, params) {
debug('got answer %s from %s', JSON.stringify(params.answer), params.peer_id)

self.getSwarm(params.info_hash, function (err, swarm) {
if (self.destroyed) return
if (err) return self.emit('warning', err)
if (!swarm) {
return self.emit('warning', new Error('no swarm with that `info_hash`'))
Expand Down Expand Up @@ -587,6 +588,7 @@ Server.prototype._onWebSocketSend = function (socket, err) {
Server.prototype._onWebSocketClose = function (socket) {
var self = this
debug('websocket close %s', socket.peerId)
socket.destroyed = true

if (socket.peerId) {
socket.infoHashes.slice(0).forEach(function (infoHash) {
Expand Down