Crash on NetSocket.swift

[Goule]

Hello,

Describe the bug
Crashlytics is reporting a crash on NetSocket.swift line 103 (NetSocket.doOutputProcess(_:maxLength:)).

To Reproduce
I can't reproduce it but it occured 10 times in 1 week in production (not many users).

Smartphone (please complete the following information):
Exemple of impacted devices :

• 12.4.1 (16G102) / iPhone 7
• 12.3.1 (16F203) / iPhone 6s
• 12.4.2 (16G114) / iPad Air
• 11.4.1 (15G77) / iPhone 6

Additional context
Here is the logs from Crashlytics :

Crashed: com.haishinkit.HaishinKit.NetSocket.output
0  CoreFoundation                 0x1d8cdd3e0 CFHash + 372
1  CoreFoundation                 0x1d8d70780 CFBasicHashGetCountOfKey + 204
2  CoreFoundation                 0x1d8cde8bc CFSetContainsValue + 116
3  CoreFoundation                 0x1d8cd6e18 CFRunLoopRemoveSource + 164
4  CFNetwork                      0x1d93ebc98 SocketStream::write(__CFWriteStream*, unsigned char const*, long, CFStreamError*) + 592
5  CoreFoundation                 0x1d8cec0c0 CFWriteStreamWrite + 300
6  HaishinKit                     0x10138dba4 NetSocket.doOutputProcess(_:maxLength:) + 103 (NetSocket.swift:103)
7  HaishinKit                     0x10138d98c closure #1 in NetSocket.doOutput(data:locked:) + 49 (NetSocket.swift:49)
8  HaishinKit                     0x1013355d8 thunk for @escaping @callee_guaranteed () -> () (<compiler-generated>)
9  libdispatch.dylib              0x1d8788a38 _dispatch_call_block_and_release + 24
10 libdispatch.dylib              0x1d87897d4 _dispatch_client_callout + 16
11 libdispatch.dylib              0x1d8732320 _dispatch_lane_serial_drain$VARIANT$mp + 592
12 libdispatch.dylib              0x1d8732e3c _dispatch_lane_invoke$VARIANT$mp + 428
13 libdispatch.dylib              0x1d873b4a8 _dispatch_workloop_worker_thread + 596
14 libsystem_pthread.dylib        0x1d8969114 _pthread_wqthread + 304
15 libsystem_pthread.dylib        0x1d896bcd4 start_wqthread + 4

crash_info_entry_1
*** CFHash() called with NULL ***

Have you any idea how to fix it ?
Thanks !

[floriangbh]

Hello,
Same issue for me, maybe this branch fixed the problem https://github.com/shogo4405/HaishinKit.swift/tree/feature/fix-crash-socket ?

[apolo2]

i had the same issue. This happens when internet connection is very bad
You can set very bad network on developer tool on your phone to try

[mkrn]

Confirm. Happened going in and out of wifi zone, trying to reconnecting frequently. Will see if a catch can be added anywhere. Crash identical to @Goule

[francisykl-91]

I am facing the same issue, do we have an update on this?

[mkrn]

I've found a similar problem in this thread daltoniam/Starscream#422 The solution is to add a timer. I've been experimenting, and crash seems to happen less often. I can only reproduce when going in and out of bad network outside of the house.

However I will do additional testing with emulating bad network to try and catch it in debugger.

[wolfcon]

Hi, @mkrn How about changing Line 99 code just like this

// for outputStream as OutputStream
// true if the receiver can be written to or if a write must be attempted 
// in order to determine if space is available, false otherwise.
guard let outputStream = outputStream, outputStream.hasSpaceAvailable else {
    return
}
let length = outputStream.write(buffer.advanced(by: total), maxLength: maxLength - total)
if 0 < length {
    total += length
    totalBytesOut.mutate { $0 += Int64(length) }
    queueBytesOut.mutate { $0 -= Int64(length) }
} else if length == 0 {
    break;
}

Maybe outputStream cannot be written by some reason, check hasSpaceAvailable first, which according to:

true if the receiver can be written to or if a write must be attempted in order to determine if space is available, false otherwise.

[wolfcon]

This problem occurs when I reconnect.
Maybe these codes are caused the problem. OutputQueue async mission mess with disconnect method and reconnect method. Reconnect before disconnecting?

// NetSocket.swift
func close(isDisconnected: Bool) {
        outputQueue.async {
            guard self.runloop != nil else {
                return
            }
            self.deinitConnection(isDisconnected: isDisconnected)
        }
    }

// RTMPConnection
func close(isDisconnected: Bool) {
        guard connected || isDisconnected else {
            timer = nil
            return
        }
        if !isDisconnected {
            uri = nil
        }
        for (id, stream) in streams {
            stream.close()
            streams.removeValue(forKey: id)
        }
        socket.close(isDisconnected: false)
        timer = nil
        
        
    }

[mkrn]

It looks like the crash happens due to a threading issue.
My guess is reinitializing the queue this way in NetSocket:
outputQueue = .init(label: "com.haishinkit.HaishinKit.NetSocket.output", qos: qualityOfService)
Some previous tasks from the outputQueue are still executing (output of packets) and they try to access the same outputStream or executing the same block.
Looks like we need to add some additional code to handle it @wolfcon @shogo4405
I will attempt but my experience is limited.

[wolfcon]

rtmpConnection.requireNetworkFramework = true

@mkrn I have already used RTMPNWSocket to avoid this problem instead of RTMPSocket.
RTMPNWSocket is using Network.framework (>= iOS 12)

According to Apple suggestion:

Discouraged APIs
Foundation and SCNetworkReachability

+[NSStream getStreamsToHostWithName:port:inputStream:outputStream:]
+[NSStream getStreamsToHost:port:inputStream:outputStream:]
-[NSNetService getInputStream:outputStream:]

NSNetServiceListenForConnections
NSSocketPort
SCNetworkReachability

[mkrn]

@wolfcon 😲 so no more crashing?

[wolfcon]

@mkrn So far so good. No crash because of that.

[mkrn]

Thanks, @wolfcon This can be closed @shogo4405 .

[floriangbh]

Hello,

Thanks for this solution !

I just tried. But since I put rtmpConnection.requireNetworkFramework = true my rtmpStatus handler is never called.
(self.rtmpConnection.addEventListener(.rtmpStatus, selector: #selector(rtmpStatusHandler), observer: self))
Is there extra modification when we use RTMPNWSocket ?

Thanks

[wolfcon]

@floriangbh No need any extra code. rtmpStatus is fine.

[floriangbh]

Ok thanks @wolfcon !

But I just tried with the sample project and Youtube RTMP live stream, the sample doesn't work with the requireNetworkFramework option. Youtube Studio display an error about the format. :-(

[giotto2012]

@floriangbh If the protocol is RTMPS, please set it like this

rtmpConnection.requireNetworkFramework = true
let params = NWParameters.tls
rtmpConnection.parameters = params

[floriangbh]

@giotto2012 thanks that was my problem with RTMPS :)