Bad Access Error on listen thread when pinging multiple IPs

[micahnap]

Hello again,

I'm trying to see if this library is capable of pinging multiple IP's. What I'm doing is basically making it ping an entire range of IPs. It seems possible, but occasionally I get this EXC_BAD_ACCESS error on this line of code that lives in the GBPing.m in the listenOnce method:

GBPingSummary *pingSummary = [(GBPingSummary *)self.pendingPings[key] copy];

I'm setting it up like this

GBPing *pinger;
    pinger = [[GBPing alloc] init];
    pinger.host = ipAddress;
    pinger.delegate = self;
    pinger.timeout = 1.0;
    pinger.pingPeriod = 0.9;

    [pinger setupWithBlock:^(BOOL success, NSError *error) { //necessary to resolve hostname
        if (success) {
            //start pinging
            [pinger startPinging];

            //stop it after 5 seconds
            [NSTimer scheduledTimerWithTimeInterval:5 repeats:NO withBlock:^{

                [pinger stop];
            }];
        }
        else {
            NSLog(@"failed to start");
        }
    }];

and pulling in the IP addresses like this - 5 at a time in 3 second chunks

-(void)pingIPRange{
    dispatch_async(backgroundQueue, ^{
        for (int i = hostCount; i < hostCount + 5; i++) {
            NSString *ip = [NSString stringWithFormat:@"192.168.11.%i", i];
            [self pingIPRangeForBroadcastIP:nil withIP:ip];
        }
        [self restartTimer];
    });
}

and then doing this in the reply delegate to kick off the next ping

- (void)restartTimer{
    hostCount += 5;
    if (hostCount > 254){
        hostCount = 101;
    }
    dispatch_async(dispatch_get_main_queue(), ^{
        [timer invalidate];
        timer = nil;
        timer = [NSTimer scheduledTimerWithTimeInterval:3.0
                                                 target:self
                                               selector:@selector(pingIPRange)
                                               userInfo:nil
                                                repeats:YES];
    });
}

starting the host count at 101. Apologies for my ignorance. Just want to see if this is possible at all and if so what the proper way might be to set it up. Thanks!

[mikumi]

I'm having this issue as well, but haven't found out why it's happening yet

[cpage13]

Same here. It is very difficult to consistently reproduce. I have a feeling it has to do with the fact that pendingPings been accessed and mutated in different threads. Maybe wrapping them in @synchronized could help?

[lmirosevic]

Can you see if 1.3.1 still exhibits this behaviour?

[cpage13]

So far looks good. Thanks for looking into this.

[ftnn]

1.3.3 still has this issue;

Crashed: listenThread

EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000000

0 CoreFoundation -[__NSDictionaryM objectForKey:] + 229
1 GBPing.m line 382 -[GBPing listenOnce]
2 GBPing.m line 346 -[GBPing listenLoop]

@synchronized(self) is needed to protect multi-thread access

[alexjessecole]

This is indeed still an issue in 1.3.3.

Crashed: listenThread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000000

Any help getting this cleared up would be amazing and greatly appreciated!

[PabloAlejandro]

Same issue here

EXC_BAD_ACCESS (code=1, address=0x0)