A pure Dart utility library that checks for an internet connection by opening a socket to a list of specified addresses, each with individual port and timeout. Defaults are provided for convenience.
Note that this plugin is in beta and may still have a few issues.Feedbackis welcome.
Checks for an internet (data) connection, by opening a socket to a list of addresses.
The defaults of the plugin should be sufficient to reliably determine if the device is currently connected to the global network, e.i. has access to the Internet.
Note that you should not be using the current network status for deciding whether you can reliably make a network connection. Always guard your app code against timeouts and errors that might come from the network layer.
DataConnectionChecker()is actually a Singleton. CallingDataConnectionChecker()
is guaranteed to always return the same instance.
You can supply a new list toDataConnectionChecker().addressesif you
need to check different destinations, ports and timeouts.
Also, each address can have its own port and timeout.
SeeInternetAddressCheckOptionsin the docs for more info.
First you need toinstall it(this is the preferred way)
Then you can start using the library:
boolresult=awaitDataConnectionChecker().hasConnection;
if(result==true) {
print('YAY! Free cute dog pics!');
}else{
print('No internet:( Reason:');
print(DataConnectionChecker().lastTryResults);
}The reason this package exists is thatconnectivitypackage cannot reliably determine if a data connection is actually available. More info on its page here:https://pub.dev/packages/connectivity
More info on the issue in general:
- https://stackoverflow /questions/1560788/how-to-check-internet-access-on-android-inetaddress-never-times-out/27312494#27312494(this is the best approach so far IMO and it's what I'm using)
You can use this package in combination withconnectivityin the following way:
varisDeviceConnected=false;
varsubscription=Connectivity().onConnectivityChanged.listen((ConnectivityResultresult)async{
if(result!=ConnectivityResult.none) {
isDeviceConnected=awaitDataConnectionChecker().hasConnection;
}
});Note: remember to properly cancel thesubscriptionwhen it's no longer needed. Seeconnectivitypackage docs for more info.
All addresses are pinged simultaneously. On successful result (socket connection to address/port succeeds) atrueboolean is pushed to a list, on failure (usually on timeout, default 10 sec) afalseboolean is pushed to the same list.
When all the requests complete with either success or failure, a check is made to see if the list contains at least onetrueboolean. If it does, then an external address is available, so we have data connection. If all the values in this list arefalse,then we have no connection to the outside world of cute cat and dog pictures, sohasConnectionalso returnsfalsetoo.
This all happens at the same time for all addresses, so the maximum waiting time is the address with the highest specified timeout, in case it's unreachable.
I believe this is areliableandfastmethod to check if a data connection is available to a device, but I may be wrong. I suggest you open an issue on the Github repository page if you have a better way of.
The defaults are based on data collected fromhttps://perfops.net/,https:// dnsperf /#!dns-resolvers
Here's some more info about the defaults:
... includes the top 3 globally available free DNS resolvers.
| Address | Provider | Info |
|---|---|---|
| 1.1.1.1 | CloudFlare | https://1.1.1.1 |
| 1.0.0.1 | CloudFlare | https://1.1.1.1 |
| 8.8.8.8 | https://developers.google /speed/public-dns/ | |
| 8.8.4.4 | https://developers.google /speed/public-dns/ | |
| 208.67.222.222 | OpenDNS | https://use.opendns / |
| 208.67.220.220 | OpenDNS | https://use.opendns / |
staticfinalList<AddressCheckOptions>DEFAULT_ADDRESSES=List.unmodifiable([
AddressCheckOptions(
InternetAddress('1.1.1.1'),
port:DEFAULT_PORT,
timeout:DEFAULT_TIMEOUT,
),
AddressCheckOptions(
InternetAddress('8.8.4.4'),
port:DEFAULT_PORT,
timeout:DEFAULT_TIMEOUT,
),
AddressCheckOptions(
InternetAddress('208.67.222.222'),
port:DEFAULT_PORT,
timeout:DEFAULT_TIMEOUT,
),
]);... is 53.
A DNS server listens for requests on port 53 (both UDP and TCP). So all DNS requests are sent to port 53...
More info:
- https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
- https:// google /search?q=dns+server+port
staticconstintDEFAULT_PORT=53;... is 10 seconds.
staticconstDurationDEFAULT_TIMEOUT=Duration(seconds:10);... is 10 seconds. Interval is the time between automatic checks. Automatic
checks start if there's a listener attached toonStatusChange,thus remember
to cancel unneeded subscriptions.
checkInterval(which controls how often a check is made) defaults
to this value. You can change it if you need to perform checks more often
or otherwise.
staticconstDurationDEFAULT_INTERVAL=constDuration(seconds:10);
...
DurationcheckInterval=DEFAULT_INTERVAL;Example:
import'package:data_connection_checker/data_connection_checker.dart';
main()async{
// Simple check to see if we have internet
print("The statement 'this machine is connected to the Internet' is:");
print(awaitDataConnectionChecker().hasConnection);
// returns a bool
// We can also get an enum value instead of a bool
print("Current status: ${awaitDataConnectionChecker().connectionStatus} ");
// prints either DataConnectionStatus.connected
// or DataConnectionStatus.disconnected
// This returns the last results from the last call
// to either hasConnection or connectionStatus
print("Last results: ${DataConnectionChecker().lastTryResults} ");
// actively listen for status updates
// this will cause DataConnectionChecker to check periodically
// with the interval specified in DataConnectionChecker().checkInterval
// until listener.cancel() is called
varlistener=DataConnectionChecker().onStatusChange.listen((status) {
switch(status) {
caseDataConnectionStatus.connected:
print('Data connection is available.');
break;
caseDataConnectionStatus.disconnected:
print('You are disconnected from the internet.');
break;
}
});
// close listener after 30 seconds, so the program doesn't run forever
awaitFuture.delayed(Duration(seconds:30));
awaitlistener.cancel();
}Note: Remember to dispose of any listeners,
when they're not needed to prevent memory leaks,
e.g. in aStatefulWidget'sdispose() method:
...
@override
voiddispose() {
listener.cancel();
super.dispose();
}
...Seeexamplefolder for more examples.
MIT
Copyright 2019 Kristiyan Mitev andSpirit Navigator
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software" ), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Please file feature requests and bugs at theissue tracker.