Why OKHttp is designed as not to retry when SocketTimeoutException - android

private boolean isRecoverable(IOException e, boolean requestSendStarted) {
....
// If there was an interruption don't recover, but if there was a
//timeout connecting to a route
// we should try the next route (if there is one).
if (e instanceof InterruptedIOException) {
return e instanceof SocketTimeoutException && !requestSendStarted;
}
....
return true;
}
Here is the code snippet in RetryAndFollowUpInterceptor in OKHttp.
My question is why OkHttp not retry when SocketTimeoutException and requestSendStarted == true?
Because I think if there are some other routers, we can retry another ip or router

Consider the case where a request was successfully sent and the problem occurred when response data was transmitted to the client. Automatic retry in this case may make the server to repeat some action (increasing some count, writing a record somewhere) which may be undesirable. OKHttp lets the user to decide what to do in this case.

The goal was to retry if OkHttp couldn’t connect at all. If the server was reachable, but just responded slowly, then it’s just as likely to be an application-layer problem where retrying won’t help.

Related

Android - OkHttp - Tagging all network requests with TrafficStats

I'm trying to figure out specifically how much of my app's data use is being used by the requests I send with OkHttpClient, and I saw that I can use TrafficStats to tag a thread and then see it's network activity with the tag.
if I do something like
TrafficStats.setThreadStatsTag(1234);
okHttpClient.execute(request);
then it actually tags it okay(ish), but then when I use the async method (okHttpClient.enqueue(request)) it doesn't (which is kinda obvious though I hoped they'd have support for that).
So I tried a couple of things:
Setting a dispatcher for the client where it's a normal dispatcher which basically on every execute replaces the Runnable it receives with a new runnable that first tags the thread an then runs the original runnable - some traffic was tagged but a lot wasn't.
Setting a socket factory which basically tags every socket it produces - still some some traffic tagged but most of it wasn't.
Any ideas?
I think TrafficStats.setThreadStatsTag() is for thread, so maybe we can add an interceptor for okhttp client.
private static class TrafficStatInterceptor implements Interceptor {
int mTrafficTag;
TrafficStatInterceptor(int trafficTag) {
mTrafficTag = trafficTag;
}
#Override
public Response intercept(Chain chain) throws IOException {
if (mTrafficTag > 0) {
TrafficStatUtils.setThreadStatsTag(mTrafficTag);
} else {
Log.w(TAG, "invalid traffic tag " + mTrafficTag);
}
return chain.proceed(chain.request());
}
}
then just add this interceptor
OkHttpClient.Builder client = new OkHttpClient.Builder();
client.addNetworkInterceptor(new TrafficStatInterceptor(trafficTag));
It’s difficult to do generally because with HTTP/2 sockets are shared across requests. With HTTP/1.1 they’re reused. Your best bet will be to write a network interceptor to tag the current thread. That’ll handle all HTTP/1.1 traffic and outgoing HTTP/2 traffic. There’s currently no API to access the thread that reads incoming HTTP/2 traffic.

AzureAD for Android throws ADALError.AUTH_REFRESH_FAILED_PROMPT_NOT_ALLOWED

I have an app in which user authentificates in Office365 with AzureAD library for Android.
It works well, users can authentificate and work with the app. Unfortunately, after a while they start hitthing AuthenticationException with ADALError.AUTH_REFRESH_FAILED_PROMPT_NOT_ALLOWED as an error code.
I checked the source code of AzurelAD. The only place, which is throughing this issue is acquireTokenAfterValidation() method:
private AuthenticationResult acquireTokenAfterValidation(CallbackHandler callbackHandle,
final IWindowComponent activity, final boolean useDialog,
final AuthenticationRequest request) {
Logger.v(TAG, "Token request started");
// BROKER flow intercepts here
// cache and refresh call happens through the authenticator service
if (mBrokerProxy.canSwitchToBroker()
&& mBrokerProxy.verifyUser(request.getLoginHint(),
request.getUserId())) {
.......
Logger.v(TAG, "Token is not returned from backgroud call");
if (!request.isSilent() && callbackHandle.callback != null && activity != null) {
....
} else {
// User does not want to launch activity
String msg = "Prompt is not allowed and failed to get token:";
Logger.e(TAG, msg, "", ADALError.AUTH_REFRESH_FAILED_PROMPT_NOT_ALLOWED);
callbackHandle.onError(new AuthenticationException(
ADALError.AUTH_REFRESH_FAILED_PROMPT_NOT_ALLOWED, msg));
}
// It will start activity if callback is provided. Return null here.
return null;
} else {
return localFlow(callbackHandle, activity, useDialog, request);
}
}
My source code:
authenticator.getAccessTokenSilentSync(getMailService());
public class Authenticator {
..............
public String getAccessTokenSilentSync(ServiceInfo serviceInfo) {
throwIfNotInitialized();
return getAuthenticationResultSilentSync(serviceInfo).getAccessToken();
}
private AuthenticationResult getAuthenticationResultSilentSync(ServiceInfo serviceInfo) {
try {
return authenticationContext.acquireTokenSilentSync(
serviceInfo.ServiceResourceId,
Client.ID,
userIdentity.getAdUserId());
} catch (AuthenticationException ex) {
// HERE THE EXCEPTION IS HANDLED.
}
}
..............
}
Stacktrace I'm getting:
<package name>.data_access.error_handler.AuthenticationExceptionWithServiceInfo: Refresh token is failed and prompt is not allowed
at com.microsoft.aad.adal.AuthenticationContext.localFlow(AuthenticationContext.java:1294)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenAfterValidation(AuthenticationContext.java:1229)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenLocalCall(AuthenticationContext.java:1123)
at com.microsoft.aad.adal.AuthenticationContext.refreshToken(AuthenticationContext.java:1609)
at com.microsoft.aad.adal.AuthenticationContext.localFlow(AuthenticationContext.java:1261)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenAfterValidation(AuthenticationContext.java:1229)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenLocalCall(AuthenticationContext.java:1123)
at com.microsoft.aad.adal.AuthenticationContext.refreshToken(AuthenticationContext.java:1609)
at com.microsoft.aad.adal.AuthenticationContext.localFlow(AuthenticationContext.java:1261)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenAfterValidation(AuthenticationContext.java:1229)
at com.microsoft.aad.adal.AuthenticationContext.acquireTokenLocalCall(AuthenticationContext.java:1123)
at com.microsoft.aad.adal.AuthenticationContext.access$600(AuthenticationContext.java:58)
at com.microsoft.aad.adal.AuthenticationContext$4.call(AuthenticationContext.java:1072)
at com.microsoft.aad.adal.AuthenticationContext$4.call(AuthenticationContext.java:1067)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
Version of AzureAD library I'm using: 1.1.7 (to prevent blaming too old version - I've checked the changelist since from 1.1.7 to 1.1.11 and haven't found anything related to question)
Problem: Right now, I'm treating this error, as a signal to through the user to the login screen. In my opinion, it leads to a poor experience for the user. The fact that it happens very often and affects many users make it even worse.
Question: Is there anything I can do different to avoid this AuthenticationException or workaround it somehow (i.e. avoid user enters credentials once again).
Have you verified that AuthenticationContext.acquireTokenSilentSync() is truly the method that you wish to invoke?
The docs indicate that this method will explicitly not show a prompt. From the docs:
This is sync function. It will first look at the cache and automatically checks for the token expiration. Additionally, if no suitable access token is found in the cache, but refresh token is available, the function will use the refresh token automatically. This method will not show UI for the user. If prompt is needed, the method will return an exception.
The refresh token you are issued should last two weeks per this AAD book. After the refresh token expires users are expected to reauthenticate. Can you inspect net traffic with Fiddler or Charles and inspect the expiry of the tokens? If you can verify that the tokens are failing to refresh before their expiry it may indicate a bug in the AD library.
To clarify the difference in methods on AuthenticationContext - there are two categories of methods: "silent" methods (which will not present a dialog to user in the event that they need to reauthenticate), and non-silent. Non-silent methods will, in the event of requiring reauthentication (or consent) from the user, start a new Activity containing the AAD login. At that point the authentication flow is restarted.
Additionally, if you make changes to your application's registration in Azure such as adding new permission scopes your users will be required to re-grant consent for the application to continue to handle their data.
This is because you need to refresh your token and implement this in your code so the user won't be prompt to login every time the access token is expired. please check out how to implement refresh token here:
https://msdn.microsoft.com/en-us/library/azure/dn645538.aspx
Hope this helps.

Android usb host: asynchronous interrupt transfer

I'm trying to connect a USB-Device ( build by myself ) to communicate with my development board ( ODROID-X )
Unfortunately, the examples are very little, as far as the asynchronous communication. I'd some problems with the interrupt driven data exchange - how to build the connection by using the asynchronous interrupt mode?
In one direction, the transmission was possible ... but in both it doesn't work. Is there an example like this:
send a ByteBuffer with endpoint_OUT
get a message from device on endpoint_IN
both in interrupt mode.
Thanks a lot for your support.
Hardy
Perhaps I am misunderstanding the question here.
The sample missile lanucher app that is part of the API package from level 12 onwards uses the queue() and requestWait() methods to handle interrupt type endpoints.
Requests are either In or Out and depend on the direction of the EndPoint.
The code for a pretty noddy request->reply looks something like this. You would want to structure real code differently but this gives you the gist of what needs to happen (I hope)
public void run() {
int bufferMaxLength=mEndpointOut.getMaxPacketSize();
ByteBuffer buffer = ByteBuffer.allocate(bufferMaxLength);
UsbRequest request = new UsbRequest(); // create an URB
request.initialize(mConnection, mEndpointOut);
buffer.put(/* your payload here */;
// queue the outbound request
boolean retval = request.queue(buffer, 1);
if (mConnection.requestWait() == request) {
// wait for confirmation (request was sent)
UsbRequest inRequest = new UsbRequest();
// URB for the incoming data
inRequest.initialize(mConnection, mEndpointIn);
// the direction is dictated by this initialisation to the incoming endpoint.
if(inRequest.queue(buffer, bufferMaxLength) == true){
mConnection.requestWait();
// wait for this request to be completed
// at this point buffer contains the data received
}
}
}
If you are actually looking for a way to run this IO in an asynchronous manner without binding a thread to it, then I think you need to consider using the DeviceConnection.getFilehandle() method to return a standard file handle which in theory you can then use as if it were any other file type resource. I would note however that I have not tried this.
If neither of these addresses the issue please revise the question to clarify what you are struggling to find examples of.
I hope this helps.

Android - Detect if Wifi Requires Browser Login

My university has an open wifi access point, however it requires you to enter your e-mail before it allows you to use the web. My problem is that the Wifi is stupid in that it seems to drop my connection and force me to enter my e-mail again every 10 minutes.
I wanted to create my own app that I can use to automatically do this step for me, but I cannot seem to find any documentation for a nice and easy way to detect if a Wifi access point has a browser login page. Is there a way in Android to get this information, or is it just to see if my connection to something is always redirected to 1.1.1.1?
See the "Handling Network Sign-On" section of the HttpUrlConnection documentation:
Some Wi-Fi networks block Internet access until the user clicks through a sign-on page. Such sign-on pages are typically presented by using HTTP redirects. You can use getURL() to test if your connection has been unexpectedly redirected. This check is not valid until after the response headers have been received, which you can trigger by calling getHeaderFields() or getInputStream().
They have a snippet of sample code there. Whether this will cover your particular WiFi AP, I can't say, but it is worth a shot.
Ping an external IP address (like google.com) to see if it responds.
try {
Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec("ping -c 1 " + "google.com");
proc.waitFor();
int exitCode = proc.exitValue();
if(exitCode == 0) {
Log.d("Ping", "Ping successful!";
} else {
Log.d("Ping", "Ping unsuccessful.");
}
}
catch (IOException e) {}
catch (InterruptedException e) {}
The only downside is this would also indicate that a web login is required when there is simply no internet connectivity on the WiFi access point.
#CommonsWare I believe this is a better answer than opening a UrlConnection and checking the host, since the host doesn't always change even when displaying the redirect page. For example, I tested on a Belkin router and it leaves whatever you typed in the browser as is, but still displays its own page. urlConnection.getUrl().getHost() returns what it should because of this.
I think #FlyWheel is on the right path, but I would use http://clients1.google.com/generate_204 and if you don't get a 204, you know you are behind a captive portal. You can run this in a loop until you do get a 204 in which case you know you are not behind a captive portal anymore.
#FlyWheel wrote: The only downside is this would also indicate that a web login is required when there is simply no internet connectivity on the WiFi access point.
You can solve this by registering a receiver to android.net.conn.CONNECTIVITY_CHANGE. You can check if Wifi is ON and is connected by looking at the Supplicant State of the connection.
Here is a snippet, but I didn't run it:
WifiManager wm = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
WifiInfo wifiInfo = wm.getConnectionInfo();
SupplicantState suppState = wifiInfo.getSupplicantState();
if (wm.isWifiEnabled()) {
if (suppState == SupplicantState.COMPLETED){
// TODO - while loop checking generate_204 (FlyWheels code)Using intent service.
}
}
I can't remember if the SupplicantState is COMPLETED or ASSOCIATED, you will have to check that. You should use an IntentService for checking the generate_204 since broadcast receivers have a short lifetime.
I used the following code using google's 204 endpoint.
private boolean networkAvailable() {
ConnectivityManager mManager = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
if(mManager != null) {
NetworkInfo activeNetwork = mManager.getActiveNetworkInfo();
if(activeNetwork== null || !activeNetwork.isConnectedOrConnecting()){
return false;
}
}
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("http://clients1.google.com/generate_204")
.build();
try {
Response response = client.newCall(request).execute();
if(response.code() != 204)
return false; // meaning it either responded with a captive html page or did a redirection to captive portal.
return true;
} catch (IOException e) {
return true;
}
}
Many applications including Google Chrome use http://clients1.google.com/generate_204 to verify that the the connection is not locked under captive portal.
The issue might rather be - today at least - that newer Android versions (5.1+?) keep the 3G/4G connection up and running until the wifi login actually leads to a fully functional wifi connection.
I haven't tried it, but maybe with the enum value CAPTIVE_PORTAL_CHECK of NetworkInfos DetailedState one can try to detect such a mode properly?

Strange problem while sending file from Android to server!

I encountered a very strange problem while sending files, such as pictures, text and zip files to server via ftp. Most of the time, it works fine. But sometimes, the server only has part of the file.
On Android, I use com.enterprisedt.net.ftp.
Here is the code piece to send a file:
public void ftpUploadFiles(ArrayList<String> fileList, boolean bDeleteAfterUploaded)
{
if(fileList.size() <= 0)
return;
// set up to transfer the files
FileTransferClient ftp = null;
try
{
//Make sure there is only FTP in the whole system at any given time.
synchronized(this)
{
// create client
ftp = new FileTransferClient();
// set remote host
ftp.setRemoteHost("xxxxxxx");
ftp.setUserName("xxxxxx");
ftp.setPassword("xxxxx");
// connect to the server
ftp.connect();
ftp.getAdvancedFTPSettings().setConnectMode(FTPConnectMode.PASV);
//1. Upload each file
for(int i = 0 ; i < fileList.size(); i++)
{
if(!FileKit.fileExist(fileList.get(i)))
continue;
ftp.uploadFile(fileList.get(i), FileKit.getFileName(fileList.get(i)));
if(bDeleteAfterUploaded)
FileKit.fileDelete(fileList.get(i));
}
ftp.disconnect();
} //End of synchronized
} catch (Exception e)
{
FileKit.handleException(e);
}
}
FileKit is a static wrap-up class for regular file functions. ftpUploadFiles() is called in a separate thread by an Intent so it can run in background. What seems to happen is, the ftp stops before finish transferring the file completely, so the server only gets part of the file. Based on the code above, what could possibly cause the problem? Or is it possible that is a issue with com.enterprisedt.net.ftp?
Thanks.
Your code appears to handle complete files only. So it should either succeed or fail for complete files only. That leaves only the com.enterprisedt.net.ftp package, which may send files in parts, for example when network failures occur.
There can be a problem if the transfer is interrupted due to network congestion, etc. "If the network connection is interrupted, the server may still think you are connected (as quit() has not been called). Hence a new connection and attempt to resume may fail for the reason given below." (https://enterprisedt.com/forums/viewtopic.php?t=960)
So I think that either the ftp software has a bug on network failure, or your code isn't handling the ftp software's handling of network failures.

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