Question

My Android code sends data all the time and it seems to be working until a totally unexpected IOException is thrown, freezing everything. I don’t understand why I can send several post requests without problem until the Exception appears, almost randomly. Here’s my code:

public class HttpsClient {

private final static String TAG = "HttpsClient";

private final static String TOKEN_HEADER_KEY = "Token";

private final String urlString;

private SSLContext sslContext;

// application-specific HTTP header
private String TokenHeaderValue = null;



public HttpsClient(String host, String path) {
    // this.sslContext will be init'ed in open()
    this.urlString = "https://" + host + ":443/" + path;
}


public boolean open() {
    try {
        this.sslContext = SSLContext.getInstance("TLS");
        this.sslContext.init(null, null, new java.security.SecureRandom());
        return true;
    } catch (NoSuchAlgorithmException e) {
        Logger.e(TAG, "NoSuchAlgorithmException:");
    } catch (KeyManagementException e) {
        Logger.e(TAG, "KeyManagementException:");
    }

    return false;
}


public byte[] send(byte[] req) {

    Logger.d(TAG, "sending " + Utils.byteArrayToString(req) + " to " + this.urlString);

    URL url;
    try {
        url = new URL(this.urlString);
    } catch (MalformedURLException e) {
        Logger.e(TAG, "MalformedURLException:");
        return null;
    }
    HttpsURLConnection connection;
    try {
        connection = (HttpsURLConnection) url.openConnection();
    } catch (IOException e) {
        Logger.e(TAG, "send IOException 1 " + ((null == e.getMessage()) ? e.getMessage() : ""));
        e.printStackTrace();
        return null;
    }

    connection.setDoInput(true);
    connection.setDoOutput(true);
    connection.setRequestProperty("Connection", "close");
    try {
        connection.setRequestMethod("POST");

    } catch (ProtocolException ignored) { }
    connection.setSSLSocketFactory(this.sslContext.getSocketFactory());
    connection.setReadTimeout(3000);



    if ( this.TokenHeaderValue != null )
        connection.setRequestProperty(TOKEN_HEADER_KEY, this.TokenHeaderValue);



    {
        final Map<String, List<String>> requestProps = connection.getRequestProperties();
        Logger.d(TAG, requestProps.size() + " Request header(s):");
        for (Map.Entry<String, List<String>> entry : requestProps.entrySet())
            for (String value : entry.getValue())
                Logger.d(TAG, " " + entry.getKey() + ": <" + value + ">");
    }

    try {
        // open up the output stream of the connection 
        DataOutputStream output = new DataOutputStream(connection.getOutputStream()); 

        // write out the data 
        output.write(req, 0, req.length);
        output.flush();


        Logger.i(TAG, "Response Code: " + connection.getResponseCode());
        Logger.i(TAG, "Response Message: " + connection.getResponseMessage()); 
    } catch (SocketTimeoutException e) {
        Logger.e(TAG, "SocketTimeoutException:" + ((null == e.getMessage()) ? e.getMessage() : ""));
        return null;
    } catch (IOException e) { // FAILS HERE !!!!!!!
        Logger.e(TAG, "send IOException 2 " + ((null == e.getMessage()) ? e.getMessage() : ""));
        return null;
    }


    final Map<String, List<String>> responseHeaderFields = connection.getHeaderFields();
    Logger.d(TAG, responseHeaderFields.size() + " Response header(s):");
    for (Map.Entry<String, List<String>> entry : responseHeaderFields.entrySet()) {
        final String key = entry.getKey();
        if ( (null != key) && key.equals(TOKEN_HEADER_KEY) )
            this.TokenHeaderValue = entry.getValue().get(0);
        for (String value : entry.getValue())
            Logger.d(TAG, " " + key + ": <" + value + ">");
    }


    // read response
    ArrayList<Byte> response = new ArrayList<Byte>();

    try {
        DataInputStream input = new DataInputStream(connection.getInputStream()); 

        // read in each character until end-of-stream is detected
        for( int c = input.read(); c != -1; c = input.read() ) {
            response.add((byte) c);
        }
        Logger.w(TAG, "Https connection is " + connection);
        connection.disconnect();
        Logger.w(TAG, "Https connection is " + connection);
        input.close();

    } catch (IOException e) {
        Logger.e(TAG, "send IOException 3 " + ((null == e.getMessage()) ? e.getMessage() : ""));
        return null;
    }

    if ( 0 == response.size() ) {
        Logger.w(TAG, "response is null");

        return null;
    }

    // else

    byte[] result = new byte[response.size()];
    for (int i = 0; i < result.length; i++)
        result[i] = response.get(i).byteValue();

    Logger.i(TAG, "Response payload: " + Utils.byteArrayToString(result));



    return result;          
}
}

I repeat: code works ’til after many post send, then crashes ’cause of an IO Exception. Moreover, server is fine, there’s something wrong in my code.

Here’s the entire error stack trace:

send IOException 2 

0: org.apache.harmony.xnet.provider.jsse.NativeCrypto.SSL_read_byte(Native Method)

1: org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl$SSLInputStream.read(OpenSSLSocketImpl.java:783)

2: org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.readLine(HttpURLConnectionImpl.java:671)

3: org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.readResponseHeaders(HttpURLConnectionImpl.java:699)

4: org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getFromNetwork(HttpURLConnectionImpl.java:1088)

5: org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.retrieveResponse(HttpURLConnectionImpl.java:1041)

6: org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:736)

7: org.apache.harmony.luni.internal.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:146)

8: com.bitstorms.gui.channels.HttpsClient.send(HttpsClient.java:117)

9: com.bitstorms.gui.apps.Application$MyRunnable.run(Application.java:81)

10: java.lang.Thread.run(Thread.java:1020)

Answer 1

The suspicious point is that you never properly release streams. For instance, you create DataOutputStream output, use it, but never close. Try to change the code that uses finally to close the stream:

DataOutputStream output = null;
try {
    output = new DataOutputStream(connection.getOutputStream());
    ...
} catch (...) {
    ...
} finally {
    if (output != null) {
         try {
             output.close();
         } catch (IOException ignored) {}
    }
}

The same should be done with DataInputStream input and the connection itself (it should be guaranteedly closed in some global finally section).