mirror of
https://github.com/oxen-io/session-android.git
synced 2023-12-14 02:53:01 +01:00
46 lines
1.5 KiB
Java
46 lines
1.5 KiB
Java
package org.thoughtcrime.securesms.glide;
|
|
|
|
import android.support.annotation.NonNull;
|
|
|
|
import java.io.IOException;
|
|
import java.security.SecureRandom;
|
|
|
|
import okhttp3.Headers;
|
|
import okhttp3.Interceptor;
|
|
import okhttp3.Request;
|
|
import okhttp3.Response;
|
|
|
|
/**
|
|
* An interceptor that adds a header with a random amount of bytes to disguise header length.
|
|
*/
|
|
public class PaddedHeadersInterceptor implements Interceptor {
|
|
|
|
private static final String PADDING_HEADER = "X-SignalPadding";
|
|
private static final int MIN_RANDOM_BYTES = 1;
|
|
private static final int MAX_RANDOM_BYTES = 64;
|
|
|
|
@Override
|
|
public @NonNull Response intercept(@NonNull Chain chain) throws IOException {
|
|
Request padded = chain.request().newBuilder()
|
|
.headers(getPaddedHeaders(chain.request().headers()))
|
|
.build();
|
|
|
|
return chain.proceed(padded);
|
|
}
|
|
|
|
private @NonNull Headers getPaddedHeaders(@NonNull Headers headers) {
|
|
return headers.newBuilder()
|
|
.add(PADDING_HEADER, getRandomString(new SecureRandom(), MIN_RANDOM_BYTES, MAX_RANDOM_BYTES))
|
|
.build();
|
|
}
|
|
|
|
private static @NonNull String getRandomString(@NonNull SecureRandom secureRandom, int minLength, int maxLength) {
|
|
char[] buffer = new char[secureRandom.nextInt(maxLength - minLength) + minLength];
|
|
|
|
for (int i = 0 ; i < buffer.length; i++) {
|
|
buffer[i] = (char) (secureRandom.nextInt(74) + 48); // Random char from 0-Z
|
|
}
|
|
|
|
return new String(buffer);
|
|
}
|
|
}
|