Limit request/response body to 100kb to address #457 (#617)

Summary:
As previously reported in https://github.com/facebook/flipper/issues/457, I immediately started to see crashes with Flipper integrated due to large responses (e.g., >= 100MB). This will only write the first 100KB of the response or request body into `RequestInfo` objects.

## Changelog

- Limits request/response body in network request info to 100KB max.
Pull Request resolved: https://github.com/facebook/flipper/pull/617

Test Plan:
- Make a network request which has a response size of < 100kb, verify that it is visible in its entirety
- Make a network request w/ response size > 100kb, verify that it is truncated
- Ideally, use your application with the Network plugin running, and do not see OOMs

Reviewed By: mweststrate

Differential Revision: D19412075

Pulled By: passy

fbshipit-source-id: c93662dba7a5f24820287e56e889576b5bcb5a72

android/plugins/network/src/main/java/com/facebook/flipper/plugins/network/FlipperOkhttpInterceptor.java

@@ -25,6 +25,11 @@ import okio.BufferedSource;
 
 public class FlipperOkhttpInterceptor implements Interceptor {
 
+  // By default, limit body size (request or response) reporting to 100KB to avoid OOM
+  private static final long DEFAULT_MAX_BODY_BYTES = 100 * 1024;
+
+  private long maxBodyBytes = DEFAULT_MAX_BODY_BYTES;
+
   public @Nullable NetworkFlipperPlugin plugin;
 
   public FlipperOkhttpInterceptor() {
@@ -35,6 +40,12 @@ public class FlipperOkhttpInterceptor implements Interceptor {
     this.plugin = plugin;
   }
 
+  /** If you want to change the number of bytes displayed for the body, use this constructor */
+  public FlipperOkhttpInterceptor(NetworkFlipperPlugin plugin, long maxBodyBytes) {
+    this.plugin = plugin;
+    this.maxBodyBytes = maxBodyBytes;
+  }
+
   @Override
   public Response intercept(Interceptor.Chain chain) throws IOException {
     Request request = chain.request();
@@ -47,10 +58,11 @@ public class FlipperOkhttpInterceptor implements Interceptor {
     return response;
   }
 
-  private static byte[] bodyToByteArray(final Request request) throws IOException {
+  private static byte[] bodyToByteArray(final Request request, final long maxBodyBytes)
+      throws IOException {
     final Buffer buffer = new Buffer();
     request.body().writeTo(buffer);
-    return buffer.readByteArray();
+    return buffer.readByteArray(Math.min(buffer.size(), maxBodyBytes));
   }
 
   private RequestInfo convertRequest(Request request, String identifier) throws IOException {
@@ -62,7 +74,7 @@ public class FlipperOkhttpInterceptor implements Interceptor {
     info.method = request.method();
     info.uri = request.url().toString();
     if (request.body() != null) {
-      info.body = bodyToByteArray(request);
+      info.body = bodyToByteArray(request, maxBodyBytes);
     }
 
     return info;
@@ -77,7 +89,7 @@ public class FlipperOkhttpInterceptor implements Interceptor {
     info.statusCode = response.code();
     info.headers = headers;
     BufferedSource source = body.source();
-    source.request(Long.MAX_VALUE);
+    source.request(maxBodyBytes);
     Buffer buffer = source.buffer().clone();
     info.body = buffer.readByteArray();
     return info;