Re-implement request body previews on Android (#55456)

Summary:
Pull Request resolved: #55456

**Context**

Follow-up to D89373824, which addressed a runtime Android crash with `FormData` uploads (#54881) but introduced a "[Preview unavailable]" fallback for the `ProgressRequestBody` case.

**This diff**

Reintroduce request body previews under this case.

Protects agains the original crash by:

- Checking `body.isOneShot()` to prevent disallowed double-reads of stream bodies.
- [Pre-existing] Preserves `BuildConfig.DEBUG` guard added in D89377163.

Changelog:
[Android][Added] - React Native DevTools: Restore request payload previews on Android

Reviewed By: vzaidman

Differential Revision: D89381124

fbshipit-source-id: ae6ce006285b4bcd7bbb09bb4413d119f18a8630

Author: huntie

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkEventUtil.kt

@@ -16,13 +16,18 @@ import com.facebook.react.bridge.ReactApplicationContext
 import com.facebook.react.bridge.WritableMap
 import com.facebook.react.bridge.buildReadableArray
 import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags
+import java.io.IOException
 import java.net.SocketTimeoutException
 import okhttp3.Headers
+import okhttp3.RequestBody
+import okio.Buffer
 
 /**
  * Utility class for reporting network lifecycle events to JavaScript and InspectorNetworkReporter.
  */
 internal object NetworkEventUtil {
+  private const val MAX_BODY_PREVIEW_SIZE = 512 * 1024 // 512KB
+
   @JvmStatic
   fun onCreateRequest(
       devToolsRequestId: String,
@@ -243,4 +248,33 @@ internal object NetworkEventUtil {
     }
     return responseHeaders
   }
+
+  @JvmStatic
+  fun getRequestBodyPreview(requestBody: RequestBody?): String? {
+    if (requestBody == null) {
+      return null
+    }
+
+    // Unwrap ProgressRequestBody
+    val body = (requestBody as? ProgressRequestBody)?.innerBody() ?: requestBody
+
+    if (body.isOneShot()) {
+      // Fallback - body cannot be read twice
+      return "[Preview unavailable]"
+    }
+
+    return try {
+      val buffer = Buffer()
+      body.writeTo(buffer)
+
+      val size = buffer.size()
+      if (size <= MAX_BODY_PREVIEW_SIZE) {
+        buffer.readUtf8()
+      } else {
+        buffer.readUtf8(MAX_BODY_PREVIEW_SIZE.toLong()) + "... (truncated, ${size} bytes total)"
+      }
+    } catch (e: IOException) {
+      "[Preview unavailable]"
+    }
+  }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.kt

@@ -610,12 +610,8 @@ public class NetworkingModule(
         request.url().toString(),
         request.method(),
         NetworkEventUtil.okHttpHeadersToMap(request.headers()),
-        if (ReactBuildConfig.DEBUG) {
-          // Debug build: Include request body for preview in DevTools
-          (request.body() as? ProgressRequestBody)?.getBodyPreview() ?: request.body()?.toString()
-        } else {
-          null
-        },
+        if (ReactBuildConfig.DEBUG) NetworkEventUtil.getRequestBodyPreview(request.body())
+        else null,
         request.body()?.contentLength() ?: 0,
     )
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/ProgressRequestBody.kt

@@ -50,6 +50,8 @@ internal class ProgressRequestBody(
     sinkWrapper.flush()
   }
 
+  fun innerBody(): RequestBody = requestBody
+
   private fun outputStreamSink(sink: BufferedSink): Sink {
     return Okio.sink(
         object : FilterOutputStream(sink.outputStream()) {
@@ -78,9 +80,4 @@ internal class ProgressRequestBody(
         }
     )
   }
-
-  fun getBodyPreview(): String {
-    // TODO: Safely implement request body previews
-    return "[Preview unavailable]"
-  }
 }