TooTallNate/Java-WebSocket · error · InvalidFrameException

1007

1007

Error message

Control frame can't have rsv1==true set

What it means

RSV bits are reserved for extensions; a control frame must have RSV1/RSV2/RSV3 all zero unless a negotiated extension explicitly defines control-frame usage (permessage-deflate does not). ControlFrame.isValid throws InvalidFrameException when RSV1 is set on a control frame.

Solutions

1. Fix the peer so control frames are never compressed and RSV1 stays 0 (per RFC 7692, only data frames are compressed).
2. If building frames manually, leave rsv1/rsv2/rsv3 false for control frames.
3. Verify which extensions were negotiated — no standard WebSocket extension sets RSV1 on control frames.
4. Log raw frame headers to identify the offending peer implementation.

Example fix

// before: compressing a ping like a data frame
Framedata ping = new FramedataImpl1(Opcode.PING);
ping.setRSV1(true); // invalid for control frames

// after
Framedata ping = new FramedataImpl1(Opcode.PING);
ping.setRSV1(false);

// control frames must not carry RSV bits
if (isControlOpcode(frame.getOpcode()) && (frame.isRSV1() || frame.isRSV2() || frame.isRSV3())) {
    throw new IllegalArgumentException("control frames must not set RSV bits");
}

try {
    validateFrame(frame);
} catch (InvalidFrameException e) {
    logger.warn("control frame with RSV bits from peer: {}", e.getMessage());
    webSocket.close(1002, "protocol error");
}

When it happens

Trigger: A ping, pong, or close frame arrives with RSV1 set — e.g. a peer wrongly applying the permessage-deflate RSV1 compression flag to control frames, or a frame builder setting extension bits indiscriminately.

Common situations: Clients that compress all frames including pings after negotiating permessage-deflate; custom/patched frame serialization; fuzzed input testing the endpoint's strictness.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• bad rsv RSV1: RSV2: RSV3
• Continuous frame cannot have RSV1, RSV2 or RSV3 set
• Control frame can't have fin==false set
• more than 125 octets
• bad rsv RSV1: RSV2: RSV3

AI-assisted analysis of TooTallNate/Java-WebSocket@afeacbf8c0 (2026-09-09). Data as JSON: /api/errors/55c0980ac67186a2. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/org/java_websocket/framing/ControlFrame.java:52

 */
public abstract class ControlFrame extends FramedataImpl1 {

  /**
   * Class to represent a control frame
   *
   * @param opcode the opcode to use
   */
  public ControlFrame(Opcode opcode) {
    super(opcode);
  }

  @Override
  public void isValid() throws InvalidDataException {
    if (!isFin()) {
      throw new InvalidFrameException("Control frame can't have fin==false set");
    }
    if (isRSV1()) {
      throw new InvalidFrameException("Control frame can't have rsv1==true set");
    }
    if (isRSV2()) {
      throw new InvalidFrameException("Control frame can't have rsv2==true set");
    }
    if (isRSV3()) {
      throw new InvalidFrameException("Control frame can't have rsv3==true set");
    }
  }
}

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