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fix: WebSocketのペイロードが0の場合に受信したパケットを送信しない問題を修正 #241

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Merged
funa-tk merged 3 commits into from
Apr 13, 2026
+214 −15
Merged

fix: WebSocketのペイロードが0の場合に受信したパケットを送信しない問題を修正 #241

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ef71e94
fix: ペイロードが0の場合に受信したパケットを送信しない問題を修正
taka2233 Apr 13, 2026
74810f0
refactor: eliminate isEmptyPlaceholder method by using Arrays.equals …
taka2233 Apr 13, 2026
00089ab
feat: add flags to track empty payload replacements in WebSocket enco…
taka2233 Apr 13, 2026
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66 changes: 60 additions & 6 deletions src/main/java/core/packetproxy/encode/EncodeHTTPWebSocket.java
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,34 @@
*/
package packetproxy.encode;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import packetproxy.http.Http;
import packetproxy.websocket.WebSocket;
import packetproxy.websocket.WebSocketFrame;

public class EncodeHTTPWebSocket extends Encoder {

/**
* Sentinel shown in History/Intercept for empty-payload WebSocket frames.
* Encode path restores this to a zero-length payload so the wire frame stays
* spec-compliant. If the user replaces this text in Intercept, the edited bytes
* are sent as the actual payload.
*/
static final byte[] EMPTY_PAYLOAD_PLACEHOLDER = "(empty WebSocket frame)".getBytes(StandardCharsets.UTF_8);

/**
* Set when {@link #clientRequestAvailable()} replaced a zero-length payload
* with {@link #EMPTY_PAYLOAD_PLACEHOLDER}.
*/
private boolean clientEmptyPayloadFlag = false;

/**
* Set when {@link #serverResponseAvailable()} replaced a zero-length payload
* with {@link #EMPTY_PAYLOAD_PLACEHOLDER}.
*/
private boolean serverEmptyPayloadFlag = false;

protected boolean binary_start = false;
WebSocket clientWebSocket = new WebSocket();
WebSocket serverWebSocket = new WebSocket();
Expand Down Expand Up @@ -107,7 +129,16 @@ public byte[] passThroughServerResponse() throws Exception {
public byte[] clientRequestAvailable() throws Exception {
if (binary_start) {

return clientWebSocket.frameAvailable();
byte[] payload = clientWebSocket.frameAvailable();
// Simplex treats byte[0] from clientRequestAvailable as "no more chunks" (same
// as Encoder base).
// Map empty WebSocket payload to the placeholder so the duplex pipeline runs
// decode/intercept/send.
if (payload != null && payload.length == 0) {
clientEmptyPayloadFlag = true;
return EMPTY_PAYLOAD_PLACEHOLDER;
}
return payload;
} else {

return super.clientRequestAvailable();
Expand All @@ -118,7 +149,12 @@ public byte[] clientRequestAvailable() throws Exception {
public byte[] serverResponseAvailable() throws Exception {
if (binary_start) {

return serverWebSocket.frameAvailable();
byte[] payload = serverWebSocket.frameAvailable();
if (payload != null && payload.length == 0) {
serverEmptyPayloadFlag = true;
return EMPTY_PAYLOAD_PLACEHOLDER;
}
return payload;
} else {

return super.serverResponseAvailable();
Expand All @@ -128,7 +164,9 @@ public byte[] serverResponseAvailable() throws Exception {
@Override
public byte[] decodeServerResponse(byte[] input) throws Exception {
if (binary_start) {

if (input.length == 0) {
return EMPTY_PAYLOAD_PLACEHOLDER;
}
return decodeWebsocketResponse(input);
} else {

Expand All @@ -141,7 +179,15 @@ public byte[] decodeServerResponse(byte[] input) throws Exception {
public byte[] encodeServerResponse(byte[] input) throws Exception {
if (binary_start) {

byte[] payload = encodeWebsocketResponse(input);
byte[] payload;
if (serverEmptyPayloadFlag) {
serverEmptyPayloadFlag = false;
payload = Arrays.equals(input, EMPTY_PAYLOAD_PLACEHOLDER)
? new byte[0]
: encodeWebsocketResponse(input);
} else {
payload = encodeWebsocketResponse(input);
}
WebSocketFrame frame = WebSocketFrame.of(serverWebSocket.lastDequeuedOpCode(), payload, false);
return frame.getBytes();
} else {
Expand All @@ -156,7 +202,9 @@ public byte[] encodeServerResponse(byte[] input) throws Exception {
@Override
public byte[] decodeClientRequest(byte[] input) throws Exception {
if (binary_start) {

if (input.length == 0) {
return EMPTY_PAYLOAD_PLACEHOLDER;
}
return decodeWebsocketRequest(input);
} else {

Expand All @@ -169,7 +217,13 @@ public byte[] decodeClientRequest(byte[] input) throws Exception {
public byte[] encodeClientRequest(byte[] input) throws Exception {
if (binary_start) {

byte[] payload = encodeWebsocketRequest(input);
byte[] payload;
if (clientEmptyPayloadFlag) {
clientEmptyPayloadFlag = false;
payload = Arrays.equals(input, EMPTY_PAYLOAD_PLACEHOLDER) ? new byte[0] : encodeWebsocketRequest(input);
} else {
payload = encodeWebsocketRequest(input);
}
WebSocketFrame frame = WebSocketFrame.of(clientWebSocket.lastDequeuedOpCode(), payload, true);
return frame.getBytes();
} else {
Expand Down
163 changes: 154 additions & 9 deletions src/test/java/packetproxy/encode/EncodeHTTPWebSocketOpCodeTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@

import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;

import java.nio.charset.StandardCharsets;
import org.junit.jupiter.api.Test;
Expand All @@ -25,22 +27,51 @@
import packetproxy.websocket.WebSocketFrame;

/**
* Ensures Text vs Binary opcode is preserved across decode (frameAvailable) and
* encode (getBytes).
* Tests that: 1. Text vs Binary opcode is preserved across decode/encode. 2.
* Empty-payload WebSocket frames flow through the pipeline.
*/
public class EncodeHTTPWebSocketOpCodeTest {

private static final byte FIN_TEXT = (byte) 0x81;
private static final byte FIN_BINARY = (byte) 0x82;
/** RFC 6455 frame byte 0: FIN (bit 7). */
private static final int WS_FIN_BIT = 0x80;

/** RFC 6455 frame byte 1: MASK (bit 7) for client-to-server frames. */
private static final int WS_MASK_BIT = 0x80;

/**
* RFC 6455 frame byte 1: bits 0–6 — payload length when that value is 0–125.
*/
private static final int WS_PAYLOAD_LEN_7BIT_MASK = 0x7F;

private static byte finFirstByte(OpCode opcode) {
return (byte) (WS_FIN_BIT | (opcode.code & 0x0F));
}

private static byte unmaskedPayloadLenByte(int payloadLength) {
return (byte) (payloadLength & WS_PAYLOAD_LEN_7BIT_MASK);
}

private static byte maskedPayloadLenByte(int payloadLength) {
return (byte) (WS_MASK_BIT | (payloadLength & WS_PAYLOAD_LEN_7BIT_MASK));
}

private static int payloadLen7Bits(byte secondByte) {
return secondByte & WS_PAYLOAD_LEN_7BIT_MASK;
}

/** Unmasked FIN+Text frame, payload "hello". */
private static byte[] textFrameHello() {
return new byte[]{FIN_TEXT, 0x05, 'h', 'e', 'l', 'l', 'o'};
byte[] payload = "hello".getBytes(StandardCharsets.UTF_8);
byte[] frame = new byte[2 + payload.length];
frame[0] = finFirstByte(OpCode.Text);
frame[1] = unmaskedPayloadLenByte(payload.length);
System.arraycopy(payload, 0, frame, 2, payload.length);
return frame;
}

/** Unmasked FIN+Binary frame, single zero byte payload. */
private static byte[] binaryFrameOneByte() {
return new byte[]{FIN_BINARY, 0x01, 0x00};
return new byte[]{finFirstByte(OpCode.Binary), unmaskedPayloadLenByte(1), 0x00};
}

@Test
Expand All @@ -66,7 +97,7 @@ public void encodeClientRequestPreservesTextOpcode() throws Exception {
encoder.clientWebSocket.frameArrived(textFrameHello());
byte[] payload = encoder.clientRequestAvailable();
byte[] wire = encoder.encodeClientRequest(payload);
assertEquals(FIN_TEXT, wire[0]);
assertEquals(finFirstByte(OpCode.Text), wire[0]);
}

@Test
Expand All @@ -76,7 +107,7 @@ public void encodeClientRequestPreservesBinaryOpcode() throws Exception {
encoder.clientWebSocket.frameArrived(binaryFrameOneByte());
byte[] payload = encoder.clientRequestAvailable();
byte[] wire = encoder.encodeClientRequest(payload);
assertEquals(FIN_BINARY, wire[0]);
assertEquals(finFirstByte(OpCode.Binary), wire[0]);
}

@Test
Expand All @@ -86,7 +117,7 @@ public void encodeServerResponsePreservesTextOpcode() throws Exception {
encoder.serverWebSocket.frameArrived(textFrameHello());
byte[] payload = encoder.serverResponseAvailable();
byte[] wire = encoder.encodeServerResponse(payload);
assertEquals(FIN_TEXT, wire[0]);
assertEquals(finFirstByte(OpCode.Text), wire[0]);
}

@Test
Expand All @@ -100,6 +131,120 @@ public void parseThenSerializeRoundTripKeepsOpcode() throws Exception {
assertArrayEquals(binaryFrameOneByte(), WebSocketFrame.of(bin.getOpcode(), bin.getPayload(), false).getBytes());
}

/** Unmasked FIN+Text frame, zero-length payload. */
private static byte[] textFrameEmptyPayload() {
return new byte[]{finFirstByte(OpCode.Text), unmaskedPayloadLenByte(0)};
}

/** Unmasked FIN+Binary frame, zero-length payload. */
private static byte[] binaryFrameEmptyPayload() {
return new byte[]{finFirstByte(OpCode.Binary), unmaskedPayloadLenByte(0)};
}

@Test
public void emptyPayloadTextFrameQueuesForDecode() throws Exception {
WebSocket ws = new WebSocket();
ws.frameArrived(textFrameEmptyPayload());
assertArrayEquals(new byte[0], ws.passThroughFrame());
assertArrayEquals(new byte[0], ws.frameAvailable());
}

@Test
public void emptyPayloadBinaryFrameQueuesForDecode() throws Exception {
WebSocket ws = new WebSocket();
ws.frameArrived(binaryFrameEmptyPayload());
assertArrayEquals(new byte[0], ws.passThroughFrame());
assertArrayEquals(new byte[0], ws.frameAvailable());
}

@Test
public void decodeClientRequestReturnsPlaceholderForEmptyPayload() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
byte[] decoded = encoder.decodeClientRequest(new byte[0]);
assertArrayEquals(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER, decoded);
}

@Test
public void decodeServerResponseReturnsPlaceholderForEmptyPayload() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
byte[] decoded = encoder.decodeServerResponse(new byte[0]);
assertArrayEquals(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER, decoded);
}

@Test
public void emptyPayloadClientRequestRoundTrip() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
encoder.clientWebSocket.frameArrived(textFrameEmptyPayload());
encoder.clientWebSocket.passThroughFrame();
byte[] payload = encoder.clientRequestAvailable();
assertNotNull(payload);
assertArrayEquals(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER, payload);
byte[] decoded = encoder.decodeClientRequest(payload);
byte[] wire = encoder.encodeClientRequest(decoded);
// lastDequeuedOpCode preserves Text from the original frame
assertEquals(finFirstByte(OpCode.Text), wire[0]);
assertEquals(0, payloadLen7Bits(wire[1]));
}

@Test
public void emptyPayloadServerResponseRoundTrip() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
encoder.serverWebSocket.frameArrived(binaryFrameEmptyPayload());
encoder.serverWebSocket.passThroughFrame();
byte[] payload = encoder.serverResponseAvailable();
assertNotNull(payload);
assertArrayEquals(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER, payload);
byte[] decoded = encoder.decodeServerResponse(payload);
byte[] wire = encoder.encodeServerResponse(decoded);
assertArrayEquals(binaryFrameEmptyPayload(), wire);
}

@Test
public void editedPlaceholderClientRequestSendsNewContent() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
encoder.clientWebSocket.frameArrived(textFrameEmptyPayload());
encoder.clientWebSocket.passThroughFrame();
encoder.clientRequestAvailable();
byte[] userEdited = "hello".getBytes(StandardCharsets.UTF_8);
byte[] wire = encoder.encodeClientRequest(userEdited);
// lastDequeuedOpCode preserves Text from the original frame
assertEquals(finFirstByte(OpCode.Text), wire[0]);
assertEquals(maskedPayloadLenByte(userEdited.length), wire[1]);
}

/**
* If the literal placeholder bytes are sent as payload without having come from
* an empty frame, encode must not collapse them to a zero-length payload.
*/
@Test
public void placeholderPayloadWithoutEmptyFrameFlagIsNotCollapsedToEmpty() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
encoder.clientWebSocket.frameArrived(textFrameHello());
encoder.clientWebSocket.passThroughFrame();
encoder.clientRequestAvailable();
byte[] wire = encoder.encodeClientRequest(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER);
assertEquals(finFirstByte(OpCode.Text), wire[0]);
assertNotEquals(0, payloadLen7Bits(wire[1]));
}

@Test
public void placeholderServerPayloadWithoutEmptyFrameFlagIsNotCollapsedToEmpty() throws Exception {
TestEncoder encoder = new TestEncoder();
encoder.setBinaryStart(true);
encoder.serverWebSocket.frameArrived(textFrameHello());
encoder.serverWebSocket.passThroughFrame();
encoder.serverResponseAvailable();
byte[] wire = encoder.encodeServerResponse(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER);
assertEquals(finFirstByte(OpCode.Text), wire[0]);
assertEquals(EncodeHTTPWebSocket.EMPTY_PAYLOAD_PLACEHOLDER.length, payloadLen7Bits(wire[1]));
}

private static final class TestEncoder extends EncodeHTTPWebSocket {

TestEncoder() throws Exception {
Expand Down
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