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Merged
atomiczsec merged 2 commits into from
Nov 16, 2025
Merged

Improve request retry and circuit breaker handling #13

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c03658f
Refine request retry and circuit breaker logic
atomiczsec Nov 16, 2025
7b74a15
Merge branch 'main' into codex/refactor-retrieveresponsedetails-for-r…
atomiczsec Nov 16, 2025
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133 changes: 80 additions & 53 deletions src/main/java/burp/RequestSender.java
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,8 @@ class RequestSender {

// Rate limiting and circuit breaker state per host
private static final Map<String, AtomicInteger> REQUEST_COUNTS = new ConcurrentHashMap<>();
private static final Map<String, AtomicLong> LAST_REQUEST_TIME = new ConcurrentHashMap<>();
private static final Map<String, AtomicLong> RATE_LIMIT_TIMESTAMPS = new ConcurrentHashMap<>();
private static final Map<String, AtomicLong> LAST_FAILURE_TIME = new ConcurrentHashMap<>();
private static final Map<String, AtomicInteger> FAILURE_COUNTS = new ConcurrentHashMap<>();
private static final int MAX_REQUESTS_PER_SECOND = 10;
private static final int CIRCUIT_BREAKER_THRESHOLD = 5;
Expand Down Expand Up @@ -405,6 +406,15 @@ private static URL createNewURLWithSegment(URL orgURL, String additional, String
* Uses Caffeine cache for high-performance caching with TTL.
*/
protected static Map<String, Object> retrieveResponseDetails(IHttpService service, byte[] request) {
String hostKey = service.getHost();
String cacheKey = service.toString() + Arrays.hashCode(request);

for (int attempt = 0; attempt < MAX_RETRIES; attempt++) {
try {
if (isCircuitOpen(hostKey)) {
BurpExtender.logDebug("Circuit breaker open for " + hostKey);
return null;
}
return retrieveResponseDetails(service, request, 0);
}

Expand All @@ -430,53 +440,56 @@ private static Map<String, Object> retrieveResponseDetails(IHttpService service,
return cached;
}

// Adaptive delay based on host response times
long delay = calculateAdaptiveDelay(hostKey);
try { Thread.sleep(delay); } catch (InterruptedException ignored) {}
waitForRateLimit(hostKey);

long startTime = System.currentTimeMillis();
IHttpRequestResponse response = BurpExtender.getCallbacks().makeHttpRequest(service, request);
long responseTime = System.currentTimeMillis() - startTime;

if (response == null) {
recordFailure(hostKey);
if (retryCount < MAX_RETRIES) {
int delayMs = calculateRetryDelay(retryCount);
try { Thread.sleep(delayMs); } catch (InterruptedException ignored) {}
return retrieveResponseDetails(service, request, retryCount + 1);
Map<String, Object> cached = RESPONSE_CACHE.getIfPresent(cacheKey);
if (cached != null) {
return cached;
}
return null;
}

IResponseInfo responseInfo = BurpExtender.getHelpers().analyzeResponse(response.getResponse());
Map<String, Object> details = new HashMap<>();
details.put("statusCode", (int) responseInfo.getStatusCode());
details.put("headers", responseInfo.getHeaders());
details.put("responseTime", responseTime);
long delay = calculateAdaptiveDelay(hostKey);
sleepRespectingInterrupts(delay);

byte[] responseBody = java.util.Arrays.copyOfRange(response.getResponse(),
responseInfo.getBodyOffset(), response.getResponse().length);
details.put("body", responseBody);
long startTime = System.currentTimeMillis();
IHttpRequestResponse response = BurpExtender.getCallbacks().makeHttpRequest(service, request);
long responseTime = System.currentTimeMillis() - startTime;

// Cache successful responses
if (responseInfo.getStatusCode() >= 200 && responseInfo.getStatusCode() < 500) {
RESPONSE_CACHE.put(cacheKey, details);
recordSuccess(hostKey, responseTime);
} else {
if (response == null) {
recordFailure(hostKey);
if (attempt < MAX_RETRIES - 1) {
sleepRespectingInterrupts(calculateRetryDelay(attempt));
continue;
}
return null;
}

IResponseInfo responseInfo = BurpExtender.getHelpers().analyzeResponse(response.getResponse());
Map<String, Object> details = new HashMap<>();
details.put("statusCode", (int) responseInfo.getStatusCode());
details.put("headers", responseInfo.getHeaders());
details.put("responseTime", responseTime);

byte[] responseBody = java.util.Arrays.copyOfRange(response.getResponse(),
responseInfo.getBodyOffset(), response.getResponse().length);
details.put("body", responseBody);

if (responseInfo.getStatusCode() >= 200 && responseInfo.getStatusCode() < 500) {
RESPONSE_CACHE.put(cacheKey, details);
recordSuccess(hostKey, responseTime);
} else {
recordFailure(hostKey);
}

return details;
} catch (Exception e) {
recordFailure(hostKey);
if (attempt < MAX_RETRIES - 1) {
sleepRespectingInterrupts(calculateRetryDelay(attempt));
}
}

return details;
} catch (Exception e) {
String hostKey = service.getHost();
recordFailure(hostKey);
if (retryCount < MAX_RETRIES) {
int delayMs = calculateRetryDelay(retryCount);
try { Thread.sleep(delayMs); } catch (InterruptedException ignored) {}
return retrieveResponseDetails(service, request, retryCount + 1);
}
return null;
}

return null;
}

/**
Expand Down Expand Up @@ -504,16 +517,14 @@ private static String buildServiceCacheKey(IHttpService service, byte[] request)
private static boolean isCircuitOpen(String hostKey) {
AtomicInteger failures = FAILURE_COUNTS.computeIfAbsent(hostKey, k -> new AtomicInteger(0));
if (failures.get() >= CIRCUIT_BREAKER_THRESHOLD) {
AtomicLong lastFailure = LAST_REQUEST_TIME.get(hostKey);
AtomicLong lastFailure = LAST_FAILURE_TIME.get(hostKey);
if (lastFailure == null) {
// No failure time recorded yet, circuit should not be open
return false;
}
long timeSinceLastFailure = System.currentTimeMillis() - lastFailure.get();
if (timeSinceLastFailure < CIRCUIT_BREAKER_RESET_MS) {
return true;
} else {
// Reset circuit breaker after reset period has elapsed
failures.set(0);
}
}
Expand All @@ -522,28 +533,27 @@ private static boolean isCircuitOpen(String hostKey) {

private static boolean checkRateLimit(String hostKey) {
AtomicInteger count = REQUEST_COUNTS.computeIfAbsent(hostKey, k -> new AtomicInteger(0));
AtomicLong lastTime = LAST_REQUEST_TIME.computeIfAbsent(hostKey, k -> new AtomicLong(System.currentTimeMillis()));
AtomicLong lastTime = RATE_LIMIT_TIMESTAMPS.computeIfAbsent(hostKey, k -> new AtomicLong(System.currentTimeMillis()));

long currentTime = System.currentTimeMillis();
long timeDiff = currentTime - lastTime.get();

if (timeDiff >= 1000) {
// Reset counter every second
count.set(0);
lastTime.set(currentTime);
}

if (count.get() >= MAX_REQUESTS_PER_SECOND) {
return false;
}

count.incrementAndGet();
lastTime.set(currentTime);
return true;
}

private static long calculateAdaptiveDelay(String hostKey) {
// Start with base delay, adjust based on response times
AtomicLong lastTime = LAST_REQUEST_TIME.get(hostKey);
AtomicLong lastTime = RATE_LIMIT_TIMESTAMPS.get(hostKey);
if (lastTime == null) {
return 50; // Base delay
}
Expand All @@ -563,7 +573,24 @@ private static void recordSuccess(String hostKey, long responseTime) {

private static void recordFailure(String hostKey) {
FAILURE_COUNTS.computeIfAbsent(hostKey, k -> new AtomicInteger(0)).incrementAndGet();
LAST_REQUEST_TIME.computeIfAbsent(hostKey, k -> new AtomicLong(System.currentTimeMillis())).set(System.currentTimeMillis());
LAST_FAILURE_TIME.computeIfAbsent(hostKey, k -> new AtomicLong(System.currentTimeMillis())).set(System.currentTimeMillis());
}

private static void waitForRateLimit(String hostKey) {
while (!checkRateLimit(hostKey)) {
sleepRespectingInterrupts(100);
}
}

private static void sleepRespectingInterrupts(long delayMs) {
if (delayMs <= 0) {
return;
}
try {
Thread.sleep(delayMs);
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
}
}

/**
Expand Down
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