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Merge pull request #39 from starkSV/fix/sentinel-lockdown-and-proxy-validation

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fix(backend): back off Sentinel lockdown retries, validate product_id in /proxy
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Shekhar 2026-07-31 11:49:57 +05:30 • committed by GitHub
commit 6ace2ceb19
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1 changed files with 12 additions and 5 deletions
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17
backend/main.go
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@ -132,7 +132,7 @@ func truncateBody(s string) string {
return s
}
// --- Negative cache (60s normal / 90min Sentinel lockdown) ---
// --- Negative cache (60s normal / 5h Sentinel lockdown) ---
type negCacheEntry struct {
Message string
@ -145,7 +145,10 @@ var (
negCache = make(map[string]negCacheEntry)
negCacheMu sync.RWMutex
negCacheTTL = 60 * time.Second
lockdownTTL = 90 * time.Minute
// Bumped from 90min on 2026-07-31: 181 retry attempts over 17 days, 0 successes.
// Retries yield zero value right now, so back off harder instead of hammering
// Microsoft (and our own IP's reputation) every 90 minutes for nothing.
lockdownTTL = 5 * time.Hour
)
// --- Singleflight (one in-flight Microsoft fetch per unique key) ---
@ -1184,6 +1187,10 @@ func handleProxy(w http.ResponseWriter, r *http.Request) {
respondJSONError(w, http.StatusBadRequest, "sku_id contains invalid characters")
return
}
if !validContributeProducts[productID] {
respondJSONError(w, http.StatusNotFound, "unknown product_id")
return
}
atomic.AddInt64(&mLinkRequests, 1)
cacheKey := productID + ":" + skuID
@ -1301,7 +1308,7 @@ func handleProxy(w http.ResponseWriter, r *http.Request) {
atomic.AddInt64(&mLinkStale, 1)
if isSentinel {
// Sentinel lockdown: set 90-min neg cache, add lockdown header, skip
// Sentinel lockdown: set lockdownTTL neg cache, add lockdown header, skip
// background refresh — retrying extends the Sentinel block timer.
negCacheMu.Lock()
negCache[negKey] = negCacheEntry{
@ -1311,7 +1318,7 @@ func handleProxy(w http.ResponseWriter, r *http.Request) {
IsSentinel: true,
}
negCacheMu.Unlock()
log.Printf("/proxy: product_id=%s sku_id=%s -> Sentinel lockdown (90min), serving stale\n", productID, skuID)
log.Printf("/proxy: product_id=%s sku_id=%s -> Sentinel lockdown (%s), serving stale\n", productID, skuID, lockdownTTL)
w.Header().Set("X-MSDL-Lockdown", "1")
w.Header().Set("X-MSDL-Link-Status", "stale")
if exp := extractRawExpiry(cached.RawJSON); exp != "" {
@ -1365,7 +1372,7 @@ func handleProxy(w http.ResponseWriter, r *http.Request) {
}
negCacheMu.Unlock()
if isSentinel {
log.Printf("/proxy: product_id=%s sku_id=%s -> Sentinel lockdown (90min), no stale\n", productID, skuID)
log.Printf("/proxy: product_id=%s sku_id=%s -> Sentinel lockdown (%s), no stale\n", productID, skuID, lockdownTTL)
w.Header().Set("X-MSDL-Lockdown", "1")
w.WriteHeader(code)
json.NewEncoder(w).Encode(map[string]interface{}{