shekhar/windows-iso-downloader
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fix: support P1 query parameter for consumer download link expiry

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This commit is contained in:
Shekhar 2026-06-21 09:09:54 +05:30
parent 3a007662be
commit 84429ebaaf
1 changed files with 23 additions and 35 deletions
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58
backend/main.go
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@ -207,40 +207,19 @@ func jitter(base, maxJ time.Duration) time.Duration {
return base + offset
}
// parseLinkExpiry reads the `se` (signed expiry) query param from the first
// parseLinkExpiry reads the expiration parameter (se or P1) from the first
// download URL in a Microsoft GetProductDownloadLinksBySku response and returns
// a cache expiry time of (se - now) - 30min, with ±5min jitter.
// a cache expiry time of (expiration - now) - 30min, with ±5min jitter.
// Falls back to 22h on any parse failure.
func parseLinkExpiry(rawJSON []byte) time.Time {
fallback := func() time.Time {
return time.Now().Add(jitter(22*time.Hour, 5*time.Minute))
}
var data map[string]interface{}
if err := json.Unmarshal(rawJSON, &data); err != nil {
expStr := extractRawExpiry(rawJSON)
if expStr == "" {
return fallback()
}
opts, ok := data["ProductDownloadOptions"].([]interface{})
if !ok || len(opts) == 0 {
return fallback()
}
first, ok := opts[0].(map[string]interface{})
if !ok {
return fallback()
}
uri, ok := first["Uri"].(string)
if !ok {
return fallback()
}
u, err := url.Parse(uri)
if err != nil {
return fallback()
}
se := u.Query().Get("se")
if se == "" {
return fallback()
}
t, err := time.Parse(time.RFC3339, se)
t, err := time.Parse(time.RFC3339, expStr)
if err != nil {
return fallback()
}
@ -251,9 +230,10 @@ func parseLinkExpiry(rawJSON []byte) time.Time {
return time.Now().Add(jitter(ttl, 5*time.Minute))
}
// extractRawExpiry returns the raw `se` signed-expiry query param from the
// first URL in a GetProductDownloadLinksBySku response (RFC3339 string).
// Returns "" if absent, unparseable, or not present in the JSON.
// extractRawExpiry returns the raw expiration timestamp from the first URL
// in a GetProductDownloadLinksBySku response (RFC3339 string).
// It supports `se` (RFC3339) and `P1` (Unix timestamp) query parameters.
// Returns "" if absent or unparseable.
func extractRawExpiry(rawJSON []byte) string {
var data map[string]interface{}
if err := json.Unmarshal(rawJSON, &data); err != nil {
@ -275,14 +255,22 @@ func extractRawExpiry(rawJSON []byte) string {
if err != nil {
return ""
}
se := u.Query().Get("se")
if se == "" {
return ""
// 1. Try "se" query parameter (used on Server/Eval ISOs)
if se := u.Query().Get("se"); se != "" {
if _, err := time.Parse(time.RFC3339, se); err == nil {
return se
}
}
if _, err := time.Parse(time.RFC3339, se); err != nil {
return ""
// 2. Try "P1" query parameter (Unix timestamp, used on Consumer ISOs)
if p1 := u.Query().Get("P1"); p1 != "" {
if p1Int, err := strconv.ParseInt(p1, 10, 64); err == nil {
return time.Unix(p1Int, 0).Format(time.RFC3339)
}
}
return se
return ""
}
// rateLimitError marks a Microsoft rate-limit response so callers can choose