Method fetchSubscriptionFromURL

app.go:2036–2218

fetchSubscriptionFromURL fetches and parses a subscription. allowInsecure must be true to accept http:// URLs; when set, we also suppress the x-hwid header because sending a stable device identifier in plaintext is exactly the leak the warning is opted into.

(subURL string, allowInsecure bool)

// x-hwid header because sending a stable device identifier in plaintext is
// exactly the leak the warning is opted into.
func (a *App) fetchSubscriptionFromURL(subURL string, allowInsecure bool) ([]config.ProxyEntry, int64, int64, int64, int64, string, string, error) {
	if resolved, err := resolveEncryptedSubscriptionURL(subURL); err != nil {
		return nil, 0, 0, 0, 0, "", "", err
	} else if resolved != "" {
		subURL = resolved
	}
	insecure := isInsecureSubURL(subURL)
	if insecure && !allowInsecure {
		return nil, 0, 0, 0, 0, "", "", ErrInsecureSubscription
	}
	jar, _ := cookiejar.New(nil)
	client := &http.Client{Timeout: 15 * time.Second, Jar: jar}
	metadata := a.subscriptionRequestMetadata()

	doFetch := func(userAgent string) ([]config.ProxyEntry, int64, int64, int64, int64, string, string, bool, error) {
		req, err := http.NewRequest(http.MethodGet, subURL, nil)
		if err != nil {
			return nil, 0, 0, 0, 0, "", "", false, fmt.Errorf("creating subscription request: %w", err)
		}
		req.Header.Set("User-Agent", userAgent)
		// Remnawave HWID device identification headers.
		req.Header.Set("x-device-os", metadata.Platform)
		req.Header.Set("x-ver-os", metadata.OSVersion)
		req.Header.Set("x-device-model", metadata.Model)
		// Only attach HWID to HTTPS requests. On plaintext http:// the HWID
		// would be sniffable end-to-end and would link the user's device
		// across every network hop and intermediary — the privacy cost
		// outweighs any HWID-based device-limit check the provider does.
		if !insecure && metadata.SendHWID {
			if hwid := a.subscriptionHWID(subURL); hwid != "" {
				req.Header.Set("x-hwid", hwid)
			}
		}

		resp, err := client.Do(req)
		if err != nil {
			return nil, 0, 0, 0, 0, "", "", false, fmt.Errorf("fetching subscription: %w", err)
		}
		defer resp.Body.Close()

		if resp.StatusCode != http.StatusOK {
			return nil, 0, 0, 0, 0, "", "", false, fmt.Errorf("subscription returned HTTP %d", resp.StatusCode)
		}

		profileTitle := parseSubscriptionHeaderText(resp.Header.Get("Profile-Title"))
		up, down, tot, exp := parseSubscriptionUserInfoHeader(resp.Header.Get("Subscription-Userinfo"))
		iconURL := resolveSubscriptionIcon(client, subURL, resp.Header)

		bodyBytes, err := io.ReadAll(resp.Body)
		if err != nil {
			return nil, up, down, tot, exp, iconURL, profileTitle, false, fmt.Errorf("reading subscription body: %w", err)
		}
		bodyStr := string(bodyBytes)

		if iconURL == "" && strings.Contains(bodyStr, "<link") {
			if fromBody := pickIconFromSubscriptionHTML(client, subURL, bodyStr); fromBody != "" {
				iconURL = fromBody
			}