fix(telegram): honor proxy fallbacks for bot api

internal/service/telegram_api.go

@@ -53,26 +53,45 @@ func telegramHTTPClient(timeout time.Duration, cfg map[string]string) *http.Clie
 func telegramHTTPClients(timeout time.Duration, cfg map[string]string) []*http.Client {
 	clients := []*http.Client{}
 	seen := map[string]bool{}
-	for _, proxyRaw := range telegramProxyCandidates(cfg) {
-		proxyURL, err := normalizeProxyURL(proxyRaw, "http")
-		if err != nil || proxyURL == nil {
-			continue
+
+	addProxy := func(proxyURL *url.URL) {
+		if proxyURL == nil {
+			return
 		}
 		key := proxyURL.String()
 		if seen[key] {
-			continue
+			return
 		}
 		seen[key] = true
 		transport := NewExternalTransport()
 		transport.Proxy = http.ProxyURL(proxyURL)
 		clients = append(clients, &http.Client{Timeout: timeout, Transport: transport})
 	}
+
+	for _, proxyRaw := range telegramExplicitProxyCandidates(cfg) {
+		proxyURL, err := normalizeProxyURL(proxyRaw, "http")
+		if err != nil || proxyURL == nil {
+			continue
+		}
+		addProxy(proxyURL)
+	}
+	if proxyURL, err := telegramAutoProxyURL(cfg); err == nil {
+		addProxy(proxyURL)
+	}
+	for _, proxyRaw := range telegramFallbackProxyCandidates() {
+		proxyURL, err := normalizeProxyURL(proxyRaw, "http")
+		if err != nil || proxyURL == nil {
+			continue
+		}
+		addProxy(proxyURL)
+	}
 	transport := NewExternalTransport()
+	transport.Proxy = nil
 	clients = append(clients, &http.Client{Timeout: timeout, Transport: transport})
 	return clients
 }
 
-func telegramProxyCandidates(cfg map[string]string) []string {
+func telegramExplicitProxyCandidates(cfg map[string]string) []string {
 	out := []string{}
 	for _, value := range []string{
 		cfg["proxy_url"],
@@ -82,22 +101,48 @@ func telegramProxyCandidates(cfg map[string]string) []string {
 			out = append(out, value)
 		}
 	}
+	return out
+}
+
+func telegramProxyCandidates(cfg map[string]string) []string {
+	out := telegramExplicitProxyCandidates(cfg)
 	if len(out) > 0 {
 		return out
 	}
-	for _, value := range []string{
-		"http://127.0.0.1:10808",
-		"http://127.0.0.1:10809",
-		"http://127.0.0.1:7890",
-		"http://127.0.0.1:7891",
+	return telegramFallbackProxyCandidates()
+}
+
+func telegramFallbackProxyCandidates() []string {
+	// Common local proxy ports used by Clash / v2rayN / v2rayA. Docker on Linux
+	// reaches host services through host.docker.internal (when extra_hosts is
+	// configured) or the bridge gateway 172.17.0.1. These are only fallbacks:
+	// explicit channel/env proxy and environment/system proxy are tried first.
+	return []string{
+		"http://host.docker.internal:20171",
+		"socks5://host.docker.internal:20170",
+		"http://172.17.0.1:20171",
+		"socks5://172.17.0.1:20170",
 		"http://host.docker.internal:7890",
 		"http://host.docker.internal:10808",
 		"http://172.17.0.1:7890",
 		"http://172.17.0.1:10808",
-	} {
-		out = append(out, value)
+		"http://127.0.0.1:10808",
+		"http://127.0.0.1:10809",
+		"http://127.0.0.1:7890",
+		"http://127.0.0.1:7891",
 	}
-	return out
+}
+
+func telegramAutoProxyURL(cfg map[string]string) (*url.URL, error) {
+	base := telegramAPIBaseURL(cfg)
+	if _, err := url.ParseRequestURI(base); err != nil {
+		return nil, err
+	}
+	req, err := http.NewRequest(http.MethodGet, base, nil)
+	if err != nil {
+		return nil, err
+	}
+	return ProxyFromEnvironmentOrSystem(req)
 }
 
 func telegramPostForm(ctx context.Context, cfg map[string]string, method string, form url.Values, timeout time.Duration) error {
@@ -193,6 +238,39 @@ func telegramPostJSONDecode(ctx context.Context, cfg map[string]string, method s
 	return errors.New("telegram request failed")
 }
 
+func telegramGetJSONDecode(ctx context.Context, cfg map[string]string, method string, timeout time.Duration, out any) error {
+	apiURL, err := telegramMethodURL(cfg, cfg["bot_token"], method)
+	if err != nil {
+		return err
+	}
+	var lastErr error
+	for _, client := range telegramHTTPClients(timeout, cfg) {
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, apiURL, nil)
+		if err != nil {
+			return err
+		}
+		resp, err := client.Do(req)
+		if err != nil {
+			lastErr = sanitizeTelegramError(err)
+			continue
+		}
+		respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		resp.Body.Close()
+		if resp.StatusCode >= 400 {
+			lastErr = fmt.Errorf("telegram api error %d: %s", resp.StatusCode, sanitizeTelegramText(string(respBody)))
+			continue
+		}
+		if out != nil {
+			return json.Unmarshal(respBody, out)
+		}
+		return nil
+	}
+	if lastErr != nil {
+		return lastErr
+	}
+	return errors.New("telegram request failed")
+}
+
 func telegramStringConfigFromAny(cfg map[string]any) map[string]string {
 	out := make(map[string]string, len(cfg))
 	for key, value := range cfg {