Function firstForwardedValue

src/video-proxy-shared.ts:27–35

(header: string | string[] | undefined)

 * valid later entries — so empty segments are skipped.
 */
export function firstForwardedValue(header: string | string[] | undefined): string | undefined {
  const raw = Array.isArray(header) ? header.join(",") : header;
  if (raw === undefined) return undefined;
  for (const segment of raw.split(",")) {
    const trimmed = segment.trim();
    if (trimmed) return trimmed;
  }
  return undefined;
}

// Conservative host[:port] shape for x-forwarded-host. Spaces, slashes,
// userinfo, or any other URL-structure character would corrupt (or smuggle