feat(youtube): add mediaCache mode and safer stream media extraction (#130)

src/media-input.ts

@@ -0,0 +1,97 @@
+export interface MediaInputOptions {
+  reconnect?: boolean;
+  userAgent?: string;
+  headers?: Record<string, string>;
+}
+
+export type MediaInput =
+  | string
+  | {
+      path: string;
+      source?: string;
+      inputOptions?: MediaInputOptions;
+      singleResolvedStream?: boolean;
+    };
+
+export type NormalizedMediaInput = {
+  path: string;
+  inputArgs: string[];
+  singleResolvedStream: boolean;
+};
+
+const BLOCKED_FFMPEG_HEADER_NAMES = new Set(['authorization', 'cookie', 'proxy-authorization']);
+
+function trimToNonEmptyString(value: unknown): string | null {
+  if (typeof value !== 'string') {
+    return null;
+  }
+  const trimmed = value.trim();
+  return trimmed.length > 0 ? trimmed : null;
+}
+
+function normalizeHeaderName(value: string): string | null {
+  const trimmed = value.trim();
+  if (!/^[A-Za-z0-9!#$%&'*+.^_`|~-]+$/.test(trimmed)) {
+    return null;
+  }
+  if (BLOCKED_FFMPEG_HEADER_NAMES.has(trimmed.toLowerCase())) {
+    return null;
+  }
+  return trimmed;
+}
+
+function serializeFfmpegHeaders(headers: Record<string, string> | undefined): string | null {
+  if (!headers) {
+    return null;
+  }
+
+  const lines: string[] = [];
+  for (const [rawName, rawValue] of Object.entries(headers)) {
+    const name = normalizeHeaderName(rawName);
+    const value = trimToNonEmptyString(rawValue);
+    if (!name || !value) {
+      continue;
+    }
+    lines.push(`${name}: ${value.replace(/[\r\n]+/g, ' ')}`);
+  }
+
+  return lines.length > 0 ? `${lines.join('\r\n')}\r\n` : null;
+}
+
+export function normalizeMediaInput(input: MediaInput): NormalizedMediaInput {
+  if (typeof input === 'string') {
+    return { path: input, inputArgs: [], singleResolvedStream: false };
+  }
+
+  const inputArgs: string[] = [];
+  if (input.inputOptions?.reconnect) {
+    inputArgs.push(
+      '-reconnect',
+      '1',
+      '-reconnect_streamed',
+      '1',
+      '-reconnect_on_network_error',
+      '1',
+      '-reconnect_on_http_error',
+      '403,5xx',
+      '-reconnect_delay_max',
+      '5',
+    );
+  }
+
+  const userAgent = trimToNonEmptyString(input.inputOptions?.userAgent);
+  if (userAgent) {
+    inputArgs.push('-user_agent', userAgent);
+  }
+
+  const headers = serializeFfmpegHeaders(input.inputOptions?.headers);
+  if (headers) {
+    inputArgs.push('-headers', headers);
+  }
+
+  return {
+    path: input.path,
+    inputArgs,
+    singleResolvedStream: input.singleResolvedStream === true,
+  };
+}