ext-apps/examples/pdf-server/server.test.ts

import { describe, it, expect, beforeEach, afterEach, spyOn } from "bun:test";
import path from "node:path";
import {
  createPdfCache,
  validateUrl,
  isAncestorDir,
  allowedLocalFiles,
  allowedLocalDirs,
  pathToFileUrl,
  CACHE_INACTIVITY_TIMEOUT_MS,
  CACHE_MAX_LIFETIME_MS,
  CACHE_MAX_PDF_SIZE_BYTES,
  type PdfCache,
} from "./server";

describe("PDF Cache with Timeouts", () => {
  let pdfCache: PdfCache;

  beforeEach(() => {
    // Each test gets its own session-local cache
    pdfCache = createPdfCache();
  });

  afterEach(() => {
    pdfCache.clearCache();
  });

  describe("cache configuration", () => {
    it("should have 10 second inactivity timeout", () => {
      expect(CACHE_INACTIVITY_TIMEOUT_MS).toBe(10_000);
    });

    it("should have 60 second max lifetime timeout", () => {
      expect(CACHE_MAX_LIFETIME_MS).toBe(60_000);
    });

    it("should have 50MB max PDF size limit", () => {
      expect(CACHE_MAX_PDF_SIZE_BYTES).toBe(50 * 1024 * 1024);
    });
  });

  describe("cache management", () => {
    it("should start with empty cache", () => {
      expect(pdfCache.getCacheSize()).toBe(0);
    });

    it("should clear all entries", () => {
      pdfCache.clearCache();
      expect(pdfCache.getCacheSize()).toBe(0);
    });

    it("should isolate caches between sessions", () => {
      // Create two independent cache instances
      const cache1 = createPdfCache();
      const cache2 = createPdfCache();

      // They should be independent (both start empty)
      expect(cache1.getCacheSize()).toBe(0);
      expect(cache2.getCacheSize()).toBe(0);
    });
  });

  describe("readPdfRange caching behavior", () => {
    const testUrl = "https://arxiv.org/pdf/test-pdf";
    const testData = new Uint8Array([0x25, 0x50, 0x44, 0x46]); // %PDF header

    it("should cache full body when server returns HTTP 200", async () => {
      // Mock fetch to return HTTP 200 (full body, no range support)
      const mockFetch = spyOn(globalThis, "fetch").mockResolvedValueOnce(
        new Response(testData, {
          status: 200,
          headers: { "Content-Type": "application/pdf" },
        }),
      );

      try {
        // First request - should fetch and cache
        const result1 = await pdfCache.readPdfRange(testUrl, 0, 1024);
        expect(result1.data).toEqual(testData);
        expect(result1.totalBytes).toBe(testData.length);
        expect(pdfCache.getCacheSize()).toBe(1);

        // Second request - should serve from cache (no new fetch)
        const result2 = await pdfCache.readPdfRange(testUrl, 0, 1024);
        expect(result2.data).toEqual(testData);
        expect(mockFetch).toHaveBeenCalledTimes(1); // Only one fetch call
      } finally {
        mockFetch.mockRestore();
      }
    });

    it("should not cache when server returns HTTP 206 (range supported)", async () => {
      const chunkData = new Uint8Array([0x25, 0x50]); // First 2 bytes

      const mockFetch = spyOn(globalThis, "fetch").mockResolvedValue(
        new Response(chunkData, {
          status: 206,
          headers: {
            "Content-Type": "application/pdf",
            "Content-Range": "bytes 0-1/100",
          },
        }),
      );

      try {
        await pdfCache.readPdfRange(testUrl, 0, 2);
        expect(pdfCache.getCacheSize()).toBe(0); // Not cached when 206
      } finally {
        mockFetch.mockRestore();
      }
    });

    it("should slice cached data for subsequent range requests", async () => {
      const fullData = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);

      const mockFetch = spyOn(globalThis, "fetch").mockResolvedValueOnce(
        new Response(fullData, { status: 200 }),
      );

      try {
        // First request caches full body
        await pdfCache.readPdfRange(testUrl, 0, 1024);
        expect(pdfCache.getCacheSize()).toBe(1);

        // Subsequent request gets slice from cache
        const result = await pdfCache.readPdfRange(testUrl, 2, 3);
        expect(result.data).toEqual(new Uint8Array([3, 4, 5]));
        expect(result.totalBytes).toBe(10);
        expect(mockFetch).toHaveBeenCalledTimes(1);
      } finally {
        mockFetch.mockRestore();
      }
    });

    it("should fall back to GET when server returns 501 for Range request", async () => {
      const fullData = new Uint8Array([0x25, 0x50, 0x44, 0x46, 0x2d]); // %PDF-

      const mockFetch = spyOn(globalThis, "fetch")
        // First call: Range request returns 501
        .mockResolvedValueOnce(
          new Response("Unsupported client Range", { status: 501 }),
        )
        // Second call: plain GET returns full body
        .mockResolvedValueOnce(
          new Response(fullData, {
            status: 200,
            headers: { "Content-Type": "application/pdf" },
          }),
        );

      try {
        const result = await pdfCache.readPdfRange(testUrl, 0, 1024);
        expect(result.data).toEqual(fullData);
        expect(result.totalBytes).toBe(fullData.length);
        expect(pdfCache.getCacheSize()).toBe(1);
        expect(mockFetch).toHaveBeenCalledTimes(2);
      } finally {
        mockFetch.mockRestore();
      }
    });

    it("should reject PDFs larger than max size limit", async () => {
      const hugeUrl = "https://arxiv.org/pdf/huge-pdf";
      // Create data larger than the limit
      const hugeData = new Uint8Array(CACHE_MAX_PDF_SIZE_BYTES + 1);

      const mockFetch = spyOn(globalThis, "fetch").mockResolvedValueOnce(
        new Response(hugeData, {
          status: 200,
          headers: { "Content-Type": "application/pdf" },
        }),
      );

      try {
        await expect(pdfCache.readPdfRange(hugeUrl, 0, 1024)).rejects.toThrow(
          /PDF too large to cache/,
        );
        expect(pdfCache.getCacheSize()).toBe(0); // Should not be cached
      } finally {
        mockFetch.mockRestore();
      }
    });

    it("should reject when Content-Length header exceeds limit", async () => {
      const headerUrl = "https://arxiv.org/pdf/huge-pdf-header";
      const smallData = new Uint8Array([1, 2, 3, 4]);

      const mockFetch = spyOn(globalThis, "fetch").mockResolvedValueOnce(
        new Response(smallData, {
          status: 200,
          headers: {
            "Content-Type": "application/pdf",
            "Content-Length": String(CACHE_MAX_PDF_SIZE_BYTES + 1),
          },
        }),
      );

      try {
        await expect(pdfCache.readPdfRange(headerUrl, 0, 1024)).rejects.toThrow(
          /PDF too large to cache/,
        );
        expect(pdfCache.getCacheSize()).toBe(0);
      } finally {
        mockFetch.mockRestore();
      }
    });
  });

  // Note: Timer-based tests (inactivity/max lifetime) would require
  // using fake timers which can be complex with async code.
  // The timeout behavior is straightforward and can be verified
  // through manual testing or E2E tests.
});

describe("validateUrl with MCP roots (allowedLocalDirs)", () => {
  const savedFiles = new Set(allowedLocalFiles);
  const savedDirs = new Set(allowedLocalDirs);

  beforeEach(() => {
    allowedLocalFiles.clear();
    allowedLocalDirs.clear();
  });

  afterEach(() => {
    allowedLocalFiles.clear();
    allowedLocalDirs.clear();
    for (const f of savedFiles) allowedLocalFiles.add(f);
    for (const d of savedDirs) allowedLocalDirs.add(d);
  });

  it("should allow a file under an allowed directory", () => {
    // Use a real existing directory+file for the existsSync check
    const dir = path.resolve(import.meta.dirname);
    allowedLocalDirs.add(dir);

    const filePath = path.join(dir, "server.ts");
    const result = validateUrl(pathToFileUrl(filePath));
    expect(result.valid).toBe(true);
  });

  it("should reject a file outside allowed directories", () => {
    allowedLocalDirs.add("/some/allowed/dir");

    const result = validateUrl("file:///other/dir/test.pdf");
    expect(result.valid).toBe(false);
    expect(result.error).toContain("not in allowed list");
  });

  it("should prevent prefix-based directory traversal", () => {
    // /tmp/safe should NOT allow /tmp/safevil/file.pdf
    allowedLocalDirs.add("/tmp/safe");

    const result = validateUrl("file:///tmp/safevil/file.pdf");
    expect(result.valid).toBe(false);
  });

  it("should still allow exact file matches from allowedLocalFiles", () => {
    const filePath = path.resolve(import.meta.dirname, "server.ts");
    allowedLocalFiles.add(filePath);

    const result = validateUrl(pathToFileUrl(filePath));
    expect(result.valid).toBe(true);
  });

  it("should reject non-existent file even if under allowed dir", () => {
    const dir = path.resolve(import.meta.dirname);
    allowedLocalDirs.add(dir);

    const result = validateUrl(
      pathToFileUrl(path.join(dir, "nonexistent-file.pdf")),
    );
    expect(result.valid).toBe(false);
    expect(result.error).toContain("File not found");
  });

  it("should allow a file under an allowed dir with trailing slash", () => {
    const dir = path.resolve(import.meta.dirname);
    // Simulate a dir stored with a trailing slash (e.g. from CLI path)
    allowedLocalDirs.add(dir + "/");

    const filePath = path.join(dir, "server.ts");
    const result = validateUrl(pathToFileUrl(filePath));
    expect(result.valid).toBe(true);
  });

  it("should allow a file under a grandparent allowed dir", () => {
    // Allow a directory two levels up from the file
    const grandparent = path.resolve(path.join(import.meta.dirname, ".."));
    allowedLocalDirs.add(grandparent);

    const filePath = path.join(import.meta.dirname, "server.ts");
    const result = validateUrl(pathToFileUrl(filePath));
    expect(result.valid).toBe(true);
  });

  it("should accept computer:// URLs as local files", () => {
    const dir = path.resolve(import.meta.dirname);
    allowedLocalDirs.add(dir);

    const filePath = path.join(dir, "server.ts");
    const encoded = encodeURIComponent(filePath).replace(/%2F/g, "/");
    const result = validateUrl(`computer://${encoded}`);
    expect(result.valid).toBe(true);
  });

  it("should accept bare absolute paths as local files", () => {
    const dir = path.resolve(import.meta.dirname);
    allowedLocalDirs.add(dir);

    const filePath = path.join(dir, "server.ts");
    const result = validateUrl(filePath);
    expect(result.valid).toBe(true);
  });

  it("should decode percent-encoded bare paths (e.g. %20 for spaces)", () => {
    const fs = require("node:fs");
    const os = require("node:os");
    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "pdf test "));
    const testFile = path.join(tmpDir, "file.txt");

    try {
      fs.writeFileSync(testFile, "hello");
      allowedLocalDirs.add(tmpDir);

      // Encode spaces as %20 in the path (as some clients do)
      const encoded = testFile.replace(/ /g, "%20");
      const result = validateUrl(encoded);
      expect(result.valid).toBe(true);
    } finally {
      fs.rmSync(tmpDir, { recursive: true });
    }
  });

  it("should allow file accessed via symlink when real dir is allowed", () => {
    const fs = require("node:fs");
    const os = require("node:os");
    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "pdf-test-"));
    const realDir = path.join(tmpDir, "real");
    const linkDir = path.join(tmpDir, "link");
    const testFile = path.join(realDir, "test.txt");

    try {
      fs.mkdirSync(realDir);
      fs.writeFileSync(testFile, "hello");
      fs.symlinkSync(realDir, linkDir);

      // Allow the REAL directory
      allowedLocalDirs.add(realDir);

      // Access via the SYMLINK path — should still be allowed
      const symlinkPath = path.join(linkDir, "test.txt");
      const result = validateUrl(symlinkPath);
      expect(result.valid).toBe(true);
    } finally {
      fs.rmSync(tmpDir, { recursive: true });
    }
  });

  it("should allow file when allowed dir is a symlink to real parent", () => {
    const fs = require("node:fs");
    const os = require("node:os");
    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "pdf-test-"));
    const realDir = path.join(tmpDir, "real");
    const linkDir = path.join(tmpDir, "link");
    const testFile = path.join(realDir, "test.txt");

    try {
      fs.mkdirSync(realDir);
      fs.writeFileSync(testFile, "hello");
      fs.symlinkSync(realDir, linkDir);

      // Allow the SYMLINK directory
      allowedLocalDirs.add(linkDir);

      // Access via the REAL path — should still be allowed
      const result = validateUrl(testFile);
      expect(result.valid).toBe(true);
    } finally {
      fs.rmSync(tmpDir, { recursive: true });
    }
  });
});

describe("isAncestorDir", () => {
  it("should return true for a direct child", () => {
    expect(isAncestorDir("/Users/test/dir", "/Users/test/dir/file.pdf")).toBe(
      true,
    );
  });

  it("should return true for a nested child", () => {
    expect(isAncestorDir("/Users/test", "/Users/test/sub/dir/file.pdf")).toBe(
      true,
    );
  });

  it("should return false for a file outside the dir", () => {
    expect(isAncestorDir("/Users/test/dir", "/Users/test/other/file.pdf")).toBe(
      false,
    );
  });

  it("should return false for the dir itself", () => {
    expect(isAncestorDir("/Users/test/dir", "/Users/test/dir")).toBe(false);
  });

  it("should prevent .. traversal", () => {
    expect(
      isAncestorDir("/Users/test/dir", "/Users/test/dir/../other/file.pdf"),
    ).toBe(false);
  });

  it("should prevent prefix-based traversal", () => {
    // /tmp/safe should NOT match /tmp/safevil/file.pdf
    expect(isAncestorDir("/tmp/safe", "/tmp/safevil/file.pdf")).toBe(false);
  });

  it("should handle dirs with trailing slash", () => {
    expect(isAncestorDir("/Users/test/dir/", "/Users/test/dir/file.pdf")).toBe(
      true,
    );
  });
});