feat: add destructive command guard binary service

Refs #1056

Author: navedmerchant

src/services/destructive-command-guard/__tests__/manager.spec.ts

@@ -0,0 +1,249 @@
+import { createHash } from "crypto"
+import { EventEmitter } from "events"
+import { access, chmod, mkdtemp, mkdir, readFile, rm, stat, writeFile } from "fs/promises"
+import { tmpdir } from "os"
+import path from "path"
+import { PassThrough } from "stream"
+
+import { spawn } from "child_process"
+import { get } from "https"
+import type { IncomingMessage, RequestOptions } from "http"
+
+import { DCG_ARCHIVES, DCG_VERSION } from "../constants"
+import {
+	downloadFile,
+	extractSingleBinary,
+	getDcgArchiveInfo,
+	getDcgBinaryPath,
+	isDcgSupportedPlatform,
+	isTrustedDownloadUrl,
+	resolveTrustedRedirect,
+	ensureDcgInstalled,
+	verifyChecksum,
+} from "../manager"
+
+vi.mock("child_process", () => ({ spawn: vi.fn() }))
+vi.mock("https", () => ({ get: vi.fn() }))
+
+const mockSpawn = vi.mocked(spawn)
+const mockGet = vi.mocked(get)
+
+describe("Destructive Command Guard manager", () => {
+	let tempDir: string
+
+	beforeEach(async () => {
+		tempDir = await mkdtemp(path.join(tmpdir(), "dcg-manager-"))
+		mockSpawn.mockReset()
+		mockGet.mockReset()
+	})
+
+	afterEach(async () => {
+		await rm(tempDir, { recursive: true, force: true })
+	})
+
+	it("maps all supported platform and architecture combinations", () => {
+		expect(Object.keys(DCG_ARCHIVES).sort()).toEqual(["darwin-arm64", "linux-arm64", "linux-x64", "win32-x64"])
+		expect(getDcgArchiveInfo("darwin", "arm64")?.archive).toBe("dcg-aarch64-apple-darwin.tar.xz")
+		expect(getDcgArchiveInfo("win32", "x64")?.binary).toBe("dcg.exe")
+	})
+
+	it("rejects unsupported platforms", () => {
+		expect(isDcgSupportedPlatform("freebsd", "x64")).toBe(false)
+		expect(getDcgBinaryPath("/storage", "freebsd", "x64")).toBeUndefined()
+	})
+
+	it("returns the managed binary path", () => {
+		expect(getDcgBinaryPath("/storage", "linux", "x64")).toBe(
+			path.join("/storage", "destructive-command-guard", "dcg"),
+		)
+	})
+
+	it("accepts only HTTPS URLs on trusted host boundaries", () => {
+		expect(isTrustedDownloadUrl("https://github.com/release")).toBe(true)
+		expect(isTrustedDownloadUrl("https://cdn.objects.githubusercontent.com/release")).toBe(true)
+		expect(isTrustedDownloadUrl("http://github.com/release")).toBe(false)
+		expect(isTrustedDownloadUrl("https://evilgithub.com/release")).toBe(false)
+		expect(isTrustedDownloadUrl("not a URL")).toBe(false)
+	})
+
+	it("rejects untrusted download URLs before opening a destination", async () => {
+		await expect(downloadFile("https://example.com/dcg", path.join(tempDir, "archive"))).rejects.toThrow(
+			"DCG download redirected to an untrusted host",
+		)
+	})
+
+	it("allows trusted relative redirects and rejects unsafe or exhausted redirects", () => {
+		expect(resolveTrustedRedirect("https://github.com/release", "/asset", 5)).toBe("https://github.com/asset")
+		expect(() => resolveTrustedRedirect("https://github.com/release", "https://example.com/asset", 5)).toThrow(
+			"DCG download redirected to an untrusted host",
+		)
+		expect(() => resolveTrustedRedirect("https://github.com/release", "/asset", 0)).toThrow(
+			"Too many DCG download redirects",
+		)
+		expect(() => resolveTrustedRedirect("https://github.com/release", undefined, 5)).toThrow(
+			"Too many DCG download redirects",
+		)
+	})
+
+	it("verifies matching checksums and rejects mismatches", async () => {
+		const filePath = path.join(tempDir, "archive")
+		const contents = Buffer.from("verified archive")
+		await writeFile(filePath, contents)
+		const checksum = createHash("sha256").update(contents).digest("hex")
+
+		await expect(verifyChecksum(filePath, checksum)).resolves.toBeUndefined()
+		await expect(verifyChecksum(filePath, "0".repeat(64))).rejects.toThrow(
+			"DCG archive checksum verification failed",
+		)
+	})
+
+	it("uses the platform ZIP extractor", async () => {
+		const child = Object.assign(new EventEmitter(), {
+			stdout: new PassThrough(),
+			stderr: new PassThrough(),
+			kill: vi.fn(),
+		})
+		// The production code uses only the event and stream subset supplied by this test double.
+		mockSpawn.mockReturnValue(child as unknown as ReturnType<typeof spawn>)
+
+		const extraction = extractSingleBinary("C:\\dcg.zip", "C:\\staging", DCG_ARCHIVES["win32-x64"])
+		child.emit("close", 0)
+		await extraction
+
+		const expectedExecutable = process.platform === "win32" ? "powershell" : "unzip"
+		const expectedArgs =
+			process.platform === "win32"
+				? ["-NoProfile", "-Command", "Expand-Archive -Path 'C:\\dcg.zip' -DestinationPath 'C:\\staging' -Force"]
+				: ["-o", "C:\\dcg.zip", "-d", "C:\\staging"]
+
+		expect(mockSpawn).toHaveBeenCalledWith(expectedExecutable, expectedArgs, {
+			shell: false,
+			stdio: ["ignore", "pipe", "pipe"],
+		})
+	})
+
+	it("extracts tar archives without imposing a single-file layout", async () => {
+		const child = Object.assign(new EventEmitter(), {
+			stdout: new PassThrough(),
+			stderr: new PassThrough(),
+			kill: vi.fn(),
+		})
+		// The production code uses only the event and stream subset supplied by this test double.
+		mockSpawn.mockReturnValue(child as unknown as ReturnType<typeof spawn>)
+
+		const extraction = extractSingleBinary("/tmp/dcg.tar.xz", tempDir, DCG_ARCHIVES["linux-x64"])
+		child.emit("close", 0)
+
+		await expect(extraction).resolves.toBeUndefined()
+		expect(mockSpawn).toHaveBeenCalledTimes(1)
+		expect(mockSpawn).toHaveBeenCalledWith(
+			"tar",
+			expect.arrayContaining(["-xJf", "/tmp/dcg.tar.xz", "-C", tempDir, "--no-same-owner"]),
+			expect.objectContaining({ shell: false }),
+		)
+	})
+
+	it("surfaces process failures during extraction", async () => {
+		const child = Object.assign(new EventEmitter(), {
+			stdout: new PassThrough(),
+			stderr: new PassThrough(),
+			kill: vi.fn(),
+		})
+		mockSpawn.mockReturnValue(child as unknown as ReturnType<typeof spawn>)
+
+		const extraction = extractSingleBinary("/tmp/dcg.tar.xz", tempDir, DCG_ARCHIVES["linux-x64"])
+		child.stderr.write("invalid archive")
+		child.emit("close", 2)
+
+		await expect(extraction).rejects.toThrow("invalid archive")
+	})
+
+	it("reuses an existing managed binary and restores its executable permissions", async () => {
+		const binaryPath = getDcgBinaryPath(tempDir)
+		expect(binaryPath).toBeDefined()
+		await mkdir(path.dirname(binaryPath!), { recursive: true })
+		await writeFile(binaryPath!, "existing binary")
+		await writeFile(path.join(path.dirname(binaryPath!), ".dcg-version"), DCG_VERSION)
+		if (process.platform !== "win32") {
+			await chmod(binaryPath!, 0o600)
+		}
+
+		await expect(ensureDcgInstalled(tempDir)).resolves.toBe(binaryPath)
+		expect(mockSpawn).not.toHaveBeenCalled()
+		if (process.platform !== "win32") {
+			expect((await stat(binaryPath!)).mode & 0o111).toBe(0o111)
+		}
+	})
+
+	it("downloads, verifies, extracts, and deduplicates a new installation", async () => {
+		const info = getDcgArchiveInfo()
+		expect(info).toBeDefined()
+		if (!info || info.archive.endsWith(".zip")) return
+
+		const archive = Buffer.from("test archive")
+		const originalChecksum = info.sha256
+		Object.defineProperty(info, "sha256", {
+			value: createHash("sha256").update(archive).digest("hex"),
+			configurable: true,
+		})
+		const response = Object.assign(new PassThrough(), {
+			statusCode: 200,
+			headers: { "content-length": String(archive.length) },
+		})
+		const request = Object.assign(new EventEmitter(), {
+			setTimeout: vi.fn(),
+			destroy: vi.fn(),
+		})
+		mockGet.mockImplementation(
+			(
+				_url: string | URL,
+				optionsOrCallback: RequestOptions | ((response: IncomingMessage) => void),
+				optionalCallback?: (response: IncomingMessage) => void,
+			) => {
+				const callback = typeof optionsOrCallback === "function" ? optionsOrCallback : optionalCallback
+				setImmediate(() => {
+					// The downloader uses only the response stream/status subset supplied here.
+					callback?.(response as unknown as IncomingMessage)
+					response.end(archive)
+				})
+				// The downloader uses only timeout/error handling from ClientRequest.
+				return request as unknown as ReturnType<typeof get>
+			},
+		)
+
+		mockSpawn.mockImplementation((executable, args) => {
+			const child = Object.assign(new EventEmitter(), {
+				stdout: new PassThrough(),
+				stderr: new PassThrough(),
+				kill: vi.fn(),
+			})
+			setImmediate(async () => {
+				if (executable === "tar") {
+					const stagingDir = args[args.indexOf("-C") + 1]
+					await writeFile(path.join(stagingDir, info.binary), "executable")
+				}
+				child.emit("close", 0)
+			})
+			// The process runner uses only the event and stream subset supplied here.
+			return child as unknown as ReturnType<typeof spawn>
+		})
+
+		try {
+			const firstInstallation = ensureDcgInstalled(tempDir)
+			const concurrentInstallation = ensureDcgInstalled(tempDir)
+			expect(concurrentInstallation).toBe(firstInstallation)
+
+			const binaryPath = await firstInstallation
+			if (!binaryPath) throw new Error("Expected DCG to be supported in this test")
+			expect(await readFile(binaryPath, "utf8")).toBe("executable")
+			expect(mockGet).toHaveBeenCalledTimes(1)
+			expect(mockSpawn).toHaveBeenCalledTimes(1)
+			await expect(access(path.join(tempDir, `${DCG_VERSION}-${info.archive}`))).rejects.toThrow()
+			expect(await readFile(path.join(tempDir, "destructive-command-guard", ".dcg-version"), "utf8")).toBe(
+				DCG_VERSION,
+			)
+		} finally {
+			Object.defineProperty(info, "sha256", { value: originalChecksum, configurable: true })
+		}
+	})
+})

src/services/destructive-command-guard/__tests__/runner.spec.ts

@@ -0,0 +1,126 @@
+import { EventEmitter } from "events"
+import { PassThrough } from "stream"
+
+import { spawn } from "child_process"
+
+import { DCG_MAX_OUTPUT_BYTES } from "../constants"
+import { runDcg } from "../runner"
+
+vi.mock("child_process", () => ({ spawn: vi.fn() }))
+
+type MockChild = EventEmitter & {
+	stdout: PassThrough
+	stderr: PassThrough
+	kill: ReturnType<typeof vi.fn>
+}
+
+const mockSpawn = vi.mocked(spawn)
+
+const useChild = (child: MockChild): void => {
+	// runDcg uses only the event, stream, and kill subset supplied by this test double.
+	mockSpawn.mockReturnValue(child as unknown as ReturnType<typeof spawn>)
+}
+
+function createChild(): MockChild {
+	return Object.assign(new EventEmitter(), {
+		stdout: new PassThrough(),
+		stderr: new PassThrough(),
+		kill: vi.fn(),
+	})
+}
+
+function emitResult(child: MockChild, payload: unknown, code: number): void {
+	child.stdout.write(JSON.stringify(payload))
+	child.emit("close", code, null)
+}
+
+describe("runDcg", () => {
+	beforeEach(() => {
+		vi.useRealTimers()
+		mockSpawn.mockReset()
+	})
+
+	afterEach(() => vi.useRealTimers())
+
+	it.each([
+		[{ schema_version: 1, decision: "allow" }, 0, { decision: "allow" }],
+		[
+			{ schema_version: 2, decision: "deny", reason: "unsafe", rule_id: "delete" },
+			1,
+			{ decision: "deny", reason: "unsafe", ruleId: "delete" },
+		],
+		[
+			{ schema_version: 2, decision: "deny", pack_id: "core", pattern_name: "delete" },
+			1,
+			{ decision: "deny", ruleId: "core:delete" },
+		],
+	])("accepts valid DCG result %#", async (payload, code, expected) => {
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		emitResult(child, payload, code)
+
+		await expect(result).resolves.toEqual(expected)
+	})
+
+	it.each([
+		["not json", 0, "DCG returned invalid JSON"],
+		[JSON.stringify({ schema_version: 3, decision: "allow" }), 0, "DCG returned an unsupported response schema"],
+		[JSON.stringify({ schema_version: 1, decision: "deny" }), 0, "DCG decision did not match its exit status"],
+	])("rejects invalid output %#", async (output, code, message) => {
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		child.stdout.write(output)
+		child.emit("close", code, null)
+
+		await expect(result).rejects.toThrow(message)
+	})
+
+	it("rejects non-DCG exit statuses with stderr", async () => {
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		child.stderr.write("failure details")
+		child.emit("close", 2, null)
+
+		await expect(result).rejects.toThrow("DCG evaluation failed: failure details")
+	})
+
+	it("rejects process startup errors", async () => {
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		child.emit("error", new Error("ENOENT"))
+
+		await expect(result).rejects.toThrow("Unable to start DCG: ENOENT")
+	})
+
+	it("rejects excessive output and kills the process", async () => {
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		child.stdout.write(Buffer.alloc(DCG_MAX_OUTPUT_BYTES + 1))
+
+		await expect(result).rejects.toThrow("DCG produced too much output")
+		expect(child.kill).toHaveBeenCalledWith("SIGKILL")
+	})
+
+	it("times out and kills the process", async () => {
+		vi.useFakeTimers()
+		const child = createChild()
+		useChild(child)
+
+		const result = runDcg("/dcg", "echo test", "/workspace")
+		const rejection = expect(result).rejects.toThrow("DCG evaluation timed out")
+		await vi.runAllTimersAsync()
+
+		await rejection
+		expect(child.kill).toHaveBeenCalledWith("SIGKILL")
+	})
+})