mfer/mfer/gpg_test.go

//nolint:testpackage // white-box tests exercise unexported internals
package mfer

import (
	"bytes"
	"context"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"github.com/spf13/afero"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// testGPGEnv sets up a temporary GPG home directory with a test key.
// Returns the key ID and the GPG home directory; callers must point
// GNUPGHOME at the returned directory (via t.Setenv) before using the
// gpg helpers under test.
func testGPGEnv(t *testing.T) (GPGKeyID, string) {
	t.Helper()

	// Check if gpg is installed
	_, err := exec.LookPath("gpg")
	if err != nil {
		t.Skip("gpg not installed, skipping signing test")
	}

	// Create temporary GPG home directory (0700 by default)
	gpgHome := t.TempDir()

	// Generate a test key with no passphrase
	keyParams := `%no-protection
Key-Type: RSA
Key-Length: 2048
Name-Real: MFER Test Key
Name-Email: test@mfer.test
Expire-Date: 0
%commit
`
	paramsFile := filepath.Join(gpgHome, "key-params")
	require.NoError(t, os.WriteFile(paramsFile, []byte(keyParams), 0o600))

	ctx, cancel := context.WithTimeout(context.Background(), gpgTimeout)
	defer cancel()

	//nolint:gosec // paramsFile is a test-controlled path inside t.TempDir()
	cmd := exec.CommandContext(ctx, "gpg",
		"--batch", "--gen-key", paramsFile)

	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)

	output, err := cmd.CombinedOutput()
	if err != nil {
		t.Skipf("failed to generate test GPG key: %v: %s", err, output)
	}

	// Get the key fingerprint
	cmd = exec.CommandContext(ctx, "gpg",
		"--list-keys", "--with-colons", "test@mfer.test")

	cmd.Env = append(os.Environ(), "GNUPGHOME="+gpgHome)

	output, err = cmd.Output()
	if err != nil {
		t.Fatalf("failed to list test key: %v", err)
	}

	// Parse fingerprint from output
	var keyID string

	for _, line := range strings.Split(string(output), "\n") {
		fields := strings.Split(line, ":")
		if len(fields) >= gpgFingerprintMinFields &&
			fields[0] == gpgFingerprintField {
			keyID = fields[9]

			break
		}
	}

	if keyID == "" {
		t.Fatal("failed to find test key fingerprint")
	}

	return GPGKeyID(keyID), gpgHome
}

func TestGPGSign(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	data := []byte("test data to sign")
	sig, err := gpgSign(context.Background(), data, keyID)
	require.NoError(t, err)
	assert.NotEmpty(t, sig)
	assert.Contains(t, string(sig), "-----BEGIN PGP SIGNATURE-----")
	assert.Contains(t, string(sig), "-----END PGP SIGNATURE-----")
}

func TestGPGExportPublicKey(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
	require.NoError(t, err)
	assert.NotEmpty(t, pubKey)
	assert.Contains(t, string(pubKey), "-----BEGIN PGP PUBLIC KEY BLOCK-----")
	assert.Contains(t, string(pubKey), "-----END PGP PUBLIC KEY BLOCK-----")
}

func TestGPGGetKeyFingerprint(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	fingerprint, err := gpgGetKeyFingerprint(context.Background(), keyID)
	require.NoError(t, err)
	assert.NotEmpty(t, fingerprint)
	// The fingerprint should be 40 hex chars
	assert.Len(t, fingerprint, 40, "fingerprint should be 40 hex chars")
}

// TestGPGArgsSeparatesPositionals pins that caller-supplied values are
// placed after an end-of-options marker. Key IDs arrive from --sign-key
// and MFER_SIGN_KEY as bare positional arguments, so without the marker
// a value beginning with "-" would be parsed by gpg as one of its own
// options.
func TestGPGArgsSeparatesPositionals(t *testing.T) {
	t.Parallel()

	assert.Equal(t,
		[]string{"--opt-a", "--opt-b", "--", "--version"},
		gpgArgs([]string{"--opt-a", "--opt-b"}, "--version"))

	assert.Equal(t,
		[]string{"--opt-c", "--", "sig", "data"},
		gpgArgs([]string{"--opt-c"}, "sig", "data"))

	assert.Equal(t, []string{"--opt-d", "--"},
		gpgArgs([]string{"--opt-d"}))
}

// TestGPGOptionLikeKeyIDIsNotAnOption drives real gpg with a key ID that
// looks like an option and asserts it is treated as a (nonexistent) key
// rather than executed as gpg's own --version.
func TestGPGOptionLikeKeyIDIsNotAnOption(t *testing.T) {
	_, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	pubKey, err := gpgExportPublicKey(context.Background(), GPGKeyID("--version"))
	require.Error(t, err)
	require.ErrorIs(t, err, errGPGKeyNotFound)
	assert.NotContains(t, string(pubKey), "gpg (GnuPG)")

	fpr, err := gpgGetKeyFingerprint(context.Background(), GPGKeyID("--version"))
	require.Error(t, err)
	assert.NotContains(t, string(fpr), "gpg (GnuPG)")
}

func TestGPGSignInvalidKey(t *testing.T) {
	// Set up test environment (we need GNUPGHOME set)
	_, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	data := []byte("test data")
	_, err := gpgSign(context.Background(), data,
		GPGKeyID("NONEXISTENT_KEY_ID_12345"))
	assert.Error(t, err)
}

func TestBuilderWithSigning(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	// Create a builder with signing options
	b := NewBuilder()
	b.SetSigningOptions(&SigningOptions{
		KeyID: keyID,
	})

	// Add a test file
	content := []byte("test file content")
	reader := bytes.NewReader(content)
	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime{}, reader, nil)
	require.NoError(t, err)

	// Build the manifest
	var buf bytes.Buffer

	err = b.Build(context.Background(), &buf)
	require.NoError(t, err)

	// Parse the manifest and verify signature fields are populated
	manifest, err := NewManifestFromReader(&buf)
	require.NoError(t, err)
	require.NotNil(t, manifest.pbOuter)

	assert.NotEmpty(t, manifest.pbOuter.GetSignature(),
		"signature should be populated")
	assert.NotEmpty(t, manifest.pbOuter.GetSigner(), "signer should be populated")
	assert.NotEmpty(t, manifest.pbOuter.GetSigningPubKey(),
		"signing public key should be populated")

	// Verify signature is a valid PGP signature
	assert.Contains(t, string(manifest.pbOuter.GetSignature()),
		"-----BEGIN PGP SIGNATURE-----")

	// Verify public key is a valid PGP public key block
	assert.Contains(t, string(manifest.pbOuter.GetSigningPubKey()),
		"-----BEGIN PGP PUBLIC KEY BLOCK-----")
}

func TestScannerWithSigning(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	// Create in-memory filesystem with test files
	fs := afero.NewMemMapFs()
	require.NoError(t, fs.MkdirAll("/testdir", 0o755))
	require.NoError(t,
		afero.WriteFile(fs, "/testdir/file1.txt", []byte("content1"), 0o644))
	require.NoError(t,
		afero.WriteFile(fs, "/testdir/file2.txt", []byte("content2"), 0o644))

	// Create scanner with signing options
	opts := &ScannerOptions{
		Fs: fs,
		SigningOptions: &SigningOptions{
			KeyID: keyID,
		},
	}
	s := NewScannerWithOptions(opts)

	// Enumerate files
	require.NoError(t, s.EnumeratePath("/testdir", nil))
	assert.Equal(t, FileCount(2), s.FileCount())

	// Generate signed manifest
	var buf bytes.Buffer
	require.NoError(t, s.ToManifest(context.Background(), &buf, nil))

	// Parse and verify
	manifest, err := NewManifestFromReader(&buf)
	require.NoError(t, err)

	assert.NotEmpty(t, manifest.pbOuter.GetSignature())
	assert.NotEmpty(t, manifest.pbOuter.GetSigner())
	assert.NotEmpty(t, manifest.pbOuter.GetSigningPubKey())
}

func TestGPGVerify(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	data := []byte("test data to sign and verify")
	sig, err := gpgSign(context.Background(), data, keyID)
	require.NoError(t, err)

	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
	require.NoError(t, err)

	// Verify the signature
	err = gpgVerify(context.Background(), data, sig, pubKey)
	require.NoError(t, err)
}

func TestGPGVerifyInvalidSignature(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	data := []byte("test data to sign")
	sig, err := gpgSign(context.Background(), data, keyID)
	require.NoError(t, err)

	pubKey, err := gpgExportPublicKey(context.Background(), keyID)
	require.NoError(t, err)

	// Try to verify with different data - should fail
	wrongData := []byte("different data")
	err = gpgVerify(context.Background(), wrongData, sig, pubKey)
	assert.Error(t, err)
}

func TestGPGVerifyBadPublicKey(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	data := []byte("test data")
	sig, err := gpgSign(context.Background(), data, keyID)
	require.NoError(t, err)

	// Try to verify with invalid public key - should fail
	badPubKey := []byte("not a valid public key")
	err = gpgVerify(context.Background(), data, sig, badPubKey)
	assert.Error(t, err)
}

func TestManifestSignatureVerification(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	// Create a builder with signing options
	b := NewBuilder()
	b.SetSigningOptions(&SigningOptions{
		KeyID: keyID,
	})

	// Add a test file
	content := []byte("test file content for verification")
	reader := bytes.NewReader(content)
	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime{}, reader, nil)
	require.NoError(t, err)

	// Build the manifest
	var buf bytes.Buffer

	err = b.Build(context.Background(), &buf)
	require.NoError(t, err)

	// Parse the manifest - signature should be verified during load
	manifest, err := NewManifestFromReader(&buf)
	require.NoError(t, err)
	require.NotNil(t, manifest)

	// Signature should be present and valid
	assert.NotEmpty(t, manifest.pbOuter.GetSignature())
}

func TestManifestTamperedSignatureFails(t *testing.T) {
	keyID, gpgHome := testGPGEnv(t)
	t.Setenv("GNUPGHOME", gpgHome)

	// Create a signed manifest
	b := NewBuilder()
	b.SetSigningOptions(&SigningOptions{
		KeyID: keyID,
	})

	content := []byte("test file content")
	reader := bytes.NewReader(content)
	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime{}, reader, nil)
	require.NoError(t, err)

	var buf bytes.Buffer

	err = b.Build(context.Background(), &buf)
	require.NoError(t, err)

	// Tamper with the signature by replacing some bytes
	data := buf.Bytes()
	// Find and modify a byte in the signature portion
	for i := range data {
		if i > 100 && data[i] == 'A' {
			data[i] = 'B'

			break
		}
	}

	// Try to load the tampered manifest - should fail
	_, err = NewManifestFromReader(bytes.NewReader(data))
	assert.Error(t, err)
}

func TestBuilderWithoutSigning(t *testing.T) {
	t.Parallel()

	// Create a builder without signing options
	b := NewBuilder()

	// Add a test file
	content := []byte("test file content")
	reader := bytes.NewReader(content)
	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime{}, reader, nil)
	require.NoError(t, err)

	// Build the manifest
	var buf bytes.Buffer

	err = b.Build(context.Background(), &buf)
	require.NoError(t, err)

	// Parse the manifest and verify signature fields are empty
	manifest, err := NewManifestFromReader(&buf)
	require.NoError(t, err)
	require.NotNil(t, manifest.pbOuter)

	assert.Empty(t, manifest.pbOuter.GetSignature(),
		"signature should be empty when not signing")
	assert.Empty(t, manifest.pbOuter.GetSigner(),
		"signer should be empty when not signing")
	assert.Empty(t, manifest.pbOuter.GetSigningPubKey(),
		"signing public key should be empty when not signing")
}

// fakeGPGPath writes script as an executable named gpg into a temporary
// directory and returns a PATH value with that directory first.
func fakeGPGPath(t *testing.T, script string) string {
	t.Helper()

	binDir := t.TempDir()
	//nolint:gosec // G306: the fake gpg has to be executable
	require.NoError(t, os.WriteFile(filepath.Join(binDir, "gpg"),
		[]byte(script), 0o700))

	return binDir + string(os.PathListSeparator) + os.Getenv("PATH")
}

// TestGPGTimeoutKillsGPG puts a fake gpg that never finishes first on
// PATH and checks that a run past its deadline is killed and reported as
// a timeout of the named operation, instead of hanging.
func TestGPGTimeoutKillsGPG(t *testing.T) {
	t.Setenv("PATH", fakeGPGPath(t, "#!/bin/sh\nexec sleep 10\n"))

	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()

	_, err := gpgSign(ctx, []byte("data"), GPGKeyID("any"))
	require.ErrorIs(t, err, context.DeadlineExceeded)
	assert.Contains(t, err.Error(), "gpg sign failed: gpg timed out")
}

// TestGPGTimeoutWhenChildHoldsOutput uses a fake gpg that runs sleep as a
// child instead of exec-ing it, the way a wrapper script around the real
// gpg might. Killing the fake gpg leaves sleep holding its stdout and
// stderr open; the call must still return shortly after the deadline
// instead of waiting for sleep to exit. The fake gpg writes the process ID
// of sleep to a file so that the test can kill it before returning.
func TestGPGTimeoutWhenChildHoldsOutput(t *testing.T) {
	pidFile := filepath.Join(t.TempDir(), "sleep.pid")
	t.Setenv("PATH", fakeGPGPath(t,
		"#!/bin/sh\nsleep 3 &\necho $! >'"+pidFile+"'\nwait\n"))
	t.Cleanup(func() {
		pid, err := os.ReadFile(pidFile) //nolint:gosec // G304: path inside t.TempDir()
		require.NoError(t, err)

		n, err := strconv.Atoi(strings.TrimSpace(string(pid)))
		require.NoError(t, err)

		sleep, err := os.FindProcess(n)
		require.NoError(t, err)
		require.NoError(t, sleep.Kill())
	})

	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()

	start := time.Now()
	_, err := gpgSign(ctx, []byte("data"), GPGKeyID("any"))
	require.ErrorIs(t, err, context.DeadlineExceeded)
	assert.Less(t, time.Since(start), 3*time.Second,
		"the call waited for the child holding gpg's output to exit")
}

// TestBuildPassesContextToSigning checks that a caller can cancel the gpg
// runs that sign a manifest through the context given to Build.
func TestBuildPassesContextToSigning(t *testing.T) {
	t.Parallel()

	b := NewBuilder()
	b.SetSigningOptions(&SigningOptions{KeyID: "any"})

	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	require.ErrorIs(t, b.Build(ctx, io.Discard), context.Canceled)
}