Merge fix/coverage-M.SSH-extended: Bundle M.SSH-extended — SSH 71.6% -> 90.2%; H-002 closed

2026-06-07 13:41:30 +00:00 · 2026-04-27 19:07:38 +00:00
parent 04bf657548 dfb083c9f4
commit 8e84f27f63
1 changed files with 628 additions and 0 deletions
@@ -0,0 +1,628 @@
+package ssh
+
+import (
+	"bytes"
+	"context"
+	"crypto/ed25519"
+	"crypto/rand"
+	"errors"
+	"io"
+	"net"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/pkg/sftp"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+// Bundle M.SSH-extended (H-002 closure): in-process SSH server fixture that
+// exercises realSSHClient.Connect, Execute, WriteFile, StatFile, and Close
+// end-to-end. Same pattern as M.Email's hand-rolled SMTP fixture — minimal
+// in-process protocol server bound to net.Listen("tcp", "127.0.0.1:0") with
+// t.Cleanup-driven shutdown.
+//
+// The SSH server uses Ed25519 host keys (lightest crypto for tests),
+// password authentication (simplest auth), and supports two channel types:
+//
+//   - "session" with "exec" subsystem — used by realSSHClient.Execute
+//   - "session" with "subsystem sftp" — used by realSSHClient.WriteFile,
+//     StatFile (proxied through pkg/sftp.NewServer over the channel)
+//
+// The fixture lives in tests only; production code never imports it.
+
+// fakeSSHServer is a minimal in-process SSH server bound to a random port.
+type fakeSSHServer struct {
+	t        *testing.T
+	listener net.Listener
+	addr     string
+	user     string
+	password string
+
+	wg       sync.WaitGroup
+	mu       sync.Mutex
+	closed   bool
+
+	// Optional behaviour toggles for failure-mode tests.
+	rejectAuth      bool   // reject all auth attempts (auth failure path)
+	dropOnHandshake bool   // close conn before SSH NewServerConn returns (handshake failure)
+	failExec        bool   // exec sessions return non-zero exit (Execute error path)
+	failSFTP        bool   // refuse sftp subsystem (SFTP failure path)
+}
+
+// startFakeSSHServer binds a fresh server on a random local port and returns
+// it ready to accept Connect calls. t.Cleanup is wired to close the listener
+// + drain in-flight handlers.
+func startFakeSSHServer(t *testing.T, opts ...func(*fakeSSHServer)) *fakeSSHServer {
+	t.Helper()
+
+	srv := &fakeSSHServer{
+		t:        t,
+		user:     "testuser",
+		password: "testpass",
+	}
+	for _, opt := range opts {
+		opt(srv)
+	}
+
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen: %v", err)
+	}
+	srv.listener = listener
+	srv.addr = listener.Addr().String()
+
+	t.Cleanup(srv.Close)
+
+	srv.wg.Add(1)
+	go srv.acceptLoop()
+
+	return srv
+}
+
+// host returns the host:port the listener is bound to. Splits via SplitHostPort
+// so the test caller can pass them separately to Config.
+func (s *fakeSSHServer) hostPort() (string, int) {
+	host, portStr, err := net.SplitHostPort(s.addr)
+	if err != nil {
+		s.t.Fatalf("SplitHostPort: %v", err)
+	}
+	var port int
+	for _, c := range portStr {
+		if c >= '0' && c <= '9' {
+			port = port*10 + int(c-'0')
+		}
+	}
+	return host, port
+}
+
+func (s *fakeSSHServer) Close() {
+	s.mu.Lock()
+	if s.closed {
+		s.mu.Unlock()
+		return
+	}
+	s.closed = true
+	s.mu.Unlock()
+
+	_ = s.listener.Close()
+	s.wg.Wait()
+}
+
+func (s *fakeSSHServer) acceptLoop() {
+	defer s.wg.Done()
+	// Generate a fresh Ed25519 host key for this server instance.
+	_, hostKey, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		s.t.Errorf("ed25519.GenerateKey: %v", err)
+		return
+	}
+	signer, err := gossh.NewSignerFromKey(hostKey)
+	if err != nil {
+		s.t.Errorf("NewSignerFromKey: %v", err)
+		return
+	}
+
+	cfg := &gossh.ServerConfig{
+		PasswordCallback: func(c gossh.ConnMetadata, p []byte) (*gossh.Permissions, error) {
+			if s.rejectAuth {
+				return nil, errors.New("auth rejected (test fixture)")
+			}
+			if c.User() == s.user && string(p) == s.password {
+				return &gossh.Permissions{}, nil
+			}
+			return nil, errors.New("invalid credentials")
+		},
+		PublicKeyCallback: func(c gossh.ConnMetadata, key gossh.PublicKey) (*gossh.Permissions, error) {
+			if s.rejectAuth {
+				return nil, errors.New("auth rejected (test fixture)")
+			}
+			// Accept any pubkey; testers using key-auth don't need to also
+			// configure trust, since this is a pure connectivity fixture.
+			return &gossh.Permissions{}, nil
+		},
+	}
+	cfg.AddHostKey(signer)
+
+	for {
+		conn, err := s.listener.Accept()
+		if err != nil {
+			// Listener closed — exit cleanly.
+			return
+		}
+
+		s.wg.Add(1)
+		go func(c net.Conn) {
+			defer s.wg.Done()
+			s.handleConn(c, cfg)
+		}(conn)
+	}
+}
+
+func (s *fakeSSHServer) handleConn(nConn net.Conn, cfg *gossh.ServerConfig) {
+	defer nConn.Close()
+
+	if s.dropOnHandshake {
+		// Close immediately to surface a handshake error on the client side.
+		return
+	}
+
+	_, chans, reqs, err := gossh.NewServerConn(nConn, cfg)
+	if err != nil {
+		// Common: closed connection during handshake (test cleanup, auth fail).
+		return
+	}
+	go gossh.DiscardRequests(reqs)
+
+	for newCh := range chans {
+		if newCh.ChannelType() != "session" {
+			_ = newCh.Reject(gossh.UnknownChannelType, "unknown channel type")
+			continue
+		}
+		ch, requests, err := newCh.Accept()
+		if err != nil {
+			continue
+		}
+		s.wg.Add(1)
+		go func() {
+			defer s.wg.Done()
+			s.handleSession(ch, requests)
+		}()
+	}
+}
+
+func (s *fakeSSHServer) handleSession(ch gossh.Channel, reqs <-chan *gossh.Request) {
+	defer ch.Close()
+
+	for req := range reqs {
+		switch req.Type {
+		case "exec":
+			if s.failExec {
+				_ = req.Reply(true, nil)
+				_, _ = ch.Write([]byte("exec failure (test fixture)\n"))
+				_, _ = ch.SendRequest("exit-status", false, []byte{0, 0, 0, 1}) // exit code 1
+				return
+			}
+			// Echo back a canned success response so Execute returns without error.
+			_ = req.Reply(true, nil)
+			_, _ = ch.Write([]byte("exec ok\n"))
+			_, _ = ch.SendRequest("exit-status", false, []byte{0, 0, 0, 0}) // exit code 0
+			return
+
+		case "subsystem":
+			// Payload is the subsystem name in standard SSH wire form: 4-byte
+			// length prefix + bytes. Look for "sftp".
+			if len(req.Payload) >= 4 {
+				name := string(req.Payload[4:])
+				if name == "sftp" {
+					if s.failSFTP {
+						_ = req.Reply(false, nil)
+						return
+					}
+					_ = req.Reply(true, nil)
+					srv, err := sftp.NewServer(ch)
+					if err != nil {
+						return
+					}
+					_ = srv.Serve()
+					return
+				}
+			}
+			_ = req.Reply(false, nil)
+
+		default:
+			if req.WantReply {
+				_ = req.Reply(false, nil)
+			}
+		}
+	}
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Connect happy path / failure paths
+// ─────────────────────────────────────────────────────────────────────────────
+
+func TestRealSSHClient_Connect_Password_Success(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host:       host,
+		Port:       port,
+		User:       srv.user,
+		AuthMethod: "password",
+		Password:   srv.password,
+		Timeout:    5,
+	}}
+
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	defer c.Close()
+
+	if c.sshClient == nil {
+		t.Errorf("expected sshClient to be set after Connect")
+	}
+	if c.sftpClient == nil {
+		t.Errorf("expected sftpClient to be set after Connect")
+	}
+}
+
+func TestRealSSHClient_Connect_Password_WrongPassword(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host:       host,
+		Port:       port,
+		User:       srv.user,
+		AuthMethod: "password",
+		Password:   "wrong-password",
+		Timeout:    5,
+	}}
+
+	if err := c.Connect(context.Background()); err == nil {
+		t.Errorf("expected wrong-password to fail Connect")
+		_ = c.Close()
+	}
+}
+
+func TestRealSSHClient_Connect_AuthRejected_AllAttempts(t *testing.T) {
+	srv := startFakeSSHServer(t, func(s *fakeSSHServer) { s.rejectAuth = true })
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host:       host,
+		Port:       port,
+		User:       srv.user,
+		AuthMethod: "password",
+		Password:   srv.password,
+		Timeout:    5,
+	}}
+
+	if err := c.Connect(context.Background()); err == nil {
+		t.Errorf("expected auth rejection to fail Connect")
+		_ = c.Close()
+	} else if !strings.Contains(err.Error(), "SSH handshake") {
+		t.Errorf("expected handshake error, got %v", err)
+	}
+}
+
+func TestRealSSHClient_Connect_HandshakeDropped(t *testing.T) {
+	srv := startFakeSSHServer(t, func(s *fakeSSHServer) { s.dropOnHandshake = true })
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host:       host,
+		Port:       port,
+		User:       srv.user,
+		AuthMethod: "password",
+		Password:   srv.password,
+		Timeout:    5,
+	}}
+
+	if err := c.Connect(context.Background()); err == nil {
+		t.Errorf("expected handshake-drop to fail Connect")
+		_ = c.Close()
+	}
+}
+
+func TestRealSSHClient_Connect_TCPConnRefused(t *testing.T) {
+	// Bind a listener, immediately close it — the port is still allocated
+	// but no one is listening. Connect must return a TCP-connection error.
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen: %v", err)
+	}
+	addr := listener.Addr().String()
+	_ = listener.Close()
+
+	host, portStr, _ := net.SplitHostPort(addr)
+	var port int
+	for _, c := range portStr {
+		if c >= '0' && c <= '9' {
+			port = port*10 + int(c-'0')
+		}
+	}
+
+	c := &realSSHClient{config: &Config{
+		Host:       host,
+		Port:       port,
+		User:       "anyone",
+		AuthMethod: "password",
+		Password:   "anything",
+		Timeout:    1, // 1-second timeout
+	}}
+
+	if err := c.Connect(context.Background()); err == nil {
+		t.Errorf("expected TCP-refused, got nil")
+		_ = c.Close()
+	} else if !strings.Contains(err.Error(), "TCP connection") {
+		t.Errorf("expected TCP-connection error, got %v", err)
+	}
+}
+
+func TestRealSSHClient_Connect_KeyAuth_Success(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+
+	// Generate an ed25519 client key and serialize it to OpenSSH PEM.
+	pub, priv, err := ed25519.GenerateKey(rand.Reader)
+	_ = pub
+	if err != nil {
+		t.Fatalf("ed25519.GenerateKey: %v", err)
+	}
+	pemBlock, err := gossh.MarshalPrivateKey(priv, "test-key")
+	if err != nil {
+		t.Fatalf("MarshalPrivateKey: %v", err)
+	}
+	keyPath := filepath.Join(t.TempDir(), "id_test")
+	if err := os.WriteFile(keyPath, encodePEMBlock(pemBlock.Type, pemBlock.Bytes), 0600); err != nil {
+		t.Fatalf("WriteFile key: %v", err)
+	}
+
+	c := &realSSHClient{config: &Config{
+		Host:           host,
+		Port:           port,
+		User:           srv.user,
+		AuthMethod:     "key",
+		PrivateKeyPath: keyPath,
+		Timeout:        5,
+	}}
+
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect (key auth): %v", err)
+	}
+	defer c.Close()
+}
+
+// encodePEMBlock builds a minimal PEM-format block with the given type+bytes.
+// (Avoids pulling in encoding/pem in the test header — it's already imported
+// transitively but this keeps the import list minimal.)
+func encodePEMBlock(blockType string, blockBytes []byte) []byte {
+	var buf bytes.Buffer
+	buf.WriteString("-----BEGIN ")
+	buf.WriteString(blockType)
+	buf.WriteString("-----\n")
+	// Base64-encode in 64-char lines.
+	enc := base64Encode(blockBytes)
+	for i := 0; i < len(enc); i += 64 {
+		end := i + 64
+		if end > len(enc) {
+			end = len(enc)
+		}
+		buf.Write(enc[i:end])
+		buf.WriteByte('\n')
+	}
+	buf.WriteString("-----END ")
+	buf.WriteString(blockType)
+	buf.WriteString("-----\n")
+	return buf.Bytes()
+}
+
+func base64Encode(in []byte) []byte {
+	const enc = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+	out := make([]byte, (len(in)+2)/3*4)
+	j := 0
+	for i := 0; i < len(in); i += 3 {
+		var v uint32
+		v = uint32(in[i]) << 16
+		if i+1 < len(in) {
+			v |= uint32(in[i+1]) << 8
+		}
+		if i+2 < len(in) {
+			v |= uint32(in[i+2])
+		}
+		out[j] = enc[(v>>18)&0x3f]
+		out[j+1] = enc[(v>>12)&0x3f]
+		if i+1 < len(in) {
+			out[j+2] = enc[(v>>6)&0x3f]
+		} else {
+			out[j+2] = '='
+		}
+		if i+2 < len(in) {
+			out[j+3] = enc[v&0x3f]
+		} else {
+			out[j+3] = '='
+		}
+		j += 4
+	}
+	return out
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Execute
+// ─────────────────────────────────────────────────────────────────────────────
+
+func TestRealSSHClient_Execute_Success(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host: host, Port: port, User: srv.user,
+		AuthMethod: "password", Password: srv.password, Timeout: 5,
+	}}
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	defer c.Close()
+
+	out, err := c.Execute(context.Background(), "echo hello")
+	if err != nil {
+		t.Fatalf("Execute: %v", err)
+	}
+	if !strings.Contains(out, "exec ok") {
+		t.Errorf("expected canned 'exec ok' output, got %q", out)
+	}
+}
+
+func TestRealSSHClient_Execute_NotConnected(t *testing.T) {
+	c := &realSSHClient{config: &Config{}}
+	if _, err := c.Execute(context.Background(), "anything"); err == nil {
+		t.Errorf("expected error when sshClient is nil")
+	}
+}
+
+func TestRealSSHClient_Execute_ExitCode1(t *testing.T) {
+	srv := startFakeSSHServer(t, func(s *fakeSSHServer) { s.failExec = true })
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host: host, Port: port, User: srv.user,
+		AuthMethod: "password", Password: srv.password, Timeout: 5,
+	}}
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	defer c.Close()
+
+	out, err := c.Execute(context.Background(), "anything")
+	if err == nil {
+		t.Errorf("expected non-zero exit code to surface as error; got out=%q", out)
+	}
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// WriteFile / StatFile via SFTP
+// ─────────────────────────────────────────────────────────────────────────────
+
+func TestRealSSHClient_WriteFile_StatFile_RoundTrip(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+
+	c := &realSSHClient{config: &Config{
+		Host: host, Port: port, User: srv.user,
+		AuthMethod: "password", Password: srv.password, Timeout: 5,
+	}}
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	defer c.Close()
+
+	// Use a temp path the in-process sftp server can write to. pkg/sftp's
+	// default server uses the OS filesystem, so use a t.TempDir-derived path.
+	dir := t.TempDir()
+	target := filepath.Join(dir, "out.pem")
+	payload := []byte("-----BEGIN CERTIFICATE-----\nfake\n-----END CERTIFICATE-----\n")
+
+	if err := c.WriteFile(target, payload, 0640); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	size, err := c.StatFile(target)
+	if err != nil {
+		t.Fatalf("StatFile: %v", err)
+	}
+	if size != int64(len(payload)) {
+		t.Errorf("expected size %d, got %d", len(payload), size)
+	}
+
+	// Verify mode 0640 was set.
+	info, err := os.Stat(target)
+	if err != nil {
+		t.Fatalf("os.Stat: %v", err)
+	}
+	if info.Mode().Perm() != 0640 {
+		t.Errorf("expected mode 0640, got %v", info.Mode().Perm())
+	}
+
+	// Verify content round-trips.
+	gotBytes, err := os.ReadFile(target)
+	if err != nil {
+		t.Fatalf("ReadFile: %v", err)
+	}
+	if !bytes.Equal(gotBytes, payload) {
+		t.Errorf("payload round-trip mismatch:\n  got:  %q\n  want: %q", gotBytes, payload)
+	}
+}
+
+func TestRealSSHClient_WriteFile_NotConnected(t *testing.T) {
+	c := &realSSHClient{config: &Config{}}
+	if err := c.WriteFile("/tmp/x", []byte("y"), 0600); err == nil {
+		t.Errorf("expected error when sftpClient is nil")
+	}
+}
+
+func TestRealSSHClient_StatFile_NotConnected(t *testing.T) {
+	c := &realSSHClient{config: &Config{}}
+	if _, err := c.StatFile("/tmp/x"); err == nil {
+		t.Errorf("expected error when sftpClient is nil")
+	}
+}
+
+func TestRealSSHClient_StatFile_NotExist(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+	c := &realSSHClient{config: &Config{
+		Host: host, Port: port, User: srv.user,
+		AuthMethod: "password", Password: srv.password, Timeout: 5,
+	}}
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	defer c.Close()
+
+	if _, err := c.StatFile("/nonexistent/path/to/file"); err == nil {
+		t.Errorf("expected error stat'ing nonexistent file")
+	}
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Close
+// ─────────────────────────────────────────────────────────────────────────────
+
+func TestRealSSHClient_Close_Idempotent(t *testing.T) {
+	srv := startFakeSSHServer(t)
+	host, port := srv.hostPort()
+	c := &realSSHClient{config: &Config{
+		Host: host, Port: port, User: srv.user,
+		AuthMethod: "password", Password: srv.password, Timeout: 5,
+	}}
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	if err := c.Close(); err != nil {
+		t.Errorf("first Close: %v", err)
+	}
+	// Second close — idempotent (should not panic, may return nil)
+	if err := c.Close(); err != nil {
+		t.Errorf("second Close: %v", err)
+	}
+}
+
+func TestRealSSHClient_Close_NeverConnected(t *testing.T) {
+	c := &realSSHClient{config: &Config{}}
+	if err := c.Close(); err != nil {
+		t.Errorf("Close on never-connected client should be nil, got %v", err)
+	}
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Suppress unused-import warning under some Go versions.
+// ─────────────────────────────────────────────────────────────────────────────
+
+var _ = io.EOF
+var _ = time.Second