Separate the window sentence from the wrapped error so a bad certificate file is not reported as a key mismatch.

Co-authored-by: Cursor <cursoragent@cursor.com>
2026-10-07 15:01:38 +02:00
parent a405048f23
commit e642b24be0
17 changed files with 842 additions and 742 deletions
@@ -0,0 +1,259 @@
+package station
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func (s *Station) onV3(ctx context.Context, wire *framed, f frame, ex *exchange) error {
+	switch f.typ {
+	case tcpCAInfo:
+		if ex.ph != phCA {
+			return nil
+		}
+		return s.onCAInfo(wire, f.body, ex)
+	case tcpCABundle:
+		if ex.ph != phBundle {
+			return nil
+		}
+		return s.onCABundle(wire, f.body, ex)
+	case tcpStartEnc:
+		if ex.ph != phStart {
+			return nil
+		}
+		return s.onStartEncryption(ctx, wire, ex)
+	case tcpCsrReq:
+		return s.sendCSR(wire, ex)
+	case tcpAuthChallenge:
+		return s.answerChallenge(wire, f.body, ex)
+	case tcpAuthOK:
+		ex.authed = true
+		ex.ph = phServer
+		newer, err := csrNewerThanCert(s.cfg.certificateDir)
+		if err != nil {
+			s.endFatalCause("Cannot create "+s.cfg.certificateDir, err, true)
+			return errStopped
+		}
+		if newer {
+			if err := s.sendCSR(wire, ex); err != nil {
+				return err
+			}
+		}
+		return nil
+	case tcpClientCert:
+		return s.saveCert(f.body)
+	case tcpServerInfo:
+		if !ex.authed {
+			return s.retry("Protocol error", nil)
+		}
+		return s.finishV3Server(wire, f.body, ex)
+	case tcpStartUDPEnc:
+		if ex.ph != phUDP {
+			return nil
+		}
+		return s.finishV3UDP(wire.conn, ex)
+	case tcpTalkerStart:
+		s.onTalker(f.body, true)
+		return nil
+	case tcpTalkerStop:
+		s.onTalker(f.body, false)
+		return nil
+	case tcpNodeList, tcpNodeJoined, tcpNodeLeft, tcpRequestQSY, tcpStateEvent, tcpSignal, tcpTxStatus:
+		if err := unpackIgnored(f); err != nil {
+			return s.retry("Protocol error", err)
+		}
+		return nil
+	default:
+		return nil
+	}
+}
+
+func (s *Station) onCAInfo(w io.Writer, body []byte, ex *exchange) error {
+	_, digest, err := parseCAInfo(body)
+	if err != nil {
+		return s.retry("Protocol error", err)
+	}
+	if err := ensureCertDir(s.cfg.certificateDir); err != nil {
+		s.endFatalCause("Cannot create "+s.cfg.certificateDir, err, true)
+		return errStopped
+	}
+	sum, ok, err := caDigest(s.cfg.certificateDir)
+	if err != nil {
+		s.endFatalCause("Cannot create "+s.cfg.certificateDir, err, true)
+		return errStopped
+	}
+	if ok {
+		if !bytes.Equal(sum[:], digest) {
+			s.mu.Lock()
+			s.writeLog(s.clock.Now(), "CA digest differs")
+			s.mu.Unlock()
+		}
+		if err := writeFrame(w, tcpStartEncReq, nil); err != nil {
+			return err
+		}
+		ex.lastTCP = s.clock.Now()
+		ex.ph = phStart
+		return nil
+	}
+	if err := writeFrame(w, tcpCABundleReq, nil); err != nil {
+		return err
+	}
+	ex.lastTCP = s.clock.Now()
+	ex.ph = phBundle
+	return nil
+}
+
+func parseCAInfo(b []byte) (uint16, []byte, error) {
+	size, rest, err := parseU16(b)
+	if err != nil {
+		return 0, nil, err
+	}
+	digest, rest, err := parseBlob(rest)
+	if err != nil {
+		return 0, nil, err
+	}
+	if len(digest) != sha256Len || len(rest) != 0 {
+		return 0, nil, io.ErrUnexpectedEOF
+	}
+	return size, digest, nil
+}
+
+const sha256Len = 32
+
+func (s *Station) onCABundle(w io.Writer, body []byte, ex *exchange) error {
+	caPEM, rest, err := parseString(body)
+	if err != nil {
+		return s.retry("CA signature rejected", err)
+	}
+	sig, rest, err := parseBlob(rest)
+	if err != nil {
+		return s.retry("CA signature rejected", err)
+	}
+	certPEM, rest, err := parseString(rest)
+	if err != nil {
+		return s.retry("CA signature rejected", err)
+	}
+	if len(rest) != 0 {
+		return s.retry("CA signature rejected", nil)
+	}
+	if err := verifyCABundle(caPEM, sig, certPEM); err != nil {
+		return s.retry("CA signature rejected", err)
+	}
+	if err := writeCABundle(s.cfg.certificateDir, caPEM); err != nil {
+		s.endFatalCause("Cannot create "+s.cfg.certificateDir, err, true)
+		return errStopped
+	}
+	if err := writeFrame(w, tcpStartEncReq, nil); err != nil {
+		return err
+	}
+	ex.lastTCP = s.clock.Now()
+	ex.ph = phStart
+	return nil
+}
+
+func (s *Station) onStartEncryption(ctx context.Context, wire *framed, ex *exchange) error {
+	pair, present, fatal, cause := prepareIdentity(s.cfg.certificateDir, s.cfg.callsign)
+	if fatal != "" {
+		s.endFatalCause(fatal, cause, true)
+		return errStopped
+	}
+	ex.client = pair
+	ex.haveCert = present
+	caPath := filepath.Join(s.cfg.certificateDir, caFileName)
+	caPEM, err := os.ReadFile(caPath)
+	if err != nil {
+		s.endFatalCause("Cannot create "+caPath, err, true)
+		return errStopped
+	}
+	cfg, err := tlsConfig(s.cfg.host, caPEM, pair, present)
+	if err != nil {
+		return s.retry("TLS handshake failed", err)
+	}
+	if err := s.startTLS(ctx, wire, cfg, ex.limit); err != nil {
+		if errors.Is(err, errHostMismatch) {
+			return s.retry("Reflector certificate does not match the host", err)
+		}
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		return s.retry("TLS handshake failed", err)
+	}
+	ex.ph = phIdent
+	return nil
+}
+
+func (s *Station) sendCSR(w io.Writer, ex *exchange) error {
+	csrPath := filepath.Join(s.cfg.certificateDir, csrFileName)
+	pem, err := readCSR(s.cfg.certificateDir)
+	if err != nil {
+		s.endFatalCause("Cannot create "+csrPath, err, true)
+		return errStopped
+	}
+	if err := writeFrame(w, tcpCsr, appendString(nil, pem)); err != nil {
+		return err
+	}
+	ex.lastTCP = s.clock.Now()
+	return nil
+}
+
+func (s *Station) saveCert(body []byte) error {
+	pem, _, err := parseString(body)
+	if err != nil || pem == "" {
+		return s.retry("Protocol error", err)
+	}
+	certPath := filepath.Join(s.cfg.certificateDir, certFileName)
+	if err := writeClientCert(s.cfg.certificateDir, pem); err != nil {
+		s.endFatalCause("Cannot create "+certPath, err, true)
+		return errStopped
+	}
+	return errReconnect
+}
+func (s *Station) finishV3Server(wire *framed, body []byte, ex *exchange) error {
+	id, enc, dec, err := s.acceptServer(body)
+	if err != nil {
+		return err
+	}
+	if enc == nil {
+		return errStopped
+	}
+	iv := make([]byte, 6)
+	key := make([]byte, 16)
+	if _, err := rand.Read(iv); err != nil {
+		enc.Close()
+		dec.Close()
+		return fmt.Errorf("udp key: %w", err)
+	}
+	if _, err := rand.Read(key); err != nil {
+		enc.Close()
+		dec.Close()
+		return fmt.Errorf("udp key: %w", err)
+	}
+	info, err := identityV3(iv, key)
+	if err != nil {
+		enc.Close()
+		dec.Close()
+		return err
+	}
+	if err := writeFrame(wire, tcpNodeInfo, info); err != nil {
+		enc.Close()
+		dec.Close()
+		return err
+	}
+	ex.lastTCP = s.clock.Now()
+	s.mu.Lock()
+	s.clientID = id
+	s.enc = enc
+	s.dec = dec
+	s.ivPrefix = iv
+	s.udpKey = key
+	s.secure = true
+	s.mu.Unlock()
+	ex.ph = phUDP
+	return nil
+}