Method sessionHandler

agent/agentssh/agentssh.go:411–579

(session ssh.Session)

}

func (s *Server) sessionHandler(session ssh.Session) {
	ctx := session.Context()
	id := uuid.New()
	logger := s.logger.With(
		slog.F("remote_addr", session.RemoteAddr()),
		slog.F("local_addr", session.LocalAddr()),
		// Assigning a random uuid for each session is useful for tracking
		// logs for the same ssh session.
		slog.F("id", id.String()),
	)
	logger.Info(ctx, "handling ssh session")

	env := session.Environ()
	magicType, magicTypeRaw, env := extractMagicSessionType(env)

	// It's not safe to assume RemoteAddr() returns a non-nil value. slog.F usage is fine because it correctly
	// handles nil.
	// c.f. https://github.com/coder/internal/issues/1143
	remoteAddr := session.RemoteAddr()
	remoteAddrString := ""
	if remoteAddr != nil {
		remoteAddrString = remoteAddr.String()
	}

	if !s.trackSession(session, true) {
		reason := "unable to accept new session, server is closing"
		// Report connection attempt even if we couldn't accept it.
		disconnected := s.config.ReportConnection(id, magicType, remoteAddrString)
		defer disconnected(1, reason)

		logger.Info(ctx, reason)
		// See (*Server).Close() for why we call Close instead of Exit.
		_ = session.Close()
		return
	}
	defer s.trackSession(session, false)

	reportSession := true

	switch magicType {
	case MagicSessionTypeVSCode:
		s.connCountVSCode.Add(1)
		defer s.connCountVSCode.Add(-1)
	case MagicSessionTypeJetBrains:
		// Do nothing here because JetBrains launches hundreds of ssh sessions.
		// We instead track JetBrains in the single persistent tcp forwarding channel.
		reportSession = false
	case MagicSessionTypeSSH:
		s.connCountSSHSession.Add(1)
		defer s.connCountSSHSession.Add(-1)
	case MagicSessionTypeUnknown:
		logger.Warn(ctx, "invalid magic ssh session type specified", slog.F("raw_type", magicTypeRaw))
	}

	closeCause := func(_ string) {}
	if reportSession {
		var reason codersdk.DisconnectReason
		closeCause = func(r string) { reason = codersdk.DisconnectReason(r) }