add SSO session extend flow (management)

Adds the management-server half of the SSO session-extension feature:

- New ExtendAuthSession gRPC RPC that refreshes a peer's session expiry
  using a fresh JWT, validated through the same pipeline as Login but
  without tearing down the tunnel or redoing the NetworkMap sync.
- Per-peer SessionExpiresAt timestamp on every LoginResponse and
  SyncResponse so connected clients learn the deadline on the existing
  long-lived stream, and admin-side changes (toggling expiration,
  changing the expiration window) reach every peer within seconds.
- SessionExpiresAt(...) helper on Peer that derives the absolute UTC
  deadline from LastLogin + the account-level PeerLoginExpiration
  setting, returning zero when the peer is not SSO-tracked or expiration
  is disabled.

The matching client-side consumer of these fields lands separately.

management/internals/shared/grpc/conversion.go

@@ -9,6 +9,7 @@ import (
 
 	log "github.com/sirupsen/logrus"
 	goproto "google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
 
 	integrationsConfig "github.com/netbirdio/management-integrations/integrations/config"
 
@@ -185,6 +186,12 @@ func ToSyncResponse(ctx context.Context, config *nbconfig.Config, httpConfig *nb
 		response.NetworkMap.SshAuth = &proto.SSHAuth{AuthorizedUsers: hashedUsers, MachineUsers: machineUsers, UserIDClaim: userIDClaim}
 	}
 
+	if settings != nil {
+		if deadline := peer.SessionExpiresAt(settings.PeerLoginExpirationEnabled, settings.PeerLoginExpiration); !deadline.IsZero() {
+			response.SessionExpiresAt = timestamppb.New(deadline)
+		}
+	}
+
 	return response
 }
 

management/internals/shared/grpc/server.go

@@ -23,6 +23,7 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
 
 	"github.com/netbirdio/netbird/shared/management/client/common"
 
@@ -821,6 +822,70 @@ func (s *Server) Login(ctx context.Context, req *proto.EncryptedMessage) (*proto
 	}, nil
 }
 
+// ExtendAuthSession refreshes the peer's SSO session expiry deadline using a
+// fresh JWT. The same JWT validation pipeline as Login is used. The tunnel
+// stays up; no network map sync is performed. The new deadline is returned
+// in ExtendAuthSessionResponse.SessionExpiresAt.
+func (s *Server) ExtendAuthSession(ctx context.Context, req *proto.EncryptedMessage) (*proto.EncryptedMessage, error) {
+	extendReq := &proto.ExtendAuthSessionRequest{}
+	peerKey, err := s.parseRequest(ctx, req, extendReq)
+	if err != nil {
+		return nil, err
+	}
+
+	//nolint
+	ctx = context.WithValue(ctx, nbContext.PeerIDKey, peerKey.String())
+	if accountID, accErr := s.accountManager.GetAccountIDForPeerKey(ctx, peerKey.String()); accErr == nil {
+		//nolint
+		ctx = context.WithValue(ctx, nbContext.AccountIDKey, accountID)
+	}
+
+	jwt := extendReq.GetJwtToken()
+	if jwt == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "jwt token is required")
+	}
+
+	var userID string
+	for i := 0; i < 3; i++ {
+		userID, err = s.validateToken(ctx, peerKey.String(), jwt)
+		if err == nil {
+			break
+		}
+		log.WithContext(ctx).Warnf("failed validating JWT token while extending session for peer %s: %v. Retrying (idP cache).", peerKey.String(), err)
+		time.Sleep(200 * time.Millisecond)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if userID == "" {
+		return nil, status.Errorf(codes.Unauthenticated, "jwt token did not yield a user id")
+	}
+
+	deadline, err := s.accountManager.ExtendPeerSession(ctx, peerKey.String(), userID)
+	if err != nil {
+		log.WithContext(ctx).Warnf("failed extending session for peer %s: %v", peerKey.String(), err)
+		return nil, mapError(ctx, err)
+	}
+
+	resp := &proto.ExtendAuthSessionResponse{}
+	if !deadline.IsZero() {
+		resp.SessionExpiresAt = timestamppb.New(deadline)
+	}
+
+	wgKey, err := s.secretsManager.GetWGKey()
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed processing request")
+	}
+	encrypted, err := encryption.EncryptMessage(peerKey, wgKey, resp)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed encrypting response")
+	}
+	return &proto.EncryptedMessage{
+		WgPubKey: wgKey.PublicKey().String(),
+		Body:     encrypted,
+	}, nil
+}
+
 func (s *Server) prepareLoginResponse(ctx context.Context, peer *nbpeer.Peer, netMap *types.NetworkMap, postureChecks []*posture.Checks) (*proto.LoginResponse, error) {
 	var relayToken *Token
 	var err error
@@ -844,6 +909,10 @@ func (s *Server) prepareLoginResponse(ctx context.Context, peer *nbpeer.Peer, ne
 		Checks:        toProtocolChecks(ctx, postureChecks),
 	}
 
+	if deadline := peer.SessionExpiresAt(settings.PeerLoginExpirationEnabled, settings.PeerLoginExpiration); !deadline.IsZero() {
+		loginResp.SessionExpiresAt = timestamppb.New(deadline)
+	}
+
 	return loginResp, nil
 }