2 The implementation of EFI_LOAD_FILE_PROTOCOL for UEFI HTTP boot.
4 Copyright (c) 2015 - 2018, Intel Corporation. All rights reserved.<BR>
5 (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
6 This program and the accompanying materials are licensed and made available under
7 the terms and conditions of the BSD License that accompanies this distribution.
8 The full text of the license may be found at
9 http://opensource.org/licenses/bsd-license.php.
11 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
12 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
16 #include "HttpBootDxe.h"
19 Install HTTP Boot Callback Protocol if not installed before.
21 @param[in] Private Pointer to HTTP Boot private data.
23 @retval EFI_SUCCESS HTTP Boot Callback Protocol installed succesfully.
24 @retval Others Failed to install HTTP Boot Callback Protocol.
28 HttpBootInstallCallback (
29 IN HTTP_BOOT_PRIVATE_DATA
*Private
33 EFI_HANDLE ControllerHandle
;
35 if (!Private
->UsingIpv6
) {
36 ControllerHandle
= Private
->Ip4Nic
->Controller
;
38 ControllerHandle
= Private
->Ip6Nic
->Controller
;
42 // Check whether gEfiHttpBootCallbackProtocolGuid already installed.
44 Status
= gBS
->HandleProtocol (
46 &gEfiHttpBootCallbackProtocolGuid
,
47 (VOID
**) &Private
->HttpBootCallback
49 if (Status
== EFI_UNSUPPORTED
) {
52 &Private
->LoadFileCallback
,
53 &gHttpBootDxeHttpBootCallback
,
54 sizeof (EFI_HTTP_BOOT_CALLBACK_PROTOCOL
)
58 // Install a default callback if user didn't offer one.
60 Status
= gBS
->InstallProtocolInterface (
62 &gEfiHttpBootCallbackProtocolGuid
,
64 &Private
->LoadFileCallback
66 if (EFI_ERROR (Status
)) {
69 Private
->HttpBootCallback
= &Private
->LoadFileCallback
;
76 Uninstall HTTP Boot Callback Protocol if it's installed by this driver.
78 @param[in] Private Pointer to HTTP Boot private data.
82 HttpBootUninstallCallback (
83 IN HTTP_BOOT_PRIVATE_DATA
*Private
86 if (Private
->HttpBootCallback
== &Private
->LoadFileCallback
) {
87 gBS
->UninstallProtocolInterface (
89 &gEfiHttpBootCallbackProtocolGuid
,
90 &Private
->HttpBootCallback
92 Private
->HttpBootCallback
= NULL
;
97 Enable the use of UEFI HTTP boot function.
99 If the driver has already been started but not satisfy the requirement (IP stack and
100 specified boot file path), this function will stop the driver and start it again.
102 @param[in] Private The pointer to the driver's private data.
103 @param[in] UsingIpv6 Specifies the type of IP addresses that are to be
104 used during the session that is being started.
105 Set to TRUE for IPv6, and FALSE for IPv4.
106 @param[in] FilePath The device specific path of the file to load.
108 @retval EFI_SUCCESS HTTP boot was successfully enabled.
109 @retval EFI_INVALID_PARAMETER Private is NULL or FilePath is NULL.
110 @retval EFI_INVALID_PARAMETER The FilePath doesn't contain a valid URI device path node.
111 @retval EFI_ALREADY_STARTED The driver is already in started state.
112 @retval EFI_OUT_OF_RESOURCES There are not enough resources.
117 IN HTTP_BOOT_PRIVATE_DATA
*Private
,
118 IN BOOLEAN UsingIpv6
,
119 IN EFI_DEVICE_PATH_PROTOCOL
*FilePath
128 if (Private
== NULL
|| FilePath
== NULL
) {
129 return EFI_INVALID_PARAMETER
;
133 // Check the URI in the input FilePath, in order to see whether it is
134 // required to boot from a new specified boot file.
136 Status
= HttpBootParseFilePath (FilePath
, &Uri
);
137 if (EFI_ERROR (Status
)) {
138 return EFI_INVALID_PARAMETER
;
142 // Check whether we need to stop and restart the HTTP boot driver.
144 if (Private
->Started
) {
146 // Restart is needed in 2 cases:
147 // 1. Http boot driver has already been started but not on the required IP stack.
148 // 2. The specified boot file URI in FilePath is different with the one we have
151 if ((UsingIpv6
!= Private
->UsingIpv6
) ||
152 ((Uri
!= NULL
) && (AsciiStrCmp (Private
->BootFileUri
, Uri
) != 0))) {
154 // Restart is required, first stop then continue this start function.
156 Status
= HttpBootStop (Private
);
157 if (EFI_ERROR (Status
)) {
165 // Restart is not required.
170 return EFI_ALREADY_STARTED
;
175 // Detect whether using ipv6 or not, and set it to the private data.
177 if (UsingIpv6
&& Private
->Ip6Nic
!= NULL
) {
178 Private
->UsingIpv6
= TRUE
;
179 } else if (!UsingIpv6
&& Private
->Ip4Nic
!= NULL
) {
180 Private
->UsingIpv6
= FALSE
;
185 return EFI_UNSUPPORTED
;
189 // Record the specified URI and prepare the URI parser if needed.
191 Private
->FilePathUri
= Uri
;
192 if (Private
->FilePathUri
!= NULL
) {
193 Status
= HttpParseUrl (
194 Private
->FilePathUri
,
195 (UINT32
) AsciiStrLen (Private
->FilePathUri
),
197 &Private
->FilePathUriParser
199 if (EFI_ERROR (Status
)) {
200 FreePool (Private
->FilePathUri
);
206 // Init the content of cached DHCP offer list.
208 ZeroMem (Private
->OfferBuffer
, sizeof (Private
->OfferBuffer
));
209 if (!Private
->UsingIpv6
) {
210 for (Index
= 0; Index
< HTTP_BOOT_OFFER_MAX_NUM
; Index
++) {
211 Private
->OfferBuffer
[Index
].Dhcp4
.Packet
.Offer
.Size
= HTTP_CACHED_DHCP4_PACKET_MAX_SIZE
;
214 for (Index
= 0; Index
< HTTP_BOOT_OFFER_MAX_NUM
; Index
++) {
215 Private
->OfferBuffer
[Index
].Dhcp6
.Packet
.Offer
.Size
= HTTP_CACHED_DHCP6_PACKET_MAX_SIZE
;
219 if (Private
->UsingIpv6
) {
221 // Set Ip6 policy to Automatic to start the Ip6 router discovery.
223 Status
= HttpBootSetIp6Policy (Private
);
224 if (EFI_ERROR (Status
)) {
228 Private
->Started
= TRUE
;
229 Print (L
"\n>>Start HTTP Boot over IPv%d", Private
->UsingIpv6
? 6 : 4);
235 Attempt to complete a DHCPv4 D.O.R.A or DHCPv6 S.R.A.A sequence to retrieve the boot resource information.
237 @param[in] Private The pointer to the driver's private data.
239 @retval EFI_SUCCESS Boot info was successfully retrieved.
240 @retval EFI_INVALID_PARAMETER Private is NULL.
241 @retval EFI_NOT_STARTED The driver is in stopped state.
242 @retval EFI_DEVICE_ERROR An unexpected network error occurred.
243 @retval Others Other errors as indicated.
248 IN HTTP_BOOT_PRIVATE_DATA
*Private
253 if (Private
== NULL
) {
254 return EFI_INVALID_PARAMETER
;
257 if (!Private
->Started
) {
258 return EFI_NOT_STARTED
;
261 Status
= EFI_DEVICE_ERROR
;
263 if (!Private
->UsingIpv6
) {
265 // Start D.O.R.A process to get a IPv4 address and other boot information.
267 Status
= HttpBootDhcp4Dora (Private
);
270 // Start S.A.R.R process to get a IPv6 address and other boot information.
272 Status
= HttpBootDhcp6Sarr (Private
);
279 Attempt to download the boot file through HTTP message exchange.
281 @param[in] Private The pointer to the driver's private data.
282 @param[in, out] BufferSize On input the size of Buffer in bytes. On output with a return
283 code of EFI_SUCCESS, the amount of data transferred to
284 Buffer. On output with a return code of EFI_BUFFER_TOO_SMALL,
285 the size of Buffer required to retrieve the requested file.
286 @param[in] Buffer The memory buffer to transfer the file to. If Buffer is NULL,
287 then the size of the requested file is returned in
289 @param[out] ImageType The image type of the downloaded file.
291 @retval EFI_SUCCESS Boot file was loaded successfully.
292 @retval EFI_INVALID_PARAMETER Private is NULL, or ImageType is NULL, or BufferSize is NULL.
293 @retval EFI_INVALID_PARAMETER *BufferSize is not zero, and Buffer is NULL.
294 @retval EFI_NOT_STARTED The driver is in stopped state.
295 @retval EFI_BUFFER_TOO_SMALL The BufferSize is too small to read the boot file. BufferSize has
296 been updated with the size needed to complete the request.
297 @retval EFI_DEVICE_ERROR An unexpected network error occurred.
298 @retval Others Other errors as indicated.
303 IN HTTP_BOOT_PRIVATE_DATA
*Private
,
304 IN OUT UINTN
*BufferSize
,
305 IN VOID
*Buffer
, OPTIONAL
306 OUT HTTP_BOOT_IMAGE_TYPE
*ImageType
311 if (Private
== NULL
|| ImageType
== NULL
|| BufferSize
== NULL
) {
312 return EFI_INVALID_PARAMETER
;
315 if (*BufferSize
!= 0 && Buffer
== NULL
) {
316 return EFI_INVALID_PARAMETER
;
319 if (!Private
->Started
) {
320 return EFI_NOT_STARTED
;
323 Status
= HttpBootInstallCallback (Private
);
324 if (EFI_ERROR(Status
)) {
328 if (Private
->BootFileUri
== NULL
) {
330 // Parse the cached offer to get the boot file URL first.
332 Status
= HttpBootDiscoverBootInfo (Private
);
333 if (EFI_ERROR (Status
)) {
334 AsciiPrint ("\n Error: Could not retrieve NBP file size from HTTP server.\n");
339 if (!Private
->HttpCreated
) {
341 // Create HTTP child.
343 Status
= HttpBootCreateHttpIo (Private
);
344 if (EFI_ERROR (Status
)) {
349 if (Private
->BootFileSize
== 0) {
351 // Discover the information about the bootfile if we haven't.
355 // Try to use HTTP HEAD method.
357 Status
= HttpBootGetBootFile (
360 &Private
->BootFileSize
,
364 if (EFI_ERROR (Status
) && Status
!= EFI_BUFFER_TOO_SMALL
) {
366 // Failed to get file size by HEAD method, may be trunked encoding, try HTTP GET method.
368 ASSERT (Private
->BootFileSize
== 0);
369 Status
= HttpBootGetBootFile (
372 &Private
->BootFileSize
,
376 if (EFI_ERROR (Status
) && Status
!= EFI_BUFFER_TOO_SMALL
) {
377 AsciiPrint ("\n Error: Could not retrieve NBP file size from HTTP server.\n");
383 if (*BufferSize
< Private
->BootFileSize
) {
384 *BufferSize
= Private
->BootFileSize
;
385 *ImageType
= Private
->ImageType
;
386 Status
= EFI_BUFFER_TOO_SMALL
;
391 // Load the boot file into Buffer
393 Status
= HttpBootGetBootFile (
402 HttpBootUninstallCallback (Private
);
404 if (EFI_ERROR (Status
)) {
405 if (Status
== EFI_ACCESS_DENIED
) {
406 AsciiPrint ("\n Error: Could not establish connection with HTTP server.\n");
407 } else if (Status
== EFI_BUFFER_TOO_SMALL
&& Buffer
!= NULL
) {
408 AsciiPrint ("\n Error: Buffer size is smaller than the requested file.\n");
409 } else if (Status
== EFI_OUT_OF_RESOURCES
) {
410 AsciiPrint ("\n Error: Could not allocate I/O buffers.\n");
411 } else if (Status
== EFI_DEVICE_ERROR
) {
412 AsciiPrint ("\n Error: Network device error.\n");
413 } else if (Status
== EFI_TIMEOUT
) {
414 AsciiPrint ("\n Error: Server response timeout.\n");
415 } else if (Status
== EFI_ABORTED
) {
416 AsciiPrint ("\n Error: Remote boot cancelled.\n");
417 } else if (Status
!= EFI_BUFFER_TOO_SMALL
) {
418 AsciiPrint ("\n Error: Unexpected network error.\n");
426 Disable the use of UEFI HTTP boot function.
428 @param[in] Private The pointer to the driver's private data.
430 @retval EFI_SUCCESS HTTP boot was successfully disabled.
431 @retval EFI_NOT_STARTED The driver is already in stopped state.
432 @retval EFI_INVALID_PARAMETER Private is NULL.
433 @retval Others Unexpected error when stop the function.
438 IN HTTP_BOOT_PRIVATE_DATA
*Private
443 if (Private
== NULL
) {
444 return EFI_INVALID_PARAMETER
;
447 if (!Private
->Started
) {
448 return EFI_NOT_STARTED
;
451 if (Private
->HttpCreated
) {
452 HttpIoDestroyIo (&Private
->HttpIo
);
453 Private
->HttpCreated
= FALSE
;
456 Private
->Started
= FALSE
;
457 ZeroMem (&Private
->StationIp
, sizeof (EFI_IP_ADDRESS
));
458 ZeroMem (&Private
->SubnetMask
, sizeof (EFI_IP_ADDRESS
));
459 ZeroMem (&Private
->GatewayIp
, sizeof (EFI_IP_ADDRESS
));
461 Private
->BootFileUri
= NULL
;
462 Private
->BootFileUriParser
= NULL
;
463 Private
->BootFileSize
= 0;
464 Private
->SelectIndex
= 0;
465 Private
->SelectProxyType
= HttpOfferTypeMax
;
467 if (!Private
->UsingIpv6
) {
469 // Stop and release the DHCP4 child.
471 Private
->Dhcp4
->Stop (Private
->Dhcp4
);
472 Private
->Dhcp4
->Configure (Private
->Dhcp4
, NULL
);
474 for (Index
= 0; Index
< HTTP_BOOT_OFFER_MAX_NUM
; Index
++) {
475 if (Private
->OfferBuffer
[Index
].Dhcp4
.UriParser
) {
476 HttpUrlFreeParser (Private
->OfferBuffer
[Index
].Dhcp4
.UriParser
);
481 // Stop and release the DHCP6 child.
483 Private
->Dhcp6
->Stop (Private
->Dhcp6
);
484 Private
->Dhcp6
->Configure (Private
->Dhcp6
, NULL
);
486 for (Index
= 0; Index
< HTTP_BOOT_OFFER_MAX_NUM
; Index
++) {
487 if (Private
->OfferBuffer
[Index
].Dhcp6
.UriParser
) {
488 HttpUrlFreeParser (Private
->OfferBuffer
[Index
].Dhcp6
.UriParser
);
493 if (Private
->DnsServerIp
!= NULL
) {
494 FreePool (Private
->DnsServerIp
);
495 Private
->DnsServerIp
= NULL
;
498 if (Private
->FilePathUri
!= NULL
) {
499 FreePool (Private
->FilePathUri
);
500 HttpUrlFreeParser (Private
->FilePathUriParser
);
501 Private
->FilePathUri
= NULL
;
502 Private
->FilePathUriParser
= NULL
;
505 ZeroMem (Private
->OfferBuffer
, sizeof (Private
->OfferBuffer
));
506 Private
->OfferNum
= 0;
507 ZeroMem (Private
->OfferCount
, sizeof (Private
->OfferCount
));
508 ZeroMem (Private
->OfferIndex
, sizeof (Private
->OfferIndex
));
510 HttpBootFreeCacheList (Private
);
516 Causes the driver to load a specified file.
518 @param This Protocol instance pointer.
519 @param FilePath The device specific path of the file to load.
520 @param BootPolicy If TRUE, indicates that the request originates from the
521 boot manager is attempting to load FilePath as a boot
522 selection. If FALSE, then FilePath must match as exact file
524 @param BufferSize On input the size of Buffer in bytes. On output with a return
525 code of EFI_SUCCESS, the amount of data transferred to
526 Buffer. On output with a return code of EFI_BUFFER_TOO_SMALL,
527 the size of Buffer required to retrieve the requested file.
528 @param Buffer The memory buffer to transfer the file to. IF Buffer is NULL,
529 then the size of the requested file is returned in
532 @retval EFI_SUCCESS The file was loaded.
533 @retval EFI_UNSUPPORTED The device does not support the provided BootPolicy
534 @retval EFI_INVALID_PARAMETER FilePath is not a valid device path, or
536 @retval EFI_NO_MEDIA No medium was present to load the file.
537 @retval EFI_DEVICE_ERROR The file was not loaded due to a device error.
538 @retval EFI_NO_RESPONSE The remote system did not respond.
539 @retval EFI_NOT_FOUND The file was not found.
540 @retval EFI_ABORTED The file load process was manually cancelled.
541 @retval EFI_BUFFER_TOO_SMALL The BufferSize is too small to read the current directory entry.
542 BufferSize has been updated with the size needed to complete
548 HttpBootDxeLoadFile (
549 IN EFI_LOAD_FILE_PROTOCOL
*This
,
550 IN EFI_DEVICE_PATH_PROTOCOL
*FilePath
,
551 IN BOOLEAN BootPolicy
,
552 IN OUT UINTN
*BufferSize
,
553 IN VOID
*Buffer OPTIONAL
556 HTTP_BOOT_PRIVATE_DATA
*Private
;
557 HTTP_BOOT_VIRTUAL_NIC
*VirtualNic
;
558 EFI_STATUS MediaStatus
;
561 HTTP_BOOT_IMAGE_TYPE ImageType
;
563 if (This
== NULL
|| BufferSize
== NULL
|| FilePath
== NULL
) {
564 return EFI_INVALID_PARAMETER
;
568 // Only support BootPolicy
571 return EFI_UNSUPPORTED
;
574 VirtualNic
= HTTP_BOOT_VIRTUAL_NIC_FROM_LOADFILE (This
);
575 Private
= VirtualNic
->Private
;
578 // Check media status before HTTP boot start
580 MediaStatus
= EFI_SUCCESS
;
581 NetLibDetectMediaWaitTimeout (Private
->Controller
, HTTP_BOOT_CHECK_MEDIA_WAITING_TIME
, &MediaStatus
);
582 if (MediaStatus
!= EFI_SUCCESS
) {
583 AsciiPrint ("\n Error: Could not detect network connection.\n");
588 // Check whether the virtual nic is using IPv6 or not.
591 if (VirtualNic
== Private
->Ip6Nic
) {
596 // Initialize HTTP boot.
598 Status
= HttpBootStart (Private
, UsingIpv6
, FilePath
);
599 if (Status
!= EFI_SUCCESS
&& Status
!= EFI_ALREADY_STARTED
) {
604 // Load the boot file.
606 ImageType
= ImageTypeMax
;
607 Status
= HttpBootLoadFile (Private
, BufferSize
, Buffer
, &ImageType
);
608 if (EFI_ERROR (Status
)) {
609 if (Status
== EFI_BUFFER_TOO_SMALL
&& (ImageType
== ImageTypeVirtualCd
|| ImageType
== ImageTypeVirtualDisk
)) {
610 Status
= EFI_WARN_FILE_SYSTEM
;
611 } else if (Status
!= EFI_BUFFER_TOO_SMALL
) {
612 HttpBootStop (Private
);
618 // Register the RAM Disk to the system if needed.
620 if (ImageType
== ImageTypeVirtualCd
|| ImageType
== ImageTypeVirtualDisk
) {
621 Status
= HttpBootRegisterRamDisk (Private
, *BufferSize
, Buffer
, ImageType
);
622 if (!EFI_ERROR (Status
)) {
623 Status
= EFI_WARN_FILE_SYSTEM
;
625 AsciiPrint ("\n Error: Could not register RAM disk to the system.\n");
630 // Stop the HTTP Boot service after the boot image is downloaded.
632 HttpBootStop (Private
);
637 /// Load File Protocol instance
639 GLOBAL_REMOVE_IF_UNREFERENCED
640 EFI_LOAD_FILE_PROTOCOL gHttpBootDxeLoadFile
= {
645 Callback function that is invoked when the HTTP Boot driver is about to transmit or has received a
648 This function is invoked when the HTTP Boot driver is about to transmit or has received packet.
649 Parameters DataType and Received specify the type of event and the format of the buffer pointed
650 to by Data. Due to the polling nature of UEFI device drivers, this callback function should not
651 execute for more than 5 ms.
652 The returned status code determines the behavior of the HTTP Boot driver.
654 @param[in] This Pointer to the EFI_HTTP_BOOT_CALLBACK_PROTOCOL instance.
655 @param[in] DataType The event that occurs in the current state.
656 @param[in] Received TRUE if the callback is being invoked due to a receive event.
657 FALSE if the callback is being invoked due to a transmit event.
658 @param[in] DataLength The length in bytes of the buffer pointed to by Data.
659 @param[in] Data A pointer to the buffer of data, the data type is specified by
662 @retval EFI_SUCCESS Tells the HTTP Boot driver to continue the HTTP Boot process.
663 @retval EFI_ABORTED Tells the HTTP Boot driver to abort the current HTTP Boot process.
668 IN EFI_HTTP_BOOT_CALLBACK_PROTOCOL
*This
,
669 IN EFI_HTTP_BOOT_CALLBACK_DATA_TYPE DataType
,
671 IN UINT32 DataLength
,
672 IN VOID
*Data OPTIONAL
675 EFI_HTTP_MESSAGE
*HttpMessage
;
676 EFI_HTTP_HEADER
*HttpHeader
;
677 HTTP_BOOT_PRIVATE_DATA
*Private
;
680 Private
= HTTP_BOOT_PRIVATE_DATA_FROM_CALLBACK_PROTOCOL(This
);
688 case HttpBootHttpRequest
:
690 HttpMessage
= (EFI_HTTP_MESSAGE
*) Data
;
691 if (HttpMessage
->Data
.Request
->Method
== HttpMethodGet
&&
692 HttpMessage
->Data
.Request
->Url
!= NULL
) {
693 Print (L
"\n URI: %s\n", HttpMessage
->Data
.Request
->Url
);
698 case HttpBootHttpResponse
:
700 HttpMessage
= (EFI_HTTP_MESSAGE
*) Data
;
702 if (HttpMessage
->Data
.Response
!= NULL
) {
703 if (HttpBootIsHttpRedirectStatusCode (HttpMessage
->Data
.Response
->StatusCode
)) {
705 // Server indicates the resource has been redirected to a different URL
706 // according to the section 6.4 of RFC7231 and the RFC 7538.
707 // Display the redirect information on the screen.
709 HttpHeader
= HttpFindHeader (
710 HttpMessage
->HeaderCount
,
711 HttpMessage
->Headers
,
714 if (HttpHeader
!= NULL
) {
715 Print (L
"\n HTTP ERROR: Resource Redirected.\n New Location: %a\n", HttpHeader
->FieldValue
);
721 HttpHeader
= HttpFindHeader (
722 HttpMessage
->HeaderCount
,
723 HttpMessage
->Headers
,
724 HTTP_HEADER_CONTENT_LENGTH
726 if (HttpHeader
!= NULL
) {
727 Private
->FileSize
= AsciiStrDecimalToUintn (HttpHeader
->FieldValue
);
728 Private
->ReceivedSize
= 0;
729 Private
->Percentage
= 0;
734 case HttpBootHttpEntityBody
:
735 if (DataLength
!= 0) {
736 if (Private
->FileSize
!= 0) {
738 // We already know the file size, print in percentage format.
740 if (Private
->ReceivedSize
== 0) {
741 Print (L
" File Size: %lu Bytes\n", Private
->FileSize
);
743 Private
->ReceivedSize
+= DataLength
;
744 Percentage
= (UINT32
) DivU64x64Remainder (MultU64x32 (Private
->ReceivedSize
, 100), Private
->FileSize
, NULL
);
745 if (Private
->Percentage
!= Percentage
) {
746 Private
->Percentage
= Percentage
;
747 Print (L
"\r Downloading...%d%%", Percentage
);
751 // In some case we couldn't get the file size from the HTTP header, so we
752 // just print the downloaded file size.
754 Private
->ReceivedSize
+= DataLength
;
755 Print (L
"\r Downloading...%lu Bytes", Private
->ReceivedSize
);
768 /// HTTP Boot Callback Protocol instance
770 GLOBAL_REMOVE_IF_UNREFERENCED
771 EFI_HTTP_BOOT_CALLBACK_PROTOCOL gHttpBootDxeHttpBootCallback
= {