Updated to use POSIX-style file I/O layer.
This commit is contained in:
Michael Brown
parent
86a948ccbe
commit
23008b9326
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@ -22,10 +22,60 @@
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "pxe.h"
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#include <stdlib.h>
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#include <stdio.h>
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#include <byteswap.h>
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#include <gpxe/uaccess.h>
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#include <gpxe/in.h>
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#include <gpxe/tftp.h>
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#include <gpxe/posix_io.h>
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#include <pxe.h>
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static int pxe_tftp_read_block ( unsigned char *data, unsigned int block,
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unsigned int len, int eof );
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/** File descriptor for "single-file-only" PXE TFTP transfer */
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static int pxe_single_fd = -1;
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/** Block size for "single-file-only" PXE TFTP transfer */
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static size_t pxe_single_blksize;
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/** Current block index for "single-file-only" PXE TFTP transfer */
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static unsigned int pxe_single_blkidx;
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/** Length of a PXE-derived URI
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*
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* The "single-file-only" API calls use a filename field of 128 bytes.
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* 256 bytes provides plenty of space for constructing the (temporary)
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* full URI.
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*/
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#define PXE_URI_LEN 256
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/**
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* Build PXE URI string
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*
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* @v uri_string URI string to fill in
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* @v ipaddress Server IP address (in network byte order)
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* @v port Server port (in network byte order)
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* @v filename File name
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* @v blksize Requested block size, or 0
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*/
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static void pxe_tftp_build_uri ( char uri_string[PXE_URI_LEN],
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uint32_t ipaddress, unsigned int port,
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const unsigned char *filename,
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int blksize ) {
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struct in_addr address;
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/* This is a fix to make Microsoft Remote Install Services work (RIS) */
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#warning "Overwrite DHCP filename"
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address.s_addr = ipaddress;
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if ( ! port )
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port = htons ( TFTP_PORT );
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if ( ! blksize )
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blksize = TFTP_MAX_BLKSIZE;
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snprintf ( uri_string, sizeof ( uri_string ),
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"tftp://%s:%d%s%s?blksize=%d", inet_ntoa ( address ),
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ntohs ( port ), ( ( filename[0] == '/' ) ? "" : "/" ),
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filename, blksize );
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}
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/**
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* TFTP OPEN
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@ -49,48 +99,16 @@ static int pxe_tftp_read_block ( unsigned char *data, unsigned int block,
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* routing will take place. See the relevant
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* @ref pxe_routing "implementation note" for more details.
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*
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* The blksize negotiated with the TFTP server will be returned in
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* s_PXENV_TFTP_OPEN::PacketSize, and will be the size of data blocks
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* returned by subsequent calls to pxenv_tftp_read(). The TFTP server
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* may negotiate a smaller blksize than the caller requested.
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*
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* Some TFTP servers do not support TFTP options, and will therefore
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* not be able to use anything other than a fixed 512-byte blksize.
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* The PXE specification version 2.1 requires that the caller must
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* pass in s_PXENV_TFTP_OPEN::PacketSize with a value of 512 or
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* greater.
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*
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* You can only have one TFTP connection open at a time, because the
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* PXE API requires the PXE stack to keep state (e.g. local and remote
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* port numbers, data block index) about the open TFTP connection,
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* rather than letting the caller do so.
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*
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* It is unclear precisely what constitutes a "TFTP open" operation.
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* Clearly, we must send the TFTP open request to the server. Since
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* we must know whether or not the open succeeded, we must wait for
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* the first reply packet from the TFTP server. If the TFTP server
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* supports options, the first reply packet will be an OACK; otherwise
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* it will be a DATA packet. In other words, we may only get to
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* discover whether or not the open succeeded when we receive the
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* first block of data. However, the pxenv_tftp_open() API provides
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* no way for us to return this block of data at this time. See the
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* relevant @ref pxe_note_tftp "implementation note" for Etherboot's
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* solution to this problem.
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* Because we support arbitrary protocols, most of which have no
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* notion of "block size" and will return data in arbitrary-sized
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* chunks, we cheat and pretend to the caller that the blocksize is
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* always accepted as-is.
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*
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* On x86, you must set the s_PXE::StatusCallout field to a nonzero
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* value before calling this function in protected mode. You cannot
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* call this function with a 32-bit stack segment. (See the relevant
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* @ref pxe_x86_pmode16 "implementation note" for more details.)
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*
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* @note If you pass in a value less than 512 for
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* s_PXENV_TFTP_OPEN::PacketSize, Etherboot will attempt to negotiate
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* this blksize with the TFTP server, even though such a value is not
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* permitted according to the PXE specification. If the TFTP server
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* ends up dictating a blksize larger than the value requested by the
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* caller (which is very probable in the case of a requested blksize
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* less than 512), then Etherboot will return the error
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* #PXENV_STATUS_TFTP_INVALID_PACKET_SIZE.
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*
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* @note According to the PXE specification version 2.1, this call
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* "opens a file for reading/writing", though how writing is to be
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* achieved without the existence of an API call %pxenv_tftp_write()
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@ -107,40 +125,30 @@ static int pxe_tftp_read_block ( unsigned char *data, unsigned int block,
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* other PXE API call "if an MTFTP connection is active".
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*/
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PXENV_EXIT_t pxenv_tftp_open ( struct s_PXENV_TFTP_OPEN *tftp_open ) {
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char uri_string[PXE_URI_LEN];
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DBG ( "PXENV_TFTP_OPEN" );
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#if 0
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/* Set server address and port */
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tftp_server.sin_addr.s_addr = tftp_open->ServerIPAddress
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? tftp_open->ServerIPAddress
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: arptable[ARP_SERVER].ipaddr.s_addr;
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tftp_server.sin_port = ntohs ( tftp_open->TFTPPort );
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#ifdef WORK_AROUND_BPBATCH_BUG
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/* Force use of port 69; BpBatch tries to use port 4 for some
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* bizarre reason. */
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tftp_server.sin_port = TFTP_PORT;
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#endif
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/* Ignore gateway address; we can route properly */
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/* Fill in request structure */
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request.server = &tftp_server;
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request.name = tftp_open->FileName;
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request.blksize = tftp_open->PacketSize;
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DBG ( " %@:%d/%s (%d)", tftp_open->ServerIPAddress,
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tftp_open->TFTPPort, request.name, request.blksize );
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if ( !request.blksize ) request.blksize = TFTP_DEFAULT_BLKSIZE;
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/* Make request and get first packet */
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if ( !tftp_block ( &request, &block ) ) {
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tftp_open->Status = PXENV_STATUS_TFTP_FILE_NOT_FOUND;
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/* Guard against callers that fail to close before re-opening */
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close ( pxe_single_fd );
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pxe_single_fd = -1;
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/* Construct URI */
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pxe_tftp_build_uri ( uri_string, tftp_open->ServerIPAddress,
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tftp_open->TFTPPort, tftp_open->FileName,
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tftp_open->PacketSize );
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DBG ( " %s", uri_string );
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/* Open URI */
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pxe_single_fd = open ( uri_string );
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if ( pxe_single_fd < 0 ) {
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tftp_open->Status = PXENV_STATUS ( pxe_single_fd );
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return PXENV_EXIT_FAILURE;
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}
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/* Fill in PacketSize */
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tftp_open->PacketSize = request.blksize;
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/* Store first block for later retrieval by TFTP_READ */
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pxe_stack->tftpdata.magic_cookie = PXE_TFTP_MAGIC_COOKIE;
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pxe_stack->tftpdata.len = block.len;
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pxe_stack->tftpdata.eof = block.eof;
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memcpy ( pxe_stack->tftpdata.data, block.data, block.len );
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#endif
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/* Record parameters for later use */
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pxe_single_blksize = tftp_open->PacketSize;
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pxe_single_blkidx = 0;
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tftp_open->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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@ -162,14 +170,12 @@ PXENV_EXIT_t pxenv_tftp_open ( struct s_PXENV_TFTP_OPEN *tftp_open ) {
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* value before calling this function in protected mode. You cannot
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* call this function with a 32-bit stack segment. (See the relevant
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* @ref pxe_x86_pmode16 "implementation note" for more details.)
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*
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* @note Since TFTP runs over UDP, which is a connectionless protocol,
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* the concept of closing a file is somewhat meaningless. This call
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* is a no-op for Etherboot.
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*/
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PXENV_EXIT_t pxenv_tftp_close ( struct s_PXENV_TFTP_CLOSE *tftp_close ) {
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DBG ( "PXENV_TFTP_CLOSE" );
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close ( pxe_single_fd );
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pxe_single_fd = -1;
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tftp_close->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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}
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@ -230,42 +236,28 @@ PXENV_EXIT_t pxenv_tftp_close ( struct s_PXENV_TFTP_CLOSE *tftp_close ) {
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* is as expected (i.e. one greater than that returned from the
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* previous call to pxenv_tftp_read()).
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*
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* Nothing in the PXE specification indicates when the TFTP
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* acknowledgement packets will be sent back to the server. See the
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* relevant @ref pxe_note_tftp "implementation note" for details on
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* when Etherboot chooses to send these packets.
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*
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* On x86, you must set the s_PXE::StatusCallout field to a nonzero
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* value before calling this function in protected mode. You cannot
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* call this function with a 32-bit stack segment. (See the relevant
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* @ref pxe_x86_pmode16 "implementation note" for more details.)
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*/
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PXENV_EXIT_t pxenv_tftp_read ( struct s_PXENV_TFTP_READ *tftp_read ) {
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DBG ( "PXENV_TFTP_READ" );
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userptr_t buffer;
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ssize_t len;
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#if 0
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/* Do we have a block pending */
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if ( pxe_stack->tftpdata.magic_cookie == PXE_TFTP_MAGIC_COOKIE ) {
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block.data = pxe_stack->tftpdata.data;
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block.len = pxe_stack->tftpdata.len;
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block.eof = pxe_stack->tftpdata.eof;
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block.block = 1; /* Will be the first block */
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pxe_stack->tftpdata.magic_cookie = 0;
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} else {
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if ( !tftp_block ( NULL, &block ) ) {
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tftp_read->Status = PXENV_STATUS_TFTP_FILE_NOT_FOUND;
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return PXENV_EXIT_FAILURE;
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}
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DBG ( "PXENV_TFTP_READ to %04x:%04x",
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tftp_read->Buffer.segment, tftp_read->Buffer.offset );
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buffer = real_to_user ( tftp_read->Buffer.segment,
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tftp_read->Buffer.offset );
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len = read_user ( pxe_single_fd, buffer, 0, pxe_single_blksize );
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if ( len < 0 ) {
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tftp_read->Status = PXENV_STATUS ( len );
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return PXENV_EXIT_FAILURE;
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}
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tftp_read->BufferSize = len;
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tftp_read->PacketNumber = ++pxe_single_blkidx;
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/* Return data */
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tftp_read->PacketNumber = block.block;
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tftp_read->BufferSize = block.len;
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memcpy ( SEGOFF16_TO_PTR(tftp_read->Buffer), block.data, block.len );
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DBG ( " %d to %hx:%hx", block.len, tftp_read->Buffer.segment,
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tftp_read->Buffer.offset );
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#endif
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tftp_read->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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}
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@ -363,53 +355,47 @@ PXENV_EXIT_t pxenv_tftp_read ( struct s_PXENV_TFTP_READ *tftp_read ) {
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*/
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PXENV_EXIT_t pxenv_tftp_read_file ( struct s_PXENV_TFTP_READ_FILE
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*tftp_read_file ) {
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DBG ( "PXENV_TFTP_READ_FILE %s to [%x,%x)", tftp_read_file->FileName,
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tftp_read_file->Buffer,
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tftp_read_file->Buffer + tftp_read_file->BufferSize );
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char uri_string[PXE_URI_LEN];
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int fd;
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userptr_t buffer;
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size_t max_len;
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ssize_t frag_len;
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size_t len = 0;
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int rc = -ENOBUFS;
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#if 0
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/* inserted by Klaus Wittemeier */
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/* KERNEL_BUF stores the name of the last required file */
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/* This is a fix to make Microsoft Remote Install Services work (RIS) */
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memcpy(KERNEL_BUF, tftp_read_file->FileName, sizeof(KERNEL_BUF));
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/* end of insertion */
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DBG ( "PXENV_TFTP_READ_FILE" );
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/* Set server address and port */
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tftp_server.sin_addr.s_addr = tftp_read_file->ServerIPAddress
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? tftp_read_file->ServerIPAddress
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: arptable[ARP_SERVER].ipaddr.s_addr;
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tftp_server.sin_port = ntohs ( tftp_read_file->TFTPSrvPort );
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/* Construct URI */
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pxe_tftp_build_uri ( uri_string, tftp_read_file->ServerIPAddress,
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tftp_read_file->TFTPSrvPort,
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tftp_read_file->FileName, 0 );
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DBG ( " %s", uri_string );
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pxe_stack->readfile.buffer = phys_to_virt ( tftp_read_file->Buffer );
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pxe_stack->readfile.bufferlen = tftp_read_file->BufferSize;
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pxe_stack->readfile.offset = 0;
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rc = tftp ( NULL, &tftp_server, tftp_read_file->FileName,
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pxe_tftp_read_block );
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if ( rc ) {
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tftp_read_file->Status = PXENV_STATUS_FAILURE;
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/* Open URI */
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fd = open ( uri_string );
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if ( fd < 0 ) {
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tftp_read_file->Status = PXENV_STATUS ( fd );
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return PXENV_EXIT_FAILURE;
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}
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#endif
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tftp_read_file->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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}
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#if 0
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static int pxe_tftp_read_block ( unsigned char *data,
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unsigned int block __unused,
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unsigned int len, int eof ) {
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if ( pxe_stack->readfile.buffer ) {
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if ( pxe_stack->readfile.offset + len >=
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pxe_stack->readfile.bufferlen ) return -1;
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memcpy ( pxe_stack->readfile.buffer +
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pxe_stack->readfile.offset, data, len );
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/* Read file */
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buffer = phys_to_user ( tftp_read_file->Buffer );
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max_len = tftp_read_file->BufferSize;
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while ( max_len ) {
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frag_len = read_user ( fd, buffer, len, max_len );
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if ( frag_len <= 0 ) {
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rc = frag_len;
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break;
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}
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len += frag_len;
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max_len -= frag_len;
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}
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pxe_stack->readfile.offset += len;
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return eof ? 0 : 1;
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close ( fd );
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tftp_read_file->BufferSize = len;
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tftp_read_file->Status = PXENV_STATUS ( rc );
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return ( rc ? PXENV_EXIT_FAILURE : PXENV_EXIT_SUCCESS );
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}
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#endif
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/**
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* TFTP GET FILE SIZE
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@ -455,168 +441,33 @@ static int pxe_tftp_read_block ( unsigned char *data,
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*/
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PXENV_EXIT_t pxenv_tftp_get_fsize ( struct s_PXENV_TFTP_GET_FSIZE
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*tftp_get_fsize ) {
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int rc;
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char uri_string[PXE_URI_LEN];
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int fd;
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ssize_t size;
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DBG ( "PXENV_TFTP_GET_FSIZE" );
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#if 0
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pxe_stack->readfile.buffer = NULL;
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pxe_stack->readfile.bufferlen = 0;
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pxe_stack->readfile.offset = 0;
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/* Construct URI */
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pxe_tftp_build_uri ( uri_string, tftp_get_fsize->ServerIPAddress,
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0, tftp_get_fsize->FileName, 0 );
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DBG ( " %s", uri_string );
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#warning "Rewrite pxenv_tftp_get_fsize, please"
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if ( rc ) {
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tftp_get_fsize->FileSize = 0;
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tftp_get_fsize->Status = PXENV_STATUS_FAILURE;
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/* Open URI */
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fd = open ( uri_string );
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if ( fd < 0 ) {
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tftp_get_fsize->Status = PXENV_STATUS ( fd );
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return PXENV_EXIT_FAILURE;
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}
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tftp_get_fsize->FileSize = pxe_stack->readfile.offset;
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#endif
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/* Determine size */
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size = fsize ( fd );
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close ( fd );
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if ( size < 0 ) {
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tftp_get_fsize->Status = PXENV_STATUS ( size );
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return PXENV_EXIT_FAILURE;
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}
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tftp_get_fsize->FileSize = size;
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tftp_get_fsize->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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}
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/** @page pxe_notes Etherboot PXE implementation notes
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@section pxe_note_tftp Welding together the TFTP protocol and the PXE TFTP API
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The PXE TFTP API is fundamentally poorly designed; the TFTP protocol
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simply does not map well into "open file", "read file block", "close
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file" operations. The problem is the unreliable nature of UDP
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transmissions and the lock-step mechanism employed by TFTP to
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guarantee file transfer. The lock-step mechanism requires that if we
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time out waiting for a packet to arrive, we must trigger its
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retransmission by retransmitting our own previously transmitted
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packet.
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For example, suppose that pxenv_tftp_read() is called to read the
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first data block of a file from a server that does not support TFTP
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options, and that no data block is received within the timeout period.
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In order to trigger the retransmission of this data block,
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pxenv_tftp_read() must retransmit the TFTP open request. However, the
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information used to build the TFTP open request is not available at
|
||||
this time; it was provided only to the pxenv_tftp_open() call. Even
|
||||
if we were able to retransmit a TFTP open request, we would have to
|
||||
allocate a new local port number (and be prepared for data to arrive
|
||||
from a new remote port number) in order to avoid violating the TFTP
|
||||
protocol specification.
|
||||
|
||||
The question of when to transmit the ACK packets is also awkward. At
|
||||
a first glance, it would seem to be fairly simple: acknowledge a
|
||||
packet immediately after receiving it. However, since the ACK packet
|
||||
may itself be lost, the next call to pxenv_tftp_read() must be
|
||||
prepared to retransmit the acknowledgement.
|
||||
|
||||
Another problem to consider is that the pxenv_tftp_open() API call
|
||||
must return an indication of whether or not the TFTP open request
|
||||
succeeded. In the case of a TFTP server that doesn't support TFTP
|
||||
options, the only indication of a successful open is the reception of
|
||||
the first data block. However, the pxenv_tftp_open() API provides no
|
||||
way to return this data block at this time.
|
||||
|
||||
At least some PXE stacks (e.g. NILO) solve this problem by violating
|
||||
the TFTP protocol and never bothering with retransmissions, relying on
|
||||
the TFTP server to retransmit when it times out waiting for an ACK.
|
||||
This approach is dubious at best; if, for example, the initial TFTP
|
||||
open request is lost then NILO will believe that it has opened the
|
||||
file and will eventually time out and give up while waiting for the
|
||||
first packet to arrive.
|
||||
|
||||
The only viable solution seems to be to allocate a buffer for the
|
||||
storage of the first data packet returned by the TFTP server, since we
|
||||
may receive this packet during the pxenv_tftp_open() call but have to
|
||||
return it from the subsequent pxenv_tftp_read() call. This buffer
|
||||
must be statically allocated and must be dedicated to providing a
|
||||
temporary home for TFTP packets. There is nothing in the PXE
|
||||
specification that prevents a caller from calling
|
||||
e.g. pxenv_undi_transmit() between calls to the TFTP API, so we cannot
|
||||
use the normal transmit/receive buffer for this purpose.
|
||||
|
||||
Having paid the storage penalty for this buffer, we can then gain some
|
||||
simplicity by exploiting it in full. There is at least one
|
||||
circumstance (pxenv_tftp_open() called to open a file on a server that
|
||||
does not support TFTP options) in which we will have to enter
|
||||
pxenv_tftp_read() knowing that our previous transmission (the open
|
||||
request, in this situation) has already been acknowledged.
|
||||
Implementation of pxenv_tftp_read() can be made simpler by making this
|
||||
condition an invariant. Specifically, on each call to
|
||||
pxenv_tftp_read(), we shall ensure that the following are true:
|
||||
|
||||
- Our previous transmission has already been acknowledged. We
|
||||
therefore do not need to keep state about our previous
|
||||
transmission.
|
||||
|
||||
- The next packet to read is already in a buffer in memory.
|
||||
|
||||
In order to maintain these two conditions, pxenv_tftp_read() must do
|
||||
the following:
|
||||
|
||||
- Copy the data packet from our buffer to the caller's buffer.
|
||||
|
||||
- Acknowledge the data packet that we have just copied. This will
|
||||
trigger transmission of the next packet from the server.
|
||||
|
||||
- Retransmit this acknowledgement packet until the next packet
|
||||
arrives.
|
||||
|
||||
- Copy the packet into our internal buffer, ready for the next call
|
||||
to pxenv_tftp_read().
|
||||
|
||||
It can be verified that this preserves the invariant condition, and it
|
||||
is clear that the resulting implementation of pxenv_tftp_read() can be
|
||||
relatively simple. (For the special case of the last data packet,
|
||||
pxenv_tftp_read() should return immediately after sending a single
|
||||
acknowledgement packet.)
|
||||
|
||||
In order to set up this invariant condition for the first call to
|
||||
pxenv_tftp_read(), pxenv_tftp_open() must do the following:
|
||||
|
||||
- Construct and transmit the TFTP open request.
|
||||
|
||||
- Retransmit the TFTP open request (using a new local port number as
|
||||
necessary) until a response (DATA, OACK, or ERROR) is received.
|
||||
|
||||
- If the response is an OACK, acknowledge the OACK and retransmit
|
||||
the acknowledgement until the first DATA packet arrives.
|
||||
|
||||
- If we have a DATA packet, store it in a buffer ready for the first
|
||||
call to pxenv_tftp_read().
|
||||
|
||||
This approach has the advantage of being fully compliant with both
|
||||
RFC1350 (TFTP) and RFC2347 (TFTP options). It avoids unnecessary
|
||||
retransmissions. The cost is approximately 1500 bytes of
|
||||
uninitialised storage. Since there is demonstrably no way to avoid
|
||||
paying this cost without either violating the protocol specifications
|
||||
or introducing unnecessary retransmissions, we deem this to be a cost
|
||||
worth paying.
|
||||
|
||||
A small performance gain may be obtained by adding a single extra
|
||||
"send ACK" in both pxenv_tftp_open() and pxenv_tftp_read() immediately
|
||||
after receiving the DATA packet and copying it into the internal
|
||||
buffer. The sequence of events for pxenv_tftp_read() then becomes:
|
||||
|
||||
- Copy the data packet from our buffer to the caller's buffer.
|
||||
|
||||
- If this was the last data packet, return immediately.
|
||||
|
||||
- Check to see if a TFTP data packet is waiting. If not, send an
|
||||
ACK for the data packet that we have just copied, and retransmit
|
||||
this ACK until the next data packet arrives.
|
||||
|
||||
- Copy the packet into our internal buffer, ready for the next call
|
||||
to pxenv_tftp_read().
|
||||
|
||||
- Send a single ACK for this data packet.
|
||||
|
||||
Sending the ACK at this point allows the server to transmit the next
|
||||
data block while our caller is processing the current packet. If this
|
||||
ACK is lost, or the DATA packet it triggers is lost or is consumed by
|
||||
something other than pxenv_tftp_read() (e.g. by calls to
|
||||
pxenv_undi_isr()), then the next call to pxenv_tftp_read() will not
|
||||
find a TFTP data packet waiting and will retransmit the ACK anyway.
|
||||
|
||||
Note to future API designers at Intel: try to understand the
|
||||
underlying network protocol first!
|
||||
|
||||
*/
|
||||
|
|
|
|||
Reference in New Issue