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Provide individually cached constructed copies of DHCP packets via
PXENV_GET_CACHED_INFO. If we dont do this, Altiris' NBP screws up; it relies on being able to grab pointers to each of the three packets and then read them at will later.
This commit is contained in:
Michael Brown
parent
3a2473f123
commit
838ecba131
@ -32,22 +32,42 @@
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#include <gpxe/netdevice.h>
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#include <gpxe/isapnp.h>
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#include <gpxe/init.h>
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#include <gpxe/if_ether.h>
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#include <basemem_packet.h>
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#include "pxe.h"
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#include "pxe_call.h"
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/** Filename used for last TFTP request
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*
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* This is a bug-for-bug compatibility hack needed in order to work
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* with Microsoft Remote Installation Services (RIS). The filename
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* used in a call to PXENV_RESTART_TFTP must be returned as the DHCP
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* filename in subsequent calls to PXENV_GET_CACHED_INFO.
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*/
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static char *pxe_ris_filename = NULL;
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/* Avoid dragging in isapnp.o unnecessarily */
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uint16_t isapnp_read_port;
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/** Zero-based versions of PXENV_GET_CACHED_INFO::PacketType */
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enum pxe_cached_info_indices {
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CACHED_INFO_DHCPDISCOVER = ( PXENV_PACKET_TYPE_DHCP_DISCOVER - 1 ),
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CACHED_INFO_DHCPACK = ( PXENV_PACKET_TYPE_DHCP_ACK - 1 ),
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CACHED_INFO_BINL = ( PXENV_PACKET_TYPE_CACHED_REPLY - 1 ),
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NUM_CACHED_INFOS
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};
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/** A cached DHCP packet */
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union pxe_cached_info {
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struct dhcphdr dhcphdr;
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char raw[ETH_FRAME_LEN];
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};
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/* The case in which the caller doesn't supply a buffer is really
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* awkward to support given that we have multiple sources of options,
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* and that we don't actually store the DHCP packets. (We may not
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* even have performed DHCP; we may have obtained all configuration
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* from non-volatile stored options or from the command line.)
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*
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* Some NBPs rely on the buffers we provide being persistent, so we
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* can't just use the temporary packet buffer. 4.5kB of base memory
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* always wasted just because some clients are too lazy to provide
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* their own buffers...
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*/
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static union pxe_cached_info __bss16_array ( cached_info, [NUM_CACHED_INFOS] );
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#define cached_info __use_data16 ( cached_info )
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/**
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* UNLOAD BASE CODE STACK
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*
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@ -72,8 +92,8 @@ PXENV_EXIT_t pxenv_get_cached_info ( struct s_PXENV_GET_CACHED_INFO
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int ( * dhcp_packet_creator ) ( struct net_device *, int,
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struct dhcp_option_block *, void *,
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size_t, struct dhcp_packet * );
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unsigned int idx;
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unsigned int msgtype;
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void *data = NULL;
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size_t len;
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userptr_t buffer;
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int rc;
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@ -83,88 +103,86 @@ PXENV_EXIT_t pxenv_get_cached_info ( struct s_PXENV_GET_CACHED_INFO
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DBG ( " to %04x:%04x+%x", get_cached_info->Buffer.segment,
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get_cached_info->Buffer.offset, get_cached_info->BufferSize );
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/* The case in which the caller doesn't supply a buffer is
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* really awkward to support given that we have multiple
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* sources of options, and that we don't actually store the
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* DHCP packets. (We may not even have performed DHCP; we may
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* have obtained all configuration from non-volatile stored
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* options or from the command line.) We provide the caller
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* with our base-memory temporary packet buffer and construct
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* the packet in there.
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*
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* To add to the fun, Intel decided at some point in the
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* evolution of the PXE specification to add the BufferLimit
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* field, which we are meant to fill in with the length of our
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* packet buffer, so that the caller can safely modify the
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* boot server reply packet stored therein. However, this
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* field was not present in earlier versions of the PXE spec,
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* and there is at least one PXE NBP (Altiris) which allocates
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* only exactly enough space for this earlier, shorter version
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* of the structure. If we actually fill in the BufferLimit
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* field, we therefore risk trashing random areas of the
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* caller's memory. If we *don't* fill it in, then the caller
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* is at liberty to assume that whatever random value happened
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* to be in that location represents the length of the buffer
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* we've just passed back to it.
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*
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* Since older PXE stacks won't fill this field in anyway,
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* it's probably safe to assume that no callers actually rely
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* on it, so we choose to not fill it in.
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*/
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/* Sanity check */
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idx = ( get_cached_info->PacketType - 1 );
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if ( idx >= ( sizeof ( cached_info ) / sizeof ( cached_info[0] ) ) ) {
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DBG ( " bad PacketType" );
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goto err;
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}
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/* Construct cached version of packet, if not already constructed. */
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if ( ! cached_info[idx].dhcphdr.op ) {
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/* Construct DHCP packet */
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if ( get_cached_info->PacketType ==
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PXENV_PACKET_TYPE_DHCP_DISCOVER ) {
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dhcp_packet_creator = create_dhcp_request;
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msgtype = DHCPDISCOVER;
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} else {
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dhcp_packet_creator = create_dhcp_response;
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msgtype = DHCPACK;
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}
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if ( ( rc = dhcp_packet_creator ( pxe_netdev, msgtype,
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NULL, &cached_info[idx],
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sizeof ( cached_info[idx] ),
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&dhcppkt ) ) != 0 ) {
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DBG ( " failed to build packet" );
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goto err;
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}
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}
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len = get_cached_info->BufferSize;
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if ( len == 0 ) {
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len = sizeof ( basemem_packet );
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/* Point client at our cached buffer.
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*
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* To add to the fun, Intel decided at some point in
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* the evolution of the PXE specification to add the
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* BufferLimit field, which we are meant to fill in
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* with the length of our packet buffer, so that the
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* caller can safely modify the boot server reply
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* packet stored therein. However, this field was not
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* present in earlier versions of the PXE spec, and
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* there is at least one PXE NBP (Altiris) which
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* allocates only exactly enough space for this
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* earlier, shorter version of the structure. If we
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* actually fill in the BufferLimit field, we
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* therefore risk trashing random areas of the
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* caller's memory. If we *don't* fill it in, then
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* the caller is at liberty to assume that whatever
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* random value happened to be in that location
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* represents the length of the buffer we've just
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* passed back to it.
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*
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* Since older PXE stacks won't fill this field in
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* anyway, it's probably safe to assume that no
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* callers actually rely on it, so we choose to not
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* fill it in.
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*/
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get_cached_info->Buffer.segment = rm_ds;
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get_cached_info->Buffer.offset =
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( unsigned int ) ( & __from_data16 ( basemem_packet ) );
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DBG ( " using %04x:%04x+'%x'", get_cached_info->Buffer.segment,
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( unsigned ) ( & __from_data16 ( cached_info[idx] ) );
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get_cached_info->BufferSize = sizeof ( cached_info[idx] );
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DBG ( " returning %04x:%04x+%04x['%x']",
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get_cached_info->Buffer.segment,
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get_cached_info->Buffer.offset,
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get_cached_info->BufferSize,
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get_cached_info->BufferLimit );
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}
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/* Allocate space for temporary copy */
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data = malloc ( len );
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if ( ! data ) {
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DBG ( " out of memory" );
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goto err;
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}
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/* Construct DHCP packet */
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if ( get_cached_info->PacketType == PXENV_PACKET_TYPE_DHCP_DISCOVER ) {
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dhcp_packet_creator = create_dhcp_request;
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msgtype = DHCPDISCOVER;
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} else {
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dhcp_packet_creator = create_dhcp_response;
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msgtype = DHCPACK;
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}
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if ( ( rc = dhcp_packet_creator ( pxe_netdev, msgtype, NULL,
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data, len, &dhcppkt ) ) != 0 ) {
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DBG ( " failed to build packet" );
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goto err;
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/* Copy packet to client buffer */
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if ( len < sizeof ( cached_info[idx] ) ) {
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DBG ( " buffer too short" );
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goto err;
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}
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buffer = real_to_user ( get_cached_info->Buffer.segment,
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get_cached_info->Buffer.offset );
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copy_to_user ( buffer, 0, &cached_info[idx],
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sizeof ( cached_info[idx] ) );
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get_cached_info->BufferSize = sizeof ( cached_info[idx] );
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}
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/* Overwrite filename to work around Microsoft RIS bug */
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if ( pxe_ris_filename ) {
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DBG ( " applying RIS hack" );
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strncpy ( dhcppkt.dhcphdr->file, pxe_ris_filename,
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sizeof ( dhcppkt.dhcphdr->file ) );
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}
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/* Copy packet to client buffer */
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buffer = real_to_user ( get_cached_info->Buffer.segment,
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get_cached_info->Buffer.offset );
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len = dhcppkt.len;
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DBG ( " length %x", len );
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copy_to_user ( buffer, 0, data, len );
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get_cached_info->BufferSize = len;
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free ( data );
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get_cached_info->Status = PXENV_STATUS_SUCCESS;
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return PXENV_EXIT_SUCCESS;
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err:
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if ( data )
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free ( data );
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get_cached_info->Status = PXENV_STATUS_OUT_OF_RESOURCES;
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return PXENV_EXIT_FAILURE;
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}
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@ -179,13 +197,18 @@ PXENV_EXIT_t pxenv_restart_tftp ( struct s_PXENV_TFTP_READ_FILE
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DBG ( "PXENV_RESTART_TFTP " );
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/* Work around Microsoft RIS bug */
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free ( pxe_ris_filename );
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pxe_ris_filename = strdup ( ( char * ) restart_tftp->FileName );
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if ( ! pxe_ris_filename ) {
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restart_tftp->Status = PXENV_STATUS_OUT_OF_RESOURCES;
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return PXENV_EXIT_FAILURE;
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}
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/* This is a bug-for-bug compatibility hack needed in order to
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* work with Microsoft Remote Installation Services (RIS).
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* The filename used in a call to PXENV_RESTART_TFTP must be
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* returned as the DHCP filename in subsequent calls to
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* PXENV_GET_CACHED_INFO.
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*/
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memcpy ( cached_info[CACHED_INFO_DHCPACK].dhcphdr.file,
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restart_tftp->FileName,
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sizeof ( cached_info[CACHED_INFO_DHCPACK].dhcphdr.file ) );
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memcpy ( cached_info[CACHED_INFO_BINL].dhcphdr.file,
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restart_tftp->FileName,
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sizeof ( cached_info[CACHED_INFO_BINL].dhcphdr.file ) );
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/* Words cannot describe the complete mismatch between the PXE
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* specification and any possible version of reality...
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