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Don't build option-overloaded packets; they just confuse people (ISC
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DHCPD and Windows RIS in particular).
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Michael Brown committed Jun 30, 2007
1 parent 9125070 commit acd598b
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Showing 3 changed files with 23 additions and 55 deletions.
8 changes: 8 additions & 0 deletions contrib/bochs/README.windows-ris
View file
Expand Up @@ -21,3 +21,11 @@ startrom.com in a hex editor, search for the hex string
now accept the "F" key instead of "F12".



DHCP filename
=============

Must use Windows backslash separator e.g. 'filename
"OSChooser\\i386\\startrom.com";', otherwise startrom.com fails to
correctly identify the path to NTLDR.

28 changes: 4 additions & 24 deletions src/include/gpxe/dhcp.h
View file
Expand Up @@ -387,12 +387,12 @@ struct dhcphdr {
*
* This field may be overridden and contain DHCP options
*/
uint8_t sname[64];
char sname[64];
/** Boot file name (null terminated)
*
* This field may be overridden and contain DHCP options
*/
uint8_t file[128];
char file[128];
/** DHCP magic cookie
*
* Must have the value @c DHCP_MAGIC_COOKIE.
Expand Down Expand Up @@ -423,20 +423,6 @@ struct dhcphdr {
*/
#define DHCP_MIN_LEN 552

/** DHCP packet option block fill order
*
* This is the order in which option blocks are filled when
* reassembling a DHCP packet. We fill the smallest field ("sname")
* first, to maximise the chances of being able to fit large options
* within fields which are large enough to contain them.
*/
enum dhcp_packet_option_block_fill_order {
OPTS_SNAME = 0,
OPTS_FILE,
OPTS_MAIN,
NUM_OPT_BLOCKS
};

/**
* A DHCP packet
*
Expand All @@ -448,14 +434,8 @@ struct dhcp_packet {
size_t max_len;
/** Used length of the DHCP packet buffer */
size_t len;
/** DHCP option blocks within a DHCP packet
*
* A DHCP packet contains three fields which can be used to
* contain options: the actual "options" field plus the "file"
* and "sname" fields (which can be overloaded to contain
* options).
*/
struct dhcp_option_block options[NUM_OPT_BLOCKS];
/** DHCP options */
struct dhcp_option_block options;
};

/**
Expand Down
42 changes: 11 additions & 31 deletions src/net/udp/dhcp.c
View file
Expand Up @@ -138,7 +138,7 @@ static int set_dhcp_packet_option ( struct dhcp_packet *dhcppkt,
unsigned int tag, const void *data,
size_t len ) {
struct dhcphdr *dhcphdr = dhcppkt->dhcphdr;
struct dhcp_option_block *options = dhcppkt->options;
struct dhcp_option_block *options = &dhcppkt->options;
struct dhcp_option *option = NULL;

/* Special-case the magic options */
Expand All @@ -152,31 +152,23 @@ static int set_dhcp_packet_option ( struct dhcp_packet *dhcppkt,
case DHCP_EB_SIADDR:
memcpy ( &dhcphdr->siaddr, data, sizeof ( dhcphdr->siaddr ) );
return 0;
case DHCP_MESSAGE_TYPE:
case DHCP_REQUESTED_ADDRESS:
case DHCP_PARAMETER_REQUEST_LIST:
/* These options have to be within the main options
* block. This doesn't seem to be required by the
* RFCs, but at least ISC dhcpd refuses to recognise
* them otherwise.
*/
options = &dhcppkt->options[OPTS_MAIN];
break;
case DHCP_TFTP_SERVER_NAME:
strncpy ( dhcphdr->sname, data, sizeof ( dhcphdr->sname ) );
return 0;
case DHCP_BOOTFILE_NAME:
strncpy ( dhcphdr->file, data, sizeof ( dhcphdr->file ) );
return 0;
default:
/* Continue processing as normal */
break;
}

/* Set option in first available options block */
for ( ; options < &dhcppkt->options[NUM_OPT_BLOCKS] ; options++ ) {
option = set_dhcp_option ( options, tag, data, len );
if ( option )
break;
}
/* Set option */
option = set_dhcp_option ( options, tag, data, len );

/* Update DHCP packet length */
dhcppkt->len = ( offsetof ( typeof ( *dhcppkt->dhcphdr ), options )
+ dhcppkt->options[OPTS_MAIN].len );
+ dhcppkt->options.len );

return ( option ? 0 : -ENOSPC );
}
Expand Down Expand Up @@ -296,8 +288,6 @@ int create_dhcp_packet ( struct net_device *netdev, uint8_t msgtype,
void *data, size_t max_len,
struct dhcp_packet *dhcppkt ) {
struct dhcphdr *dhcphdr = data;
static const uint8_t overloading = ( DHCP_OPTION_OVERLOAD_FILE |
DHCP_OPTION_OVERLOAD_SNAME );
int rc;

/* Sanity check */
Expand All @@ -316,20 +306,10 @@ int create_dhcp_packet ( struct net_device *netdev, uint8_t msgtype,
/* Initialise DHCP packet structure */
dhcppkt->dhcphdr = dhcphdr;
dhcppkt->max_len = max_len;
init_dhcp_options ( &dhcppkt->options[OPTS_MAIN], dhcphdr->options,
init_dhcp_options ( &dhcppkt->options, dhcphdr->options,
( max_len -
offsetof ( typeof ( *dhcphdr ), options ) ) );
init_dhcp_options ( &dhcppkt->options[OPTS_FILE], dhcphdr->file,
sizeof ( dhcphdr->file ) );
init_dhcp_options ( &dhcppkt->options[OPTS_SNAME], dhcphdr->sname,
sizeof ( dhcphdr->sname ) );

/* Set DHCP_OPTION_OVERLOAD option within the main options block */
if ( set_dhcp_option ( &dhcppkt->options[OPTS_MAIN],
DHCP_OPTION_OVERLOAD, &overloading,
sizeof ( overloading ) ) == NULL )
return -ENOSPC;

/* Set DHCP_MESSAGE_TYPE option */
if ( ( rc = set_dhcp_packet_option ( dhcppkt, DHCP_MESSAGE_TYPE,
&msgtype,
Expand Down

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