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[dhcp] Clarify language surrounding ProxyDHCP
Remove the lazy assumption that ProxyDHCP == "DHCP with option 60 set
to PXEClient", and explicitly separate the notion of ProxyDHCP from
the notion of packets containing PXE options.
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Michael Brown committed Jan 23, 2009
1 parent 773d963 commit 3f814f0
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Showing 2 changed files with 56 additions and 55 deletions.
10 changes: 5 additions & 5 deletions src/include/gpxe/dhcp.h
Expand Up @@ -25,8 +25,8 @@ struct dhcp_pxe_boot_menu_item;
/** BOOTP/DHCP client port */
#define BOOTPC_PORT 68

/** ProxyDHCP server port */
#define PROXYDHCP_PORT 4011
/** PXE server port */
#define PXE_PORT 4011

/** Construct a tag value for an encapsulated option
*
Expand Down Expand Up @@ -207,12 +207,12 @@ struct dhcp_pxe_boot_menu_item;
*
*/

/** Ignore ProxyDHCP
/** Skip PXE DHCP protocol extensions such as ProxyDHCP
*
* If set to a non-zero value, gPXE will not wait for ProxyDHCP offers
* and will ignore any ProxyDHCP offers that it receives.
* and will ignore any PXE-specific DHCP offers that it receives.
*/
#define DHCP_EB_NO_PROXYDHCP DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb0 )
#define DHCP_EB_NO_PXEDHCP DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb0 )

/** Network device descriptor
*
Expand Down
101 changes: 51 additions & 50 deletions src/net/udp/dhcp.c
Expand Up @@ -340,14 +340,16 @@ struct dhcp_session {
* (e.g. @c DHCPDISCOVER).
*/
enum dhcp_session_state state;
/** DHCPOFFER obtained during DHCPDISCOVER */
/** DHCPOFFER obtained during DHCPDISCOVER containing IP address */
struct dhcp_settings *dhcpoffer;
/** ProxyDHCPOFFER obtained during DHCPDISCOVER */
struct dhcp_settings *proxydhcpoffer;
/** DHCPACK obtained during DHCPREQUEST */
/** DHCPOFFER obtained during DHCPDISCOVER containing "PXEClient" */
struct dhcp_settings *pxedhcpoffer;
/** DHCPACK obtained during DHCPREQUEST containing IP address */
struct dhcp_settings *dhcpack;
/** ProxyDHCPACK obtained during ProxyDHCPREQUEST */
struct dhcp_settings *proxydhcpack;
/** DHCPACK obtained during DHCPREQUEST or ProxyDHCPREQUEST
* containing "PXEClient"
*/
struct dhcp_settings *pxedhcpack;
/** BootServerDHCPACK obtained during BootServerDHCPREQUEST */
struct dhcp_settings *bsdhcpack;
/** Retransmission timer */
Expand All @@ -367,9 +369,9 @@ static void dhcp_free ( struct refcnt *refcnt ) {

netdev_put ( dhcp->netdev );
dhcpset_put ( dhcp->dhcpoffer );
dhcpset_put ( dhcp->proxydhcpoffer );
dhcpset_put ( dhcp->pxedhcpoffer );
dhcpset_put ( dhcp->dhcpack );
dhcpset_put ( dhcp->proxydhcpack );
dhcpset_put ( dhcp->pxedhcpack );
dhcpset_put ( dhcp->bsdhcpack );
free ( dhcp );
}
Expand Down Expand Up @@ -586,7 +588,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
static int dhcp_tx ( struct dhcp_session *dhcp ) {
static struct sockaddr_in dest = {
.sin_family = AF_INET,
.sin_port = htons ( PROXYDHCP_PORT ),
.sin_port = htons ( PXE_PORT ),
};
static struct sockaddr_in src = {
.sin_family = AF_INET,
Expand Down Expand Up @@ -624,11 +626,11 @@ static int dhcp_tx ( struct dhcp_session *dhcp ) {
break;
case DHCP_STATE_PROXYREQUEST:
assert ( dhcp->dhcpoffer );
assert ( dhcp->proxydhcpoffer );
assert ( dhcp->pxedhcpoffer );
assert ( dhcp->dhcpack );
msgtype = DHCPREQUEST;
ciaddr = dhcp->dhcpoffer->dhcppkt.dhcphdr->yiaddr;
dhcppkt_fetch ( &dhcp->proxydhcpoffer->dhcppkt,
dhcppkt_fetch ( &dhcp->pxedhcpoffer->dhcppkt,
DHCP_SERVER_IDENTIFIER, &dest.sin_addr,
sizeof ( dest.sin_addr ) );
meta.dest = ( struct sockaddr * ) &dest;
Expand All @@ -638,16 +640,16 @@ static int dhcp_tx ( struct dhcp_session *dhcp ) {
break;
case DHCP_STATE_BSREQUEST:
assert ( dhcp->dhcpoffer );
assert ( dhcp->proxydhcpoffer );
assert ( dhcp->pxedhcpoffer );
assert ( dhcp->dhcpack );
assert ( dhcp->proxydhcpack );
assert ( dhcp->pxedhcpack );
msgtype = DHCPREQUEST;
ciaddr = dhcp->dhcpoffer->dhcppkt.dhcphdr->yiaddr;
dhcppkt_fetch ( &dhcp->proxydhcpack->dhcppkt,
dhcppkt_fetch ( &dhcp->pxedhcpack->dhcppkt,
DHCP_PXE_BOOT_SERVER_MCAST,
&dest.sin_addr, sizeof ( dest.sin_addr ) );
meta.dest = ( struct sockaddr * ) &dest;
dhcppkt_fetch ( &dhcp->proxydhcpack->dhcppkt,
dhcppkt_fetch ( &dhcp->pxedhcpack->dhcppkt,
DHCP_PXE_BOOT_MENU, &menu_item.type,
sizeof ( menu_item.type ) );
assert ( dest.sin_addr.s_addr );
Expand Down Expand Up @@ -744,21 +746,21 @@ static void dhcp_next_state ( struct dhcp_session *dhcp ) {
dhcp_set_state ( dhcp, DHCP_STATE_REQUEST );
break;
case DHCP_STATE_REQUEST:
if ( dhcp->proxydhcpoffer ) {
/* Store DHCPACK as ProxyDHCPACK. This
* handles the case in which the DHCP server
* itself responds with "PXEClient" and PXE
* options but there is no actual ProxyDHCP
* server resident on the machine.
if ( dhcp->pxedhcpoffer ) {
/* Store DHCPACK as PXEDHCPACK. This handles
* the case in which the DHCP server itself
* responds with "PXEClient" and PXE options
* but there is no ProxyDHCP server resident
* on the machine.
*/
dhcp->proxydhcpack = dhcpset_get ( dhcp->dhcpack );
dhcp->pxedhcpack = dhcpset_get ( dhcp->dhcpack );
dhcp_set_state ( dhcp, DHCP_STATE_PROXYREQUEST );
break;
}
/* Fall through */
case DHCP_STATE_PROXYREQUEST:
if ( dhcp->proxydhcpack ) {
dhcppkt_fetch ( &dhcp->proxydhcpack->dhcppkt,
if ( dhcp->pxedhcpack ) {
dhcppkt_fetch ( &dhcp->pxedhcpack->dhcppkt,
DHCP_PXE_BOOT_SERVER_MCAST,
&bs_mcast, sizeof ( bs_mcast ) );
if ( bs_mcast.s_addr ) {
Expand Down Expand Up @@ -827,7 +829,7 @@ static void dhcp_rx_dhcpoffer ( struct dhcp_session *dhcp,
struct in_addr server_id = { 0 };
char vci[9]; /* "PXEClient" */
int len;
uint8_t ignore_proxy = 0;
uint8_t ignore_pxe = 0;
unsigned long elapsed;

/* Check for presence of DHCP server ID */
Expand All @@ -849,47 +851,46 @@ static void dhcp_rx_dhcpoffer ( struct dhcp_session *dhcp,
}

/* If there is a "PXEClient" vendor class ID, it's a
* ProxyDHCPOFFER. Note that it could be both a normal
* DHCPOFFER and a ProxyDHCPOFFER.
* PXEDHCPOFFER. Note that it could be both a normal
* DHCPOFFER and a PXEDHCPOFFER.
*/
len = dhcppkt_fetch ( &dhcpoffer->dhcppkt, DHCP_VENDOR_CLASS_ID,
vci, sizeof ( vci ) );
if ( ( server_id.s_addr != 0 ) &&
( len >= ( int ) sizeof ( vci ) ) &&
( strncmp ( "PXEClient", vci, sizeof ( vci ) ) == 0 ) ) {
DBGC ( dhcp, "DHCP %p DHCPOFFER %p from %s is a "
"ProxyDHCPOFFER\n",
DBGC ( dhcp, "DHCP %p DHCPOFFER %p from %s has PXE options\n",
dhcp, dhcpoffer, inet_ntoa ( server_id ) );
dhcp_store_dhcpoffer ( dhcp, dhcpoffer,
&dhcp->proxydhcpoffer );
&dhcp->pxedhcpoffer );
}

/* We can transition to making the DHCPREQUEST when we have a
* valid DHCPOFFER, and either:
*
* o The DHCPOFFER instructs us to not wait for ProxyDHCP, or
* o We have a valid ProxyDHCPOFFER, or
* o The DHCPOFFER instructs us to ignore PXEDHCPOFFERs, or
* o We have a valid PXEDHCPOFFER, or
* o We have allowed sufficient time for ProxyDHCPOFFERs.
*/

/* If we don't yet have a DHCPOFFER, do nothing */
if ( ! dhcp->dhcpoffer )
return;

/* If the DHCPOFFER instructs us to ignore ProxyDHCP, discard
* any ProxyDHCPOFFER
/* If the DHCPOFFER instructs us to ignore PXEDHCP, discard
* any PXEDHCPOFFER
*/
dhcppkt_fetch ( &dhcp->dhcpoffer->dhcppkt, DHCP_EB_NO_PROXYDHCP,
&ignore_proxy, sizeof ( ignore_proxy ) );
if ( ignore_proxy && dhcp->proxydhcpoffer ) {
DBGC ( dhcp, "DHCP %p discarding ProxyDHCPOFFER\n", dhcp );
dhcpset_put ( dhcp->proxydhcpoffer );
dhcp->proxydhcpoffer = NULL;
dhcppkt_fetch ( &dhcp->dhcpoffer->dhcppkt, DHCP_EB_NO_PXEDHCP,
&ignore_pxe, sizeof ( ignore_pxe ) );
if ( ignore_pxe && dhcp->pxedhcpoffer ) {
DBGC ( dhcp, "DHCP %p discarding PXEDHCPOFFER\n", dhcp );
dhcpset_put ( dhcp->pxedhcpoffer );
dhcp->pxedhcpoffer = NULL;
}

/* If we can't yet transition to DHCPREQUEST, do nothing */
elapsed = ( currticks() - dhcp->start );
if ( ! ( ignore_proxy || dhcp->proxydhcpoffer ||
if ( ! ( ignore_pxe || dhcp->pxedhcpoffer ||
( elapsed > PROXYDHCP_WAIT_TIME ) ) )
return;

Expand Down Expand Up @@ -978,11 +979,11 @@ static void dhcp_rx_proxydhcpack ( struct dhcp_session *dhcp,
int rc;

/* Verify server ID matches, if present */
assert ( dhcp->proxydhcpoffer != NULL );
assert ( dhcp->pxedhcpoffer != NULL );
if ( ( rc = dhcppkt_fetch ( &proxydhcpack->dhcppkt,
DHCP_SERVER_IDENTIFIER, &ack_server_id,
sizeof ( ack_server_id ) ) ) > 0 ) {
dhcppkt_fetch ( &dhcp->proxydhcpoffer->dhcppkt,
dhcppkt_fetch ( &dhcp->pxedhcpoffer->dhcppkt,
DHCP_SERVER_IDENTIFIER, &offer_server_id,
sizeof ( offer_server_id ) );
if ( offer_server_id.s_addr != ack_server_id.s_addr ) {
Expand All @@ -996,9 +997,9 @@ static void dhcp_rx_proxydhcpack ( struct dhcp_session *dhcp,
/* Rename settings */
proxydhcpack->settings.name = PROXYDHCP_SETTINGS_NAME;

/* Record ProxyDHCPACK */
dhcpset_put ( dhcp->proxydhcpack );
dhcp->proxydhcpack = dhcpset_get ( proxydhcpack );
/* Record ProxyDHCPACK as PXEDHCPACK */
dhcpset_put ( dhcp->pxedhcpack );
dhcp->pxedhcpack = dhcpset_get ( proxydhcpack );

/* Register settings */
if ( ( rc = dhcp_store_dhcpack ( dhcp, proxydhcpack, NULL ) ) != 0 )
Expand All @@ -1012,7 +1013,7 @@ static void dhcp_rx_proxydhcpack ( struct dhcp_session *dhcp,
* Handle received BootServerDHCPACK
*
* @v dhcp DHCP session
* @v bsdhcpack Received BootServerDHCPACK
* @v bsdhcpack Received BootServerDHCPACK
*/
static void dhcp_rx_bsdhcpack ( struct dhcp_session *dhcp,
struct dhcp_settings *bsdhcpack ) {
Expand All @@ -1021,7 +1022,7 @@ static void dhcp_rx_bsdhcpack ( struct dhcp_session *dhcp,
/* Rename settings */
bsdhcpack->settings.name = BSDHCP_SETTINGS_NAME;

/* Record ProxyDHCPACK */
/* Record BootServerDHCPACK */
assert ( dhcp->bsdhcpack == NULL );
dhcp->bsdhcpack = dhcpset_get ( bsdhcpack );

Expand Down Expand Up @@ -1107,12 +1108,12 @@ static int dhcp_deliver_iob ( struct xfer_interface *xfer,
break;
case DHCP_STATE_PROXYREQUEST:
if ( ( msgtype == DHCPACK ) &&
( src_port == htons ( PROXYDHCP_PORT ) ) )
( src_port == htons ( PXE_PORT ) ) )
dhcp_rx_proxydhcpack ( dhcp, dhcpset );
break;
case DHCP_STATE_BSREQUEST:
if ( ( msgtype == DHCPACK ) &&
( src_port == htons ( PROXYDHCP_PORT ) ) )
( src_port == htons ( PXE_PORT ) ) )
dhcp_rx_bsdhcpack ( dhcp, dhcpset );
break;
default:
Expand Down

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