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[dhcp] Omit ProxyDHCPREQUEST if PXE options are present in ProxyDHCPO…
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…FFER

Some ProxyDHCP implementations seem to violate the PXE specification
by expecting the client to retain options from the ProxyDHCPOFFER
rather than issuing a separate ProxyDHCPREQUEST.

Work around such broken clients by retaining the ProxyDHCPOFFER
packet, and proceeding to a ProxyDHCPREQUEST only if the
ProxyDHCPOFFER does not already contain PXE options.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
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@mcb30
mcb30 committed Oct 8, 2010
1 parent ba6aca3 commit 831106a
Showing 1 changed file with 67 additions and 37 deletions.
104 changes: 67 additions & 37 deletions src/net/udp/dhcp.c
View file
Expand Up @@ -231,9 +231,9 @@ struct dhcp_session {
int no_pxedhcp;
/** ProxyDHCP server */
struct in_addr proxy_server;
/** ProxyDHCP port */
uint16_t proxy_port;
/** ProxyDHCP server priority */
/** ProxyDHCP offer */
struct dhcp_packet *proxy_offer;
/** ProxyDHCP offer priority */
int proxy_priority;

/** PXE Boot Server type */
Expand All @@ -259,6 +259,7 @@ static void dhcp_free ( struct refcnt *refcnt ) {
container_of ( refcnt, struct dhcp_session, refcnt );

netdev_put ( dhcp->netdev );
dhcppkt_put ( dhcp->proxy_offer );
free ( dhcp );
}

Expand Down Expand Up @@ -297,6 +298,28 @@ static void dhcp_set_state ( struct dhcp_session *dhcp,
start_timer_nodelay ( &dhcp->timer );
}

/**
* Check if DHCP packet contains PXE options
*
* @v dhcppkt DHCP packet
* @ret has_pxeopts DHCP packet contains PXE options
*
* It is assumed that the packet is already known to contain option 60
* set to "PXEClient".
*/
static int dhcp_has_pxeopts ( struct dhcp_packet *dhcppkt ) {

/* Check for a boot filename */
if ( dhcppkt_fetch ( dhcppkt, DHCP_BOOTFILE_NAME, NULL, 0 ) > 0 )
return 1;

/* Check for a PXE boot menu */
if ( dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU, NULL, 0 ) > 0 )
return 1;

return 0;
}

/****************************************************************************
*
* DHCP state machine
Expand Down Expand Up @@ -340,8 +363,6 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
char vci[9]; /* "PXEClient" */
int vci_len;
int has_pxeclient;
int pxeopts_len;
int has_pxeopts;
int8_t priority = 0;
uint8_t no_pxedhcp = 0;
unsigned long elapsed;
Expand All @@ -362,12 +383,10 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
vci, sizeof ( vci ) );
has_pxeclient = ( ( vci_len >= ( int ) sizeof ( vci ) ) &&
( strncmp ( "PXEClient", vci, sizeof (vci) ) == 0 ));

/* Identify presence of PXE-specific options */
pxeopts_len = dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU, NULL, 0 );
has_pxeopts = ( pxeopts_len >= 0 );
if ( has_pxeclient )
DBGC ( dhcp, "%s", ( has_pxeopts ? " pxe" : " proxy" ) );
if ( has_pxeclient ) {
DBGC ( dhcp, "%s",
( dhcp_has_pxeopts ( dhcppkt ) ? " pxe" : " proxy" ) );
}

/* Identify priority */
dhcppkt_fetch ( dhcppkt, DHCP_EB_PRIORITY, &priority,
Expand All @@ -393,17 +412,11 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
}

/* Select as ProxyDHCP offer, if applicable */
if ( has_pxeclient && ( msgtype == DHCPOFFER ) &&
if ( server_id.s_addr && has_pxeclient &&
( priority >= dhcp->proxy_priority ) ) {
/* If the offer already includes the PXE options, then
* assume that we can send the ProxyDHCPREQUEST to
* port 67 (since the DHCPDISCOVER that triggered this
* ProxyDHCPOFFER was sent to port 67). Otherwise,
* send the ProxyDHCPREQUEST to port 4011.
*/
dhcppkt_put ( dhcp->proxy_offer );
dhcp->proxy_server = server_id;
dhcp->proxy_port = ( has_pxeopts ? htons ( BOOTPS_PORT )
: htons ( PXE_PORT ) );
dhcp->proxy_offer = dhcppkt_get ( dhcppkt );
dhcp->proxy_priority = priority;
}

Expand All @@ -421,7 +434,7 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp,

/* If we can't yet transition to DHCPREQUEST, do nothing */
elapsed = ( currticks() - dhcp->start );
if ( ! ( dhcp->no_pxedhcp || dhcp->proxy_server.s_addr ||
if ( ! ( dhcp->no_pxedhcp || dhcp->proxy_offer ||
( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) )
return;

Expand Down Expand Up @@ -507,6 +520,7 @@ static void dhcp_request_rx ( struct dhcp_session *dhcp,
struct in_addr server_id ) {
struct in_addr ip;
struct settings *parent;
struct settings *settings;
int rc;

DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
Expand Down Expand Up @@ -536,21 +550,36 @@ static void dhcp_request_rx ( struct dhcp_session *dhcp,

/* Register settings */
parent = netdev_settings ( dhcp->netdev );
if ( ( rc = register_settings ( &dhcppkt->settings, parent ) ) != 0 ){
settings = &dhcppkt->settings;
if ( ( rc = register_settings ( settings, parent ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
}

/* Start ProxyDHCPREQUEST if applicable */
if ( dhcp->proxy_server.s_addr /* Have ProxyDHCP server */ &&
( ! dhcp->no_pxedhcp ) /* ProxyDHCP not disabled */ &&
( /* ProxyDHCP server is not just the DHCP server itself */
( dhcp->proxy_server.s_addr != dhcp->server.s_addr ) ||
( dhcp->proxy_port != htons ( BOOTPS_PORT ) ) ) ) {
dhcp_set_state ( dhcp, &dhcp_state_proxy );
return;
/* Perform ProxyDHCP if applicable */
if ( dhcp->proxy_offer /* Have ProxyDHCP offer */ &&
( ! dhcp->no_pxedhcp ) /* ProxyDHCP not disabled */ ) {
if ( dhcp_has_pxeopts ( dhcp->proxy_offer ) ) {
/* PXE options already present; register settings
* without performing a ProxyDHCPREQUEST
*/
settings = &dhcp->proxy_offer->settings;
settings->name = PROXYDHCP_SETTINGS_NAME;
if ( ( rc = register_settings ( settings,
NULL ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register "
"proxy settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
}
} else {
/* PXE options not present; use a ProxyDHCPREQUEST */
dhcp_set_state ( dhcp, &dhcp_state_proxy );
return;
}
}

/* Terminate DHCP */
Expand Down Expand Up @@ -590,8 +619,8 @@ static int dhcp_proxy_tx ( struct dhcp_session *dhcp,
struct sockaddr_in *peer ) {
int rc;

DBGC ( dhcp, "DHCP %p ProxyDHCP REQUEST to %s:%d\n", dhcp,
inet_ntoa ( dhcp->proxy_server ), ntohs ( dhcp->proxy_port ) );
DBGC ( dhcp, "DHCP %p ProxyDHCP REQUEST to %s\n", dhcp,
inet_ntoa ( dhcp->proxy_server ) );

/* Set server ID */
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_SERVER_IDENTIFIER,
Expand All @@ -601,7 +630,7 @@ static int dhcp_proxy_tx ( struct dhcp_session *dhcp,

/* Set server address */
peer->sin_addr = dhcp->proxy_server;
peer->sin_port = dhcp->proxy_port;
peer->sin_port = htons ( PXE_PORT );

return 0;
}
Expand All @@ -619,6 +648,7 @@ static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer, uint8_t msgtype,
struct in_addr server_id ) {
struct settings *settings = &dhcppkt->settings;
int rc;

DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
Expand All @@ -629,7 +659,7 @@ static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
DBGC ( dhcp, "\n" );

/* Filter out unacceptable responses */
if ( peer->sin_port != dhcp->proxy_port )
if ( peer->sin_port != ntohs ( PXE_PORT ) )
return;
if ( ( msgtype != DHCPOFFER ) && ( msgtype != DHCPACK ) )
return;
Expand All @@ -638,9 +668,9 @@ static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
return;

/* Register settings */
dhcppkt->settings.name = PROXYDHCP_SETTINGS_NAME;
if ( ( rc = register_settings ( &dhcppkt->settings, NULL ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
settings->name = PROXYDHCP_SETTINGS_NAME;
if ( ( rc = register_settings ( settings, NULL ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register proxy settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
Expand Down

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