mirror of https://github.com/ipxe/ipxe.git
[dhcp] Use a random DHCP transaction identifier (xid)
iPXE currently uses the last four bytes of the MAC address as the DHCP transaction identifier. Reduce the probability of collisions by generating a random transaction identifier. Originally-implemented-by: Amos Kong <akong@redhat.com> Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/5/head
Michael Brown
parent
8b092f4c50
commit
12767d2202
|
|
@ -660,15 +660,18 @@ struct dhcphdr {
|
|||
/** Setting block name used for BootServerDHCP responses */
|
||||
#define PXEBS_SETTINGS_NAME "pxebs"
|
||||
|
||||
extern uint32_t dhcp_last_xid;
|
||||
extern unsigned int dhcp_chaddr ( struct net_device *netdev, void *chaddr,
|
||||
uint16_t *flags );
|
||||
extern int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
|
||||
struct net_device *netdev, uint8_t msgtype,
|
||||
const void *options, size_t options_len,
|
||||
void *data, size_t max_len );
|
||||
uint32_t xid, const void *options,
|
||||
size_t options_len, void *data,
|
||||
size_t max_len );
|
||||
extern int dhcp_create_request ( struct dhcp_packet *dhcppkt,
|
||||
struct net_device *netdev,
|
||||
unsigned int msgtype, struct in_addr ciaddr,
|
||||
unsigned int msgtype, uint32_t xid,
|
||||
struct in_addr ciaddr,
|
||||
void *data, size_t max_len );
|
||||
extern int start_dhcp ( struct interface *job, struct net_device *netdev );
|
||||
extern int start_pxebs ( struct interface *job, struct net_device *netdev,
|
||||
|
|
|
|||
|
|
@ -114,7 +114,8 @@ int create_fakedhcpdiscover ( struct net_device *netdev,
|
|||
int rc;
|
||||
|
||||
if ( ( rc = dhcp_create_request ( &dhcppkt, netdev, DHCPDISCOVER,
|
||||
ciaddr, data, max_len ) ) != 0 ) {
|
||||
dhcp_last_xid, ciaddr, data,
|
||||
max_len ) ) != 0 ) {
|
||||
DBG ( "Could not create DHCPDISCOVER: %s\n",
|
||||
strerror ( rc ) );
|
||||
return rc;
|
||||
|
|
@ -139,7 +140,8 @@ int create_fakedhcpack ( struct net_device *netdev,
|
|||
int rc;
|
||||
|
||||
/* Create base DHCPACK packet */
|
||||
if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK, NULL, 0,
|
||||
if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK,
|
||||
dhcp_last_xid, NULL, 0,
|
||||
data, max_len ) ) != 0 ) {
|
||||
DBG ( "Could not create DHCPACK: %s\n", strerror ( rc ) );
|
||||
return rc;
|
||||
|
|
@ -190,7 +192,8 @@ int create_fakepxebsack ( struct net_device *netdev,
|
|||
}
|
||||
|
||||
/* Create base DHCPACK packet */
|
||||
if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK, NULL, 0,
|
||||
if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK,
|
||||
dhcp_last_xid, NULL, 0,
|
||||
data, max_len ) ) != 0 ) {
|
||||
DBG ( "Could not create PXE BS ACK: %s\n",
|
||||
strerror ( rc ) );
|
||||
|
|
|
|||
|
|
@ -116,6 +116,14 @@ struct setting use_cached_setting __setting ( SETTING_MISC ) = {
|
|||
.type = &setting_type_uint8,
|
||||
};
|
||||
|
||||
/**
|
||||
* Most recent DHCP transaction ID
|
||||
*
|
||||
* This is exposed for use by the fakedhcp code when reconstructing
|
||||
* DHCP packets for PXE NBPs.
|
||||
*/
|
||||
uint32_t dhcp_last_xid;
|
||||
|
||||
/**
|
||||
* Name a DHCP packet type
|
||||
*
|
||||
|
|
@ -137,23 +145,6 @@ static inline const char * dhcp_msgtype_name ( unsigned int msgtype ) {
|
|||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Calculate DHCP transaction ID for a network device
|
||||
*
|
||||
* @v netdev Network device
|
||||
* @ret xid DHCP XID
|
||||
*
|
||||
* Extract the least significant bits of the hardware address for use
|
||||
* as the transaction ID.
|
||||
*/
|
||||
static uint32_t dhcp_xid ( struct net_device *netdev ) {
|
||||
uint32_t xid;
|
||||
|
||||
memcpy ( &xid, ( netdev->ll_addr + netdev->ll_protocol->ll_addr_len
|
||||
- sizeof ( xid ) ), sizeof ( xid ) );
|
||||
return xid;
|
||||
}
|
||||
|
||||
/****************************************************************************
|
||||
*
|
||||
* DHCP session
|
||||
|
|
@ -219,6 +210,8 @@ struct dhcp_session {
|
|||
struct sockaddr_in local;
|
||||
/** State of the session */
|
||||
struct dhcp_session_state *state;
|
||||
/** Transaction ID (in network-endian order) */
|
||||
uint32_t xid;
|
||||
|
||||
/** Offered IP address */
|
||||
struct in_addr offer;
|
||||
|
|
@ -916,6 +909,7 @@ unsigned int dhcp_chaddr ( struct net_device *netdev, void *chaddr,
|
|||
* @v dhcppkt DHCP packet structure to fill in
|
||||
* @v netdev Network device
|
||||
* @v msgtype DHCP message type
|
||||
* @v xid Transaction ID (in network-endian order)
|
||||
* @v options Initial options to include (or NULL)
|
||||
* @v options_len Length of initial options
|
||||
* @v data Buffer for DHCP packet
|
||||
|
|
@ -927,7 +921,7 @@ unsigned int dhcp_chaddr ( struct net_device *netdev, void *chaddr,
|
|||
*/
|
||||
int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
|
||||
struct net_device *netdev, uint8_t msgtype,
|
||||
const void *options, size_t options_len,
|
||||
uint32_t xid, const void *options, size_t options_len,
|
||||
void *data, size_t max_len ) {
|
||||
struct dhcphdr *dhcphdr = data;
|
||||
int rc;
|
||||
|
|
@ -938,7 +932,7 @@ int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
|
|||
|
||||
/* Initialise DHCP packet content */
|
||||
memset ( dhcphdr, 0, max_len );
|
||||
dhcphdr->xid = dhcp_xid ( netdev );
|
||||
dhcphdr->xid = xid;
|
||||
dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
|
||||
dhcphdr->htype = ntohs ( netdev->ll_protocol->ll_proto );
|
||||
dhcphdr->op = dhcp_op[msgtype];
|
||||
|
|
@ -964,6 +958,7 @@ int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
|
|||
* @v dhcppkt DHCP packet structure to fill in
|
||||
* @v netdev Network device
|
||||
* @v msgtype DHCP message type
|
||||
* @v xid Transaction ID (in network-endian order)
|
||||
* @v ciaddr Client IP address
|
||||
* @v data Buffer for DHCP packet
|
||||
* @v max_len Size of DHCP packet buffer
|
||||
|
|
@ -974,7 +969,8 @@ int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
|
|||
*/
|
||||
int dhcp_create_request ( struct dhcp_packet *dhcppkt,
|
||||
struct net_device *netdev, unsigned int msgtype,
|
||||
struct in_addr ciaddr, void *data, size_t max_len ) {
|
||||
uint32_t xid, struct in_addr ciaddr,
|
||||
void *data, size_t max_len ) {
|
||||
struct dhcp_netdev_desc dhcp_desc;
|
||||
struct dhcp_client_id client_id;
|
||||
struct dhcp_client_uuid client_uuid;
|
||||
|
|
@ -985,7 +981,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
|
|||
int rc;
|
||||
|
||||
/* Create DHCP packet */
|
||||
if ( ( rc = dhcp_create_packet ( dhcppkt, netdev, msgtype,
|
||||
if ( ( rc = dhcp_create_packet ( dhcppkt, netdev, msgtype, xid,
|
||||
dhcp_request_options_data,
|
||||
sizeof ( dhcp_request_options_data ),
|
||||
data, max_len ) ) != 0 ) {
|
||||
|
|
@ -1099,7 +1095,8 @@ static int dhcp_tx ( struct dhcp_session *dhcp ) {
|
|||
|
||||
/* Create basic DHCP packet in temporary buffer */
|
||||
if ( ( rc = dhcp_create_request ( &dhcppkt, dhcp->netdev, msgtype,
|
||||
dhcp->local.sin_addr, iobuf->data,
|
||||
dhcp->xid, dhcp->local.sin_addr,
|
||||
iobuf->data,
|
||||
iob_tailroom ( iobuf ) ) ) != 0 ) {
|
||||
DBGC ( dhcp, "DHCP %p could not construct DHCP request: %s\n",
|
||||
dhcp, strerror ( rc ) );
|
||||
|
|
@ -1187,7 +1184,7 @@ static int dhcp_deliver ( struct dhcp_session *dhcp,
|
|||
&server_id, sizeof ( server_id ) );
|
||||
|
||||
/* Check for matching transaction ID */
|
||||
if ( dhcphdr->xid != dhcp_xid ( dhcp->netdev ) ) {
|
||||
if ( dhcphdr->xid != dhcp->xid ) {
|
||||
DBGC ( dhcp, "DHCP %p %s from %s:%d has bad transaction "
|
||||
"ID\n", dhcp, dhcp_msgtype_name ( msgtype ),
|
||||
inet_ntoa ( peer->sin_addr ),
|
||||
|
|
@ -1311,6 +1308,10 @@ int start_dhcp ( struct interface *job, struct net_device *netdev ) {
|
|||
dhcp->netdev = netdev_get ( netdev );
|
||||
dhcp->local.sin_family = AF_INET;
|
||||
dhcp->local.sin_port = htons ( BOOTPC_PORT );
|
||||
dhcp->xid = random();
|
||||
|
||||
/* Store DHCP transaction ID for fakedhcp code */
|
||||
dhcp_last_xid = dhcp->xid;
|
||||
|
||||
/* Instantiate child objects and attach to our interfaces */
|
||||
if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
|
||||
|
|
|
|||
Loading…
Reference in New Issue