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-rw-r--r--src/include/errno.h1
-rw-r--r--src/include/gpxe/dhcp.h22
-rw-r--r--src/net/dhcpopts.c32
-rw-r--r--src/net/udp/dhcp.c196
4 files changed, 243 insertions, 8 deletions
diff --git a/src/include/errno.h b/src/include/errno.h
index 8c9f515e..d59880bc 100644
--- a/src/include/errno.h
+++ b/src/include/errno.h
@@ -151,6 +151,7 @@
#define ENOENT 0xe8 /**< No such file or directory */
#define ENOEXEC 0xe9 /**< Exec format error */
#define ENOMSG ENODATA /**< No message of the desired type */
+#define ENOSPC ENOMEM /**< No space left on device */
#define ENOSR 0xea /**< No stream resources */
#define ENOSTR 0xeb /**< Not a stream */
#define ENOSYS 0xec /**< Function not implemented */
diff --git a/src/include/gpxe/dhcp.h b/src/include/gpxe/dhcp.h
index 9442f857..e35b7eab 100644
--- a/src/include/gpxe/dhcp.h
+++ b/src/include/gpxe/dhcp.h
@@ -118,6 +118,12 @@ struct dhcp_packet {
*/
#define DHCP_PAD 0
+/** Minimum normal DHCP option */
+#define DHCP_MIN_OPTION 1
+
+/** Vendor encapsulated options */
+#define DHCP_VENDOR_ENCAP 43
+
/** Option overloading
*
* The value of this option is the bitwise-OR of zero or more
@@ -131,6 +137,17 @@ struct dhcp_packet {
/** The "sname" field is overloaded to contain extra DHCP options */
#define DHCP_OPTION_OVERLOAD_SNAME 2
+/** DHCP message type */
+#define DHCP_MESSAGE_TYPE 53
+#define DHCPDISCOVER 1
+#define DHCPOFFER 2
+#define DHCPREQUEST 3
+#define DHCPDECLINE 4
+#define DHCPACK 5
+#define DHCPNAK 6
+#define DHCPRELEASE 7
+#define DHCPINFORM 8
+
/** TFTP server name
*
* This option replaces the fixed "sname" field, when that field is
@@ -178,6 +195,9 @@ struct dhcp_packet {
*/
#define DHCP_EB_SIADDR DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 3 )
+/** Maximum normal DHCP option */
+#define DHCP_MAX_OPTION 254
+
/** End of options
*
* This tag does not have a length field; it is always only a single
@@ -260,6 +280,8 @@ find_dhcp_option ( struct dhcp_option_block *options, unsigned int tag );
extern struct dhcp_option * find_global_dhcp_option ( unsigned int tag );
extern void register_dhcp_options ( struct dhcp_option_block *options );
extern void unregister_dhcp_options ( struct dhcp_option_block *options );
+extern void init_dhcp_options ( struct dhcp_option_block *options,
+ void *data, size_t max_len );
extern struct dhcp_option_block * alloc_dhcp_options ( size_t max_len );
extern void free_dhcp_options ( struct dhcp_option_block *options );
extern struct dhcp_option *
diff --git a/src/net/dhcpopts.c b/src/net/dhcpopts.c
index 6b06b9a2..70196346 100644
--- a/src/net/dhcpopts.c
+++ b/src/net/dhcpopts.c
@@ -228,6 +228,27 @@ void unregister_dhcp_options ( struct dhcp_option_block *options ) {
}
/**
+ * Initialise empty block of DHCP options
+ *
+ * @v options Uninitialised DHCP option block
+ * @v data Memory for DHCP option data
+ * @v max_len Length of memory for DHCP option data
+ *
+ * Populates the DHCP option data with a single @c DHCP_END option and
+ * fills in the fields of the @c dhcp_option_block structure.
+ */
+void init_dhcp_options ( struct dhcp_option_block *options,
+ void *data, size_t max_len ) {
+ struct dhcp_option *option;
+
+ options->data = data;
+ options->max_len = max_len;
+ option = options->data;
+ option->tag = DHCP_END;
+ options->len = 1;
+}
+
+/**
* Allocate space for a block of DHCP options
*
* @v max_len Maximum length of option block
@@ -238,17 +259,12 @@ void unregister_dhcp_options ( struct dhcp_option_block *options ) {
*/
struct dhcp_option_block * alloc_dhcp_options ( size_t max_len ) {
struct dhcp_option_block *options;
- struct dhcp_option *option;
options = malloc ( sizeof ( *options ) + max_len );
if ( options ) {
- options->data = ( ( void * ) options + sizeof ( *options ) );
- options->max_len = max_len;
- if ( max_len ) {
- option = options->data;
- option->tag = DHCP_END;
- options->len = 1;
- }
+ init_dhcp_options ( options,
+ ( (void *) options + sizeof ( *options ) ),
+ max_len );
}
return options;
}
diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index 89c3eb90..1523e404 100644
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -17,6 +17,7 @@
*/
#include <string.h>
+#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <gpxe/netdevice.h>
@@ -28,6 +29,197 @@
*
*/
+struct dhcp_session {
+ struct net_device *netdev;
+ uint32_t xid;
+};
+
+/** DHCP operation types
+ *
+ * This table maps from DHCP message types (i.e. values of the @c
+ * DHCP_MESSAGE_TYPE option) to values of the "op" field within a DHCP
+ * packet.
+ */
+static const uint8_t dhcp_op[] = {
+ [DHCPDISCOVER] = BOOTP_REQUEST,
+ [DHCPOFFER] = BOOTP_REPLY,
+ [DHCPREQUEST] = BOOTP_REQUEST,
+ [DHCPDECLINE] = BOOTP_REQUEST,
+ [DHCPACK] = BOOTP_REPLY,
+ [DHCPNAK] = BOOTP_REPLY,
+ [DHCPRELEASE] = BOOTP_REQUEST,
+ [DHCPINFORM] = BOOTP_REQUEST,
+};
+
+/** 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
+};
+
+/** 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_packet_option_blocks {
+ struct dhcp_option_block options[NUM_OPT_BLOCKS];
+};
+
+/**
+ * Set option within DHCP packet
+ *
+ * @v optblocks DHCP packet option blocks
+ * @v tag DHCP option tag
+ * @v data New value for DHCP option
+ * @v len Length of value, in bytes
+ * @ret option DHCP option, or NULL
+ *
+ * Sets the option within the first available options block within the
+ * DHCP packet. Option blocks are tried in the order specified by @c
+ * dhcp_option_block_fill_order.
+ */
+static struct dhcp_option *
+set_dhcp_packet_option ( struct dhcp_packet_option_blocks *optblocks,
+ unsigned int tag, const void *data, size_t len ) {
+ struct dhcp_option_block *options;
+ struct dhcp_option *option;
+
+ for ( options = optblocks->options ;
+ options < &optblocks->options[NUM_OPT_BLOCKS] ; options++ ) {
+ option = set_dhcp_option ( options, tag, data, len );
+ if ( option )
+ return option;
+ }
+ return NULL;
+}
+
+/**
+ * Copy options to DHCP packet
+ *
+ * @v optblocks DHCP packet option blocks
+ * @v encapsulator Encapsulating option, or zero
+ * @ret rc Return status code
+ *
+ * Copies options from DHCP options blocks into a DHCP packet. Most
+ * options are copied verbatim. Recognised encapsulated options
+ * fields are handled as such. Selected options (e.g. @c
+ * DHCP_OPTION_OVERLOAD) are always ignored, since these special cases
+ * are handled by other code.
+ */
+static int
+copy_dhcp_options_to_packet ( struct dhcp_packet_option_blocks *optblocks,
+ unsigned int encapsulator ) {
+ unsigned int subtag;
+ unsigned int tag;
+ struct dhcp_option *option;
+ struct dhcp_option *copied;
+ int rc;
+
+ for ( subtag = DHCP_MIN_OPTION; subtag <= DHCP_MAX_OPTION; subtag++ ) {
+ tag = DHCP_ENCAP_OPT ( encapsulator, subtag );
+ switch ( tag ) {
+ case DHCP_OPTION_OVERLOAD:
+ /* Hard-coded in packets we reassemble; skip
+ * this option
+ */
+ break;
+ case DHCP_EB_ENCAP:
+ case DHCP_VENDOR_ENCAP:
+ /* Process encapsulated options field */
+ if ( ( rc = copy_dhcp_options_to_packet ( optblocks,
+ tag ) ) != 0)
+ return rc;
+ break;
+ default:
+ /* Copy option to reassembled packet */
+ option = find_global_dhcp_option ( tag );
+ if ( ! option )
+ break;
+ copied = set_dhcp_packet_option ( optblocks, tag,
+ &option->data,
+ option->len );
+ if ( ! copied )
+ return -ENOSPC;
+ break;
+ };
+ }
+
+ return 0;
+}
+
+/**
+ * Assemble a DHCP packet
+ *
+ * @v dhcp DHCP session
+ * @v data Packet to be filled in
+ * @v max_len Length of packet buffer
+ * @ret len Length of assembled packet
+ *
+ * Reconstruct a DHCP packet from a DHCP options list.
+ */
+size_t dhcp_assemble ( struct dhcp_session *dhcp, void *data,
+ size_t max_len ) {
+ struct dhcp_packet *dhcppkt = data;
+ struct dhcp_option *option;
+ struct dhcp_packet_option_blocks optblocks;
+ unsigned int dhcp_message_type;
+ static const uint8_t overloading = ( DHCP_OPTION_OVERLOAD_FILE |
+ DHCP_OPTION_OVERLOAD_SNAME );
+
+ /* Fill in constant fields */
+ memset ( dhcppkt, 0, max_len );
+ dhcppkt->xid = dhcp->xid;
+ dhcppkt->magic = htonl ( DHCP_MAGIC_COOKIE );
+
+ /* Derive "op" field from DHCP_MESSAGE_TYPE option value */
+ dhcp_message_type = find_global_dhcp_num_option ( DHCP_MESSAGE_TYPE );
+ dhcppkt->op = dhcp_op[dhcp_message_type];
+
+ /* Fill in NIC details */
+ dhcppkt->htype = dhcp->netdev->ll_protocol->ll_proto;
+ dhcppkt->hlen = dhcp->netdev->ll_protocol->ll_addr_len;
+ memcpy ( dhcppkt->chaddr, dhcp->netdev->ll_addr, dhcppkt->hlen );
+
+ /* Fill in IP addresses if present */
+ option = find_global_dhcp_option ( DHCP_EB_YIADDR );
+ if ( option ) {
+ memcpy ( &dhcppkt->yiaddr, &option->data,
+ sizeof ( dhcppkt->yiaddr ) );
+ }
+ option = find_global_dhcp_option ( DHCP_EB_SIADDR );
+ if ( option ) {
+ memcpy ( &dhcppkt->siaddr, &option->data,
+ sizeof ( dhcppkt->siaddr ) );
+ }
+
+ /* Initialise option blocks */
+ init_dhcp_options ( &optblocks.options[OPTS_MAIN], dhcppkt->options,
+ ( max_len -
+ offsetof ( typeof ( *dhcppkt ), options ) ) );
+ init_dhcp_options ( &optblocks.options[OPTS_FILE], dhcppkt->file,
+ sizeof ( dhcppkt->file ) );
+ init_dhcp_options ( &optblocks.options[OPTS_SNAME], dhcppkt->sname,
+ sizeof ( dhcppkt->sname ) );
+ set_dhcp_option ( &optblocks.options[OPTS_MAIN], DHCP_OPTION_OVERLOAD,
+ &overloading, sizeof ( overloading ) );
+
+ /* Populate option blocks */
+ copy_dhcp_options_to_packet ( &optblocks, 0 );
+
+ return ( offsetof ( typeof ( *dhcppkt ), options )
+ + optblocks.options[OPTS_MAIN].len );
+}
+
/**
* Calculate used length of a field containing DHCP options
*
@@ -107,6 +299,10 @@ struct dhcp_option_block * dhcp_parse ( const void *data, size_t len ) {
size_t options_len;
unsigned int overloading;
+ /* Sanity check */
+ if ( len < sizeof ( *dhcppkt ) )
+ return NULL;
+
/* Calculate size of resulting concatenated option block:
*
* The "options" field : length of the field minus the DHCP_END tag.
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-07-16 23:14:06 +0200