164 lines
3.6 KiB
C
164 lines
3.6 KiB
C
#ifndef _GPXE_PKBUFF_H
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#define _GPXE_PKBUFF_H
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/** @file
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*
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* Packet buffers
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*
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* Packet buffers are used to contain network packets. Methods are
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* provided for appending, prepending, etc. data.
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*
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*/
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#include <stdint.h>
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#include <assert.h>
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#include <gpxe/list.h>
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/**
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* Packet buffer alignment
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*
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* Packet buffers allocated via alloc_pkb() are guaranteed to be
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* physically aligned to this boundary. Some cards cannot DMA across
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* a 4kB boundary. With a standard Ethernet MTU, aligning to a 2kB
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* boundary is sufficient to guarantee no 4kB boundary crossings. For
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* a jumbo Ethernet MTU, a packet may be larger than 4kB anyway.
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*/
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#define PKBUFF_ALIGN 2048
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/**
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* Minimum packet buffer length
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*
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* alloc_pkb() will round up the allocated length to this size if
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* necessary. This is used on behalf of hardware that is not capable
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* of auto-padding.
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*/
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#define PKB_ZLEN 64
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/** A packet buffer
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*
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* This structure is used to represent a network packet within gPXE.
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*/
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struct pk_buff {
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/** List of which this buffer is a member */
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struct list_head list;
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/** Start of the buffer */
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void *head;
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/** Start of data */
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void *data;
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/** End of data */
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void *tail;
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/** End of the buffer */
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void *end;
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};
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/**
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* Reserve space at start of packet buffer
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*
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* @v pkb Packet buffer
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* @v len Length to reserve
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* @ret data Pointer to new start of buffer
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*/
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static inline void * pkb_reserve ( struct pk_buff *pkb, size_t len ) {
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pkb->data += len;
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pkb->tail += len;
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assert ( pkb->tail <= pkb->end );
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return pkb->data;
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}
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/**
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* Add data to start of packet buffer
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*
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* @v pkb Packet buffer
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* @v len Length to add
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* @ret data Pointer to new start of buffer
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*/
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static inline void * pkb_push ( struct pk_buff *pkb, size_t len ) {
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pkb->data -= len;
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assert ( pkb->data >= pkb->head );
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return pkb->data;
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}
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/**
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* Remove data from start of packet buffer
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*
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* @v pkb Packet buffer
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* @v len Length to remove
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* @ret data Pointer to new start of buffer
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*/
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static inline void * pkb_pull ( struct pk_buff *pkb, size_t len ) {
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pkb->data += len;
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assert ( pkb->data <= pkb->tail );
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return pkb->data;
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}
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/**
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* Add data to end of packet buffer
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*
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* @v pkb Packet buffer
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* @v len Length to add
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* @ret data Pointer to newly added space
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*/
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static inline void * pkb_put ( struct pk_buff *pkb, size_t len ) {
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void *old_tail = pkb->tail;
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pkb->tail += len;
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assert ( pkb->tail <= pkb->end );
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return old_tail;
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}
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/**
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* Remove data from end of packet buffer
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*
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* @v pkb Packet buffer
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* @v len Length to remove
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*/
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static inline void pkb_unput ( struct pk_buff *pkb, size_t len ) {
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pkb->tail -= len;
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assert ( pkb->tail >= pkb->data );
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}
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/**
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* Empty a packet buffer
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*
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* @v pkb Packet buffer
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*/
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static inline void pkb_empty ( struct pk_buff *pkb ) {
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pkb->tail = pkb->data;
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}
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/**
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* Calculate length of data in a packet buffer
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*
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* @v pkb Packet buffer
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* @ret len Length of data in buffer
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*/
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static inline size_t pkb_len ( struct pk_buff *pkb ) {
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return ( pkb->tail - pkb->data );
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}
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/**
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* Calculate available space at start of a packet buffer
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*
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* @v pkb Packet buffer
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* @ret len Length of data available at start of buffer
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*/
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static inline size_t pkb_headroom ( struct pk_buff *pkb ) {
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return ( pkb->data - pkb->head );
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}
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/**
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* Calculate available space at end of a packet buffer
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*
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* @v pkb Packet buffer
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* @ret len Length of data available at end of buffer
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*/
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static inline size_t pkb_tailroom ( struct pk_buff *pkb ) {
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return ( pkb->end - pkb->tail );
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}
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extern struct pk_buff * alloc_pkb ( size_t len );
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extern void free_pkb ( struct pk_buff *pkb );
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extern void pkb_pad ( struct pk_buff *pkb, size_t min_len );
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#endif /* _GPXE_PKBUFF_H */
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