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Diffstat (limited to 'include/linux/skbuff.h')
| -rw-r--r-- | include/linux/skbuff.h | 1253 |
1 files changed, 1253 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h new file mode 100644 index 00000000000..aa35797ebfb --- /dev/null +++ b/include/linux/skbuff.h @@ -0,0 +1,1253 @@ +/* + * Definitions for the 'struct sk_buff' memory handlers. + * + * Authors: + * Alan Cox, <gw4pts@gw4pts.ampr.org> + * Florian La Roche, <rzsfl@rz.uni-sb.de> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#ifndef _LINUX_SKBUFF_H +#define _LINUX_SKBUFF_H + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/compiler.h> +#include <linux/time.h> +#include <linux/cache.h> + +#include <asm/atomic.h> +#include <asm/types.h> +#include <linux/spinlock.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/poll.h> +#include <linux/net.h> +#include <net/checksum.h> + +#define HAVE_ALLOC_SKB /* For the drivers to know */ +#define HAVE_ALIGNABLE_SKB /* Ditto 8) */ +#define SLAB_SKB /* Slabified skbuffs */ + +#define CHECKSUM_NONE 0 +#define CHECKSUM_HW 1 +#define CHECKSUM_UNNECESSARY 2 + +#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \ + ~(SMP_CACHE_BYTES - 1)) +#define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \ + sizeof(struct skb_shared_info)) & \ + ~(SMP_CACHE_BYTES - 1)) +#define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0)) +#define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2)) + +/* A. Checksumming of received packets by device. + * + * NONE: device failed to checksum this packet. + * skb->csum is undefined. + * + * UNNECESSARY: device parsed packet and wouldbe verified checksum. + * skb->csum is undefined. + * It is bad option, but, unfortunately, many of vendors do this. + * Apparently with secret goal to sell you new device, when you + * will add new protocol to your host. F.e. IPv6. 8) + * + * HW: the most generic way. Device supplied checksum of _all_ + * the packet as seen by netif_rx in skb->csum. + * NOTE: Even if device supports only some protocols, but + * is able to produce some skb->csum, it MUST use HW, + * not UNNECESSARY. + * + * B. Checksumming on output. + * + * NONE: skb is checksummed by protocol or csum is not required. + * + * HW: device is required to csum packet as seen by hard_start_xmit + * from skb->h.raw to the end and to record the checksum + * at skb->h.raw+skb->csum. + * + * Device must show its capabilities in dev->features, set + * at device setup time. + * NETIF_F_HW_CSUM - it is clever device, it is able to checksum + * everything. + * NETIF_F_NO_CSUM - loopback or reliable single hop media. + * NETIF_F_IP_CSUM - device is dumb. It is able to csum only + * TCP/UDP over IPv4. Sigh. Vendors like this + * way by an unknown reason. Though, see comment above + * about CHECKSUM_UNNECESSARY. 8) + * + * Any questions? No questions, good. --ANK + */ + +#ifdef __i386__ +#define NET_CALLER(arg) (*(((void **)&arg) - 1)) +#else +#define NET_CALLER(arg) __builtin_return_address(0) +#endif + +struct net_device; + +#ifdef CONFIG_NETFILTER +struct nf_conntrack { + atomic_t use; + void (*destroy)(struct nf_conntrack *); +}; + +#ifdef CONFIG_BRIDGE_NETFILTER +struct nf_bridge_info { + atomic_t use; + struct net_device *physindev; + struct net_device *physoutdev; +#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE) + struct net_device *netoutdev; +#endif + unsigned int mask; + unsigned long data[32 / sizeof(unsigned long)]; +}; +#endif + +#endif + +struct sk_buff_head { + /* These two members must be first. */ + struct sk_buff *next; + struct sk_buff *prev; + + __u32 qlen; + spinlock_t lock; +}; + +struct sk_buff; + +/* To allow 64K frame to be packed as single skb without frag_list */ +#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2) + +typedef struct skb_frag_struct skb_frag_t; + +struct skb_frag_struct { + struct page *page; + __u16 page_offset; + __u16 size; +}; + +/* This data is invariant across clones and lives at + * the end of the header data, ie. at skb->end. + */ +struct skb_shared_info { + atomic_t dataref; + unsigned int nr_frags; + unsigned short tso_size; + unsigned short tso_segs; + struct sk_buff *frag_list; + skb_frag_t frags[MAX_SKB_FRAGS]; +}; + +/* We divide dataref into two halves. The higher 16 bits hold references + * to the payload part of skb->data. The lower 16 bits hold references to + * the entire skb->data. It is up to the users of the skb to agree on + * where the payload starts. + * + * All users must obey the rule that the skb->data reference count must be + * greater than or equal to the payload reference count. + * + * Holding a reference to the payload part means that the user does not + * care about modifications to the header part of skb->data. + */ +#define SKB_DATAREF_SHIFT 16 +#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1) + +/** + * struct sk_buff - socket buffer + * @next: Next buffer in list + * @prev: Previous buffer in list + * @list: List we are on + * @sk: Socket we are owned by + * @stamp: Time we arrived + * @dev: Device we arrived on/are leaving by + * @input_dev: Device we arrived on + * @real_dev: The real device we are using + * @h: Transport layer header + * @nh: Network layer header + * @mac: Link layer header + * @dst: FIXME: Describe this field + * @cb: Control buffer. Free for use by every layer. Put private vars here + * @len: Length of actual data + * @data_len: Data length + * @mac_len: Length of link layer header + * @csum: Checksum + * @__unused: Dead field, may be reused + * @cloned: Head may be cloned (check refcnt to be sure) + * @nohdr: Payload reference only, must not modify header + * @pkt_type: Packet class + * @ip_summed: Driver fed us an IP checksum + * @priority: Packet queueing priority + * @users: User count - see {datagram,tcp}.c + * @protocol: Packet protocol from driver + * @security: Security level of packet + * @truesize: Buffer size + * @head: Head of buffer + * @data: Data head pointer + * @tail: Tail pointer + * @end: End pointer + * @destructor: Destruct function + * @nfmark: Can be used for communication between hooks + * @nfcache: Cache info + * @nfct: Associated connection, if any + * @nfctinfo: Relationship of this skb to the connection + * @nf_debug: Netfilter debugging + * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c + * @private: Data which is private to the HIPPI implementation + * @tc_index: Traffic control index + * @tc_verd: traffic control verdict + * @tc_classid: traffic control classid + */ + +struct sk_buff { + /* These two members must be first. */ + struct sk_buff *next; + struct sk_buff *prev; + + struct sk_buff_head *list; + struct sock *sk; + struct timeval stamp; + struct net_device *dev; + struct net_device *input_dev; + struct net_device *real_dev; + + union { + struct tcphdr *th; + struct udphdr *uh; + struct icmphdr *icmph; + struct igmphdr *igmph; + struct iphdr *ipiph; + struct ipv6hdr *ipv6h; + unsigned char *raw; + } h; + + union { + struct iphdr *iph; + struct ipv6hdr *ipv6h; + struct arphdr *arph; + unsigned char *raw; + } nh; + + union { + unsigned char *raw; + } mac; + + struct dst_entry *dst; + struct sec_path *sp; + + /* + * This is the control buffer. It is free to use for every + * layer. Please put your private variables there. If you + * want to keep them across layers you have to do a skb_clone() + * first. This is owned by whoever has the skb queued ATM. + */ + char cb[40]; + + unsigned int len, + data_len, + mac_len, + csum; + unsigned char local_df, + cloned:1, + nohdr:1, + pkt_type, + ip_summed; + __u32 priority; + unsigned short protocol, + security; + + void (*destructor)(struct sk_buff *skb); +#ifdef CONFIG_NETFILTER + unsigned long nfmark; + __u32 nfcache; + __u32 nfctinfo; + struct nf_conntrack *nfct; +#ifdef CONFIG_NETFILTER_DEBUG + unsigned int nf_debug; +#endif +#ifdef CONFIG_BRIDGE_NETFILTER + struct nf_bridge_info *nf_bridge; +#endif +#endif /* CONFIG_NETFILTER */ +#if defined(CONFIG_HIPPI) + union { + __u32 ifield; + } private; +#endif +#ifdef CONFIG_NET_SCHED + __u32 tc_index; /* traffic control index */ +#ifdef CONFIG_NET_CLS_ACT + __u32 tc_verd; /* traffic control verdict */ + __u32 tc_classid; /* traffic control classid */ +#endif + +#endif + + + /* These elements must be at the end, see alloc_skb() for details. */ + unsigned int truesize; + atomic_t users; + unsigned char *head, + *data, + *tail, + *end; +}; + +#ifdef __KERNEL__ +/* + * Handling routines are only of interest to the kernel + */ +#include <linux/slab.h> + +#include <asm/system.h> + +extern void __kfree_skb(struct sk_buff *skb); +extern struct sk_buff *alloc_skb(unsigned int size, int priority); +extern struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp, + unsigned int size, int priority); +extern void kfree_skbmem(struct sk_buff *skb); +extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority); +extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority); +extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask); +extern int pskb_expand_head(struct sk_buff *skb, + int nhead, int ntail, int gfp_mask); +extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, + unsigned int headroom); +extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb, + int newheadroom, int newtailroom, + int priority); +extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad); +#define dev_kfree_skb(a) kfree_skb(a) +extern void skb_over_panic(struct sk_buff *skb, int len, + void *here); +extern void skb_under_panic(struct sk_buff *skb, int len, + void *here); + +/* Internal */ +#define skb_shinfo(SKB) ((struct skb_shared_info *)((SKB)->end)) + +/** + * skb_queue_empty - check if a queue is empty + * @list: queue head + * + * Returns true if the queue is empty, false otherwise. + */ +static inline int skb_queue_empty(const struct sk_buff_head *list) +{ + return list->next == (struct sk_buff *)list; +} + +/** + * skb_get - reference buffer + * @skb: buffer to reference + * + * Makes another reference to a socket buffer and returns a pointer + * to the buffer. + */ +static inline struct sk_buff *skb_get(struct sk_buff *skb) +{ + atomic_inc(&skb->users); + return skb; +} + +/* + * If users == 1, we are the only owner and are can avoid redundant + * atomic change. + */ + +/** + * kfree_skb - free an sk_buff + * @skb: buffer to free + * + * Drop a reference to the buffer and free it if the usage count has + * hit zero. + */ +static inline void kfree_skb(struct sk_buff *skb) +{ + if (likely(atomic_read(&skb->users) == 1)) + smp_rmb(); + else if (likely(!atomic_dec_and_test(&skb->users))) + return; + __kfree_skb(skb); +} + +/** + * skb_cloned - is the buffer a clone + * @skb: buffer to check + * + * Returns true if the buffer was generated with skb_clone() and is + * one of multiple shared copies of the buffer. Cloned buffers are + * shared data so must not be written to under normal circumstances. + */ +static inline int skb_cloned(const struct sk_buff *skb) +{ + return skb->cloned && + (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1; +} + +/** + * skb_header_cloned - is the header a clone + * @skb: buffer to check + * + * Returns true if modifying the header part of the buffer requires + * the data to be copied. + */ +static inline int skb_header_cloned(const struct sk_buff *skb) +{ + int dataref; + + if (!skb->cloned) + return 0; + + dataref = atomic_read(&skb_shinfo(skb)->dataref); + dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT); + return dataref != 1; +} + +/** + * skb_header_release - release reference to header + * @skb: buffer to operate on + * + * Drop a reference to the header part of the buffer. This is done + * by acquiring a payload reference. You must not read from the header + * part of skb->data after this. + */ +static inline void skb_header_release(struct sk_buff *skb) +{ + BUG_ON(skb->nohdr); + skb->nohdr = 1; + atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref); +} + +/** + * skb_shared - is the buffer shared + * @skb: buffer to check + * + * Returns true if more than one person has a reference to this + * buffer. + */ +static inline int skb_shared(const struct sk_buff *skb) +{ + return atomic_read(&skb->users) != 1; +} + +/** + * skb_share_check - check if buffer is shared and if so clone it + * @skb: buffer to check + * @pri: priority for memory allocation + * + * If the buffer is shared the buffer is cloned and the old copy + * drops a reference. A new clone with a single reference is returned. + * If the buffer is not shared the original buffer is returned. When + * being called from interrupt status or with spinlocks held pri must + * be GFP_ATOMIC. + * + * NULL is returned on a memory allocation failure. + */ +static inline struct sk_buff *skb_share_check(struct sk_buff *skb, int pri) +{ + might_sleep_if(pri & __GFP_WAIT); + if (skb_shared(skb)) { + struct sk_buff *nskb = skb_clone(skb, pri); + kfree_skb(skb); + skb = nskb; + } + return skb; +} + +/* + * Copy shared buffers into a new sk_buff. We effectively do COW on + * packets to handle cases where we have a local reader and forward + * and a couple of other messy ones. The normal one is tcpdumping + * a packet thats being forwarded. + */ + +/** + * skb_unshare - make a copy of a shared buffer + * @skb: buffer to check + * @pri: priority for memory allocation + * + * If the socket buffer is a clone then this function creates a new + * copy of the data, drops a reference count on the old copy and returns + * the new copy with the reference count at 1. If the buffer is not a clone + * the original buffer is returned. When called with a spinlock held or + * from interrupt state @pri must be %GFP_ATOMIC + * + * %NULL is returned on a memory allocation failure. + */ +static inline struct sk_buff *skb_unshare(struct sk_buff *skb, int pri) +{ + might_sleep_if(pri & __GFP_WAIT); + if (skb_cloned(skb)) { + struct sk_buff *nskb = skb_copy(skb, pri); + kfree_skb(skb); /* Free our shared copy */ + skb = nskb; + } + return skb; +} + +/** + * skb_peek + * @list_: list to peek at + * + * Peek an &sk_buff. Unlike most other operations you _MUST_ + * be careful with this one. A peek leaves the buffer on the + * list and someone else may run off with it. You must hold + * the appropriate locks or have a private queue to do this. + * + * Returns %NULL for an empty list or a pointer to the head element. + * The reference count is not incremented and the reference is therefore + * volatile. Use with caution. + */ +static inline struct sk_buff *skb_peek(struct sk_buff_head *list_) +{ + struct sk_buff *list = ((struct sk_buff *)list_)->next; + if (list == (struct sk_buff *)list_) + list = NULL; + return list; +} + +/** + * skb_peek_tail + * @list_: list to peek at + * + * Peek an &sk_buff. Unlike most other operations you _MUST_ + * be careful with this one. A peek leaves the buffer on the + * list and someone else may run off with it. You must hold + * the appropriate locks or have a private queue to do this. + * + * Returns %NULL for an empty list or a pointer to the tail element. + * The reference count is not incremented and the reference is therefore + * volatile. Use with caution. + */ +static inline struct sk_buff *skb_peek_tail(struct sk_buff_head *list_) +{ + struct sk_buff *list = ((struct sk_buff *)list_)->prev; + if (list == (struct sk_buff *)list_) + list = NULL; + return list; +} + +/** + * skb_queue_len - get queue length + * @list_: list to measure + * + * Return the length of an &sk_buff queue. + */ +static inline __u32 skb_queue_len(const struct sk_buff_head *list_) +{ + return list_->qlen; +} + +static inline void skb_queue_head_init(struct sk_buff_head *list) +{ + spin_lock_init(&list->lock); + list->prev = list->next = (struct sk_buff *)list; + list->qlen = 0; +} + +/* + * Insert an sk_buff at the start of a list. + * + * The "__skb_xxxx()" functions are the non-atomic ones that + * can only be called with interrupts disabled. + */ + +/** + * __skb_queue_head - queue a buffer at the list head + * @list: list to use + * @newsk: buffer to queue + * + * Queue a buffer at the start of a list. This function takes no locks + * and you must therefore hold required locks before calling it. + * + * A buffer cannot be placed on two lists at the same time. + */ +extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk); +static inline void __skb_queue_head(struct sk_buff_head *list, + struct sk_buff *newsk) +{ + struct sk_buff *prev, *next; + + newsk->list = list; + list->qlen++; + prev = (struct sk_buff *)list; + next = prev->next; + newsk->next = next; + newsk->prev = prev; + next->prev = prev->next = newsk; +} + +/** + * __skb_queue_tail - queue a buffer at the list tail + * @list: list to use + * @newsk: buffer to queue + * + * Queue a buffer at the end of a list. This function takes no locks + * and you must therefore hold required locks before calling it. + * + * A buffer cannot be placed on two lists at the same time. + */ +extern void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk); +static inline void __skb_queue_tail(struct sk_buff_head *list, + struct sk_buff *newsk) +{ + struct sk_buff *prev, *next; + + newsk->list = list; + list->qlen++; + next = (struct sk_buff *)list; + prev = next->prev; + newsk->next = next; + newsk->prev = prev; + next->prev = prev->next = newsk; +} + + +/** + * __skb_dequeue - remove from the head of the queue + * @list: list to dequeue from + * + * Remove the head of the list. This function does not take any locks + * so must be used with appropriate locks held only. The head item is + * returned or %NULL if the list is empty. + */ +extern struct sk_buff *skb_dequeue(struct sk_buff_head *list); +static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list) +{ + struct sk_buff *next, *prev, *result; + + prev = (struct sk_buff *) list; + next = prev->next; + result = NULL; + if (next != prev) { + result = next; + next = next->next; + list->qlen--; + next->prev = prev; + prev->next = next; + result->next = result->prev = NULL; + result->list = NULL; + } + return result; +} + + +/* + * Insert a packet on a list. + */ +extern void skb_insert(struct sk_buff *old, struct sk_buff *newsk); +static inline void __skb_insert(struct sk_buff *newsk, + struct sk_buff *prev, struct sk_buff *next, + struct sk_buff_head *list) +{ + newsk->next = next; + newsk->prev = prev; + next->prev = prev->next = newsk; + newsk->list = list; + list->qlen++; +} + +/* + * Place a packet after a given packet in a list. + */ +extern void skb_append(struct sk_buff *old, struct sk_buff *newsk); +static inline void __skb_append(struct sk_buff *old, struct sk_buff *newsk) +{ + __skb_insert(newsk, old, old->next, old->list); +} + +/* + * remove sk_buff from list. _Must_ be called atomically, and with + * the list known.. + */ +extern void skb_unlink(struct sk_buff *skb); +static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list) +{ + struct sk_buff *next, *prev; + + list->qlen--; + next = skb->next; + prev = skb->prev; + skb->next = skb->prev = NULL; + skb->list = NULL; + next->prev = prev; + prev->next = next; +} + + +/* XXX: more streamlined implementation */ + +/** + * __skb_dequeue_tail - remove from the tail of the queue + * @list: list to dequeue from + * + * Remove the tail of the list. This function does not take any locks + * so must be used with appropriate locks held only. The tail item is + * returned or %NULL if the list is empty. + */ +extern struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list); +static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list) +{ + struct sk_buff *skb = skb_peek_tail(list); + if (skb) + __skb_unlink(skb, list); + return skb; +} + + +static inline int skb_is_nonlinear(const struct sk_buff *skb) +{ + return skb->data_len; +} + +static inline unsigned int skb_headlen(const struct sk_buff *skb) +{ + return skb->len - skb->data_len; +} + +static inline int skb_pagelen(const struct sk_buff *skb) +{ + int i, len = 0; + + for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) + len += skb_shinfo(skb)->frags[i].size; + return len + skb_headlen(skb); +} + +static inline void skb_fill_page_desc(struct sk_buff *skb, int i, + struct page *page, int off, int size) +{ + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + + frag->page = page; + frag->page_offset = off; + frag->size = size; + skb_shinfo(skb)->nr_frags = i + 1; +} + +#define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags) +#define SKB_FRAG_ASSERT(skb) BUG_ON(skb_shinfo(skb)->frag_list) +#define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb)) + +/* + * Add data to an sk_buff + */ +static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len) +{ + unsigned char *tmp = skb->tail; + SKB_LINEAR_ASSERT(skb); + skb->tail += len; + skb->len += len; + return tmp; +} + +/** + * skb_put - add data to a buffer + * @skb: buffer to use + * @len: amount of data to add + * + * This function extends the used data area of the buffer. If this would + * exceed the total buffer size the kernel will panic. A pointer to the + * first byte of the extra data is returned. + */ +static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len) +{ + unsigned char *tmp = skb->tail; + SKB_LINEAR_ASSERT(skb); + skb->tail += len; + skb->len += len; + if (unlikely(skb->tail>skb->end)) + skb_over_panic(skb, len, current_text_addr()); + return tmp; +} + +static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len) +{ + skb->data -= len; + skb->len += len; + return skb->data; +} + +/** + * skb_push - add data to the start of a buffer + * @skb: buffer to use + * @len: amount of data to add + * + * This function extends the used data area of the buffer at the buffer + * start. If this would exceed the total buffer headroom the kernel will + * panic. A pointer to the first byte of the extra data is returned. + */ +static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len) +{ + skb->data -= len; + skb->len += len; + if (unlikely(skb->data<skb->head)) + skb_under_panic(skb, len, current_text_addr()); + return skb->data; +} + +static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len) +{ + skb->len -= len; + BUG_ON(skb->len < skb->data_len); + return skb->data += len; +} + +/** + * skb_pull - remove data from the start of a buffer + * @skb: buffer to use + * @len: amount of data to remove + * + * This function removes data from the start of a buffer, returning + * the memory to the headroom. A pointer to the next data in the buffer + * is returned. Once the data has been pulled future pushes will overwrite + * the old data. + */ +static inline unsigned char *skb_pull(struct sk_buff *skb, unsigned int len) +{ + return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len); +} + +extern unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta); + +static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len) +{ + if (len > skb_headlen(skb) && + !__pskb_pull_tail(skb, len-skb_headlen(skb))) + return NULL; + skb->len -= len; + return skb->data += len; +} + +static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len) +{ + return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len); +} + +static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len) +{ + if (likely(len <= skb_headlen(skb))) + return 1; + if (unlikely(len > skb->len)) + return 0; + return __pskb_pull_tail(skb, len-skb_headlen(skb)) != NULL; +} + +/** + * skb_headroom - bytes at buffer head + * @skb: buffer to check + * + * Return the number of bytes of free space at the head of an &sk_buff. + */ +static inline int skb_headroom(const struct sk_buff *skb) +{ + return skb->data - skb->head; +} + +/** + * skb_tailroom - bytes at buffer end + * @skb: buffer to check + * + * Return the number of bytes of free space at the tail of an sk_buff + */ +static inline int skb_tailroom(const struct sk_buff *skb) +{ + return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail; +} + +/** + * skb_reserve - adjust headroom + * @skb: buffer to alter + * @len: bytes to move + * + * Increase the headroom of an empty &sk_buff by reducing the tail + * room. This is only allowed for an empty buffer. + */ +static inline void skb_reserve(struct sk_buff *skb, unsigned int len) +{ + skb->data += len; + skb->tail += len; +} + +/* + * CPUs often take a performance hit when accessing unaligned memory + * locations. The actual performance hit varies, it can be small if the + * hardware handles it or large if we have to take an exception and fix it + * in software. + * + * Since an ethernet header is 14 bytes network drivers often end up with + * the IP header at an unaligned offset. The IP header can be aligned by + * shifting the start of the packet by 2 bytes. Drivers should do this + * with: + * + * skb_reserve(NET_IP_ALIGN); + * + * The downside to this alignment of the IP header is that the DMA is now + * unaligned. On some architectures the cost of an unaligned DMA is high + * and this cost outweighs the gains made by aligning the IP header. + * + * Since this trade off varies between architectures, we allow NET_IP_ALIGN + * to be overridden. + */ +#ifndef NET_IP_ALIGN +#define NET_IP_ALIGN 2 +#endif + +extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc); + +static inline void __skb_trim(struct sk_buff *skb, unsigned int len) +{ + if (!skb->data_len) { + skb->len = len; + skb->tail = skb->data + len; + } else + ___pskb_trim(skb, len, 0); +} + +/** + * skb_trim - remove end from a buffer + * @skb: buffer to alter + * @len: new length + * + * Cut the length of a buffer down by removing data from the tail. If + * the buffer is already under the length specified it is not modified. + */ +static inline void skb_trim(struct sk_buff *skb, unsigned int len) +{ + if (skb->len > len) + __skb_trim(skb, len); +} + + +static inline int __pskb_trim(struct sk_buff *skb, unsigned int len) +{ + if (!skb->data_len) { + skb->len = len; + skb->tail = skb->data+len; + return 0; + } + return ___pskb_trim(skb, len, 1); +} + +static inline int pskb_trim(struct sk_buff *skb, unsigned int len) +{ + return (len < skb->len) ? __pskb_trim(skb, len) : 0; +} + +/** + * skb_orphan - orphan a buffer + * @skb: buffer to orphan + * + * If a buffer currently has an owner then we call the owner's + * destructor function and make the @skb unowned. The buffer continues + * to exist but is no longer charged to its former owner. + */ +static inline void skb_orphan(struct sk_buff *skb) +{ + if (skb->destructor) + skb->destructor(skb); + skb->destructor = NULL; + skb->sk = NULL; +} + +/** + * __skb_queue_purge - empty a list + * @list: list to empty + * + * Delete all buffers on an &sk_buff list. Each buffer is removed from + * the list and one reference dropped. This function does not take the + * list lock and the caller must hold the relevant locks to use it. + */ +extern void skb_queue_purge(struct sk_buff_head *list); +static inline void __skb_queue_purge(struct sk_buff_head *list) +{ + struct sk_buff *skb; + while ((skb = __skb_dequeue(list)) != NULL) + kfree_skb(skb); +} + +/** + * __dev_alloc_skb - allocate an skbuff for sending + * @length: length to allocate + * @gfp_mask: get_free_pages mask, passed to alloc_skb + * + * Allocate a new &sk_buff and assign it a usage count of one. The + * buffer has unspecified headroom built in. Users should allocate + * the headroom they think they need without accounting for the + * built in space. The built in space is used for optimisations. + * + * %NULL is returned in there is no free memory. + */ +#ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB +static inline struct sk_buff *__dev_alloc_skb(unsigned int length, + int gfp_mask) +{ + struct sk_buff *skb = alloc_skb(length + 16, gfp_mask); + if (likely(skb)) + skb_reserve(skb, 16); + return skb; +} +#else +extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask); +#endif + +/** + * dev_alloc_skb - allocate an skbuff for sending + * @length: length to allocate + * + * Allocate a new &sk_buff and assign it a usage count of one. The + * buffer has unspecified headroom built in. Users should allocate + * the headroom they think they need without accounting for the + * built in space. The built in space is used for optimisations. + * + * %NULL is returned in there is no free memory. Although this function + * allocates memory it can be called from an interrupt. + */ +static inline struct sk_buff *dev_alloc_skb(unsigned int length) +{ + return __dev_alloc_skb(length, GFP_ATOMIC); +} + +/** + * skb_cow - copy header of skb when it is required + * @skb: buffer to cow + * @headroom: needed headroom + * + * If the skb passed lacks sufficient headroom or its data part + * is shared, data is reallocated. If reallocation fails, an error + * is returned and original skb is not changed. + * + * The result is skb with writable area skb->head...skb->tail + * and at least @headroom of space at head. + */ +static inline int skb_cow(struct sk_buff *skb, unsigned int headroom) +{ + int delta = (headroom > 16 ? headroom : 16) - skb_headroom(skb); + + if (delta < 0) + delta = 0; + + if (delta || skb_cloned(skb)) + return pskb_expand_head(skb, (delta + 15) & ~15, 0, GFP_ATOMIC); + return 0; +} + +/** + * skb_padto - pad an skbuff up to a minimal size + * @skb: buffer to pad + * @len: minimal length + * + * Pads up a buffer to ensure the trailing bytes exist and are + * blanked. If the buffer already contains sufficient data it + * is untouched. Returns the buffer, which may be a replacement + * for the original, or NULL for out of memory - in which case + * the original buffer is still freed. + */ + +static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len) +{ + unsigned int size = skb->len; + if (likely(size >= len)) + return skb; + return skb_pad(skb, len-size); +} + +static inline int skb_add_data(struct sk_buff *skb, + char __user *from, int copy) +{ + const int off = skb->len; + + if (skb->ip_summed == CHECKSUM_NONE) { + int err = 0; + unsigned int csum = csum_and_copy_from_user(from, + skb_put(skb, copy), + copy, 0, &err); + if (!err) { + skb->csum = csum_block_add(skb->csum, csum, off); + return 0; + } + } else if (!copy_from_user(skb_put(skb, copy), from, copy)) + return 0; + + __skb_trim(skb, off); + return -EFAULT; +} + +static inline int skb_can_coalesce(struct sk_buff *skb, int i, + struct page *page, int off) +{ + if (i) { + struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1]; + + return page == frag->page && + off == frag->page_offset + frag->size; + } + return 0; +} + +/** + * skb_linearize - convert paged skb to linear one + * @skb: buffer to linarize + * @gfp: allocation mode + * + * If there is no free memory -ENOMEM is returned, otherwise zero + * is returned and the old skb data released. + */ +extern int __skb_linearize(struct sk_buff *skb, int gfp); +static inline int skb_linearize(struct sk_buff *skb, int gfp) +{ + return __skb_linearize(skb, gfp); +} + +/** + * skb_postpull_rcsum - update checksum for received skb after pull + * @skb: buffer to update + * @start: start of data before pull + * @len: length of data pulled + * + * After doing a pull on a received packet, you need to call this to + * update the CHECKSUM_HW checksum, or set ip_summed to CHECKSUM_NONE + * so that it can be recomputed from scratch. + */ + +static inline void skb_postpull_rcsum(struct sk_buff *skb, + const void *start, int len) +{ + if (skb->ip_summed == CHECKSUM_HW) + skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0)); +} + +/** + * pskb_trim_rcsum - trim received skb and update checksum + * @skb: buffer to trim + * @len: new length + * + * This is exactly the same as pskb_trim except that it ensures the + * checksum of received packets are still valid after the operation. + */ + +static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len) +{ + if (len >= skb->len) + return 0; + if (skb->ip_summed == CHECKSUM_HW) + skb->ip_summed = CHECKSUM_NONE; + return __pskb_trim(skb, len); +} + +static inline void *kmap_skb_frag(const skb_frag_t *frag) +{ +#ifdef CONFIG_HIGHMEM + BUG_ON(in_irq()); + + local_bh_disable(); +#endif + return kmap_atomic(frag->page, KM_SKB_DATA_SOFTIRQ); +} + +static inline void kunmap_skb_frag(void *vaddr) +{ + kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ); +#ifdef CONFIG_HIGHMEM + local_bh_enable(); +#endif +} + +#define skb_queue_walk(queue, skb) \ + for (skb = (queue)->next; \ + prefetch(skb->next), (skb != (struct sk_buff *)(queue)); \ + skb = skb->next) + + +extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, + int noblock, int *err); +extern unsigned int datagram_poll(struct file *file, struct socket *sock, + struct poll_table_struct *wait); +extern int skb_copy_datagram_iovec(const struct sk_buff *from, + int offset, struct iovec *to, + int size); +extern int skb_copy_and_csum_datagram_iovec(const + struct sk_buff *skb, + int hlen, + struct iovec *iov); +extern void skb_free_datagram(struct sock *sk, struct sk_buff *skb); +extern unsigned int skb_checksum(const struct sk_buff *skb, int offset, + int len, unsigned int csum); +extern int skb_copy_bits(const struct sk_buff *skb, int offset, + void *to, int len); +extern unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, + int offset, u8 *to, int len, + unsigned int csum); +extern void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to); +extern void skb_split(struct sk_buff *skb, + struct sk_buff *skb1, const u32 len); + +static inline void *skb_header_pointer(const struct sk_buff *skb, int offset, + int len, void *buffer) +{ + int hlen = skb_headlen(skb); + + if (offset + len <= hlen) + return skb->data + offset; + + if (skb_copy_bits(skb, offset, buffer, len) < 0) + return NULL; + + return buffer; +} + +extern void skb_init(void); +extern void skb_add_mtu(int mtu); + +#ifdef CONFIG_NETFILTER +static inline void nf_conntrack_put(struct nf_conntrack *nfct) +{ + if (nfct && atomic_dec_and_test(&nfct->use)) + nfct->destroy(nfct); +} +static inline void nf_conntrack_get(struct nf_conntrack *nfct) +{ + if (nfct) + atomic_inc(&nfct->use); +} +static inline void nf_reset(struct sk_buff *skb) +{ + nf_conntrack_put(skb->nfct); + skb->nfct = NULL; +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug = 0; +#endif +} +static inline void nf_reset_debug(struct sk_buff *skb) +{ +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug = 0; +#endif +} + +#ifdef CONFIG_BRIDGE_NETFILTER +static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge) +{ + if (nf_bridge && atomic_dec_and_test(&nf_bridge->use)) + kfree(nf_bridge); +} +static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge) +{ + if (nf_bridge) + atomic_inc(&nf_bridge->use); +} +#endif /* CONFIG_BRIDGE_NETFILTER */ +#else /* CONFIG_NETFILTER */ +static inline void nf_reset(struct sk_buff *skb) {} +#endif /* CONFIG_NETFILTER */ + +#endif /* __KERNEL__ */ +#endif /* _LINUX_SKBUFF_H */ |