1. Socket Buffer
발표자 유 종 욱
발표일 년 10월

2. 1. Flow of Packet

3. Flow of Packet Device Input User Process sk_buff Skb_queue_tail
Skb_dequeue

4. 2. Socket buffer Data Structure

5. 주요 Field Struct sk_buff *next; Struct sk_buff *prev;
Linked-list 중에 다음 sk buff 에 대한 pointer
Struct sk_buff *prev;
Linked-list 중에 이전 sk buff 에 대한 pointer
Struct sk_buff_head *list;
현재 sk_buff 가 속한 sk_buff_head에 대한 pointer
Struct sock *sk;
Queue 의 owner 인 struct sock 의 pointer
Struct net_device *dev;
받거나 보낼 device pointer

6. 주요 Field 각각의 layer 별 header point Union mac <- link layer
Struct ethhdr *ethernet;
Union nh <- network layer
Struct iphdr *iph;
Struct ipv6hdr *ipv6h;
Struct ipxhdr *ipxh;
Union h <- transport layer
Struct tcphdr *th;
Struct udphdr *uh;
Struct icmphdr *icmph;
Struct igmphdr *igmph;
Struct iphdr *ipiph;
Struct spxhdr *spxh;

7. 주요 Field Struct dst_entry *dst; Unsigned int len;
실제 데이터의 길이
Unsigned int data_len;
어떨때 어떤 값으로 바뀌는지는 잘모르겠음.
Unsigned int truesize;
버퍼의 실제 길이
volatile char userd;
데이터가 사용자에게 넘어갔음을 나타냄
Unsigned char cloned;
Header 가 복제되었음을 나타냄

8. 주요 Field Unsigned short portocol; Unsigned char *head;
Device로부터 받은 패킷의 프로토콜
Unsigned char *head;
데이터 버퍼의 headerroom의 pointer
Unsigned char *data;
데이터 버퍼의 data 부분의 pointer
Unsigned char *tail;
데이터 버퍼의 tailroom의 pointer
Unsigned char *end;
데이터 버퍼의 마지막의 pointer

9. sk_buff 의 구조 Header Room Data Tail Room truesize len
Sutuct sk_buff *next
Sutuct sk_buff *prev
Sutuct net_device *dev
---
Union h
Union nh
Union mac
Unsigned char *head
Unsigned char *data
Unsigned char *tail
Unsigned char *end
Header Room
Link layer header
Network layer header
Transport layer header
Data
Tail Room
truesize
len

10. 3. Socket buffer 관련 함수

11. 주요 함수 struct sk_buff *alloc_skb(unsigned int size,int gfp_mask)
Head
Data
Tail
End
Tail Room
size

12. 주요 함수 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
Data
Tail
Head
End
Head
Room
Tail Room 16
length

13. 주요 함수
static inline void skb_reserve(struct sk_buff *skb, unsigned int len)
Tail Room
Head
Data
Tail
End
Tail Room
Head Room
Head
End
len
Data
Tail

14. 주요 함수
static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
Tail Room
Head
Data
Tail
End
Tail Room
Data
Head
End
len
Tail
Tail Room
Head
Room
End
Data
Tail
Tail Room
Head
Room
len
End
Data
Tail

15. 주요 함수
static inline unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
Tail Room
Data
Head
Room
End
len
Tail
Tail Room
Data
Head
Room
End
Tail

16. 주요 함수
static inline void skb_trim(struct sk_buff *skb, unsigned int len)
Tail Room
Data
Head
Room
len
End
Tail
Tail Room
Data
Head
Room
End
Tail

17. 주요 함수
static inline unsigned char * pskb_pull(struct sk_buff *skb, unsigned int len)
len
Tail Room
Data
Head
Room
End
Tail
Tail Room
Data
Head
Room
End
Tail

18. 주요 함수 Sk_buff_head 의 linked list 관련 함수
static inline void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
Static inline void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
static inline struct sk_buff *skb_dequeue(struct sk_buff_head *list)
static inline void skb_insert(struct sk_buff *old, struct sk_buff *newsk)
static inline void skb_append(struct sk_buff *old, struct sk_buff *newsk)
static inline struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)

19. 주요 함수 기타 static inline int skb_headroom(const struct sk_buff *skb)
Headroom size를 반환
static inline int skb_tailroom(const struct sk_buff *skb)
tailroom size를 반환
struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
duplicate an sk_buff
struct sk_buff *skb_copy(const struct sk_buff *skb, int gfp_mask)
create private copy of an sk_buff
int skb_linearize(struct sk_buff *skb, int gfp_mask)
keep head the same: replace data
static inline void kfree_skb(struct sk_buff *skb)
skb free

20. 4. 끝(질의 & 응답)