Messages in this thread | | | Date | Mon, 20 Oct 2003 11:23:23 +0200 (CEST) | From | an7 <> | Subject | Network implementation |
| |
Hi, i am a french engineer who has some work to do on TCP/IP implementation in the linux kernel.
I have three questions on it :
1) What are the advantages of using a ring buffer for receiving and queuing packets ?
2) in tcp_minisocks.c in linux i get, in the function which handles segment arrival in FIN_WAIT_2 state :
if (th->syn && !before(TCP_SKB_CB(skb)->seq, tw->rcv_nxt)) goto kill_with_rst;
Just to confirm : in the state FIN_WAIT_2 a SYN segment is automatically killed by a RST, unless its sequence number is superior to the waited sequence number. But in this case , what happens ? I think the RFC tells to send a ACK. Am i right ?
3) the function tcp_recv_skb() (tcp.c)
struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) 1383 { 1384 struct sk_buff *skb; 1385 u32 offset; 1386 1387 skb_queue_walk(&sk->receive_queue, skb) { 1388 offset = seq - TCP_SKB_CB(skb)->seq; 1389 if (skb->h.th->syn) 1390 offset--; 1391 if (offset < skb->len || skb->h.th->fin) { 1392 *off = offset; 1393 return skb; 1394 } 1395 } 1396 return NULL; 1397 }
I just can't understand the role of offset (and thus, i can't undersand why it is decremented with a syn segment, and why we can return the skb structure when we have an offset inferior to the skb len, or a FIN segment)
Could you help please ?
___________________________________________________________ Do You Yahoo!? -- Une adresse @yahoo.fr gratuite et en français ! Yahoo! Mail : http://fr.mail.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |