From 59435444a13ed52d3444c5df26b73d3086bcd57b Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sat, 26 Jul 2008 11:59:09 +0100 Subject: [PATCH] dccp: Allow to distinguish original and retransmitted packets This patch allows the sender to distinguish original and retransmitted packets, which is in particular needed for the retransmission of DCCP-Requests: * the first Request uses ISS (generated in net/dccp/ip*.c), and sets GSS = ISS; * all retransmitted Requests use GSS' = GSS + 1, so that the n-th retransmitted Request has sequence number ISS + n (mod 48). To add generic support, the patch reorganises existing code so that: * icsk_retransmits == 0 for the original packet and * icsk_retransmits = n > 0 for the n-th retransmitted packet at the time dccp_transmit_skb() is called, via dccp_retransmit_skb(). Thanks to Wei Yongjun for pointing this problem out. Further changes: ---------------- * removed the `skb' argument from dccp_retransmit_skb(), since sk_send_head is used for all retransmissions (the exception is client-Acks in PARTOPEN state, but these do not use sk_send_head); * since sk_send_head always contains the original skb (via dccp_entail()), skb_cloned() never evaluated to true and thus pskb_copy() was never used. Signed-off-by: Gerrit Renker --- net/dccp/dccp.h | 2 +- net/dccp/output.c | 20 ++++++++++++++++---- net/dccp/timer.c | 20 ++++---------------- 3 files changed, 21 insertions(+), 21 deletions(-) diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 743d85fcd6..1c2e3ec2eb 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -226,7 +226,7 @@ static inline void dccp_csum_outgoing(struct sk_buff *skb) extern void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb); -extern int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb); +extern int dccp_retransmit_skb(struct sock *sk); extern void dccp_send_ack(struct sock *sk); extern void dccp_reqsk_send_ack(struct sk_buff *sk, struct request_sock *rsk); diff --git a/net/dccp/output.c b/net/dccp/output.c index fe20068c5d..d19d481950 100644 --- a/net/dccp/output.c +++ b/net/dccp/output.c @@ -284,14 +284,26 @@ void dccp_write_xmit(struct sock *sk, int block) } } -int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb) +/** + * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets + * There are only four retransmittable packet types in DCCP: + * - Request in client-REQUEST state (sec. 8.1.1), + * - CloseReq in server-CLOSEREQ state (sec. 8.3), + * - Close in node-CLOSING state (sec. 8.3), + * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()). + * This function expects sk->sk_send_head to contain the original skb. + */ +int dccp_retransmit_skb(struct sock *sk) { + WARN_ON(sk->sk_send_head == NULL); + if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) return -EHOSTUNREACH; /* Routing failure or similar. */ - return dccp_transmit_skb(sk, (skb_cloned(skb) ? - pskb_copy(skb, GFP_ATOMIC): - skb_clone(skb, GFP_ATOMIC))); + /* this count is used to distinguish original and retransmitted skb */ + inet_csk(sk)->icsk_retransmits++; + + return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC)); } struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, diff --git a/net/dccp/timer.c b/net/dccp/timer.c index 6a5b961b6f..54b3c7e9e0 100644 --- a/net/dccp/timer.c +++ b/net/dccp/timer.c @@ -98,22 +98,12 @@ static void dccp_retransmit_timer(struct sock *sk) goto backoff; } - /* - * sk->sk_send_head has to have one skb with - * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP - * packet types. The only packets eligible for retransmission are: - * -- Requests in client-REQUEST state (sec. 8.1.1) - * -- Acks in client-PARTOPEN state (sec. 8.1.5) - * -- CloseReq in server-CLOSEREQ state (sec. 8.3) - * -- Close in node-CLOSING state (sec. 8.3) */ - WARN_ON(sk->sk_send_head == NULL); - /* * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was * sent, no need to retransmit, this sock is dead. */ if (dccp_write_timeout(sk)) - goto out; + return; /* * We want to know the number of packets retransmitted, not the @@ -122,30 +112,28 @@ static void dccp_retransmit_timer(struct sock *sk) if (icsk->icsk_retransmits == 0) DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS); - if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) { + if (dccp_retransmit_skb(sk) != 0) { /* * Retransmission failed because of local congestion, * do not backoff. */ - if (icsk->icsk_retransmits == 0) + if (--icsk->icsk_retransmits == 0) icsk->icsk_retransmits = 1; inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL), DCCP_RTO_MAX); - goto out; + return; } backoff: icsk->icsk_backoff++; - icsk->icsk_retransmits++; icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX); inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, DCCP_RTO_MAX); if (icsk->icsk_retransmits > sysctl_dccp_retries1) __sk_dst_reset(sk); -out:; } static void dccp_write_timer(unsigned long data) -- 2.39.5