Re: [PATCH] ipvs: Fix reuse connection if real server is dead

[Hans Schillstrom <hans@xxxxxxxxxxxxxxx>]

Hello
On Tue, 2013-05-07 at 23:54 +0200, Grzegorz Lyczba wrote:
> Expire cached connection for new TCP connection if real server is down

This patch will break some "common" use cases,
on the other hand it also solves some issues...
 
I would prefer to have a sysctl to turn it on.

Should we have something similar for sctp?


Regards
Hans

> Signed-off-by: Grzegorz Lyczba <grzegorz.lyczba@xxxxxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_core.c |   20 ++++++++++++++++++++
>  1 files changed, 20 insertions(+), 0 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 47edf5a..7c5f083 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -1002,6 +1002,17 @@ static inline int is_tcp_reset(const struct sk_buff 
> *skb, int nh_len)
>       return th->rst;
>  }
>  
> +static inline int is_tcp_syn(const struct sk_buff *skb, int nh_len)
> +{
> +    struct tcphdr _tcph, *th;
> +
> +    th = skb_header_pointer(skb, nh_len, sizeof(_tcph), &_tcph);
> +    if (th == NULL)
> +        return 0;
> +    return th->syn;
> +}
> +
> +
>  /* Handle response packets: rewrite addresses and send away...
>   */
>  static unsigned int
> @@ -1627,6 +1638,15 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, 
> int af)
>        * Check if the packet belongs to an existing connection entry
>        */
>       cp = pp->conn_in_get(af, skb, &iph, 0);
> +
> +     if (likely(cp) && likely(cp->dest) &&
> +         unlikely(!atomic_read(&cp->dest->weight)) &&
> +         iph.protocol == IPPROTO_TCP && is_tcp_syn(skb, iph.len)) {
> +             ip_vs_conn_expire_now(cp);
> +             __ip_vs_conn_put(cp);
> +             cp = NULL;
> +     }
> +
>       if (unlikely(!cp) && !iph.fragoffs) {
>               /* No (second) fragments need to enter here, as nf_defrag_ipv6
>                * replayed fragment zero will already have created the cp

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