Re: [Qemu-devel] [PATCHv7 7/9] slirp: Handle IPv6 in TCP functions

[Thomas Huth <thuth@redhat.com>]

On 14.02.2016 18:47, Samuel Thibault wrote:
> From: Guillaume Subiron <maethor@subiron.org>
> 
> This patch adds IPv6 case in TCP functions refactored by the last
> patches.
> This also adds IPv6 pseudo-header in tcpiphdr structure.
> Finally, tcp_input() is called by ip6_input().
> 
> Signed-off-by: Guillaume Subiron <maethor@subiron.org>
> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
> ---
...
> diff --git a/slirp/tcp_input.c b/slirp/tcp_input.c
> index fac2a24..7aad1bc 100644
> --- a/slirp/tcp_input.c
> +++ b/slirp/tcp_input.c
> @@ -216,7 +216,8 @@ present:
>  void
>  tcp_input(struct mbuf *m, int iphlen, struct socket *inso, unsigned short af)
>  {
> -  	struct ip save_ip, *ip;
> +	struct ip save_ip, *ip;
> +	struct ip6 save_ip6, *ip6;
>  	register struct tcpiphdr *ti;
>  	caddr_t optp = NULL;
>  	int optlen = 0;
> @@ -230,6 +231,7 @@ tcp_input(struct mbuf *m, int iphlen, struct socket *inso, unsigned short af)
>  	int ret;
>  	struct sockaddr_storage lhost, fhost;
>  	struct sockaddr_in *lhost4, *fhost4;
> +	struct sockaddr_in6 *lhost6, *fhost6;
>      struct ex_list *ex_ptr;
>      Slirp *slirp;
>  
> @@ -256,21 +258,18 @@ tcp_input(struct mbuf *m, int iphlen, struct socket *inso, unsigned short af)
>  	}
>  	slirp = m->slirp;
>  
> +	ip = mtod(m, struct ip *);
> +	ip6 = mtod(m, struct ip6 *);
> +
>  	switch (af) {
>  	case AF_INET:
> +	    save_ip = *ip;
>  	    if (iphlen > sizeof(struct ip)) {
>  	        ip_stripoptions(m, (struct mbuf *)0);
>  	        iphlen = sizeof(struct ip);
>  	    }
>  	    /* XXX Check if too short */
>  
> -
> -	    /*
> -	     * Save a copy of the IP header in case we want restore it
> -	     * for sending an ICMP error message in response.
> -	     */
> -	    ip = mtod(m, struct ip *);
> -	    save_ip = *ip;

I think you could also leave the "save_ip = *ip" here instead of moving
it to the beginning of this case statement.

>  	    save_ip.ip_len += iphlen;
>  
>  	    /*
> @@ -295,16 +294,36 @@ tcp_input(struct mbuf *m, int iphlen, struct socket *inso, unsigned short af)
>  	    ti->ti_dst = save_ip.ip_dst;
>  	    ti->ti_pr = save_ip.ip_p;
>  	    ti->ti_len = htons((uint16_t)tlen);
> -	    len = ((sizeof(struct tcpiphdr) - sizeof(struct tcphdr)) + tlen);
> -	    if (cksum(m, len)) {
> -	        goto drop;
> -	    }
> +	    break;
> +
> +	case AF_INET6:
> +	    save_ip6 = *ip6;
> +	    m->m_data -= sizeof(struct tcpiphdr) - (sizeof(struct ip6)
> +	                                         + sizeof(struct tcphdr));
> +	    m->m_len  += sizeof(struct tcpiphdr) - (sizeof(struct ip6)
> +	                                         + sizeof(struct tcphdr));
> +	    ti = mtod(m, struct tcpiphdr *);
> +
> +	    tlen = ip6->ip_pl;
> +	    tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
> +	    memset(&ti->ih_mbuf, 0 , sizeof(struct mbuf_ptr));
> +	    memset(&ti->ti, 0, sizeof(ti->ti));
> +	    ti->ti_x0 = 0;
> +	    ti->ti_src6 = save_ip6.ip_src;
> +	    ti->ti_dst6 = save_ip6.ip_dst;
> +	    ti->ti_nh6 = save_ip6.ip_nh;
> +	    ti->ti_len = htons((uint16_t)tlen);
>  	    break;
>  
>  	default:
>  	    g_assert_not_reached();
>  	}
>  
> +	len = ((sizeof(struct tcpiphdr) - sizeof(struct tcphdr)) + tlen);
> +	if (cksum(m, len)) {
> +	    goto drop;
> +	}
> +
...
> diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
> index c16b29d..6991b21 100644
> --- a/slirp/tcp_subr.c
> +++ b/slirp/tcp_subr.c
> @@ -88,6 +88,15 @@ tcp_template(struct tcpcb *tp)
>  	    n->ti_dport = so->so_lport;
>  	    break;
>  
> +	case AF_INET6:
> +	    n->ti_nh6 = IPPROTO_TCP;
> +	    n->ti_len = htons(sizeof(struct tcphdr));
> +	    n->ti_src6 = so->so_faddr6;
> +	    n->ti_dst6 = so->so_laddr6;
> +	    n->ti_sport = so->so_fport6;
> +	    n->ti_dport = so->so_lport6;
> +	    break;
> +
>  	default:
>  	    g_assert_not_reached();
>  	}
> @@ -156,6 +165,10 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
>  		    xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, uint32_t);
>  		    xchg(ti->ti_dport, ti->ti_sport, uint16_t);
>  		    break;
> +		case AF_INET6:
> +		    xchg(ti->ti_dst6, ti->ti_src6, struct in6_addr);
> +		    xchg(ti->ti_dport, ti->ti_sport, uint16_t);
> +		    break;
>  		default:
>  		    g_assert_not_reached();
>  		}
> @@ -182,6 +195,7 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
>  
>  	struct tcpiphdr tcpiph_save = *(mtod(m, struct tcpiphdr *));
>  	struct ip *ip;
> +	struct ip6 *ip6;
>  
>  	switch (af) {
>  	case AF_INET:
> @@ -204,6 +218,20 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
>  	    (void) ip_output((struct socket *)0, m);
>  	    break;
>  
> +	case AF_INET6:
> +	    m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
> +	                                         - sizeof(struct ip6);
> +	    m->m_len  -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
> +	                                         - sizeof(struct ip6);
> +	    ip6 = mtod(m, struct ip6 *);
> +	    ip6->ip_pl = tlen;
> +	    ip6->ip_dst = tcpiph_save.ti_dst6;
> +	    ip6->ip_src = tcpiph_save.ti_src6;
> +	    ip6->ip_nh = tcpiph_save.ti_nh6;
> +
> +	    (void) ip6_output((struct socket *)0, m, 0);

Is that "(void)" really necessary here? Also, I think you could simply
use "NULL" instead of "(struct socket *)0".

> +	    break;
> +
>  	default:
>  	    g_assert_not_reached();
>  	}
...

Just some cosmetic nits, patch generally looks fine to me, so:

Reviewed-by: Thomas Huth <thuth@redhat.com>