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

[Thomas Huth]

On 14.02.2016 18:47, Samuel Thibault wrote:
> From: Guillaume Subiron <address@hidden>
> 
> 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 <address@hidden>
> Signed-off-by: Samuel Thibault <address@hidden>
> ---
...
> 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 <address@hidden>