Re: [Qemu-devel] [PATCH 02/18] slirp: Generalizing and neutralizing code before adding IPv6 stuff

[Thomas Huth <thuth@redhat.com>]

On 11/12/15 01:15, Samuel Thibault wrote:
> From: Guillaume Subiron <maethor@subiron.org>
> 
> Basically, this patch replaces "arp" by "resolution" every time "arp"
> means "mac resolution" and not specifically ARP.
> 
> Some indentation problems are solved in functions that will be modified
> in the next patches (ip_input…).
> 
> In if_encap, a switch is added to prepare for the IPv6 case. Some code
> is factorized.
> 
> Signed-off-by: Guillaume Subiron <maethor@subiron.org>
> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
> ---
>  slirp/mbuf.c  |  2 +-
>  slirp/mbuf.h  |  2 +-
>  slirp/slirp.c | 24 ++++++++++++++++++++----
>  3 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/slirp/mbuf.c b/slirp/mbuf.c
> index 795fc29..bc942b6 100644
> --- a/slirp/mbuf.c
> +++ b/slirp/mbuf.c
> @@ -91,7 +91,7 @@ m_get(Slirp *slirp)
>  	m->m_len = 0;
>          m->m_nextpkt = NULL;
>          m->m_prevpkt = NULL;
> -        m->arp_requested = false;
> +        m->resolution_requested = false;
>          m->expiration_date = (uint64_t)-1;
>  end_error:
>  	DEBUG_ARG("m = %p", m);
> diff --git a/slirp/mbuf.h b/slirp/mbuf.h
> index b144f1c..38fedf4 100644
> --- a/slirp/mbuf.h
> +++ b/slirp/mbuf.h
> @@ -79,7 +79,7 @@ struct mbuf {
>  	int	m_len;			/* Amount of data in this mbuf */
>  
>  	Slirp *slirp;
> -	bool	arp_requested;
> +	bool	resolution_requested;
>  	uint64_t expiration_date;
>  	/* start of dynamic buffer area, must be last element */
>  	union {
> diff --git a/slirp/slirp.c b/slirp/slirp.c
> index 35f819a..380ddc3 100644
> --- a/slirp/slirp.c
> +++ b/slirp/slirp.c
> @@ -776,6 +776,8 @@ int if_encap(Slirp *slirp, struct mbuf *ifm)
>          return 1;
>      }
>  
> +    switch (iph->ip_v) {
> +    case IPVERSION:
>      if (iph->ip_dst.s_addr == 0) {
>          /* 0.0.0.0 can not be a destination address, something went wrong,
>           * avoid making it worse */

That indentation looks now broken - shouldn't the if-statement now be
indented with four more spaces now?

> @@ -786,7 +788,7 @@ int if_encap(Slirp *slirp, struct mbuf *ifm)
>          struct ethhdr *reh = (struct ethhdr *)arp_req;
>          struct arphdr *rah = (struct arphdr *)(arp_req + ETH_HLEN);
>  
> -        if (!ifm->arp_requested) {
> +        if (!ifm->resolution_requested) {
>              /* If the client addr is not known, send an ARP request */
>              memset(reh->h_dest, 0xff, ETH_ALEN);
>              memcpy(reh->h_source, special_ethaddr, ETH_ALEN - 4);
> @@ -812,22 +814,36 @@ int if_encap(Slirp *slirp, struct mbuf *ifm)
>              rah->ar_tip = iph->ip_dst.s_addr;
>              slirp->client_ipaddr = iph->ip_dst;
>              slirp_output(slirp->opaque, arp_req, sizeof(arp_req));
> -            ifm->arp_requested = true;
> +            ifm->resolution_requested = true;
>  
>              /* Expire request and drop outgoing packet after 1 second */
>              ifm->expiration_date = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + 1000000000ULL;
>          }
>          return 0;
>      } else {
> -        memcpy(eh->h_dest, ethaddr, ETH_ALEN);
>          memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 4);
>          /* XXX: not correct */
>          memcpy(&eh->h_source[2], &slirp->vhost_addr, 4);
>          eh->h_proto = htons(ETH_P_IP);
> +        break;
> +    }
> +
> +    default:
> +        /* Do not assert while we don't manage IP6VERSION */
> +        /* assert(0); */
> +        break;
> +    }
> +
> +        memcpy(eh->h_dest, ethaddr, ETH_ALEN);
> +        DEBUG_ARGS((dfd, " src = %02x:%02x:%02x:%02x:%02x:%02x\n",
> +                    eh->h_source[0], eh->h_source[1], eh->h_source[2],
> +                    eh->h_source[3], eh->h_source[4], eh->h_source[5]));
> +        DEBUG_ARGS((dfd, " dst = %02x:%02x:%02x:%02x:%02x:%02x\n",
> +                    eh->h_dest[0], eh->h_dest[1], eh->h_dest[2],
> +                    eh->h_dest[3], eh->h_dest[4], eh->h_dest[5]));
>          memcpy(buf + sizeof(struct ethhdr), ifm->m_data, ifm->m_len);
>          slirp_output(slirp->opaque, buf, ifm->m_len + ETH_HLEN);
>          return 1;
> -    }
>  }

The lines after the switch statement should also only be indented with 4
spaces, not with 8.

Also, I'd prefer if you could split this patch into two: One for
renaming the "arp_requested" field, and one for adding the additional
logic with the switch statement (since there are two different kind of
changes).

 Thomas