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

[Thomas Huth <thuth@redhat.com>]

On 11/12/15 14:38, Thomas Huth wrote:
> 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.

Ah, well, never mind, I did not see the comment in the patch description
that you fix it up in the next patch.

Anyway, it's IMHO a somewhat strange way to structure a patch ... maybe
it would be nicer to do it in one go instead (after splitting off the
arp_requested renaming)?

 Thomas