Re: [dpdk-dev] [PATCH v7 3/3] net/virtio: support GUEST ANNOUNCE

[Thomas Monjalon <thomas@monjalon.net>]

09/01/2018 12:03, Wang, Xiao W:
> > From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> > On 01/09/2018 03:26 PM, Xiao Wang wrote:
> > > +#define RARP_PKT_SIZE	64
> > > +static int
> > > +make_rarp_packet(struct rte_mbuf *rarp_mbuf, const struct ether_addr
> > *mac)
> > > +{
> > > +	struct ether_hdr *eth_hdr;
> > > +	struct arp_hdr *rarp;
> > > +
> > > +	if (rarp_mbuf->buf_len < RARP_PKT_SIZE) {
> > > +		PMD_DRV_LOG(ERR, "mbuf size too small %u (< %d)",
> > > +				rarp_mbuf->buf_len, RARP_PKT_SIZE);
> > > +		return -1;
> > > +	}
> > > +
> > > +	/* Ethernet header. */
> > > +	eth_hdr = rte_pktmbuf_mtod(rarp_mbuf, struct ether_hdr *);
> > > +	memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
> > > +	ether_addr_copy(mac, &eth_hdr->s_addr);
> > > +	eth_hdr->ether_type = htons(ETHER_TYPE_RARP);
> > > +
> > > +	/* RARP header. */
> > > +	rarp = (struct arp_hdr *)(eth_hdr + 1);
> > > +	rarp->arp_hrd = htons(ARP_HRD_ETHER);
> > > +	rarp->arp_pro = htons(ETHER_TYPE_IPv4);
> > > +	rarp->arp_hln = ETHER_ADDR_LEN;
> > > +	rarp->arp_pln = 4;
> > > +	rarp->arp_op  = htons(ARP_OP_REVREQUEST);
> > > +
> > > +	ether_addr_copy(mac, &rarp->arp_data.arp_sha);
> > > +	ether_addr_copy(mac, &rarp->arp_data.arp_tha);
> > > +	memset(&rarp->arp_data.arp_sip, 0x00, 4);
> > > +	memset(&rarp->arp_data.arp_tip, 0x00, 4);
> > > +
> > > +	rarp_mbuf->data_len = RARP_PKT_SIZE;
> > > +	rarp_mbuf->pkt_len = RARP_PKT_SIZE;
> > > +
> > > +	return 0;
> > > +}
> > 
> > Do you think it could make sense to have this function in a lib, as
> > vhost user lib does exactly the same?
> > 
> > I don't know if it could be useful to others than vhost/virtio though.
> 
> Hi Thomas,
> 
> Do you think it's worth adding a new helper for ARP in lib/librte_net/?
> Currently we just need a helper to build RARP packet (the above make_rarp_packet)

Yes, good idea