Hi Olivier,
> -----Original Message-----
> From: Olivier Matz [mailto:olivier.m...@6wind.com]
> Sent: Tuesday, January 16, 2018 5:01 PM
> To: Wang, Xiao W <xiao.w.w...@intel.com>
> Cc: y...@fridaylinux.org; tho...@monjalon.net; Bie, Tiwei
> <tiwei....@intel.com>; dev@dpdk.org; step...@networkplumber.org;
> maxime.coque...@redhat.com
> Subject: Re: [dpdk-dev] [PATCH v10 3/5] net: add a helper for making RARP
> packet
>
> Hi Xiao,
>
> Please find few comments below.
>
> On Wed, Jan 10, 2018 at 09:23:54AM +0800, Xiao Wang wrote:
> > Suggested-by: Maxime Coquelin <maxime.coque...@redhat.com>
> > Signed-off-by: Xiao Wang <xiao.w.w...@intel.com>
> > Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>
> > ---
> > lib/librte_net/Makefile | 1 +
> > lib/librte_net/rte_arp.c | 42
> ++++++++++++++++++++++++++++++++++++++
> > lib/librte_net/rte_arp.h | 17 +++++++++++++++
> > lib/librte_net/rte_net_version.map | 6 ++++++
> > 4 files changed, 66 insertions(+)
> > create mode 100644 lib/librte_net/rte_arp.c
> >
> > diff --git a/lib/librte_net/Makefile b/lib/librte_net/Makefile
> > index 5e8a76b68..ab290c382 100644
> > --- a/lib/librte_net/Makefile
> > +++ b/lib/librte_net/Makefile
> > @@ -13,6 +13,7 @@ LIBABIVER := 1
> >
> > SRCS-$(CONFIG_RTE_LIBRTE_NET) := rte_net.c
> > SRCS-$(CONFIG_RTE_LIBRTE_NET) += rte_net_crc.c
> > +SRCS-$(CONFIG_RTE_LIBRTE_NET) += rte_arp.c
> >
> > # install includes
> > SYMLINK-$(CONFIG_RTE_LIBRTE_NET)-include := rte_ip.h rte_tcp.h
> rte_udp.h rte_esp.h
> > diff --git a/lib/librte_net/rte_arp.c b/lib/librte_net/rte_arp.c
> > new file mode 100644
> > index 000000000..d7223b044
> > --- /dev/null
> > +++ b/lib/librte_net/rte_arp.c
> > @@ -0,0 +1,42 @@
> > +/* SPDX-License-Identifier: BSD-3-Clause
> > + * Copyright(c) 2018 Intel Corporation
> > + */
> > +
> > +#include <arpa/inet.h>
> > +
> > +#include <rte_arp.h>
> > +
> > +#define RARP_PKT_SIZE 64
> > +int
> > +rte_net_make_rarp_packet(struct rte_mbuf *mbuf, const struct ether_addr
> *mac)
> > +{
> > + struct ether_hdr *eth_hdr;
> > + struct arp_hdr *rarp;
> > +
> > + if (mbuf->buf_len < RARP_PKT_SIZE)
> > + return -1;
> > +
> > + /* Ethernet header. */
> > + eth_hdr = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);
> > + memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
> > + ether_addr_copy(mac, ð_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);
> > +
> > + mbuf->data_len = RARP_PKT_SIZE;
> > + mbuf->pkt_len = RARP_PKT_SIZE;
> > +
> > + return 0;
> > +}
>
> You don't check that there is enough tailroom to write the packet data.
Yes, tailroom can be used.
> Also, nothing verifies that the mbuf passed to the function is empty.
> I suggest to do the allocation in this function, what do you think?
>
I agree to allocate in this function and let it do all the checks.
> You can also use rte_pktmbuf_append() to check for the tailroom and
> update data_len/pkt_len:
>
> m = rte_pktmbuf_alloc();
> if (m == NULL)
> return NULL;
> eth_hdr = rte_pktmbuf_append(m, RARP_PKT_SIZE);
When data_len is not enough, we need to rte_pktmbuf_append(m, RARP_PKT_SIZE -
m->data_len);
> if (eth_hdr == NULL) {
> m_freem(m);
> return NULL;
> }
> eth_hdr->... = ...;
> ...
> rarp = (struct arp_hdr *)(eth_hdr + 1);
> rarp->... = ...;
> ...
>
> return m;
>
Will change it in next version, thanks for the comments.
BRs,
Xiao
