Dear Klement,
thanks for the hint. I had a look at the code bfd_main.c and in particular
at the function bfd_send_periodic().
I wrote the function send_udp_packet() -- see below -- in order to send
out UDP packets.
The function is executed (I can see from the VPP terminal) and no exception
is raised, however I do not see any packet out.
1 -- is the function correct or I am missing something?
2 -- if it is not correct, how I can see where the problem is?
Thanks,
Alessio
static void send_udp_packet(vlib_main_t * vm, vlib_node_runtime_t * rt){
u32 bi;
vlib_buffer_alloc (vm, &bi, 1)
vlib_buffer_t *b = vlib_get_buffer (vm, bi);
ASSERT (b->current_data == 0);
memset (vnet_buffer (b), 0, sizeof (*vnet_buffer (b)));
VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
add_udp4_transport (vm,b);
}
int add_udp4_transport (vlib_main_t * vm, vlib_buffer_t * b)
{
vnet_buffer (b)->ip.adj_index[VLIB_RX] = ~0;
vnet_buffer (b)->ip.adj_index[VLIB_TX]= ~0;
vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
vnet_buffer (b)->sw_if_index[VLIB_TX] = ~0;
u8 *data;
udp_header_t *udp;
ip4_header_t *ip;
data = vlib_buffer_get_current (b);
udp = (udp_header_t *) (data - sizeof (udp_header_t));
ip = (ip4_header_t *) ((u8 *) udp - sizeof (ip4_header_t));
// Build packet header
u32 src_address = 167772161; //10.0.0.1 u32 version
u32 dst_address = 167772162; // 10.0.0.2 u32 version
ip->src_address.as_u32 = src_address;
ip->dst_address.as_u32 = dst_address;
ip->ip_version_and_header_length = 0x45;
ip->ttl = 254;
ip->protocol = IP_PROTOCOL_UDP; //0x45 == IP_PROTOCOL_UDP
ip->length = clib_host_to_net_u16 (b->current_length + sizeof (*udp));
ip->checksum = ip4_header_checksum (ip);
udp->src_port = DNS_SERVER_PORT;
udp->dst_port = DNS_DST_PORT;
udp->length = clib_host_to_net_u16 (b->current_length);
udp->checksum = 0;
b->current_length = sizeof (*ip) + sizeof (*udp);
return 1;
}
On Wed, Jun 14, 2017 at 6:56 PM, Klement Sekera -X (ksekera - PANTHEON
TECHNOLOGIES at Cisco) <ksek...@cisco.com> wrote:
> Hi Alessio,
>
> you can take a look at BFD code which
>
> a.) creates and sends its own UDP packets - bfd_main.c -
> bfd_send_periodic() creates, encapsulates (UDP) and sends a packet out
> b.) loops back packets received - bfd_udp.c - bfd_udp_echo_input()
>
> I'm not sure what's your use case, whether you are trying to reuse
> existing buffer, but one of these should fit it.
>
> Regards,
> Klement
>
> Quoting Alessio Silvestro (2017-06-14 17:22:14)
> > Dear all,
> > I implemented a new VPP node that receives UDP traffic using the
> following
> > function:
> >
> > udp_register_dst_port (vm, PORT, my_node.index , 1 /* is_ip4 */);
> >
> > I am able to parse the packet and I would like to be able to send
> back an
> > UDP packet.
> >
> > Looking at the source code, the only function that seems fit my scope
> is
> > the following (in ~/vpp/src/vnet/udp/udp.h)
> >
> > ip_udp_encap_one (vlib_main_t * vm, vlib_buffer_t * b0, u8 * ec0, word
> > ec_len,
> >
> > u8 is_ip4)
> >
> > Is that correct or there is another function for this purpose?
> >
> > Thanks in advance for any help.
> >
> > Best regards,
> >
> > Alessio
>
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