Hey Flavio
I am so sorry for the inconvenience caused.
Next time I will take care of it. You have been a great help for me.
I thank you from the bottom of my heart. I was stuck on this part since
last few days.
Now, it has been resolved.
Thanks
Krish
On Wed, Feb 20, 2019 at 8:25 PM Flavio Leitner wrote:
> On Tue, Feb 19, 2019 at 12:43:08PM +0800, Krish wrote:
> > Hi Flavio,
> >
> > I think I got tcp_src and tcp_dst values, I can also successfully print
> > them.
> > Here is what I did:
> > for(numb=0;numb > {
> >
> > uint8_t nw_proto = 0;
> > packet=packets->packets[numb];
> > size_t size = dp_packet_size(packet);
> > const void *data = dp_packet_data(packet);
> > const char *frame = (const char *)data;
> > dp_packet_reset_offsets(packet);
> > *data_pull(, , ETH_ADDR_LEN * 2);*
> > //dl_type = parse_ether(, );
> > //VLOG_DBG("parse ether type DL TYPE: 0x%4x", dl_type);
> > packet->l3_ofs = (char *)data - frame;
> > const struct ip_header *ip = dp_packet_l3(packet);
> > nw_proto = ip->ip_proto;
> > VLOG_DBG("IP proto---> %d ", nw_proto);
> > int ip_len;
> > ip_len = IP_IHL(ip->ip_ihl_ver) * 4;
> >
> > *data_pull(, , ip_len);*
> > packet->l4_ofs = (char *)data - frame;
> > if(nw_proto == 6)
> > {
> > struct tcp_header *th = dp_packet_l4(packet);
> > VLOG_DBG( "tcp_src ---> %d", ntohs(th->tcp_src));
> > VLOG_DBG( "tcp_dst ---> %d", ntohs(th->tcp_dst));
> > }
> > }
> >
> >
> > Can you please confirm, if this is the right approach I have used and not
> > seeing the old values like before?
>
> It's hard to read code using html (bold, etc), could you please use
> text only and indent the code properly? It makes our life a lot easier.
>
> When you pull ETH_ADDR_LEN*2, the offset now points to ethernet_type
> which is not the l3_ofs as you set next. I don't think the above code
> works unless you uncomment parse_ethertype() which pulls more 4 bytes.
>
> fbl
>
>
>
> >
> > Thank you so much,
> > Krish
> >
> > On Tue, Feb 19, 2019 at 11:25 AM Krish wrote:
> >
> > > Flavio,
> > >
> > > Thank you for the clarification. You explained it very well.
> > >
> > > I don't want to wait for the miniflow_extraction, so I am left with
> > > parsing packet myself.
> > >
> > > Here is what I am doing now:
> > >
> > > for(numb=0;numb > > {
> > >
> > > uint8_t nw_proto;
> > > const char *frame;
> > > packet=packets->packets[numb];
> > > const void *data = dp_packet_data(packet);
> > > frame = data;
> > > *dp_packet_reset_offsets(packet);*
> > > * packet->l3_ofs = (char *)data - frame;*
> > > * const struct ip_header *ip = dp_packet_l3(packet);*
> > > nw_proto = ip->ip_proto;
> > > VLOG_DBG("IP proto---> %d ", nw_proto); // This is 0
> > >
> > > }
> > >
> > > I followed almost the same approach of what is going in
> miniflow_extract.
> > > nw_proto(ip protocol) is printing out to be 0.
> > > I am using this code just before emc_processing and inside
> > > dp_netdev_input__.
> > > Can you please help me here?
> > >
> > > Thanks
> > > Krish
> > >
> > >
> > > On Mon, Feb 18, 2019 at 8:11 PM Flavio Leitner
> wrote:
> > >
> > >> On Mon, Feb 18, 2019 at 11:05:53AM +0800, Krish wrote:
> > >> > Thanks for reply Ben.
> > >> > Does it mean that *miniflow_extract* will also initialize the L3
> header
> > >> > pointer?
> > >>
> > >> If you look at the miniflow_extract(), you will see that it calls
> > >> dp_packet_reset_offsets(packet) which will set all the header pointers
> > >> to their defaults meaning that they are not pointing to anything real.
> > >>
> > >> These pointers are used by dp_packet_l3 (or 4) functions to locate
> > >> the header.
> > >>
> > >> Then if you continue following the function, you will notice that
> > >> the code parses the packet from the outer header to the inner header
> > >> and as the parser goes, it updates the header offsets, like this line:
> > >>
> > >> packet->l3_ofs = (char *)data - frame;
> > >>
> > >> At this point, you have the pointer to the l3 header and you could use
> > >> dp_packet_l3().
> > >>
> > >>
> > >> > But I am getting the correct values for *nw_proto* from the L3
> header.
> > >> > struct ip_header *ip = dp_packet_l3(packet);
> > >> > nw_proto = ip->ip_proto;
> > >> >
> > >> > Any comments on this? Whether its right or wrong?
> > >>
> > >> When using DPDK, the packet is represented by two parts. One if the
> > >> rte buffer (packet data) that comes from DPDK library and the second
> > >> part is the packet's metadata (the offsets you need). This offsets
> > >> are allocated in the stack at dp_netdev_process_rxq_port(), so most
> > >> probably you are seeing old values from previous packets which
> > >> happens to work, but they are not correct.
> > >>
> > >> As I said above miniflow_extract() initializes those offsets to a
> > >> known state and then parse the packet to update with the correct
> > >> values.
> > >>
> > >> In summary, you will need to either wait for miniflow_extract() or
> > >> parse the packet yourself
