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List:       dpdk-users
Subject:    Re: [dpdk-users] Unable to Forward the Packet after UDP Payload Modification
From:       satyavalli rama <satyavalli.rama () gmail ! com>
Date:       2019-07-02 7:49:09
Message-ID: CAECt3bMFhmWNup7-n-0nEFeBnbwgySzeqpBxH0GybYLuyqv8vQ () mail ! gmail ! com
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> 
> I tried to create a completely new packet with my received mbuf, but still
> > I'm unable to forward packets with the appended payload, (Im able to
> > replace the RX payload but I'm unable to add or append additional payload
> > to the RX pkts)..
> > 
> > If I'm changing IP Header Total Length or Checksum, the packets are not
> > getting transmitted..
> > 
> > Kindly help me...
> > 
> > Thanks
> > Satya
> > 
> > On Mon, Jul 1, 2019, 11:08 satyavalli rama <satyavalli.rama@gmail.com>
> > wrote:
> > 
> > > 
> > > 
> > > On Sat, Jun 29, 2019, 14:07 satyavalli rama <satyavalli.rama@gmail.com>
> > > wrote:
> > > 
> > > > I've modified a data of 12 bytes to the udp  payload, and the same ive
> > > > triednto add to the the IP header total length and udp dgram length, but
> > > > still packets are dropping or Not getting forwaded...
> > > > Plz help me..
> > > > 
> > > > On Fri, Jun 28, 2019, 21:08 Stephen Hemminger <
> > > > stephen@networkplumber.org> wrote:
> > > > 
> > > > > On Thu, 27 Jun 2019 23:00:35 +0530
> > > > > satyavalli rama <satyavalli.rama@gmail.com> wrote:
> > > > > 
> > > > > > Hi
> > > > > > 
> > > > > > 
> > > > > > With Scapy we are sending UDP Packets to ‘P0' of DPDK - VM -1 as
> > > > > below
> > > > > > 
> > > > > > 
> > > > > > > > sendp(Ether(src="52:00:00:00:00:4a",dst="50:00:00:00:00:8F")/IP(dst="20.20.20.20",proto=17)/UDP(sport=4009,dport=4019)/Raw(load=('Helllo
> > > > > > > > 
> > > > > Basha')), iface="ens9", loop=1, count=10, inter=1.0002)
> > > > > > 
> > > > > > 
> > > > > > I'm modifying MAC address in l2fwd_simple_forward (52:00:00:00:AB:CD)
> > > > > > and calling the below API after mac updation, in the ‘l2fwd' DPDK
> > > > > > Sample application.
> > > > > > 
> > > > > > But I'm unable to receive the ‘Appended Data' on the Destination
> > > > > Port.
> > > > > > P0 itself is dropping our packets...
> > > > > > 
> > > > > > Without Appending the Payload/Data we are able to see our packets on
> > > > > > the Destination Port.
> > > > > > 
> > > > > > Please let me know whether this issue is with respect to appending or
> > > > > > buffering or checksum related...
> > > > > > 
> > > > > > static void
> > > > > > 
> > > > > > pkt_modify(struct rte_mbuf *m, unsigned dest_portid)
> > > > > > 
> > > > > > {
> > > > > > 
> > > > > > struct ether_hdr *eth;
> > > > > > 
> > > > > > struct ipv4_hdr *ipv4;
> > > > > > 
> > > > > > struct udp_hdr *udp;
> > > > > > 
> > > > > > char *udpData;
> > > > > > 
> > > > > > int len = 0;
> > > > > > 
> > > > > > const char *mess = "Eureka";
> > > > > > 
> > > > > > char *newData = NULL;
> > > > > > 
> > > > > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *);
> > > > > > 
> > > > > > ipv4 = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *,sizeof(struct
> > > > > ether_hdr));
> > > > > > 
> > > > > > udp = rte_pktmbuf_mtod_offset(m, struct udp_hdr *, sizeof(struct
> > > > > > ether_hdr)+sizeof(struct ipv4_hdr));
> > > > > > 
> > > > > > len = m->data_len;
> > > > > > 
> > > > > > udpData = rte_pktmbuf_mtod_offset(m, char *, len);
> > > > > > 
> > > > > > newData = rte_pktmbuf_append(m, 6);
> > > > > > 
> > > > > > if (newData != NULL)
> > > > > > 
> > > > > > rte_memcpy(newData, mess, 6);
> > > > > > 
> > > > > > 
> > > > > > len = m->data_len;
> > > > > > 
> > > > > > udpData = rte_pktmbuf_mtod_offset(m, char *, sizeof(struct
> > > > > > ether_hdr)+sizeof(struct ipv4_hdr)+
> > > > > > 
> > > > > > sizeof(struct udp_hdr));
> > > > > > 
> > > > > > return ;
> > > > > > 
> > > > > > }
> > > > > > 
> > > > > > 
> > > > > > Please help me on figuring out this....
> > > > > > 
> > > > > > Thanks,
> > > > > > 
> > > > > > Satya Valli.
> > > > > 
> > > > > You aren't changing the ip header length or checksum.
> > > > > So your message at the end just looks like additional L2 trailer.
> > > > > 
> > > > 


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