[dpdk-dev] Packet crafting....

[Richardson, Bruce]

> Hello friends,
> 
> As of now... I know on how to create an ipv4 header using the 'struct
> ipv4_hdr'.
> My requirement is to craft a packet and sent it via 'rte_eth_tx_burst'.
> I know that there should be an 'ether_hdr' created before, the packet could
> be sent.
> Could someone help me on how to set the address fields and type in
> 'ether_hdr' and how to put the ipv4 header as the payload for ether_hdr.
> 

You probably want to do something like this to craft a full packet. First allocate an mbuf, then get it's data pointer as a ether_hdr structure, then an ip_hdr beyond that and then any L4 headers, e.g. udp, beyond that. For example, assuming mempool variable p:

    struct rte_mbuf *buf = rte_pktmbuf_alloc(p);
    struct ether_hdr *ehdr = rte_pktmbuf_mtod(buf, struct ether_hdr *);
/* set ether_hdr fields here e.g. */
    ehdr->ether_type = rte_bswap16(ETHER_TYPE_IPv4);
    struct ipv4_hdr *iphdr = (struct ipv4_hdr *)(&ehdr[1]);
/* set ipv4 header fields here */
    struct udp_hdr *uhdr = (struct udp_hdr *)(&iphdr[1]);
/* set udp header fields here, e.g. */
    uhdr->src_port = rte_bswap16(0x5000);