On Thu, 9 Jan 2003, Joshua Stewart wrote:
Hi,
> I'm trying to take "hand-built" sk_buffs with little more than some data
> and a dev member and push them to the NIC for transmission. I would
> like to simply give them to dev_queue_xmit. Does anybody know what
> state I should have them in before handing them to dev_queue_xmit?
In a driver I wrote I setup (for a newly allocated skb and a 2.4 kernel):
some_header = (struct some_header *) skb_push(skb, sizeof(struct
some_header));
skb->nh.raw = (unsigned char *) some_header;
this_eth_hdr = (struct ethhdr *) skb_push(skb, ETH_HLEN);
this_eth_hdr->h_proto = __constant_htons(ETH_P_SOME_HEADER);
memcpy(this_eth_hdr->h_source, dev->dev_addr, ETH_ALEN);
skb->dev = dev;
skb->protocol = __constant_htons(ETH_P_CSM_ENCAPS);
dev_queue_xmit(skb);
where some_header for you is probably an IP header and dev is the "struct
net_device" of the device you are using to send the packet out on the
wire.
> Should skb->data point to the start of a MAC header or an IP header?
MAC
> Also, given an IP address in skb->nh.iph->daddr, what's the easiest way
> to get the appropriate MAC address?
First you need to get the device, then the MAC address is easy. This
should be what normal IP routing code does...
> J
>
>
Rui
> -
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