lkml.org 
[lkml]   [2003]   [Jan]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Pushing a stray sk_buff to the NIC
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

> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:32    [W:0.043 / U:1.800 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site