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Yay.. Just looks like there was some weird stuff going on with the
reported sk_buff length. I was expecting it to include ethernet header
length, but it doesn't - It's just the data length.
Woohoo..
Mike Tyson wrote:
> Hi!
>
> I've written most of a layer 2.5 ad hoc network driver, which sits
> between the IP stack and the physical device drivers. I'm having
> trouble sending packets, however; I can send, but all packets get
> truncated to 46 bytes (Ethernet's minimum).
>
> Debug messages on the sending host show correct packet lengths
> (skb->len), but debug messages on the receiver show all packets are 46
> bytes long.
>
> I'm creating a sk_buff with data copied from my own packet structures
> (which are shared with a userland daemon).
>
> Here's my transmission code:
>
>
> ---
>
> /**
> * sahn_tx_packetbuf - prepare and dispatch a pktbuf for transmission
> * @pkt packet to send
> * @dest Dest address
> * @dev device to send with
> * @priv sahn private structure
> *
> * Returns error code, 0 on success.
> */
> int sahn_tx_packetbuf(struct sahn_pktbuf* pkt, void* dest, struct
> net_device* dev, struct sahn_priv* priv)
> {
> // Allocate sk_buff
> struct sk_buff* skb;
> char* data;
>
> if ( !sahn_pb_alldata(pkt) )
> {
> SAHNDP(1, "Invalid packet encountered!\n");
> return -EINVAL;
> }
>
> skb = alloc_skb(sahn_pb_len(pkt) + LL_RESERVED_SPACE(dev),
> GFP_KERNEL);
>
> if ( !skb )
> {
> SAHNERRP("Could not allocate packet buffer while
> transmitting.\n");
> priv->stats.tx_dropped++;
> return -ENOMEM;
> }
>
> skb_reserve(skb, LL_RESERVED_SPACE(dev));
>
> // Prepare space, and copy packet data in
> data = skb_put(skb, sahn_pb_len(pkt));
> memcpy(data, sahn_pb_alldata(pkt), sahn_pb_len(pkt));
>
> // Set parameters
> skb->dev = dev;
> skb->input_dev = dev;
> skb->nh.raw = (unsigned char*) data;
> skb->protocol = htons(SAHN_ETHERTYPE);
>
> if ( dev->hard_header &&
> dev->hard_header(skb, dev, SAHN_ETHERTYPE, dest, dev->dev_addr,
> skb->len) < 0 )
> {
> SAHNERRP("Could not create hardware header while
> transmitting.\n");
> priv->stats.tx_dropped++;
> return -EINVAL;
> }
>
> SAHNDP(9, "Transmitting packet of %lu bytes (%u with header) from
> %s.\n", sahn_pb_len(pkt), skb->len, dev->name);
>
> // Send to device driver
> dev_queue_xmit(skb);
>
> // Update statistics
> priv->stats.tx_packets++;
> priv->stats.tx_bytes += sahn_pb_len(pkt);
> }
>
> ---
>
>
>
>
> Have I missed something obvious?
>
> Cheers =)
>
> Mike
>
>
>
>
- --
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FAQ: http://kernelnewbies.org/faq/
- --
Mike Tyson <mike@xxxxxxxxxxx>
M: (+61) 0407 754 124
W: http://mike.tyson.id.au
B: http://mike.tyson.id.au/blog
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