Re: [B.A.T.M.A.N.] [PATCH v2] batman-adv: Record route for ICMP messages

Daniel Seither
2010-02-15T21:21:56Z

Andrew Lunn schrieb:
>> + uint8_t rr[BAT_RR_LEN];
>
> This might be more readable as
>
> uint8_t rr[BAT_RR_ENTRIES][ETH_ALEN];
>
> and then your memcpy becomes
>
> /* add record route information if not full */
> if (icmp_packet->rr_cur < BAT_RR_ENTRIES) {
> memcpy(icmp_packet->rr[icmp_packet->rr_cur++],
> ethhdr->h_dest, ETH_ALEN);
> }

You're right, this makes things easier => changed.

>> ssize_t bat_device_write(struct file *file, const char __user *buff,
>> @@ -206,28 +210,42 @@
>> {
>> struct device_client *device_client =
>> (struct device_client *)file->private_data;
>> - struct icmp_packet icmp_packet;
>> + struct icmp_packet_rr icmp_packet;
>> struct orig_node *orig_node;
>> struct batman_if *batman_if;
>> uint8_t dstaddr[ETH_ALEN];
>> unsigned long flags;
>> + size_t packet_len = sizeof(struct icmp_packet);
>> + int with_rr = 0;
>>
>> if (len < sizeof(struct icmp_packet)) {
>> bat_dbg(DBG_BATMAN, "batman-adv:Error - can't send packet from char device: invalid packet size\n");
>> return -EINVAL;
>> }
>>
>> - if (!access_ok(VERIFY_READ, buff, sizeof(struct icmp_packet)))
>> + if (len >= sizeof(struct icmp_packet_rr)) {
>
> At first look, this looks wrong. I would of expected icmp_packet, not
> icmp_packet_rr. But maybe it is right?

It is right: At this point, the program doesn't know whether an
icmp_packet or an icmp_packet_rr is written. However, it can distinguish
these two by looking at the length of the data: if len >= sizeof(struct
icmp_packet_rr), the packet is long enough to include RR info and is
therefore treated as such.

>> int recv_icmp_packet(struct sk_buff *skb)
>> {
>> - struct icmp_packet *icmp_packet;
>> + struct icmp_packet_rr *icmp_packet;
>> struct ethhdr *ethhdr;
>> struct orig_node *orig_node;
>> struct sk_buff *skb_old;
>> @@ -860,8 +868,24 @@
>> if (!is_my_mac(ethhdr->h_dest))
>> return NET_RX_DROP;
>>
>> - icmp_packet = (struct icmp_packet *) skb->data;
>> + icmp_packet = (struct icmp_packet_rr *) skb->data;
>>
>> + if (icmp_packet->packet_type == BAT_ICMP_RR) {
>> + hdr_size = sizeof(struct icmp_packet_rr);
>> +
>> + /* drop packet if it has not necessary minimum size */
>> + if (skb_headlen(skb) < hdr_size)
>> + return NET_RX_DROP;
>> +
>> + /* add record route information if not full */
>> + if (icmp_packet->rr_cur > 0
>> + && icmp_packet->rr_cur < BAT_RR_LEN / ETH_ALEN) {
>> + memcpy(&(icmp_packet->rr[icmp_packet->rr_cur * ETH_ALEN]),
>> + ethhdr->h_dest, ETH_ALEN);
>
> Why rr_cur > 0?

For historical reasons ;-) rr_cur generally is the index for rr that
indicates the next position to be written to. In the first version of
the patch, a value of 0 for rr_cur indicated that RR is not active. This
is no longer neccessary => changed. Thanks for pointing out.

Regards, Daniel