[dpdk-users] rte_flow() usage of htonl() for ipv4 addr masks?

[Arvind Narayanan]

On Sun, Aug 9, 2020 at 9:56 PM Cliff Burdick <shaklee3 at gmail.com> wrote:
>
> It should convert to network order, although many applications it won't matter since they use all F's. If you follow the code in flow_filtering, indeed it's using:
>
> #define FULL_MASK 0xffffffff /* full mask */
>
> So it won't make any difference. The example should probably be updated, though..

Thanks Cliff! Yes, when it's all Fs, it doesn't matter.
But I am trying to install rte_flow rules for subnets by parsing a
file which has IPv4 ranges mentioned using CIDR format.

I have it working for say /24 ranges, but as I go to /30 or /29, the
same implementation is not working. I followed the flow classify
example. https://doc.dpdk.org/guides/sample_app_ug/flow_classify.html
as it does the same thing.

```
static uint32_t
convert_depth_to_bitmask(uint32_t depth_val) {
  uint32_t bitmask = 0;
  int i, j;

  for (i = depth_val, j = 0; i > 0; i--, j++)
    bitmask |= (1 << (31 - j));
  return bitmask;
}

ip_mask.hdr.dst_addr = htonl(convert_depth_to_bitmask(29))
```
and https://github.com/DPDK/dpdk/blob/master/examples/flow_classify/flow_classify.c#L377-L396
for ipv4 parsing.

I'll keep digging. As always, it seems too trivial to fix as a bug,
but it's been driving me crazy.. haha

- Arvind


>
> On Sun, Aug 9, 2020 at 7:03 PM Arvind Narayanan <webguru2688 at gmail.com> wrote:
>>
>> Hi,
>>
>> In the flow_filtering sample application, the IP's mask was set without
>> using htonl().
>> https://github.com/DPDK/dpdk/blob/master/examples/flow_filtering/flow_blocks.c#L85
>>
>> Another DPDK page <https://doc.dpdk.org/guides/howto/rte_flow.html> shows
>> how a testpmd command is translated to C code.
>> On this page though, Example 4.2 (Range IPv4 drop) has used htonl() to set
>> the mask.
>>
>> Any clarification on how to load the mask would be helpful.
>>
>> Thanks,
>> Arvind