The packet parser does not parse packets

[Lukas955]

It looks like that the packet parser is not able to parse packets if --with-pcap option is enabled during compilation and input modules like dpdk, dpdk-ring or nfb are later used as packet providers.

The issues seems to be here in "ifdef" section. If the PCAP option is enabled, the parser behaviour is significantly changed as it needs "opt->datalink" with information about the first layer of the packet as it can start with Ethernet, IP layer or something else. However, if the option is disabled, it assumes that the first layer is always Ethernet.

Inputs like dpdk, dpdk-ring or nfb don't fill the information about the first layer (see links) and always fill zero. This causes the packet parser not to recognize the first layer.

[SiskaPavel]

Solved in #256