How to find 802.11 protocol variant, and decipher packet_payload_info in PcapNG files?

Question

I'm building a (Python) parser of PcapNG files created by Wireshark.
After reading https://www.winpcap.org/ntar/draft/PCAP-DumpFileFormat.html, I'm having the following problems:

1. I'd like to determine each packet's protocol variant (802.11b, 802.11a, 802.11g or 802.11n).
   However, the PcapNG defines only the following link types:
   

   • LINKTYPE_IEEE802_11 105 IEEE 802.11 (wireless)
   • LINKTYPE_IEEE802_11_RADIO 127 802.11 plus BSD radio header

Is there a way to find the protocol variant inside a PcapNG trace file?

2. Is there a way to decipher the data inside the packet_payload_info, e.g. in the following:

   EnhancedPacket(interface_id=0, timestamp_high=332139, timestamp_low=2801116213L, packet_payload_info=(57, 57, '\x00\x00\x19\x00o\x08\x00\x00\tJ\xb2&\x00\x00\x00\x00\x12\x18q\x16@\x01\xca\xaa\x00\x94\x00\x00\x00`\x92\x175\x00\x01\xf4\x0f\x1b\xb8sL\x04\x00\xc0#\xff\xff\xff\xff\xff\xff\xff\xffX\xd0Y\'), options=Options({}))

Answer 1

The IEEE802_11_RADIO data link type is what you want. It allows the receiving radio to tack on a radio meta-data header (the "radiotap" a.k.a. BSD radio header) onto each packet. This meta-data header contains things the receiving radio observed about the transmission, that were not actually bits transmitted across the air. This includes things like which PHY type was used, which data rate or MCS was used, what channel the radio was tuned to when it received it, what the strength of the signal at the receiver (RSSI) was, and more.