lldp

import binascii
import socket
import struct
import sys
import select

LLDP_ETHERTYPE = 0x88cc

s1 = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, 0x88cc)
s1.bind(('ens9f0', 0x88cc))
s2 = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, 0x88cc)
s2.bind(('ens9f1', 0x88cc))


def _parse_tlv(buff):
    """Iterate over a buffer and generate structured TLV data.

    :param buff: An ethernet packet with the header trimmed off (first
                 14 bytes)
    """
    lldp_info = []
    while buff:
        tlvhdr = struct.unpack('!H', buff[:2])[0]
        tlvtype = (tlvhdr & 0xfe00) >> 9
        tlvlen = (tlvhdr & 0x01ff)
        tlvdata = buff[2:tlvlen + 2]
        buff = buff[tlvlen + 2:]
        lldp_info.append((tlvtype, tlvdata))
    return lldp_info

def _receive_lldp_packets(sock):
    """Receive LLDP packets and process them.

    :param sock: A bound socket
    :return: A list of tuples in the form (lldp_type, lldp_data)
    """
    pkt = sock.recv(1600)
    # Filter invalid packets
    if not pkt or len(pkt) < 14:
        return
    # Skip header (dst MAC, src MAC, ethertype)
    pkt = pkt[14:]
    return _parse_tlv(pkt)

def get_lldp_info(interface_name=None):
    """Get LLDP info from the switch(es) the agent is connected to.

    Listens on either a single or all interfaces for LLDP packets, then
    parses them. If no LLDP packets are received before lldp_timeout,
    returns a dictionary in the form {'interface': [],...}.

    :param interface_name: The interface to listen for packets on. If
                           None, will listen on each interface.
    :return: A dictionary in the form {'interface': [lldp_info],...}
    """
    lldp_info = {}
    read_list = {}
    interfaces = ['ens9f0', 'ens9f1']
    for interface in interfaces:
        s = socket.socket(socket.AF_PACKET, socket.SOCK_RAW,
                          LLDP_ETHERTYPE)
        s.bind((interface, LLDP_ETHERTYPE))
        # Add interface name to object for returning data later

        read_list[interface] = s

    if not read_list:
        return {}

    while read_list:
        r = select.select(read_list.values(), [], [], 30)
        if not r[0]:
            # Empty read list means timeout
            break
        for s in r[0]:
            # Find interface name matching socket ready for read
            for interface_name, sock in read_list.items():
                if s == sock:
                    lldp_info[interface_name] = (
                        _receive_lldp_packets(s))
                    # Remove successfully read sockets from read_list
                    del read_list[interface_name]

    return lldp_info

if __name__ == '__main__':
    print get_lldp_info()