DHCP Decoding Class

class bloxone.dhcp_decode

Class to assist with Hex Encoding of DHCP Options and sub_options

check_data_type(optcode, sub_defs=[])

Get data_type for optcode from sub optino definitions

Parameters:

• optcode (int) – Option code to check
• sub_defs (list of dict) – sub option definitions to cross reference

Returns:

data_type as str

decode_data(data, data_type='string', padding=False, pad_bytes=1, array=False)

decode_dhcp_option(hex_string, sub_opt_defs=[], padding=False, pad_bytes=1, encapsulated=False, id=None, prefix='')

Attempt to decode DHCP options from hex representation

Parameters:

• sub_opt_defs (list) – List of Sub Option definition dictionaries
• padding (bool) – Whether extra ‘null’ termination bytes are req.
• pad_bytes (int) – Number of null bytes to append
• encapsulate (bool) – Add id and total length as prefix
• id (int) – option code to prepend
• prefix (str) – String value to prepend to encoded options

Returns:

Encoded suboption as a hex string

get_name(optcode, sub_defs=[])

Get data_type for optcode from sub optino definitions

Parameters:

• optcode (int) – Option code to check
• sub_defs (list of dict) – sub option definitions to cross reference

Returns:

name as str

guess_data_type(subopt, padding=False)

hex_length(hex_string)

Encode Option Length in hex (1-octet)

Parameters:hex_string (str) – Octet Encoded Hex String Returns:Number of Hex Octects as hex encoded string

hex_string_to_list(hex_string)

Take a hex string and convert in to a list

Parameters:hex_string (str) – Hex represented as string Returns:list of hex bytes

hex_to_array_of_ip(hex_string)

Decode array of IPv4 or IPv6 addresses to CSV string

Parameters:hex_string (str) – Hex representation of an array of IPv4 or IPv6 Returns:IP Addresses in a CSV string

hex_to_binary(data)

Format hex string of binary/hex encoded data

Parameters:data (str) – data to format Returns:hex encoding as string

hex_to_boolean(hex_string)

Decode Hex value as a string to ‘true’ or ‘false’

Parameters:hex_string (str) – Hex value as a str Returns:string representation of a boolean

hex_to_empty(data)

Return empyt hex string ‘’

Parameters:data (str) – Data not to encode (should be empty) Returns:Empty String ‘’

hex_to_fqdn(hex_string)

Decode RFC 1035 Section 3.1 formatted hexa to fqdn

Parameters:hex_string (str) – hex encoded fqdn Returns:fqdn as string

hex_to_int(hex_string, size=8)

Decode hex to signed integer of defined size

Parameters:

• hex_string (str) – hex value as string
• size (int) – size in bits [8, 16, 32]

Returns:

integer

hex_to_ip(hex_string)

Decode a 4 or 16 octect hex string to an IPv4 or IPv6 string

Parameters:hex_string (str) – Hex representation of an IPv4 or IPv6 address Returns:IP Address as a string

hex_to_ipv4_address(hex_string)

Decode a hex string to an IPv4 Address as a string

Parameters:hex_string (str) – Hex representation of an IPv4 address Returns:IPv4 Address as a string

hex_to_ipv6_address(hex_string)

Decode a hex string to an IPv6 address as a string

Parameters:hex_string (str) – Hex representation of an IPv6 address Returns:IPv6 Address as a string

hex_to_optcode(hex_string)

Encode Option Code in hex (1-octet)

Parameters:optcode (str/int) – Option Code Returns:hex encoding as string

hex_to_string(hex_string)

Decode a string of hex values to a text string

Parameters:hex_string (str) – Hex representation of a string Returns:text string (str)

hex_to_suboptions(hex_string, encapsulated=False)

Extract the sub-options from the hex data

hex_to_uint(hex_string, size=8)

Encode integer of specified size as unsigned int in hex Uses 2’s compliment if supplied with negative number

Parameters:

• i (int) – integer value to encode
• size (int) – size in bits [8, 16, 32]

Returns:

hex encoding as string

output_decoded_options(decoded_opts=[], output='pprint')

Simple output for decode_dhcp_options() data

Parameters:

• decoded_opts (list) – List of dict
• output (str) – specify format [pprint, csv, yaml]

tests()

Run through encoding methods and output example results

validate_ip(ip)

Validate input data is a valid IP address (Supports both IPv4 and IPv6)

Parameters:ip (str) – ip address as a string Returns:Return True for valid and False otherwise Return type:bool