Module extensions 

ICMP Extensions Framework (RFC 4884)

ICMP error messages can include extensions that provide additional diagnostic information. The extensions framework defines:

• Extension Header (4 bytes: version, reserved, checksum)
• Extension Objects (variable length: len, classnum, classtype, data)

Common extension classes:

• Class 1: MPLS Label Stack
• Class 2: Interface Information (RFC 5837)
• Class 3: Interface Identification

Modules

class_nums

ICMP Extension class numbers (IANA registry)

header_offsets

ICMP Extension Header offsets (RFC 4884)

object_offsets

ICMP Extension Object offsets

Structs

InterfaceInfoFlags

Interface Information Object flags (RFC 5837)

InterfaceInformation

Parsed Interface Information extension data (RFC 5837)

Enums

Afi

Address Family Identifier (AFI) for interface IP addresses

IpAddr

IP address enum for interface information

Constants

EXTENSION_HEADER_LEN

EXTENSION_OBJECT_MIN_LEN

Functions

class_name

Get human-readable name for extension class number

extension_offset

Get the offset where ICMP extensions begin in an error message.

has_extensions

Check if ICMP extensions are present in an ICMP error message.

parse_extension_header

Parse the ICMP Extension Header

parse_extension_object

Parse an Extension Object header

parse_interface_information

Parse Interface Information extension object (RFC 5837)

verify_extension_checksum

Verify the extension header checksum