ipv4(version=4, header_length=5, tos=0, total_length=0, identification=0, flags=0, offset=0, ttl=255, proto=0, csum=0, src='10.0.0.1', dst='10.0.0.2', option=None)¶
IPv4 (RFC 791) header encoder/decoder class.
NOTE: When decoding, this implementation tries to decode the upper layer protocol even for a fragmented datagram. It isn't likely what a user would want.
An instance has the following attributes at least. Most of them are same to the on-wire counterparts but in host byte order. IPv4 addresses are represented as a string like '192.0.2.1'. __init__ takes the corresponding args in this order.
Attribute Description Example version Version header_length IHL tos Type of Service total_length Total Length (0 means automatically-calculate when encoding) identification Identification flags Flags offset Fragment Offset ttl Time to Live proto Protocol csum Header Checksum (Ignored and automatically-calculated when encoding) src Source Address '192.0.2.1' dst Destination Address '192.0.2.2' option A bytearray which contains the entire Options, or None for no Options
Decode a protocol header.
This method is used only when decoding a packet.
Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.
- An object to describe the decoded header.
- A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.
- The rest of packet.
Encode a protocol header.
This method is used only when encoding a packet.
Encode a protocol header. Returns a bytearray which contains the header.
payload is the rest of the packet which will immediately follow this header.
prev is a packet_base.PacketBase subclass for the outer protocol header. prev is None if the current header is the outer-most. For example, prev is ipv4 or ipv6 for tcp.serialize.