Dwm::Dns::LabelSequence Class Reference

From RFC1035 section 4.1.4: The compression scheme allows a domain name in a message to be represented as either: More...

#include <DwmDnsLabelSequence.hh>

Public Member Functions
	LabelSequence ()
	Constructs an empty label sequence.
	LabelSequence (const std::string &value)
	Construct a label sequence from given string value.
	operator std::string () const
	Convert to a string.
uint8_t *	Encode (uint8_t *pkt, uint8_t *ptr, uint16_t pktlen, LabelPositions &lps) const
	Encodes the label sequence into buffer @ pkt of length pktlen, starting at ptr. More...
uint8_t *	Encode (uint8_t *pkt, uint8_t *ptr, uint16_t pktlen) const
	Encode without compression. Used for NSEC records, for example.
const uint8_t *	Decode (const uint8_t *pkt, const uint8_t *ptr, uint16_t pktlen)
	Decodes the label sequence from buffer pkt of length pktlen, starting at ptr. More...

Protected Attributes
std::string	_value

Detailed Description

From RFC1035 section 4.1.4: The compression scheme allows a domain name in a message to be represented as either:

• a sequence of labels ending in a zero octet
• a pointer
• a sequence of labels ending with a pointer

What this means is that a domain name isn't standalone, since it can contain a pointer to elsewhere. Of course this completely defeats encapsulation. I only need the compression facilities when encoding packets. To facilitate encoding, I use an instance of LabelPositions to keep track of potential pointer targets.

Member Function Documentation

Decode()

const uint8_t* Dwm::Dns::LabelSequence::Decode	(	const uint8_t *	pkt,
		const uint8_t *	ptr,
		uint16_t	pktlen
	)

Decodes the label sequence from buffer pkt of length pktlen, starting at ptr.

Returns the address immediately following the encoded label sequence in pkt on success. Throws std::out_of_range if pkt was too short to contain an encoded label sequence.

Encode()

uint8_t* Dwm::Dns::LabelSequence::Encode	(	uint8_t *	pkt,
		uint8_t *	ptr,
		uint16_t	pktlen,
		LabelPositions &	lps
	)		const

Encodes the label sequence into buffer @ pkt of length pktlen, starting at ptr.

Returns the address immediately following the encoded label sequence in pkt on success. Throws std::out_of_range if pkt is too short to contain the encoded label sequence. lps is used for label compression as documented in section 4.1.4 of RFC1035.

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The documentation for this class was generated from the following file:

• DwmDnsLabelSequence.hh