DNS message parser and composer

Parsing and composition of DNS messages. More...

Detailed Description

Parsing and composition of DNS messages.

Modules
	DNS message parsing and composition configuration

Files
file	msg.h
	Definitions for parsing and composition of DNS messages.

Data Structures
struct	dns_hdr_t
	DNS internal structure. More...

Functions
size_t	dns_msg_compose_query (void *dns_buf, const char *domain_name, uint16_t id, int family)
	Composes a DNS query message.
int	dns_msg_parse_reply (const uint8_t *buf, size_t len, int family, void *addr_out, uint32_t *ttl)
	Parses a DNS response message.

Function Documentation

dns_msg_compose_query()

size_t dns_msg_compose_query	(	void *	dns_buf,
		const char *	domain_name,
		uint16_t	id,
		int	family
	)

Composes a DNS query message.

The query will request an A or AAAA IN record for domain_name depending on family:

• When family is AF_INET or AF_UNSPEC a query for an A record will be added
• When family is AF_INET6 or AF_UNSPEC a query for an AAAA record will be added

Parameters

[out]	dns_buf	A buffer of length CONFIG_DNS_MSG_LEN
[in]	domain_name	The domain name to query.
[in]	id	The ID for the query.
[in]	family	Either AF_UNSPEC, AF_INET, or AF_INET6. Determines the address records for domain_name queried.

Returns

Size of the composed query in bytes.

dns_msg_parse_reply()

int dns_msg_parse_reply	(	const uint8_t *	buf,
		size_t	len,
		int	family,
		void *	addr_out,
		uint32_t *	ttl
	)

Parses a DNS response message.

Parameters

[in]	buf	The message to parse.
[in]	len	Length of buf.
[in]	family	The address family used to compose the query for this response (see dns_msg_compose_query())
[out]	addr_out	The IP address returned by the response.
[out]	ttl	The live time of the entry in seconds

Returns

Length of the addr_out on success.

-EBADMSG, when an address corresponding to family can not be found in buf.