File syn_dns.c¶

UDP DNS resolver and mDNS responder implementation.

#include "../port/syn_port_system.h"
#include "../util/syn_assert.h"
#include "../util/syn_pack.h"
#include "syn_dns.h"
#include <string.h>

Public Functions¶

Type	Name
SYN_PT_Status	syn_dns_resolve_task (SYN_PT * pt, SYN_Task * task) Cooperative task for resolving a hostname via DNS.
SYN_Status	syn_mdns_init (SYN_Mdns * mdns, const char * hostname, const uint8_t ip) Initialize the mDNS responder.
SYN_PT_Status	syn_mdns_task (SYN_PT * pt, SYN_Task * task) Cooperative task for responding to local mDNS queries.

Public Static Functions¶

Type	Name
size_t	encode_qname (uint8_t * dest, const char * src) Encode a hostname as a DNS QNAME (label-length format).
bool	match_qname_local (const uint8_t * buf, size_t buf_len, size_t * pos, const char * hostname) Check if QNAME matches hostname.local.
bool	parse_qname (const uint8_t * buf, size_t buf_len, size_t * pos) Skip a QNAME in a DNS packet (handles compression pointers).
SYN_Status	parse_response (const uint8_t * buf, size_t rx_len, SYN_SockAddr * addr_out, uint16_t expected_txid) Parse a DNS response packet to extract the resolved IP.

Public Functions Documentation¶

function syn_dns_resolve_task¶

Cooperative task for resolving a hostname via DNS.

SYN_PT_Status syn_dns_resolve_task (
    SYN_PT * pt,
    SYN_Task * task
)

Register this as a SYN_TaskFunc with user_data pointing to a SYN_DnsResolver instance. The task runs non-blocking UDP queries, yielding via PT_YIELD until resolution completes or times out.

Parameters:

pt Protothread pointer.
task Task structure whose user_data points to a SYN_DnsResolver.

Returns:

PT_WAITING while running, PT_EXITED when done, or PT_ENDED on early exit.

function syn_mdns_init¶

Initialize the mDNS responder.

SYN_Status syn_mdns_init (
    SYN_Mdns * mdns,
    const char * hostname,
    const uint8_t ip
)

Parameters:

mdns mDNS instance.
hostname Hostname to respond to (without .local suffix).
ip IPv4 address to advertise.

Returns:

SYN_OK on success.

function syn_mdns_task¶

Cooperative task for responding to local mDNS queries.

SYN_PT_Status syn_mdns_task (
    SYN_PT * pt,
    SYN_Task * task
)

Parameters:

pt Protothread pointer.
task Task structure whose user_data points to a SYN_Mdns.

Returns:

PT_WAITING while running, PT_EXITED when done.

Public Static Functions Documentation¶

function encode_qname¶

Encode a hostname as a DNS QNAME (label-length format).

static size_t encode_qname (
    uint8_t * dest,
    const char * src
)

Parameters:

dest [out] Destination buffer.
src Dot-separated hostname.

Returns:

Total bytes written.

function match_qname_local¶

Check if QNAME matches hostname.local.

static bool match_qname_local (
    const uint8_t * buf,
    size_t buf_len,
    size_t * pos,
    const char * hostname
)

Parameters:

buf Packet buffer.
buf_len Buffer length.
pos [in/out] Parse position.
hostname Expected hostname.

Returns:

true if match.

function parse_qname¶

Skip a QNAME in a DNS packet (handles compression pointers).

static bool parse_qname (
    const uint8_t * buf,
    size_t buf_len,
    size_t * pos
)

Parameters:

buf Packet buffer.
buf_len Buffer length.
pos [in/out] Current parse position.

Returns:

true on success.

function parse_response¶

Parse a DNS response packet to extract the resolved IP.

static SYN_Status parse_response (
    const uint8_t * buf,
    size_t rx_len,
    SYN_SockAddr * addr_out,
    uint16_t expected_txid
)

Checks transaction ID, question count, and pulls the first IPv4 A record.

Parameters:

buf Received UDP packet buffer.
rx_len Received packet length.
addr_out [out] Output structure for resolved IPv4 address.
expected_txid Transaction ID to verify.

Returns:

SYN_OK on success, SYN_ERROR on format/parsing error.

The documentation for this class was generated from the following file src/syntropic/net/syn_dns.c