ESP32-P4_DANTE/components/dante/include/dante_discovery.h

/*
 * SPDX-FileCopyrightText: 2026 Benjamin Harris
 * SPDX-License-Identifier: Apache-2.0
 *
 * Dante device discovery over mDNS / DNS-SD.
 *
 * CLEAN-ROOM: implemented from the behavioural notes in
 * docs/dante-protocol-notes.md (service types, ports, TXT keys), NOT from
 * any GPL/AGPL reference source. See CLAUDE.md.
 *
 * This is the read-only half of Dante discovery: it browses the network for
 * Dante devices and their transmit channels / multicast bundles and reports
 * what it finds. It does not advertise this device (that needs the ARC/CMC
 * servers behind it) and does not touch audio.
 *
 * Dante publishes these DNS-SD service types, all under _udp.local:
 *   _netaudio-arc   device control endpoint          (ARC port, e.g. 4440)
 *   _netaudio-cmc   device announce endpoint         (CMC port, e.g. 8800)
 *   _netaudio-chan  one instance per TX channel      (flow-control port)
 *   _netaudio-bund  a multicast bundle other devices can join
 */
#pragma once

#include <stdint.h>
#include <stdbool.h>
#include "esp_err.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Which Dante DNS-SD service a result came from. */
typedef enum {
    DANTE_SVC_ARC = 0,  /* _netaudio-arc  — device control endpoint */
    DANTE_SVC_CMC,      /* _netaudio-cmc  — device announce endpoint */
    DANTE_SVC_CHAN,     /* _netaudio-chan — a transmit channel */
    DANTE_SVC_BUND,     /* _netaudio-bund — a multicast bundle */
    DANTE_SVC_COUNT
} dante_service_type_t;

/* One discovered service instance, flattened from an mDNS PTR+SRV+TXT+A set.
 * String fields are only valid for the duration of the callback. */
typedef struct {
    dante_service_type_t service;   /* which _netaudio-* type */
    const char          *instance;  /* DNS-SD instance name, e.g. "chanName@host" */
    const char          *hostname;  /* SRV target host */
    uint32_t             ipv4;       /* resolved IPv4 (host byte order), 0 if none */
    uint16_t             port;       /* SRV port */
    const char *const   *txt_keys;   /* TXT record keys   (txt_count entries) */
    const char *const   *txt_vals;   /* TXT record values (txt_count entries) */
    size_t               txt_count;
} dante_discovery_result_t;

/* Callback invoked once per discovered instance. `user` is passed through
 * from the scan/start call. Must not block for long. */
typedef void (*dante_discovery_cb_t)(const dante_discovery_result_t *result,
                                     void *user);

/*
 * One-shot synchronous scan of all Dante service types.
 *
 * Issues an mDNS PTR query per service type, waits up to `timeout_ms` for
 * each, and invokes `cb` for every instance found. If `cb` is NULL, results
 * are logged at INFO level instead. Safe to call whether or not the AES67
 * stack has already initialised mDNS (init is shared and idempotent).
 *
 * Returns ESP_OK if the scan ran (even if nothing was found).
 */
esp_err_t dante_discovery_scan(uint32_t timeout_ms,
                               dante_discovery_cb_t cb, void *user);

/*
 * Start a background task that repeats dante_discovery_scan() every
 * `interval_ms`. `cb`/`user` are as above. Only one background scanner may
 * run at a time. Pin/priority follow project convention (core 0, low prio).
 */
esp_err_t dante_discovery_start(uint32_t interval_ms,
                                dante_discovery_cb_t cb, void *user);

/* Stop the background scanner started by dante_discovery_start(). */
void dante_discovery_stop(void);

/* Human-readable name for a service type, e.g. "_netaudio-arc". */
const char *dante_service_type_str(dante_service_type_t svc);

#ifdef __cplusplus
}
#endif