lwip_dns_resolver.cpp

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#include "lwip/dns.h"
#include "lwip/ip_addr.h"
#include "lwip/err.h"
#include "pico/time.h"
#include <cstring>
#include "framework_config.h"
#include "DebugTrace.h"
TRACE_INIT(LwipDnsResolver);
 
static volatile bool dns_done = false;
static ip_addr_t resolved_ip;
 
static void dns_callback(const char* name, const ip_addr_t* ipaddr, void* callback_arg) {
    if (ipaddr) {
        resolved_ip = *ipaddr;
    } else {
        ip_addr_set_any(IPADDR_TYPE_V4, &resolved_ip);
    }
    dns_done = true;
}
 
bool resolveHostnameBlocking(const char* hostname, ip_addr_t* result, uint32_t timeout_ms = 5000) {
 
    TRACE("[DNS] Starting DNS lookup for %s\n", hostname);
 
    dns_done = false;
    err_t err = dns_gethostbyname(hostname, &resolved_ip, dns_callback, nullptr);
 
    if (err == ERR_OK) {
        TRACE("[DNS] Hostname resolved immediately: %s -> %s\n", hostname, ipaddr_ntoa(&resolved_ip));
        *result = resolved_ip;
        return true;
    } else if (err == ERR_INPROGRESS) {
        TRACE("[DNS] Lookup in progress for %s, waiting...\n", hostname);
    } else {
        TRACE("[DNS] dns_gethostbyname failed with error %d\n", err);
        return false;
    }
 
    // Wait for async resolution
    absolute_time_t deadline = make_timeout_time_ms(timeout_ms);
    while (!dns_done && absolute_time_diff_us(get_absolute_time(), deadline) > 0) {
        sleep_ms(10);
    }
 
    if (dns_done && !ip_addr_isany(&resolved_ip)) {
        TRACE("[DNS] DNS resolved after wait: %s -> %s\n", hostname, ipaddr_ntoa(&resolved_ip));
        *result = resolved_ip;
        return true;
    } else {
        printf("[DNS] DNS resolution timed out or returned null\n");
        return false;
    }
}