lwip_dns_resolver.h File Reference

#include "lwip/ip_addr.h"
#include <stdint.h>

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Functions
bool	resolveHostnameBlocking (const char *hostname, ip_addr_t *result, uint32_t timeout_ms=5000)
	Resolve hostname to IP address using lwIP DNS (blocking).

Function Documentation

resolveHostnameBlocking()

bool resolveHostnameBlocking	(	const char *	hostname,
		ip_addr_t *	result,
		uint32_t	timeout_ms = 5000
	)

Parameters

hostname	The hostname to resolve.
result	Pointer to store resolved IP address.
timeout_ms	Max wait time in milliseconds.

Returns

true if resolved successfully, false otherwise.

Resolve hostname to IP address using lwIP DNS (blocking).

Parameters

hostname	The host to resolve.
result	Pointer to an ip_addr_t to store the result.
timeout_ms	Max time to wait for resolution.

Returns

true if successful, false otherwise.

Definition at line 29 of file lwip_dns_resolver.cpp.

                                                                                                  {
 
    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;
    }
}

References dns_callback(), dns_done, resolved_ip, and TRACE.

Referenced by Tcp::connect().

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