lwip_dns_resolver.cpp File Reference

#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"

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Functions
	TRACE_INIT (LwipDnsResolver)
static void	dns_callback (const char *name, const ip_addr_t *ipaddr, void *callback_arg)
bool	resolveHostnameBlocking (const char *hostname, ip_addr_t *result, uint32_t timeout_ms=5000)
	Blocking DNS resolution using lwIP.

Variables
static volatile bool	dns_done = false
static ip_addr_t	resolved_ip

Function Documentation

dns_callback()

static void dns_callback ( const char *  name, const ip_addr_t *  ipaddr, void *  callback_arg  )

static

Definition at line 13 of file lwip_dns_resolver.cpp.

                                                                                        {
    if (ipaddr) {
        resolved_ip = *ipaddr;
    } else {
        ip_addr_set_any(IPADDR_TYPE_V4, &resolved_ip);
    }
    dns_done = true;
}

References dns_done, and resolved_ip.

Referenced by resolveHostnameBlocking().

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resolveHostnameBlocking()

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

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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TRACE_INIT()

TRACE_INIT

(

LwipDnsResolver

)

Variable Documentation

dns_done

volatile bool dns_done = false

static

Definition at line 10 of file lwip_dns_resolver.cpp.

Referenced by dns_callback(), and resolveHostnameBlocking().

resolved_ip

ip_addr_t resolved_ip

static

Definition at line 11 of file lwip_dns_resolver.cpp.

Referenced by dns_callback(), and resolveHostnameBlocking().