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Fix race condition in WiFiGenericClass::hostByName #8672

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merged 1 commit into from
Dec 5, 2023
Merged

Fix race condition in WiFiGenericClass::hostByName #8672

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27 changes: 23 additions & 4 deletions libraries/WiFi/src/WiFiGeneric.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@ extern "C" {
#include <esp_wifi.h>
#include <esp_event.h>
#include <esp_mac.h>
#include <esp_netif.h>
#include "lwip/ip_addr.h"
#include "lwip/opt.h"
#include "lwip/err.h"
Expand Down Expand Up @@ -1559,6 +1560,22 @@ static void wifi_dns_found_callback(const char *name, const ip_addr_t *ipaddr, v
xEventGroupSetBits(_arduino_event_group, WIFI_DNS_DONE_BIT);
}

typedef struct gethostbynameParameters {
const char *hostname;
ip_addr_t addr;
void *callback_arg;
} gethostbynameParameters_t;

/**
* Callback to execute dns_gethostbyname in lwIP's TCP/IP context
* @param param Parameters for dns_gethostbyname call
*/
static esp_err_t wifi_gethostbyname_tcpip_ctx(void *param)
{
gethostbynameParameters_t *parameters = static_cast<gethostbynameParameters_t *>(param);
return dns_gethostbyname(parameters->hostname, &parameters->addr, &wifi_dns_found_callback, parameters->callback_arg);
}

/**
* Resolve the given hostname to an IP address. If passed hostname is an IP address, it will be parsed into IPAddress structure.
* @param aHostname Name to be resolved or string containing IP address
Expand All @@ -1570,13 +1587,15 @@ int WiFiGenericClass::hostByName(const char* aHostname, IPAddress& aResult)
{
if (!aResult.fromString(aHostname))
{
ip_addr_t addr;
gethostbynameParameters_t params;
params.hostname = aHostname;
params.callback_arg = &aResult;
aResult = static_cast<uint32_t>(0);
waitStatusBits(WIFI_DNS_IDLE_BIT, 16000);
clearStatusBits(WIFI_DNS_IDLE_BIT | WIFI_DNS_DONE_BIT);
err_t err = dns_gethostbyname(aHostname, &addr, &wifi_dns_found_callback, &aResult);
if(err == ERR_OK && addr.u_addr.ip4.addr) {
aResult = addr.u_addr.ip4.addr;
err_t err = esp_netif_tcpip_exec(wifi_gethostbyname_tcpip_ctx, &params);
if(err == ERR_OK && params.addr.u_addr.ip4.addr) {
aResult = params.addr.u_addr.ip4.addr;
} else if(err == ERR_INPROGRESS) {
waitStatusBits(WIFI_DNS_DONE_BIT, 15000); //real internal timeout in lwip library is 14[s]
clearStatusBits(WIFI_DNS_DONE_BIT);
Expand Down