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Fix pool DNS resolution: don't cache 0.0.0.0 when hostByName fails #801

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Fix pool DNS resolution: don't cache 0.0.0.0 when hostByName fails #801

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15 changes: 10 additions & 5 deletions src/mining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -84,17 +84,22 @@ bool checkPoolConnection(void) {

Serial.println("Client not connected, trying to connect...");

//Resolve first time pool DNS and save IP
//Resolve pool DNS. WiFi.hostByName() returns 0 and writes 0.0.0.0 into serverIP on
//failure, so check the return value: otherwise a failed first resolve caches 0.0.0.0
//and the client can never connect until the device is rebooted.
if(serverIP == IPAddress(1,1,1,1)) {
WiFi.hostByName(Settings.PoolAddress.c_str(), serverIP);
Serial.printf("Resolved DNS and save ip (first time) got: %s\n", serverIP.toString());
if (WiFi.hostByName(Settings.PoolAddress.c_str(), serverIP) != 1 || serverIP == IPAddress(0,0,0,0)) {
Serial.println("DNS resolve failed, will retry next attempt");
serverIP = IPAddress(1,1,1,1); //keep unresolved so we retry
return false;
}
Serial.printf("Resolved DNS got: %s\n", serverIP.toString());
}

//Try connecting pool IP
if (!client.connect(serverIP, Settings.PoolPort)) {
Serial.println("Imposible to connect to : " + Settings.PoolAddress);
WiFi.hostByName(Settings.PoolAddress.c_str(), serverIP);
Serial.printf("Resolved DNS got: %s\n", serverIP.toString());
serverIP = IPAddress(1,1,1,1); //force a fresh DNS resolve on next attempt
return false;
}

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