use libconfig for a /etc/iprefresher.cfg config file

there can all the api credentials be specified

src/Credentials.cpp

@@ -3,14 +3,50 @@
 //
 
 #include <Credentials.h>
+#include <iostream>
+#include <cstring>
 
-std::string Credentials::dynuapikey = "";
-std::string Credentials::domainid = ""; //id of the dynu domain
-std::string Credentials::domainname = "";
+#include "libconfig.h++"
 
-std::string Credentials::telegramApiKey = "";
-std::string Credentials::chatId = "";
+std::string Credentials::dynuapikey;
+std::string Credentials::domainid; //id of the dynu domain
+std::string Credentials::domainname;
 
-bool Credentials::checkCredentialValidity() {
+std::string Credentials::telegramApiKey;
+std::string Credentials::chatId;
+
+bool Credentials::readCredentials() {
+    libconfig::Config cfg;
+    try {
+        cfg.readFile("/etc/iprefresher.cfg");
+    }
+    catch (const libconfig::FileIOException &fioex) {
+        std::cout << "I/O error while reading config file." << std::endl << "creating new config file!" << std::endl;
+        cfg.writeFile("/etc/iprefresher.cfg");
+        return false;
+    }
+    catch (const libconfig::ParseException &pex) {
+        std::cerr << "Parse error at " << pex.getFile() << ":" << pex.getLine()
+                  << " - " << pex.getError() << std::endl;
+        return false;
+    }
+
+    // Get the store name.
+    try {
+        // needed parameters
+        dynuapikey = (std::string) cfg.lookup("dynuapikey");
+        domainid = (std::string) cfg.lookup("domainid");
+        domainname = (std::string) cfg.lookup("domainname");
+        // optional parameters
+        telegramApiKey = (std::string) cfg.lookup("telegramApiKey");
+        chatId = (std::string) cfg.lookup("chatId");
+        std::cout << "Store name: " << dynuapikey << std::endl;
+    }
+    catch (const libconfig::SettingNotFoundException &nfex) {
+        // triggered if setting is missing in config
+        if (!(std::strcmp("telegramApiKey", nfex.getPath()) == 0 || std::strcmp("chatId", nfex.getPath()) == 0)) {
+            std::cerr << "No '" << nfex.getPath() << "' setting in configuration file." << std::endl;
+        }
+    }
     return !(Credentials::dynuapikey.empty() || Credentials::domainid.empty() || Credentials::domainname.empty());
 }

src/main.cpp

@@ -5,7 +5,7 @@
 #include <Credentials.h>
 
 int main(int argc, char *argv[]) {
-    if (!Credentials::checkCredentialValidity()) {
+    if (!Credentials::readCredentials()) {
         std::cout << "incorrect credentials!" << std::endl;
         return -1;
     }