Add a list of servers to the "Multiplayer" tab

If USE_CURL is set, it also downloads a list from a remote server.
The url of this list is configurable in minetest.conf using the setting "serverlist_url"
The local list of favorite servers is saved in client/serverlist/filename
filename is also configureable using the setting "serverlist_file"

src/serverlist.cpp

@@ -0,0 +1,185 @@
+/*
+Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <iostream>
+#include <sstream>
+#include <algorithm>
+
+#include "main.h" // for g_settings
+#include "settings.h"
+#include "serverlist.h"
+#include "filesys.h"
+#include "porting.h"
+#include "log.h"
+#if USE_CURL
+#include <curl/curl.h>
+#endif
+
+namespace ServerList
+{
+std::string getFilePath()
+{
+	std::string serverlist_file = g_settings->get("serverlist_file");
+
+	std::string rel_path = std::string("client") + DIR_DELIM
+		+ "serverlist" + DIR_DELIM
+		+ serverlist_file;
+	std::string path = porting::path_share + DIR_DELIM + rel_path;
+	return path;
+}
+
+std::vector<ServerListSpec> getLocal()
+{
+	std::string path = ServerList::getFilePath();
+	std::string liststring;
+	if(fs::PathExists(path))
+	{
+		std::ifstream istream(path.c_str(), std::ios::binary);
+		if(istream.is_open())
+		{
+			std::ostringstream ostream;
+			ostream << istream.rdbuf();
+			liststring = ostream.str();
+			istream.close();
+		}
+	}
+
+	return ServerList::deSerialize(liststring);
+}
+
+
+#if USE_CURL
+
+static size_t WriteCallback(void *contents, size_t size, size_t nmemb, void *userp)
+{
+    ((std::string*)userp)->append((char*)contents, size * nmemb);
+    return size * nmemb;
+}
+
+
+std::vector<ServerListSpec> getOnline()
+{
+	std::string liststring;
+	CURL *curl;
+
+	curl = curl_easy_init();
+	if (curl)
+	{
+		CURLcode res;
+
+		curl_easy_setopt(curl, CURLOPT_URL, g_settings->get("serverlist_url").c_str());
+		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, ServerList::WriteCallback);
+		curl_easy_setopt(curl, CURLOPT_WRITEDATA, &liststring);
+
+		res = curl_easy_perform(curl);
+		if (res != CURLE_OK)
+			errorstream<<"Serverlist at url "<<g_settings->get("serverlist_url")<<" not found (internet connection?)"<<std::endl;
+		curl_easy_cleanup(curl);
+	}
+
+	return ServerList::deSerialize(liststring);
+}
+
+#endif
+
+/*
+	Delete a server fromt he local favorites list
+*/
+bool deleteEntry (ServerListSpec server)
+{
+	std::vector<ServerListSpec> serverlist = ServerList::getLocal();
+	for(unsigned i = 0; i < serverlist.size(); i++)
+	{
+		if  (serverlist[i].address == server.address
+		&&   serverlist[i].port    == server.port)
+		{
+			serverlist.erase(serverlist.begin() + i);
+		}
+	}
+
+	std::string path = ServerList::getFilePath();
+	std::ofstream stream (path.c_str());
+	if (stream.is_open())
+	{
+		stream<<ServerList::serialize(serverlist);
+		return true;
+	}
+	return false;
+}
+
+/*
+	Insert a server to the local favorites list
+*/
+bool insert (ServerListSpec server)
+{
+	// Remove duplicates
+	ServerList::deleteEntry(server);
+
+	std::vector<ServerListSpec> serverlist = ServerList::getLocal();
+
+	// Insert new server at the top of the list
+	serverlist.insert(serverlist.begin(), server);
+
+	std::string path = ServerList::getFilePath();
+	std::ofstream stream (path.c_str());
+	if (stream.is_open())
+	{
+		stream<<ServerList::serialize(serverlist);
+	}
+
+	return false;
+}
+
+std::vector<ServerListSpec> deSerialize(std::string liststring)
+{
+	std::vector<ServerListSpec> serverlist;
+	std::istringstream stream(liststring);
+	std::string line;
+	while (std::getline(stream, line))
+	{
+		std::transform(line.begin(), line.end(),line.begin(), ::toupper);
+		if (line == "[SERVER]")
+		{
+			ServerListSpec thisserver;
+			std::getline(stream, thisserver.name);
+			std::getline(stream, thisserver.address);
+			std::getline(stream, thisserver.port);
+			std::getline(stream, thisserver.description);
+			serverlist.push_back(thisserver);
+		}
+	}
+	return serverlist;
+}
+
+std::string serialize(std::vector<ServerListSpec> serverlist)
+{
+	std::string liststring;
+	for(std::vector<ServerListSpec>::iterator i = serverlist.begin(); i != serverlist.end(); i++)
+	{
+		liststring += "[server]\n";
+		liststring += i->name + "\n";
+		liststring += i->address + "\n";
+		liststring += i->port + "\n";
+		liststring += i->description + "\n";
+		liststring += "\n";
+	}
+	return liststring;
+}
+
+} //namespace ServerList