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I'm not looking to use boost::asio, it is overly complex for my needs.
I'm building a game that is cross platform, for desktop, iPhone and Android.
I found a library called ENet which is pretty much what I need, but it uses UDP which does not seem to support encryption and a few other things. Given that the game is an event driven card game, TCP seems like the right fit.
However, all I have found is WINSOCK / berkley sockets and bost::asio.
Here is a sample client server application with ENet:
#include <enet/enet.h>
#include <stdlib.h>
#include <string>
#include <iostream>
class Host
{
ENetAddress address;
ENetHost * server;
ENetHost* client;
ENetEvent event;
public:
Host()
:server(NULL)
{
enet_initialize();
setupServer();
}
void setupServer()
{
if(server)
{
enet_host_destroy(server);
server = NULL;
}
address.host = ENET_HOST_ANY;
/* Bind the server to port 1234. */
address.port = 1721;
server = enet_host_create (& address /* the address to bind the server host to */,
32 /* allow up to 32 clients and/or outgoing connections */,
2 /* allow up to 2 channels to be used, 0 and 1 */,
0 /* assume any amount of incoming bandwidth */,
0 /* assume any amount of outgoing bandwidth */);
}
void daLoop()
{
while(true)
{
/* Wait up to 1000 milliseconds for an event. */
while (enet_host_service (server, & event, 5000) > 0)
{
ENetPacket * packet;
switch (event.type)
{
case ENET_EVENT_TYPE_CONNECT:
printf ("A new client connected from %x:%u.\n",
event.peer -> address.host,
event.peer -> address.port);
/* Store any relevant client information here. */
event.peer -> data = "Client information";
/* Create a reliable packet of size 7 containing "packet\0" */
packet = enet_packet_create ("packet",
strlen ("packet") + 1,
ENET_PACKET_FLAG_RELIABLE);
/* Extend the packet so and append the string "foo", so it now */
/* contains "packetfoo\0" */
enet_packet_resize (packet, strlen ("packetfoo") + 1);
strcpy ((char*)& packet -> data [strlen ("packet")], "foo");
/* Send the packet to the peer over channel id 0. */
/* One could also broadcast the packet by */
/* enet_host_broadcast (host, 0, packet); */
enet_peer_send (event.peer, 0, packet);
/* One could just use enet_host_service() instead. */
enet_host_flush (server);
break;
case ENET_EVENT_TYPE_RECEIVE:
printf ("A packet of length %u containing %s was received from %s on channel %u.\n",
event.packet -> dataLength,
event.packet -> data,
event.peer -> data,
event.channelID);
/* Clean up the packet now that we're done using it. */
enet_packet_destroy (event.packet);
break;
case ENET_EVENT_TYPE_DISCONNECT:
printf ("%s disconected.\n", event.peer -> data);
/* Reset the peer's client information. */
event.peer -> data = NULL;
}
}
}
}
~Host()
{
if(server)
{
enet_host_destroy(server);
server = NULL;
}
atexit (enet_deinitialize);
}
};
class Client
{
ENetAddress address;
ENetEvent event;
ENetPeer *peer;
ENetHost* client;
public:
Client()
:peer(NULL)
{
enet_initialize();
setupPeer();
}
void setupPeer()
{
client = enet_host_create (NULL /* create a client host */,
1 /* only allow 1 outgoing connection */,
2 /* allow up 2 channels to be used, 0 and 1 */,
57600 / 8 /* 56K modem with 56 Kbps downstream bandwidth */,
14400 / 8 /* 56K modem with 14 Kbps upstream bandwidth */);
if (client == NULL)
{
fprintf (stderr,
"An error occurred while trying to create an ENet client host.\n");
exit (EXIT_FAILURE);
}
/* Connect to some.server.net:1234. */
enet_address_set_host (& address, "192.168.2.13");
address.port = 1721;
/* Initiate the connection, allocating the two channels 0 and 1. */
peer = enet_host_connect (client, & address, 2, 0);
if (peer == NULL)
{
fprintf (stderr,
"No available peers for initiating an ENet connection.\n");
exit (EXIT_FAILURE);
}
/* Wait up to 5 seconds for the connection attempt to succeed. */
if (enet_host_service (client, & event, 20000) > 0 &&
event.type == ENET_EVENT_TYPE_CONNECT)
{
std::cout << "Connection to some.server.net:1234 succeeded." << std::endl;
}
else
{
/* Either the 5 seconds are up or a disconnect event was */
/* received. Reset the peer in the event the 5 seconds */
/* had run out without any significant event. */
enet_peer_reset (peer);
puts ("Connection to some.server.net:1234 failed.");
}
}
void daLoop()
{
ENetPacket* packet;
/* Create a reliable packet of size 7 containing "packet\0" */
packet = enet_packet_create ("backet",
strlen ("backet") + 1,
ENET_PACKET_FLAG_RELIABLE);
/* Extend the packet so and append the string "foo", so it now */
/* contains "packetfoo\0" */
enet_packet_resize (packet, strlen ("backetfoo") + 1);
strcpy ((char*)& packet -> data [strlen ("backet")], "foo");
/* Send the packet to the peer over channel id 0. */
/* One could also broadcast the packet by */
/* enet_host_broadcast (host, 0, packet); */
enet_peer_send (event.peer, 0, packet);
/* One could just use enet_host_service() instead. */
enet_host_flush (client);
while(true)
{
/* Wait up to 1000 milliseconds for an event. */
while (enet_host_service (client, & event, 1000) > 0)
{
ENetPacket * packet;
switch (event.type)
{
case ENET_EVENT_TYPE_RECEIVE:
printf ("A packet of length %u containing %s was received from %s on channel %u.\n",
event.packet -> dataLength,
event.packet -> data,
event.peer -> data,
event.channelID);
/* Clean up the packet now that we're done using it. */
enet_packet_destroy (event.packet);
break;
}
}
}
}
~Client()
{
atexit (enet_deinitialize);
}
};
int main()
{
std::string a;
std::cin >> a;
if(a == "host")
{
Host host;
host.daLoop();
}
else
{
Client c;
c.daLoop();
}
return 0;
}
I looked at some socket tutorials and they seemed a bit too low level.
I just need something that abstracts away the platform (eg, no WINSOCKS) and that has basic ability to keep track of connected clients and send them messages.
Thanks
961
ENet aggregates all protocol commands, including acknowledgements and packet transfer, into larger protocol packets to ensure the proper utilization of the connection and to limit the opportunities for packet loss that might otherwise result in further delivery latency.
ENet is good because it provides the benefits of both worlds - the reliability of TCP and the freedom and light weight of UDP. There is nothing wrong with the fact that ENet internally uses only UDP and not TCP, because ENet is able to provide almost everything that TCP does, and much more.
Summary: The Main Differences Between UDP and TCP TCP is more reliable than UDP. It provides error-checking and ensures data packets are delivered to the communicating application in the correct order. TCP is slightly more secure than UDP. It is harder to insert malicious data as TCP tracks all data packets.
A late reply but maybe it will help someone else.
Encryption is a high level feature. TCP nor UDP alone does not support encryption by itself. They are both low level protocols. Actually, we could say that TCP is a higher level protocol compared to UDP, because TCP includes some advanced features which might be useful ... or not, depending on a project where it will be used.
ENet is good because it provides the benefits of both worlds - the reliability of TCP and the freedom and light weight of UDP. There is nothing wrong with the fact that ENet internally uses only UDP and not TCP, because ENet is able to provide almost everything that TCP does, and much more.
If you wish to have encryption, you will have to add it yourself, no matter if you chose TCP, UDP or ENet. So I suggest you to continue using ENet if you feel comfortable with it, and when you get your game up and running, you can add any encryption algorithm you wish, as long as you choose the same algorithm for both client and server. You can pick a 3rd party encryption library and just pass your network packets through it. ENet doesn't care, what data is being sent through it.
Maybe the following article will help with ENet:
Network Programming with ENet By Mike Diehl
and also take a look at the following Stackoverflow topic about encryption for small network packets:
Best practices for encrypting continuous/small UDP data
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