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authoreihrul <eihrul>2004-10-20 17:17:51 +0000
committereihrul <eihrul>2004-10-20 17:17:51 +0000
commit3010e46b47c36a25f44c80b31daaf887ab1d8de5 (patch)
treef64bced38da8159f0eb70a09eb8863a417d59ef5 /docs
downloadenet-3010e46b47c36a25f44c80b31daaf887ab1d8de5.tar.gz
enet-3010e46b47c36a25f44c80b31daaf887ab1d8de5.zip
Initial revision
Diffstat (limited to 'docs')
-rwxr-xr-xdocs/FAQ.dox24
-rwxr-xr-xdocs/design.dox126
-rwxr-xr-xdocs/install.dox37
-rwxr-xr-xdocs/license.dox26
-rwxr-xr-xdocs/mainpage.dox84
-rwxr-xr-xdocs/tutorial.dox349
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diff --git a/docs/FAQ.dox b/docs/FAQ.dox
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+/**
+ @page FAQ Frequently Answered Questions
+
+@section Q1 Is ENet thread safe?
+
+ENet does not use any significant global variables, the vast majority
+of state is encapsulated in the ENetHost structure. As such, as long
+as the application guards access to this structure, then ENet should
+operate fine in a multithreaded environment.
+
+@section Q2 Isn't ENet just re-inventing TCP?! What's the point?
+
+In a perfect world, that would be true. But as many have found, using
+TCP either in lieu of or in conjunction with UDP can lead to all kinds
+of nightmares. TCP is a good, solid protocol, however it simply isn't
+up to the task of real-time games. Too much of TCP's implementation
+dictates a policy that isn't practical for games. If you want to use
+TCP, then do so -- this library is for people that either don't want
+to use TCP or have tried and ended up being discouraged with the
+performance.
+
+*/
+
+
diff --git a/docs/design.dox b/docs/design.dox
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+/**
+@page Features Features and Architecture
+
+ENet evolved specifically as a UDP networking layer for the
+multiplayer first person shooter Cube. Cube necessitated low latency
+communcation with data sent out very frequently, so TCP was an
+unsuitable choice due to its high latency and stream orientation. UDP,
+however, lacks many sometimes necessary features from TCP such as
+reliability, sequencing, unrestricted packet sizes, and connection
+management. So UDP by itself was not suitable as a network protocol
+either. No suitable freely available networking libraries existed at
+the time of ENet's creation to fill this niche.
+
+UDP and TCP could have been used together in Cube to benefit somewhat
+from both of their features, however, the resulting combinations of
+protocols still leaves much to be desired. TCP lacks multiple streams
+of communication without resorting to opening many sockets and
+complicates delineation of packets due to its buffering behavior. UDP
+lacks sequencing, connection management, management of bandwidth
+resources, and imposes limitations on the size of packets. A
+significant investment is required to integrate these two protocols,
+and the end result is worse off in features and performance than the
+uniform protocol presented by ENet.
+
+ENet thus attempts to address these issues and provide a single,
+uniform protocol layered over UDP to the developer with the best
+features of UDP and TCP as well as some useful features neither
+provide, with a much cleaner integration than any resulting from a
+mixture of UDP and TCP.
+
+@section CM Connection Management
+
+ENet provides a simple connection interface over which to communicate
+with a foreign host. The liveness of the connection is actively
+monitored by pinging the foreign host at frequent intervals, and also
+monitors the network conditions from the local host to the foreign
+host such as the mean round trip time and packet loss in this fashion.
+
+@section Sequencing Sequencing
+
+Rather than a single byte stream that complicates the delineation of
+packets, ENet presents connections as multiple, properly sequenced
+packet streams that simplify the transfer of various types of data.
+
+ENet provides sequencing for all packets by assigning to each sent
+packet a sequence number that is incremented as packets are sent. ENet
+guarentees that no packet with a higher sequence number will be
+delivered before a packet with a lower sequence number, thus ensuring
+packets are delivered exactly in the order they are sent.
+
+For unreliable packets, ENet will simply discard the lower sequence
+number packet if a packet with a higher sequence number has already
+been delivered. This allows the packets to be dispatched immediately
+as they arrive, and reduce latency of unreliable packets to an
+absolute minimum. For reliable packets, if a higher sequence number
+packet arrives, but the preceding packets in the sequence have not yet
+arrived, ENet will stall delivery of the higher sequence number
+packets until its predecessors have arrived.
+
+@section Channels Channels
+
+Since ENet will stall delivery of reliable packets to ensure proper
+sequencing, and consequently any packets of higher sequence number
+whether reliable or unreliable, in the event the reliable packet's
+predecessors have not yet arrived, this can introduce latency into the
+delivery of other packets which may not need to be as strictly ordered
+with respect to the packet that stalled their delivery.
+
+To combat this latency and reduce the ordering restrictions on
+packets, ENet provides multiple channels of communication over a given
+connection. Each channel is independently sequenced, and so the
+delivery status of a packet in one channel will not stall the delivery
+of other packets in another channel.
+
+@section Reliability Reliability
+
+ENet provides optional reliability of packet delivery by ensuring the
+foreign host acknowledges receipt of all reliable packets. ENet will
+attempt to resend the packet up to a reasonable amount of times, if no
+acknowledgement of the packet's receipt happens within a specified
+timeout. Retry timeouts are progressive and become more lenient with
+every failed attempt to allow for temporary turbulence in network
+conditions.
+
+@section FaR Fragmentation and Reassembly
+
+ENet will send and deliver packets regardless of size. Large packets
+are fragmented into many smaller packets of suitable size, and
+reassembled on the foreign host to recover the original packet for
+delivery. The process is entirely transparent to the developer.
+
+@section Aggregation Aggregation
+
+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.
+
+@section Adaptability Adaptability
+
+ENet provides an in-flight data window for reliable packets to ensure
+connections are not overwhelmed by volumes of packets. It also
+provides a static bandwidth allocation mechanism to ensure the total
+volume of packets sent and received to a host don't exceed the host's
+capabilities. Further, ENet also provides a dynamic throttle that
+responds to deviations from normal network connections to rectify
+various types of network congestion by further limiting the volume of
+packets sent.
+
+@section Portability Portability
+
+ENet works on Windows and any other Unix or Unix-like platform
+providing a BSD sockets interface. The library has a small and stable
+code base that can easily be extended to support other platforms and
+integrates easily. ENet makes no assumptions about the underlying
+platform's endianess or word size.
+
+@section Freedom Freedom
+
+ENet demands no royalties and doesn't carry a viral license that would
+restrict you in how you might use it in your programs. ENet is
+licensed under a short-and-sweet MIT-style license, which gives you
+the freedom to do anything you want with it (well, almost anything).
+
+*/
+
diff --git a/docs/install.dox b/docs/install.dox
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+/**
+@page Installation Installation
+
+ENet should be trivially simple to integrate with most applications.
+First, make sure you download the latest source distribution here @ref
+SourceDistro.
+
+@section Unix Unix-like Operating Systems
+
+[to be completed]
+
+@subsection SolarisBSD Solaris and BSD
+
+When building ENet under Solaris, you must specify the -lsocket and
+-lnsl parameters to your compiler to ensure that the sockets library
+is linked in.
+
+@section Windows Microsoft Windows
+
+Using MSVC 6 under Windows simply drag all the ENet source files into
+your main project or, better yet, create a new static library project
+and make your executable dependent (Project|Dependencies) on ENet.
+There is also an enet.dsp provided.
+
+You will have to link to the Winsock2 libraries, so make sure to add
+ws2_32.lib to your library list (Project Settings | Link |
+Object/library modules).
+
+@subsection DLL DLL
+
+If you wish to build ENet as a DLL you must first define ENET_DLL
+within the project (Project Settings | C/C++ | Preprocessor |
+Preprocessor definitions) or, more invasively, simply define ENET_DLL
+at the top of enet.h.
+
+*/
+
diff --git a/docs/license.dox b/docs/license.dox
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+/**
+ @page License License
+
+Copyright (c) 2002 Lee Salzman
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+*/
+
diff --git a/docs/mainpage.dox b/docs/mainpage.dox
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+/** @mainpage enet
+ <center>http://enet.cubik.org</center>
+ <hr>
+
+ENet's purpose is to provide a relatively thin, simple and robust
+network communication layer on top of UDP (User Datagram Protocol).
+The primary feature it provides is optional reliable, in-order
+delivery of packets.
+
+ENet is NOT intended to be a general purpose high level networking
+library that handles authentication, lobbying, server discovery,
+compression, encryption and other high level, often application level
+or dependent tasks.
+
+@ref Features
+
+@ref SourceDistro
+
+@ref Installation
+
+@ref Tutorial
+
+@ref MailingList
+
+@ref Extending
+
+@ref FAQ
+
+@ref License
+
+ */
+
+/**
+@page SourceDistro Source Distribution
+
+You can retrieve the source to ENet by downloading it in either .zip
+form, .tar.gz form, or accessing the cvs distribution directly.
+
+The most recent CVS can be downloaded <a href="http://enet.cubik.org/download/enet.tar.gz">here</a>
+
+To access ENet via anonymous CVS, you must use the CVSROOT
+:pserver:anoncvs\@sferik.cubik.org:/home/enet/cvsroot with an empty
+password.
+
+@code
+ $ cvs -z3 -d :pserver:[email protected]:/home/enet/cvsroot login
+@endcode
+ Hit the return key when prompted for a password.
+@code
+ $ cvs -z3 -d :pserver:[email protected]:/home/enet/cvsroot co -l .
+ $ cvs -z3 co enet
+@endcode
+
+This will create a CVS directory in the current directory, and with
+the second command will proceed to check the enet module out of CVS.
+Any problems with CVS access or request for write access should be
+sent via email to @ref MailingList.
+
+*/
+
+/**
+@page Extending Extending and Modifying ENet
+
+Since ENet is distributed in source form, you can easily extend and
+modify it to suit your needs. For example, some users prefer to use
+their own memory management routines and can thus replace the
+appropriate functions in memory.c
+
+*/
+
+/**
+@page MailingList ENet Related Mailing Lists
+
+The <a
+href="http://lists.cubik.org/mailman/listinfo/enet-discuss">
+enet-discuss</a> list is for discussion of ENet, including bug reports
+or feature requests.
+
+The CVS commits are also sent to <a
+href="http://lists.cubik.org/mailman/listinfo/enet-cvs">enet-cvs</a>,
+so feel free to subscribe if you want to keep up with the latest
+developments.
+
+*/
diff --git a/docs/tutorial.dox b/docs/tutorial.dox
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+/**
+@page Tutorial Tutorial
+
+@ref Initialization
+
+@ref CreateServer
+
+@ref CreateClient
+
+@ref ManageHost
+
+@ref SendingPacket
+
+@ref Disconnecting
+
+@ref Connecting
+
+@section Initialization Initialization
+
+Before using ENet, you must call enet_initialize() to initialize the
+library. Upon program exit, you should call enet_deinitialize() so
+that the library may clean up any used resources.
+
+@code
+int
+main (int argc, char ** argv)
+{
+ if (enet_initialize () != 0)
+ {
+ fprintf (stderr, "An error occurred while initializing ENet.\n");
+ return EXIT_FAILURE;
+ }
+ atexit (enet_deinitialize);
+ ...
+ ...
+ ...
+}
+@endcode
+
+@section CreateServer Creating an ENet server
+
+Servers in ENet are constructed with enet_host_create(). You must
+specify an address on which to receive data and new connections, as
+well as the maximum allowable numbers of connected peers. You may
+optionally specify the incoming and outgoing bandwidth of the server
+in bytes per second so that ENet may try to statically manage
+bandwidth resources among connected peers in addition to its dynamic
+throttling algorithm; specifying 0 for these two options will cause
+ENet to rely entirely upon its dynamic throttling algorithm to manage
+bandwidth.
+
+When done with a host, the host may be destroyed with
+enet_host_destroy(). All connected peers to the host will be reset,
+and the resources used by the host will be freed.
+
+@code
+ ENetAddress address;
+ ENetHost * server;
+
+ /* Bind the server to the default localhost. */
+ /* A specific host address can be specified by */
+ /* enet_address_set_host (& address, "x.x.x.x"); */
+
+ address.host = ENET_HOST_ANY;
+ /* Bind the server to port 1234. */
+ address.port = 1234;
+
+ server = enet_host_create (& address /* the address to bind the server host to */,
+ 32 /* allow up to 32 clients and/or outgoing connections */,
+ 0 /* assume any amount of incoming bandwidth */,
+ 0 /* assume any amount of outgoing bandwidth */);
+ if (server == NULL)
+ {
+ fprintf (stderr,
+ "An error occurred while trying to create an ENet server host.\n");
+ exit (EXIT_FAILURE);
+ }
+ ...
+ ...
+ ...
+ enet_host_destroy(server);
+@endcode
+
+@section CreateClient Creating an ENet client
+
+Clients in ENet are similarly constructed with enet_host_create() when
+no address is specified to bind the host to. Bandwidth may be
+specified for the client host as in the above example. The peer count
+controls the maximum number of connections to other server hosts that
+may be simultaneously open.
+
+@code
+ ENetHost * client;
+
+ client = enet_host_create (NULL /* create a client host */,
+ 1 /* only allow 1 outgoing connection */,
+ 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);
+ }
+ ...
+ ...
+ ...
+ enet_host_destroy(client);
+@endcode
+
+@section ManageHost Managing an ENet host
+
+ENet uses a polled event model to notify the programmer of significant
+events. ENet hosts are polled for events with enet_host_service(),
+where an optional timeout value in milliseconds may be specified to
+control how long ENet will poll; if a timeout of 0 is specified,
+enet_host_service() will return immediately if there are no events to
+dispatch. enet_host_service() will return 1 if an event was dispatched
+within the specified timeout.
+
+Currently there are only four types of significant events in ENet:
+
+An event of type ENET_EVENT_TYPE_NONE is returned if no event occurred
+within the specified time limit. enet_host_service() will return 0
+with this event.
+
+An event of type ENET_EVENT_TYPE_CONNECT is returned when either a new client
+host has connected to the server host or when an attempt to establish a
+connection with a foreign host has succeeded. Only the "peer" field of the
+event structure is valid for this event and contains the newly connected peer.
+
+An event of type ENET_EVENT_TYPE_RECEIVE is returned when a packet is received
+from a connected peer. The "peer" field contains the peer the packet was
+received from, "channelID" is the channel on which the packet was sent, and
+"packet" is the packet that was sent. The packet contained in the "packet"
+field must be destroyed with enet_packet_destroy() when you are done
+inspecting its contents.
+
+An event of type ENET_EVENT_TYPE_DISCONNECT is returned when a connected peer
+has either explicitly disconnected or timed out. Only the "peer" field of the
+event structure is valid for this event and contains the peer that
+disconnected. Only the "data" field of the peer is still valid on a
+disconnect event and must be explicitly reset.
+
+@code
+ ENetEvent event;
+
+ /* Wait up to 1000 milliseconds for an event. */
+ while (enet_host_service (client, & event, 1000) > 0)
+ {
+ 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";
+
+ 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;
+ }
+ }
+ ...
+ ...
+ ...
+@endcode
+
+@section SendingPacket Sending a packet to an ENet peer
+
+Packets in ENet are created with enet_packet_create(), where the size
+of the packet must be specified. Optionally, initial data may be
+specified to copy into the packet.
+
+Certain flags may also be supplied to enet_packet_create() to control
+various packet features:
+
+ENET_PACKET_FLAG_RELIABLE specifies that the packet must use reliable
+delivery. A reliable packet is guarenteed to be delivered, and a
+number of retry attempts will be made until an acknowledgement is
+received from the foreign host the packet is sent to. If a certain
+number of retry attempts is reached without any acknowledgement, ENet
+will assume the peer has disconnected and forcefully reset the
+connection. If this flag is not specified, the packet is assumed an
+unreliable packet, and no retry attempts will be made nor
+acknowledgements generated.
+
+A packet may be resized (extended or truncated) with
+enet_packet_resize().
+
+A packet is sent to a foreign host with
+enet_peer_send(). enet_peer_send() accepts a channel id over which to
+send the packet to a given peer. Once the packet is handed over to
+ENet with enet_peer_send(), ENet will handle its deallocation and
+enet_packet_destroy() should not be used upon it.
+
+One may also use enet_host_broadcast() to send a packet to all
+connected peers on a given host over a specified channel id, as with
+enet_peer_send().
+
+Queued packets will be sent on a call to enet_host_service().
+Alternatively, enet_host_flush() will send out queued packets without
+dispatching any events.
+
+@code
+ /* Create a reliable packet of size 7 containing "packet\0" */
+ ENetPacket * 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 (& packet -> data [strlen ("packet")], "foo");
+
+ /* Send the packet to the peer over channel id 3. */
+ /* One could also broadcast the packet by */
+ /* enet_host_broadcast (host, 3, packet); */
+ enet_peer_send (peer, 3, packet);
+ ...
+ ...
+ ...
+ /* One could just use enet_host_service() instead. */
+ enet_host_flush (host);
+@endcode
+
+@section Disconnecting Disconnecting an ENet peer
+
+Peers may be gently disconnected with enet_peer_disconnect(). A
+disconnect request will be sent to the foreign host, and ENet will
+wait for an acknowledgement from the foreign host before finally
+disconnecting. An event of type ENET_EVENT_TYPE_DISCONNECT will be
+generated once the disconnection succeeds. Normally timeouts apply to
+the disconnect acknowledgement, and so if no acknowledgement is
+received after a length of time the peer will be forcefully
+disconnected.
+
+enet_peer_reset() will forcefully disconnect a peer. The foreign host
+will get no notification of a disconnect and will time out on the
+foreign host. No event is generated.
+
+@code
+ ENetEvent event;
+
+ enet_peer_disconnect (& client -> peers [0]);
+
+ /* Allow up to 3 seconds for the disconnect to succeed
+ * and drop any packets received packets.
+ */
+ while (enet_host_service (client, & event, 3000) > 0)
+ {
+ switch (event.type)
+ {
+ case ENET_EVENT_TYPE_RECEIVE:
+ enet_packet_destroy (event.packet);
+ break;
+
+ case ENET_EVENT_TYPE_DISCONNECT:
+ puts ("Disconnection succeeded.");
+ return;
+ ...
+ ...
+ ...
+ }
+ }
+
+ /* We've arrived here, so the disconnect attempt didn't */
+ /* succeed yet. Force the connection down. */
+ enet_peer_reset (& client -> peers [0]);
+ ...
+ ...
+ ...
+@endcode
+
+@section Connecting Connecting to an ENet host
+
+A connection to a foreign host is initiated with enet_host_connect().
+It accepts the address of a foreign host to connect to, and the number
+of channels that should be allocated for communication. If N channels
+are allocated for use, their channel ids will be numbered 0 through
+N-1. A peer representing the connection attempt is returned, or NULL
+if there were no available peers over which to initiate the
+connection. When the connection attempt succeeds, an event of type
+ENET_EVENT_TYPE_CONNECT will be generated. If the connection attempt
+times out or otherwise fails, an event of type
+ENET_EVENT_TYPE_DISCONNECT will be generated.
+
+@code
+ ENetAddress address;
+ ENetEvent event;
+ ENetPeer *peer;
+
+ /* Connect to some.server.net:1234. */
+ enet_address_set_host (& address, "some.server.net");
+ address.port = 1234;
+
+ /* Initiate the connection, allocating the two channels 0 and 1. */
+ peer = enet_host_connect (client, & address, 2);
+
+ 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, 5000) > 0 &&
+ event.type == ENET_EVENT_TYPE_CONNECT)
+ {
+ puts ("Connection to some.server.net:1234 succeeded.");
+ ...
+ ...
+ ...
+ }
+ 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.");
+ }
+ ...
+ ...
+ ...
+@endcode
+*/