Initial revision

1 files changed, 644 insertions, 0 deletions

diff --git a/peer.c b/peer.c
new file mode 100644
index 0000000..47c878c
--- /dev/null
+++ b/peer.c
@@ -0,0 +1,644 @@
+/** 
+ @file  peer.c
+ @brief ENet peer management functions
+*/
+#define ENET_BUILDING_LIB 1
+#include "enet/enet.h"
+
+/** @defgroup peer ENet peer functions 
+    @{
+*/
+
+/** Configures throttle parameter for a peer.
+
+    Unreliable packets are dropped by ENet in response to the varying conditions
+    of the Internet connection to the peer.  The throttle represents a probability
+    that an unreliable packet should not be dropped and thus sent by ENet to the peer.
+    The lowest mean round trip time from the sending of a reliable packet to the
+    receipt of its acknowledgement is measured over an amount of time specified by
+    the interval parameter in milliseconds.  If a measured round trip time happens to
+    be significantly less than the mean round trip time measured over the interval, 
+    then the throttle probability is increased to allow more traffic by an amount
+    specified in the acceleration parameter, which is a ratio to the ENET_PEER_PACKET_THROTTLE_SCALE
+    constant.  If a measured round trip time happens to be significantly greater than
+    the mean round trip time measured over the interval, then the throttle probability
+    is decreased to limit traffic by an amount specified in the deceleration parameter, which
+    is a ratio to the ENET_PEER_PACKET_THROTTLE_SCALE constant.  When the throttle has
+    a value of ENET_PEER_PACKET_THROTTLE_SCALE, on unreliable packets are dropped by 
+    ENet, and so 100% of all unreliable packets will be sent.  When the throttle has a
+    value of 0, all unreliable packets are dropped by ENet, and so 0% of all unreliable
+    packets will be sent.  Intermediate values for the throttle represent intermediate
+    probabilities between 0% and 100% of unreliable packets being sent.  The bandwidth
+    limits of the local and foreign hosts are taken into account to determine a 
+    sensible limit for the throttle probability above which it should not raise even in
+    the best of conditions.
+
+    @param peer peer to configure 
+    @param interval interval, in milliseconds, over which to measure lowest mean RTT; the default value is ENET_PEER_PACKET_THROTTLE_INTERVAL.
+    @param acceleration rate at which to increase the throttle probability as mean RTT declines
+    @param deceleration rate at which to decrease the throttle probability as mean RTT increases
+*/
+void
+enet_peer_throttle_configure (ENetPeer * peer, enet_uint32 interval, enet_uint32 acceleration, enet_uint32 deceleration)
+{
+    ENetProtocol command;
+
+    peer -> packetThrottleInterval = interval;
+    peer -> packetThrottleAcceleration = acceleration;
+    peer -> packetThrottleDeceleration = deceleration;
+
+    command.header.command = ENET_PROTOCOL_COMMAND_THROTTLE_CONFIGURE;
+    command.header.channelID = 0xFF;
+    command.header.flags = ENET_PROTOCOL_FLAG_ACKNOWLEDGE;
+    command.header.commandLength = sizeof (ENetProtocolThrottleConfigure);
+
+    command.throttleConfigure.packetThrottleInterval = ENET_HOST_TO_NET_32 (interval);
+    command.throttleConfigure.packetThrottleAcceleration = ENET_HOST_TO_NET_32 (acceleration);
+    command.throttleConfigure.packetThrottleDeceleration = ENET_HOST_TO_NET_32 (deceleration);
+
+    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
+}
+
+int
+enet_peer_throttle (ENetPeer * peer, enet_uint32 rtt)
+{
+    if (peer -> lastRoundTripTime <= peer -> lastRoundTripTimeVariance)
+    {
+        peer -> packetThrottle = peer -> packetThrottleLimit;
+    }
+    else
+    if (rtt < peer -> lastRoundTripTime)
+    {
+        peer -> packetThrottle += peer -> packetThrottleAcceleration;
+
+        if (peer -> packetThrottle > peer -> packetThrottleLimit)
+          peer -> packetThrottle = peer -> packetThrottleLimit;
+
+        return 1;
+    }
+    else
+    if (rtt > peer -> lastRoundTripTime + 2 * peer -> lastRoundTripTimeVariance)
+    {
+        if (peer -> packetThrottle > peer -> packetThrottleDeceleration)
+          peer -> packetThrottle -= peer -> packetThrottleDeceleration;
+        else
+          peer -> packetThrottle = 0;
+
+        return -1;
+    }
+
+    return 0;
+}
+
+/** Queues a packet to be sent.
+    @param peer destination for the packet
+    @param channelID channel on which to send
+    @param packet packet to send
+    @retval 0 on success
+    @retval < 0 on failure
+*/
+int
+enet_peer_send (ENetPeer * peer, enet_uint8 channelID, ENetPacket * packet)
+{
+   ENetChannel * channel = & peer -> channels [channelID];
+   ENetProtocol command;
+   size_t fragmentLength;
+
+   if (peer -> state != ENET_PEER_STATE_CONNECTED ||
+       channelID >= peer -> channelCount)
+     return -1;
+
+   fragmentLength = peer -> mtu - sizeof (ENetProtocolHeader) - sizeof (ENetProtocolSendFragment);
+
+   if (packet -> dataLength > fragmentLength)
+   {
+      enet_uint32 fragmentCount = ENET_HOST_TO_NET_32 ((packet -> dataLength + fragmentLength - 1) / fragmentLength),
+             startSequenceNumber = ENET_HOST_TO_NET_32 (channel -> outgoingReliableSequenceNumber + 1),
+             fragmentNumber,
+             fragmentOffset;
+
+      packet -> flags = ENET_PACKET_FLAG_RELIABLE;
+
+      for (fragmentNumber = 0,
+             fragmentOffset = 0;
+           fragmentOffset < packet -> dataLength;
+           ++ fragmentNumber,
+             fragmentOffset += fragmentLength)
+      {
+         command.header.command = ENET_PROTOCOL_COMMAND_SEND_FRAGMENT;
+         command.header.channelID = channelID;
+         command.header.flags = ENET_PROTOCOL_FLAG_ACKNOWLEDGE;
+         command.header.commandLength = sizeof (ENetProtocolSendFragment);
+         command.sendFragment.startSequenceNumber = startSequenceNumber;
+         command.sendFragment.fragmentCount = fragmentCount;
+         command.sendFragment.fragmentNumber = ENET_HOST_TO_NET_32 (fragmentNumber);
+         command.sendFragment.totalLength = ENET_HOST_TO_NET_32 (packet -> dataLength);
+         command.sendFragment.fragmentOffset = ENET_NET_TO_HOST_32 (fragmentOffset);
+
+         if (packet -> dataLength - fragmentOffset < fragmentLength)
+           fragmentLength = packet -> dataLength - fragmentOffset;
+
+         enet_peer_queue_outgoing_command (peer, & command, packet, fragmentOffset, fragmentLength);
+      }
+
+      return 0;
+   }
+
+   command.header.channelID = channelID;
+
+   if (packet -> flags & ENET_PACKET_FLAG_RELIABLE)
+   {
+      command.header.command = ENET_PROTOCOL_COMMAND_SEND_RELIABLE;
+      command.header.flags = ENET_PROTOCOL_FLAG_ACKNOWLEDGE;
+      command.header.commandLength = sizeof (ENetProtocolSendReliable);
+   }
+   else
+   if (packet -> flags & ENET_PACKET_FLAG_UNSEQUENCED)
+   {
+      command.header.command = ENET_PROTOCOL_COMMAND_SEND_UNSEQUENCED;
+      command.header.flags = ENET_PROTOCOL_FLAG_UNSEQUENCED;
+      command.header.commandLength = sizeof (ENetProtocolSendUnsequenced);
+      command.sendUnsequenced.unsequencedGroup = ENET_HOST_TO_NET_32 (peer -> outgoingUnsequencedGroup + 1);
+   }
+   else
+   {
+      command.header.command = ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE;
+      command.header.flags = 0;
+      command.header.commandLength = sizeof (ENetProtocolSendUnreliable);
+      command.sendUnreliable.unreliableSequenceNumber = ENET_HOST_TO_NET_32 (channel -> outgoingUnreliableSequenceNumber + 1);
+   }
+
+   enet_peer_queue_outgoing_command (peer, & command, packet, 0, packet -> dataLength);
+
+   return 0;
+}
+
+/** Attempts to dequeue any incoming queued packet.
+    @param peer peer to dequeue packets from
+    @param channelID channel on which to receive
+    @returns a pointer to the packet, or NULL if there are no available incoming queued packets
+*/
+ENetPacket *
+enet_peer_receive (ENetPeer * peer, enet_uint8 channelID)
+{
+   ENetChannel * channel = & peer -> channels [channelID];
+   ENetIncomingCommand * incomingCommand = NULL;
+   ENetPacket * packet;
+
+   if (enet_list_empty (& channel -> incomingUnreliableCommands) == 0)
+   {
+      incomingCommand = (ENetIncomingCommand *) enet_list_front (& channel -> incomingUnreliableCommands);
+
+      if (incomingCommand -> unreliableSequenceNumber > 0)
+      {
+         if (incomingCommand -> reliableSequenceNumber > channel -> incomingReliableSequenceNumber)
+           incomingCommand = NULL;
+         else
+           channel -> incomingUnreliableSequenceNumber = incomingCommand -> unreliableSequenceNumber;
+      }
+   }
+
+   if (incomingCommand == NULL &&
+       enet_list_empty (& channel -> incomingReliableCommands) == 0)
+   {
+      do
+      {
+        incomingCommand = (ENetIncomingCommand *) enet_list_front (& channel -> incomingReliableCommands);
+
+        if (incomingCommand -> fragmentsRemaining > 0 ||
+            incomingCommand -> reliableSequenceNumber > channel -> incomingReliableSequenceNumber + 1)
+          return NULL;
+
+        if (incomingCommand -> reliableSequenceNumber <= channel -> incomingReliableSequenceNumber)
+        {
+           -- incomingCommand -> packet -> referenceCount;
+
+           if (incomingCommand -> packet -> referenceCount == 0)
+             enet_packet_destroy (incomingCommand -> packet);
+
+           if (incomingCommand -> fragments != NULL)
+             enet_free (incomingCommand -> fragments);
+
+           enet_list_remove (& incomingCommand -> incomingCommandList);
+
+           enet_free (incomingCommand);
+
+           incomingCommand = NULL;
+        }
+      } while (incomingCommand == NULL &&
+               enet_list_empty (& channel -> incomingReliableCommands) == 0);
+
+      if (incomingCommand == NULL)
+        return NULL;
+
+      channel -> incomingReliableSequenceNumber = incomingCommand -> reliableSequenceNumber;
+
+      if (incomingCommand -> fragmentCount > 0)
+        channel -> incomingReliableSequenceNumber += incomingCommand -> fragmentCount - 1;
+   }
+
+   if (incomingCommand == NULL)
+     return NULL;
+
+   enet_list_remove (& incomingCommand -> incomingCommandList);
+
+   packet = incomingCommand -> packet;
+
+   -- packet -> referenceCount;
+
+   if (incomingCommand -> fragments != NULL)
+     enet_free (incomingCommand -> fragments);
+
+   enet_free (incomingCommand);
+
+   return packet;
+}
+
+static void
+enet_peer_reset_outgoing_commands (ENetList * queue)
+{
+    ENetOutgoingCommand * outgoingCommand;
+
+    while (enet_list_empty (queue) == 0)
+    {
+       outgoingCommand = (ENetOutgoingCommand *) enet_list_remove (enet_list_begin (queue));
+
+       if (outgoingCommand -> packet != NULL)
+       {
+          -- outgoingCommand -> packet -> referenceCount;
+
+          if (outgoingCommand -> packet -> referenceCount == 0)
+            enet_packet_destroy (outgoingCommand -> packet);
+       }
+
+       enet_free (outgoingCommand);
+    }
+}
+
+static void
+enet_peer_reset_incoming_commands (ENetList * queue)
+{
+    ENetIncomingCommand * incomingCommand;
+
+    while (enet_list_empty (queue) == 0)
+    {
+       incomingCommand = (ENetIncomingCommand *) enet_list_remove (enet_list_begin (queue));
+
+       if (incomingCommand -> packet != NULL)
+       {
+          -- incomingCommand -> packet -> referenceCount;
+
+          if (incomingCommand -> packet -> referenceCount == 0)
+            enet_packet_destroy (incomingCommand -> packet);
+       }
+
+       enet_free (incomingCommand);
+    }
+}
+
+void
+enet_peer_reset_queues (ENetPeer * peer)
+{
+    ENetChannel * channel;
+
+    while (enet_list_empty (& peer -> acknowledgements) == 0)
+      enet_free (enet_list_remove (enet_list_begin (& peer -> acknowledgements)));
+
+    enet_peer_reset_outgoing_commands (& peer -> sentReliableCommands);
+    enet_peer_reset_outgoing_commands (& peer -> sentUnreliableCommands);
+    enet_peer_reset_outgoing_commands (& peer -> outgoingReliableCommands);
+    enet_peer_reset_outgoing_commands (& peer -> outgoingUnreliableCommands);
+
+    if (peer -> channels != NULL && peer -> channelCount > 0)
+    {
+        for (channel = peer -> channels;
+             channel < & peer -> channels [peer -> channelCount];
+             ++ channel)
+        {
+            enet_peer_reset_incoming_commands (& channel -> incomingReliableCommands);
+            enet_peer_reset_incoming_commands (& channel -> incomingUnreliableCommands);
+        }
+
+        enet_free (peer -> channels);
+    }
+
+    peer -> channels = NULL;
+    peer -> channelCount = 0;
+}
+
+/** Forcefully disconnects a peer.
+    @param peer peer to forcefully disconnect
+    @remarks The foreign host represented by the peer is not notified of the disconnection and will timeout
+    on its connection to the local host.
+*/
+void
+enet_peer_reset (ENetPeer * peer)
+{
+    peer -> outgoingPeerID = 0xFFFF;
+    peer -> challenge = 0;
+
+    peer -> address.host = ENET_HOST_ANY;
+    peer -> address.port = 0;
+
+    peer -> state = ENET_PEER_STATE_DISCONNECTED;
+
+    peer -> incomingBandwidth = 0;
+    peer -> outgoingBandwidth = 0;
+    peer -> incomingBandwidthThrottleEpoch = 0;
+    peer -> outgoingBandwidthThrottleEpoch = 0;
+    peer -> incomingDataTotal = 0;
+    peer -> outgoingDataTotal = 0;
+    peer -> lastSendTime = 0;
+    peer -> lastReceiveTime = 0;
+    peer -> nextTimeout = 0;
+    peer -> packetLossEpoch = 0;
+    peer -> packetsSent = 0;
+    peer -> packetsLost = 0;
+    peer -> packetLoss = 0;
+    peer -> packetLossVariance = 0;
+    peer -> packetThrottle = ENET_PEER_DEFAULT_PACKET_THROTTLE;
+    peer -> packetThrottleLimit = ENET_PEER_PACKET_THROTTLE_SCALE;
+    peer -> packetThrottleCounter = 0;
+    peer -> packetThrottleEpoch = 0;
+    peer -> packetThrottleAcceleration = ENET_PEER_PACKET_THROTTLE_ACCELERATION;
+    peer -> packetThrottleDeceleration = ENET_PEER_PACKET_THROTTLE_DECELERATION;
+    peer -> packetThrottleInterval = ENET_PEER_PACKET_THROTTLE_INTERVAL;
+    peer -> lastRoundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
+    peer -> lowestRoundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
+    peer -> lastRoundTripTimeVariance = 0;
+    peer -> highestRoundTripTimeVariance = 0;
+    peer -> roundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
+    peer -> roundTripTimeVariance = 0;
+    peer -> mtu = peer -> host -> mtu;
+    peer -> reliableDataInTransit = 0;
+    peer -> outgoingReliableSequenceNumber = 0;
+    peer -> windowSize = ENET_PROTOCOL_MAXIMUM_WINDOW_SIZE;
+    peer -> incomingUnsequencedGroup = 0;
+    peer -> outgoingUnsequencedGroup = 0;
+
+    memset (peer -> unsequencedWindow, 0, sizeof (peer -> unsequencedWindow));
+    
+    enet_peer_reset_queues (peer);
+}
+
+/** Sends a ping request to a peer.
+    @param peer destination for the ping request
+    @remarks ping requests factor into the mean round trip time as designated by the 
+    roundTripTime field in the ENetPeer structure.  Enet automatically pings all connected
+    peers at regular intervals, however, this function may be called to ensure more
+    frequent ping requests.
+*/
+void
+enet_peer_ping (ENetPeer * peer)
+{
+    ENetProtocol command;
+
+    if (peer -> state != ENET_PEER_STATE_CONNECTED)
+      return;
+
+    command.header.command = ENET_PROTOCOL_COMMAND_PING;
+    command.header.channelID = 0xFF;
+    command.header.flags = ENET_PROTOCOL_FLAG_ACKNOWLEDGE;
+    command.header.commandLength = sizeof (ENetProtocolPing);
+   
+    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
+}
+
+/** Force an immediate disconnection from a peer.
+    @param peer peer to disconnect
+    @remarks No ENET_EVENT_DISCONNECT event will be generated. The foreign peer is not
+    guarenteed to receive the disconnect notification, and is reset immediately upon
+    return from this function.
+*/
+void
+enet_peer_disconnect_now (ENetPeer * peer)
+{
+    ENetProtocol command;
+
+    if (peer -> state == ENET_PEER_STATE_DISCONNECTED)
+      return;
+
+    if (peer -> state != ENET_PEER_STATE_ZOMBIE &&
+        peer -> state != ENET_PEER_STATE_DISCONNECTING)
+    {
+        enet_peer_reset_queues (peer);
+
+        command.header.command = ENET_PROTOCOL_COMMAND_DISCONNECT;
+        command.header.channelID = 0xFF;
+        command.header.flags = ENET_PROTOCOL_FLAG_UNSEQUENCED;
+        command.header.commandLength = sizeof (ENetProtocolDisconnect);
+
+        enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
+
+        enet_host_flush (peer -> host);
+    }
+
+    enet_peer_reset (peer);
+}
+
+/** Request a disconnection from a peer.
+    @param peer peer to request a disconnection
+    @remarks An ENET_EVENT_DISCONNECT event will be generated by enet_host_service()
+    once the disconnection is complete.
+*/
+void
+enet_peer_disconnect (ENetPeer * peer)
+{
+    ENetProtocol command;
+
+    if (peer -> state == ENET_PEER_STATE_DISCONNECTING ||
+        peer -> state == ENET_PEER_STATE_DISCONNECTED ||
+        peer -> state == ENET_PEER_STATE_ZOMBIE)
+      return;
+
+    enet_peer_reset_queues (peer);
+
+    command.header.command = ENET_PROTOCOL_COMMAND_DISCONNECT;
+    command.header.channelID = 0xFF;
+    command.header.flags = ENET_PROTOCOL_FLAG_UNSEQUENCED;
+    command.header.commandLength = sizeof (ENetProtocolDisconnect);
+
+    if (peer -> state == ENET_PEER_STATE_CONNECTED)
+      command.header.flags = ENET_PROTOCOL_FLAG_ACKNOWLEDGE;
+    
+    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
+
+    if (peer -> state == ENET_PEER_STATE_CONNECTED)
+      peer -> state = ENET_PEER_STATE_DISCONNECTING;
+    else
+    {
+        enet_host_flush (peer -> host);
+        enet_peer_reset (peer);
+    }
+}
+
+ENetAcknowledgement *
+enet_peer_queue_acknowledgement (ENetPeer * peer, const ENetProtocol * command, enet_uint32 sentTime)
+{
+    ENetAcknowledgement * acknowledgement;
+
+    peer -> outgoingDataTotal += sizeof (ENetProtocolAcknowledge);
+
+    acknowledgement = (ENetAcknowledgement *) enet_malloc (sizeof (ENetAcknowledgement));
+
+    acknowledgement -> sentTime = sentTime;
+    acknowledgement -> command = * command;
+    
+    enet_list_insert (enet_list_end (& peer -> acknowledgements), acknowledgement);
+    
+    return acknowledgement;
+}
+
+ENetOutgoingCommand *
+enet_peer_queue_outgoing_command (ENetPeer * peer, const ENetProtocol * command, ENetPacket * packet, enet_uint32 offset, enet_uint16 length)
+{
+    ENetChannel * channel = & peer -> channels [command -> header.channelID];
+    ENetOutgoingCommand * outgoingCommand;
+
+    peer -> outgoingDataTotal += command -> header.commandLength + length;
+
+    outgoingCommand = (ENetOutgoingCommand *) enet_malloc (sizeof (ENetOutgoingCommand));
+
+    if (command -> header.channelID == 0xFF)
+    {
+       ++ peer -> outgoingReliableSequenceNumber;
+
+       outgoingCommand -> reliableSequenceNumber = peer -> outgoingReliableSequenceNumber;
+       outgoingCommand -> unreliableSequenceNumber = 0;
+    }
+    else
+    if (command -> header.flags & ENET_PROTOCOL_FLAG_ACKNOWLEDGE)
+    {
+       ++ channel -> outgoingReliableSequenceNumber;
+       
+       outgoingCommand -> reliableSequenceNumber = channel -> outgoingReliableSequenceNumber;
+       outgoingCommand -> unreliableSequenceNumber = 0;
+    }
+    else
+    if (command -> header.flags & ENET_PROTOCOL_FLAG_UNSEQUENCED)
+    {
+       outgoingCommand -> reliableSequenceNumber = channel -> outgoingReliableSequenceNumber;
+       outgoingCommand -> unreliableSequenceNumber = 0;
+    }
+    else
+    {
+       ++ channel -> outgoingUnreliableSequenceNumber;
+        
+       outgoingCommand -> reliableSequenceNumber = channel -> outgoingReliableSequenceNumber;
+       outgoingCommand -> unreliableSequenceNumber = channel -> outgoingUnreliableSequenceNumber;
+    }
+   
+    outgoingCommand -> sentTime = 0;
+    outgoingCommand -> roundTripTimeout = 0;
+    outgoingCommand -> roundTripTimeoutLimit = 0;
+    outgoingCommand -> fragmentOffset = offset;
+    outgoingCommand -> fragmentLength = length;
+    outgoingCommand -> packet = packet;
+    outgoingCommand -> command = * command;
+    outgoingCommand -> command.header.reliableSequenceNumber = ENET_HOST_TO_NET_32 (outgoingCommand -> reliableSequenceNumber);
+
+    if (packet != NULL)
+      ++ packet -> referenceCount;
+
+    if (command -> header.flags & ENET_PROTOCOL_FLAG_ACKNOWLEDGE)
+      enet_list_insert (enet_list_end (& peer -> outgoingReliableCommands), outgoingCommand);
+    else
+      enet_list_insert (enet_list_end (& peer -> outgoingUnreliableCommands), outgoingCommand);
+
+    return outgoingCommand;
+}
+
+ENetIncomingCommand *
+enet_peer_queue_incoming_command (ENetPeer * peer, const ENetProtocol * command, ENetPacket * packet, enet_uint32 fragmentCount)
+{
+    ENetChannel * channel = & peer -> channels [command -> header.channelID];
+    enet_uint32 unreliableSequenceNumber = 0;
+    ENetIncomingCommand * incomingCommand;
+    ENetListIterator currentCommand;
+
+    switch (command -> header.command)
+    {
+    case ENET_PROTOCOL_COMMAND_SEND_RELIABLE:
+       for (currentCommand = enet_list_previous (enet_list_end (& channel -> incomingReliableCommands));
+            currentCommand != enet_list_end (& channel -> incomingReliableCommands);
+            currentCommand = enet_list_previous (currentCommand))
+       {
+          incomingCommand = (ENetIncomingCommand *) currentCommand;
+
+          if (incomingCommand -> reliableSequenceNumber <= command -> header.reliableSequenceNumber)
+          {
+             if (incomingCommand -> reliableSequenceNumber < command -> header.reliableSequenceNumber)
+               break;
+
+             goto freePacket;
+          }
+       }
+       break;
+
+    case ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE:
+       unreliableSequenceNumber = ENET_NET_TO_HOST_32 (command -> sendUnreliable.unreliableSequenceNumber);
+
+       if (command -> header.reliableSequenceNumber < channel -> incomingReliableSequenceNumber)
+         goto freePacket;
+
+       if (unreliableSequenceNumber <= channel -> incomingUnreliableSequenceNumber)
+         goto freePacket;
+
+       for (currentCommand = enet_list_previous (enet_list_end (& channel -> incomingUnreliableCommands));
+            currentCommand != enet_list_end (& channel -> incomingUnreliableCommands);
+            currentCommand = enet_list_previous (currentCommand))
+       {
+          incomingCommand = (ENetIncomingCommand *) currentCommand;
+
+          if (incomingCommand -> unreliableSequenceNumber <= unreliableSequenceNumber)
+          {
+             if (incomingCommand -> unreliableSequenceNumber < unreliableSequenceNumber)
+               break;
+
+             goto freePacket;
+          }
+       }
+       break;
+
+    case ENET_PROTOCOL_COMMAND_SEND_UNSEQUENCED:
+       currentCommand = enet_list_end (& channel -> incomingUnreliableCommands);
+       break;
+
+    default:
+       goto freePacket;
+    }
+
+    incomingCommand = (ENetIncomingCommand *) enet_malloc (sizeof (ENetIncomingCommand));
+
+    incomingCommand -> reliableSequenceNumber = command -> header.reliableSequenceNumber;
+    incomingCommand -> unreliableSequenceNumber = unreliableSequenceNumber;
+    incomingCommand -> command = * command;
+    incomingCommand -> fragmentCount = fragmentCount;
+    incomingCommand -> fragmentsRemaining = fragmentCount;
+    incomingCommand -> packet = packet;
+    incomingCommand -> fragments = NULL;
+    
+    if (fragmentCount > 0)
+    { 
+       incomingCommand -> fragments = (enet_uint32 *) enet_malloc ((fragmentCount + 31) / 32 * sizeof (enet_uint32));
+       memset (incomingCommand -> fragments, 0, (fragmentCount + 31) / 32 * sizeof (enet_uint32));
+    }
+
+    if (packet != NULL)
+      ++ packet -> referenceCount;
+
+    enet_list_insert (enet_list_next (currentCommand), incomingCommand);
+
+    return incomingCommand;
+
+freePacket:
+    if (packet != NULL)
+    {
+       if (packet -> referenceCount == 0)
+         enet_packet_destroy (packet);
+    }
+
+    return NULL;
+}
+
+/** @} */