[Tutorial] Handlers - Pawn.RakNet

• Handlers - Pawn.RakNet

Other Pawn.RakNet tutorials: RPC - Pawn.RakNet | Packets - Pawn.RakNet

With handlers, you can assign a callback to handle packets and RPCs. Basically, it would be the same as using them in the main callbacks (OnIncomingRPC/Packet and OnOutcomingRPC/Packet), except only the RPC/Packet you assigned to that specific callback will reach it.

Handler types:

-PR_INCOMING_RPC: RPCs sent by the client to the server.
-PR_INCOMING_PACKET: Packets sent by client to the server.
-PR_OUTCOMING_RPC: RPCs sent by the server to the cliente.
-PR_OUTCOMING_PACKET: Packets sent by the server to the client.

Function:

Code:

---

PR_RegHandler(id, const publicname[], PR_HandlerType:type)

---

id - The packet/RPC id you are going to create the handler for.
publicname - Callback used by the handler.
type - Handler type.

• Creating a handler

To create a handler is pretty simple. Take into account that the handler's callback must have two parameters, one for the player receiving/sending the packet/RPC (playerid) and another one for the BitStream (BitStream:bs).

PHP Code:

---

#define ID_PLAYER_SYNC  207

public OnGameModeInit()
{
    PR_RegHandler(ID_PLAYER_SYNC, "OnFootSync", PR_INCOMING_PACKET);
    return 1;
}

forward OnFootSync(playerid, BitStream:bs);
public OnFootSync(playerid, BitStream:bs)
{
    new On_FootSync[PR_OnFootSync];

    BS_IgnoreBits(bs, 8);
    BS_ReadOnFootSync(bs, On_FootSync);

    printf("My weapon id is: %i", On_FootSync[PR_weaponId]);
    return 1;
} 


---

The example above is pretty easy to understand, we can manipulate the packet 207 (on foot sync) through OnFootSync callback.

I'm not going to explain why you should ignore 8 bits, that is something I explained in my last Pawn.RakNet tutorial about packets. I recommend you to read my last two tutorials about RPCs and Packets before reading this thread.

• Errors related with handlers

These are two errors that might show up in your logs/console:

n_PR_RegHandler: Public "YourCallbackName" does not exist. - Pretty obvious, the callback you assigned to your handler does not exist.

n_PR_RegHandler: invalid array(T, N) subscript - Your RPC/Packet ID is undefined. For example, your RPC id is above MAX_RPC_MAP_SIZE (254) which is undefined/invalid.

• Considerations

- Take into account that OnIncomingPacket/RPC and OnOutcomingPacket/RPC callbacks will always be called before any handler's callback. So, if you return 0 in the main callbacks, handler callbacks won't be called. The same applies to other handlers, if you have two handlers for the same packet and return 0 in the one you created first, the other one's callback won't be called as well.

-If you create a handler and not assign any callback to it (leave the 2nd parameter empty/null), the server will crash.