LightMessaging is an inter-process communication header-only library by Ryan Petrich. According to its GitHub page, it is a "simple low-level replacement for CFMessagePort".
How to use this library
Headers are available from LightMessaging's GitHub project. If using Theos, place the headers in $THEOS/include/LightMessaging.
Include directive
#import <LightMessaging/LightMessaging.h>
RocketBootstrap
LightMessaging uses RocketBootstrap by default, so be sure to have it set up (instructions here). To have LightMessaging **not** use RBS, add the following directive before including the LM header:
#define LIGHTMESSAGING_USE_ROCKETBOOTSTRAP 0
Server
It is recommended that this is done in somewhere better designed to act as a server, such as SpringBoard or a daemon.
The Callback
void some_callback(CFMachPortRef port,
LMMessage *request,
CFIndex size,
void *info)
{
// get the reply port
mach_port_t replyPort = request->head.msgh_remote_port;
// sanity check
if (size < sizeof(LMMessage)) {
LMSendReply(replyPort, NULL, 0);
LMResponseBufferFree((LMResponseBuffer *)request);
return;
}
// get the data you recieved
void *data = LMMessageGetData(request);
// send some data back
const char *msg = "lol";
LMSendReply(replyPort, msg, strlen(msg) + 1);
// free the response buffer??
LMResponseBufferFree((LMResponseBuffer *)request);
}
Starting the Server
LMStartService("net.iphonedevwiki.some.server", CFRunLoopGetCurrent(), (CFMachPortCallBack)some_callback);
Client
This can be run anywhere that has the appropriate permissions to send/receive data on a message port.
// setup connection
LMConnection connection = {
MACH_PORT_NULL,
"net.iphonedevwiki.some.server"
};
//send message
LMResponseBuffer buffer;
const char *msg = "lol wtf";
SInt32 messageId = 0x1111; // this is arbitrary i think
LMConnectionSendTwoWay(&connection, messageId, msg, strlen(msg) + 1, &buffer);
LMMessage *response = &(buffer.message);
// do whatever you want !!!!
const char *data = LMMessageGetData(response);
Type helpers
There are some cool helper functions for if you want to send Images / PropertyLists / etc instead of just strings. Look at the header file or other examples to see how to use them.