LightMessaging

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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.

Examples

External links