/*
 *  Collin's Binary Instrumentation Tool/Framework for Android
 *  Collin Mulliner <collin[at]mulliner.org>
 *  http://www.mulliner.org/android/
 *
 *  (c) 2012
 *
 *  License: GPL v2
 *
 */

#define _GNU_SOURCE

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <string.h>
#include <termios.h>


#include "phNfcStatus.h"
#include "phNfcTypes.h"
#include "phLibNfc.h"
#include "phFriNfc_NdefMap.h"

#include "util.h"
#include "libt.h"

// autogenerated
#include "hijacks.h"

int msgsend;

// communication socket, a pty :)
int coms;

void __attribute__ ((constructor)) my_init(void);

void my_cacheflush(unsigned int begin, unsigned int end)
{	
	const int syscall = 0xf0002;
	__asm __volatile (
		"mov	 r0, %0\n"			
		"mov	 r1, %1\n"
		"mov	 r7, %2\n"
		"mov     r2, #0x0\n"
		"svc     0x00000000\n"
		:
		:	"r" (begin), "r" (end), "r" (syscall)
		:	"r0", "r1", "r7"
		);
}

// -----------------------------------------------------------

int hook(struct hook_t *h, int pid, char *libname, char *funcname, void *hookf)
{
	unsigned long int addr;
	int i;

	if (find_name(pid, funcname, libname, &addr) < 0) {
		log("can't find: %s\n", funcname)
		return 0;
	}
	
	log("hooking   %s = %x  hook = %x  target:", funcname, addr, hookf)
	strncpy(h->name, funcname, sizeof(h->name)-1);
	
	if (addr % 4 == 0) {
		log("ARM\n")
		h->thumb = 0;
		h->patch = (unsigned int)hookf;
		h->orig = addr;
		h->jump[0] = 0xe59ff000; // LDR pc, [pc, #0]
		h->jump[1] = h->patch;
		h->jump[2] = h->patch;
		for (i = 0; i < 3; i++)
			h->store[i] = ((int*)h->orig)[i];
		for (i = 0; i < 3; i++)
			((int*)h->orig)[i] = h->jump[i];
	}
	else {
		h->thumb = 1;
		log("THUMB\n")
		h->patch = (unsigned int)hookf;
		h->orig = addr;	
		h->jumpt[1] = 0xb4;
		h->jumpt[0] = 0x30; // push {r4,r5}
		h->jumpt[3] = 0xa5;
		h->jumpt[2] = 0x03; // add r5, pc, #12
		h->jumpt[5] = 0x68;
		h->jumpt[4] = 0x2d; // ldr r5, [r5]
		h->jumpt[7] = 0xb0;
		h->jumpt[6] = 0x02; // add sp,sp,#8
		h->jumpt[9] = 0xb4;
		h->jumpt[8] = 0x20; // push {r5}
		h->jumpt[11] = 0xb0;
		h->jumpt[10] = 0x81; // sub sp,sp,#4
		h->jumpt[13] = 0xbd;
		h->jumpt[12] = 0x20; // pop {r5, pc}
		h->jumpt[15] = 0x46;
		h->jumpt[14] = 0xaf; // mov pc, r5 ; just to pad to 4 byte boundary
		memcpy(&h->jumpt[16], (unsigned char*)&h->patch, sizeof(unsigned int));
		unsigned int orig = addr - 1; // sub 1 to get real address
		for (i = 0; i < 20; i++) {
			h->storet[i] = ((unsigned char*)orig)[i];
			log("%0.2x ", h->storet[i])
		}
		log("\n")
		for (i = 0; i < 20; i++) {
			((unsigned char*)orig)[i] = h->jumpt[i];
			log("%0.2x ", ((unsigned char*)orig)[i])
		}
	}
	my_cacheflush((unsigned int)h->orig, (unsigned int)h->orig+12);
	return 1;
}

void hook_precall(struct hook_t *h)
{
	int i;
	
	if (h->thumb) {
		unsigned int orig = h->orig - 1;
		for (i = 0; i < 12; i++) {
			((unsigned char*)orig)[i] = h->storet[i];
		}
	}
	else {
		for (i = 0; i < 3; i++)
			((int*)h->orig)[i] = h->store[i];
	}
	
	my_cacheflush((unsigned int)h->orig, (unsigned int)h->orig+12);
}

void hook_postcall(struct hook_t *h)
{
	int i;
	
	if (h->thumb) {
		unsigned int orig = h->orig - 1;
		for (i = 0; i < 12; i++)
			((unsigned char*)orig)[i] = h->jumpt[i];
	}
	else {
		for (i = 0; i < 3; i++)
			((int*)h->orig)[i] = h->jump[i];
	}
		
	my_cacheflush((unsigned int)h->orig, (unsigned int)h->orig+12);	
}

void unhook(struct hook_t *h)
{
	log("unhooking %s = %x  hook = %x ", h->name, h->orig, h->patch)
	hook_precall(h);
}

extern int ifc_start();

void start_coms()
{
	// workaround for missing socket permission :)
	coms = open("/dev/ptmx", O_RDWR|O_NOCTTY);
	if (coms <= 0)
		log("posix_openpt failed\n")
	else
		log("pt ok\n")
	if (unlockpt(coms) < 0)
		log("unlockpt failed\n")
	log("pty name: %s\n", ptsname(coms))
	
	struct termios  ios;
    tcgetattr(coms, &ios);
    ios.c_lflag = 0;  /* disable ECHO, ICANON, etc... */
    tcsetattr(coms, TCSANOW, &ios);
}

void my_init()
{
	log("libt loaded...\n")
	
	int pid = getpid();
	fake_card_state = 0;
	
	HOOK_phLibNfc_Ndef_Read
	HOOK_phLibNfc_RemoteDev_CheckPresence
	HOOK_phLibNfc_RemoteDev_NtfRegister
	HOOK_phLibNfc_RemoteDev_Connect
	HOOK_phLibNfc_Ndef_CheckNdef
	HOOK_phLibNfc_Mgt_ConfigureDiscovery
	HOOK_phDal4Nfc_msgrcv
	//HOOK_nfc_jni_get_technology_tree
	
	find_name(pid, "phDal4Nfc_msgsnd", "libnfc", &msgsend);
	log("msgsend = %x\n", msgsend)

	ifc_start();
	start_coms();

	log("libt init done.\n")
}