Handle nocash footer embedding into nand

Another step the unlaunch installer does but wasn't being handled yet

arm9/src/main.c

@@ -8,6 +8,7 @@
 #include "unlaunch.h"
 #include "nitrofs.h"
 #include "deviceList.h"
+#include "nocashFooter.h"
 
 volatile bool programEnd = false;
 static volatile bool arm7Exiting = false;
@@ -22,7 +23,9 @@ static const char* splashSoundBinaryPatchPath = NULL;
 static const char* customBgPath = NULL;
 volatile bool charging = false;
 volatile u8 batteryLevel = 0;
-static bool wantsUnsafeUnlaunchUninstall = false;
+static bool advancedOptionsUnlocked = false;
+static bool needsNocashFooterToBeWritten = false;
+static NocashFooter computedNocashFooter;
 
 PrintConsole topScreen;
 PrintConsole bottomScreen;
@@ -35,6 +38,7 @@ enum {
 	MAIN_MENU_SAFE_UNLAUNCH_INSTALL,
 	MAIN_MENU_EXIT,
 	MAIN_MENU_SAFE_UNLAUNCH_UNINSTALL_NO_BACKUP,
+	MAIN_MENU_WRITE_NOCASH_FOOTER_ONLY,
 };
 
 static void setupScreens()
@@ -94,8 +98,11 @@ static int mainMenu(int cursor)
 	addMenuItem(m, soundPatchesStr, NULL, foundUnlaunchInstallerVersion == v2_0 && !disableAllPatches && splashSoundBinaryPatchPath != NULL, false);
 	addMenuItem(m, installUnlaunchStr, NULL, foundUnlaunchInstallerVersion != INVALID && !unlaunchFound, false);
 	addMenuItem(m, "Exit", NULL, true, false);
-	if(wantsUnsafeUnlaunchUninstall)
+	if(advancedOptionsUnlocked)
+	{
 		addMenuItem(m, "Uninstall unlaunch no backup", NULL, unlaunchFound, false);
+		addMenuItem(m, "Write nocash footer", NULL, needsNocashFooterToBeWritten, false);
+	}
 
 	m->cursor = cursor;
 
@@ -116,7 +123,7 @@ static int mainMenu(int cursor)
 		if (keysDown() & KEY_A)
 			break;
 
-		if(wantsUnsafeUnlaunchUninstall)
+		if(advancedOptionsUnlocked)
 			continue;
 
 		int held = keysHeld();
@@ -135,8 +142,9 @@ static int mainMenu(int cursor)
 		}
 		if (konamiCode == 5)
 		{
-			wantsUnsafeUnlaunchUninstall = true;
+			advancedOptionsUnlocked = true;
 			addMenuItem(m, "Uninstall unlaunch no backup", NULL, unlaunchFound, false);
+			addMenuItem(m, "Write nocash footer", NULL, needsNocashFooterToBeWritten, false);
 		}
 	}
 
@@ -189,6 +197,25 @@ int main(int argc, char **argv)
 		return 0;
 	}
 	
+	NocashFooter footer;
+	
+	nandio_read_nocash_footer(&footer);
+	nandio_construct_nocash_footer(&computedNocashFooter);
+	
+	if(!(needsNocashFooterToBeWritten = !isFooterValid(&footer)))
+	{
+		if(memcmp(&footer, &computedNocashFooter, sizeof(footer)) != 0)
+		{
+			messageBox("\x1B[31mError:\x1B[33m This console has a\n"
+						"nocash footer embedded in its\n"
+						"nand that doesn't match the one\n"
+						"generated.\n"
+						"The footer already present will\n"
+						"be overwritten.");
+			needsNocashFooterToBeWritten = true;
+		}
+	}
+	
 	while (batteryLevel < 7 && !charging)
 	{
 		if (choiceBox("\x1B[47mBattery is too low!\nPlease plug in the console.\n\nContinue?") == NO)
@@ -292,7 +319,18 @@ int main(int argc, char **argv)
 			case MAIN_MENU_SAFE_UNLAUNCH_UNINSTALL:
 			case MAIN_MENU_SAFE_UNLAUNCH_UNINSTALL_NO_BACKUP:
 				if(unlaunchFound && nandio_unlock_writing()) {
-					bool unsafeUninstall = wantsUnsafeUnlaunchUninstall && cursor == MAIN_MENU_SAFE_UNLAUNCH_UNINSTALL_NO_BACKUP;
+					bool unsafeUninstall = advancedOptionsUnlocked && cursor == MAIN_MENU_SAFE_UNLAUNCH_UNINSTALL_NO_BACKUP;
+					printf("Uninstalling");
+					if(needsNocashFooterToBeWritten)
+					{
+						printf("Writing nocash footer\n");
+						if(!nandio_write_nocash_footer(&computedNocashFooter))
+						{
+							messageBox("Failed to write nocash footer");
+							break;
+						}
+						needsNocashFooterToBeWritten = false;
+					}
 					if(uninstallUnlaunch(retailConsole, hnaaUnlaunchFound, retailLauncherTmdPath, unsafeUninstall))
 					{
 						messageBox("Uninstall successful!\n");
@@ -340,6 +378,16 @@ int main(int argc, char **argv)
 					&& nandio_unlock_writing())
 				{
 					printf("Installing\n");
+					if(needsNocashFooterToBeWritten)
+					{
+						printf("Writing nocash footer\n");
+						if(!nandio_write_nocash_footer(&computedNocashFooter))
+						{
+							messageBox("Failed to write nocash footer");
+							break;
+						}
+						needsNocashFooterToBeWritten = false;
+					}
 					if(installUnlaunch(retailConsole,
 										retailLauncherTmdPresentAndToBePatched ? retailLauncherTmdPath : NULL,
 										disableAllPatches,
@@ -357,6 +405,18 @@ int main(int argc, char **argv)
 				}
 				break;
 				
+			case MAIN_MENU_WRITE_NOCASH_FOOTER_ONLY:
+				if(needsNocashFooterToBeWritten)
+				{
+					if(!nandio_write_nocash_footer(&computedNocashFooter))
+					{
+						messageBox("Failed to write nocash footer");
+						break;
+					}
+					needsNocashFooterToBeWritten = false;
+				}
+				break;
+
 			case MAIN_MENU_EXIT:
 				programEnd = true;
 				break;

arm9/src/nand/nandio.c

@@ -10,6 +10,8 @@
 #include "nandio.h"
 #include "u128_math.h"
 
+#define NOCASH_FOOTER_SECTOR 2044
+
 /************************ Function Protoypes **********************************/
 
 static bool nandio_startup();
@@ -51,7 +53,16 @@ void nandio_set_fat_sig_fix(u32 offset)
 	fat_sig_fix_offset = offset;
 }
 
-static void getConsoleID(u8 *consoleID)
+void getCID(u8 *CID)
+{
+	vu8* CIDbuff = (vu8*)0x2FFD7BC;
+	for(int i = 0; i < 16; ++i)
+	{
+		CID[i] = CIDbuff[i];
+	}
+}
+
+void getConsoleID(u8 *consoleID)
 {
 	vu8 *fifo=(vu8*)0x02300000; //shared mem address that has our computed key3 stuff
 	u8 key[16]; //key3 normalkey - keyslot 3 is used for DSi/twln NAND crypto
@@ -89,6 +100,7 @@ static bool nandio_startup()
 
 	u8 consoleID[8];
 	u8 consoleIDfixed[8];
+	u8 CID[16];
 
 	// Get ConsoleID
 	getConsoleID(consoleID);
@@ -97,8 +109,10 @@ static bool nandio_startup()
 		consoleIDfixed[i] = consoleID[7-i];
 	}
 	
+	getCID(CID);
+	
 	// iprintf("sector 0 is %s\n", is3DS ? "3DS" : "DSi");
-	dsi_crypt_init((const u8*)consoleIDfixed, (const u8*)0x2FFD7BC, is3DS);
+	dsi_crypt_init((const u8*)consoleIDfixed, (const u8*)CID, is3DS);
 	dsi_nand_crypt(sector_buf, sector_buf, 0, SECTOR_SIZE / AES_BLOCK_SIZE);
 
 	parse_mbr(sector_buf, is3DS);
@@ -144,6 +158,49 @@ static bool read_sectors(sec_t start, sec_t len, void *buffer)
 	}
 }
 
+void nandio_construct_nocash_footer(NocashFooter* footer)
+{	
+	u8 CID[16];
+	u8 consoleID[8];
+	
+	getCID(CID);
+	getConsoleID(consoleID);
+	
+	constructNocashFooter(footer, CID, consoleID);
+}
+
+bool nandio_read_nocash_footer(NocashFooter* footer)
+{
+	if(!nand_ReadSectors(NOCASH_FOOTER_SECTOR, 1, crypt_buf))
+	{
+		return false;
+	}
+	
+	memcpy(footer, crypt_buf, sizeof(NocashFooter));
+	return true;
+}
+
+bool nandio_write_nocash_footer(NocashFooter* footer)
+{
+	if (writingLocked)
+		return false;
+	
+	if(!nand_ReadSectors(NOCASH_FOOTER_SECTOR, 1, crypt_buf))
+	{
+		return false;
+	}
+	
+	memcpy(crypt_buf, footer, sizeof(NocashFooter));
+	
+	
+	if(!nand_WriteSectors(NOCASH_FOOTER_SECTOR, 1, crypt_buf))
+	{
+		return false;
+	}
+	
+	return true;
+}
+
 // len is guaranteed <= CRYPT_BUF_LEN
 static bool write_sectors(sec_t start, sec_t len, const void *buffer)
 {

arm9/src/nand/nandio.h

@@ -2,6 +2,7 @@
 
 #include <stdint.h>
 #include <nds/disc_io.h>
+#include "../nocashFooter.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -26,6 +27,10 @@ extern bool nandio_unlock_writing();
 extern bool nandio_force_fat_fix();
 extern void nandio_synchronize_fats();
 
+extern void nandio_construct_nocash_footer(NocashFooter* footer);
+extern bool nandio_read_nocash_footer(NocashFooter* footer);
+extern bool nandio_write_nocash_footer(NocashFooter* footer);
+
 #ifdef __cplusplus
 }
 #endif

arm9/src/nocashFooter.c

@@ -0,0 +1,17 @@
+#include "nocashFooter.h"
+#include <string.h>
+
+static const char* nocashMagicString = "DSi eMMC CID/CPU";
+
+bool isFooterValid(const NocashFooter* footer)
+{
+	return memcmp(nocashMagicString, footer->footerID, sizeof(footer->footerID)) == 0;
+}
+
+void constructNocashFooter(NocashFooter* footer, const u8* CID, const u8* consoleID)
+{
+	memset(footer, 0, sizeof(NocashFooter));
+	memcpy(footer->footerID, nocashMagicString, sizeof(footer->footerID));
+	memcpy(footer->CID, CID, sizeof(footer->CID));
+	memcpy(footer->consoleId, consoleID, sizeof(footer->consoleId));
+}

arm9/src/nocashFooter.h

@@ -0,0 +1,23 @@
+#ifndef NOCASH_FOOTER_H
+#define NOCASH_FOOTER_H
+#include <nds/ndstypes.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct NocashFooter {
+	char footerID[16]; //DSi eMMC CID/CPU
+	u8 CID[16];
+	u8 consoleId[8];
+	u8 pad[0x18];
+} NocashFooter;
+
+bool isFooterValid(const NocashFooter* footer);
+void constructNocashFooter(NocashFooter* footer, const u8* CID, const u8* consoleID);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif