initial commit

1 files changed, 479 insertions, 0 deletions

diff --git a/ipchanger.cc b/ipchanger.cc
new file mode 100644
index 0000000..db1d546
--- /dev/null
+++ b/ipchanger.cc
@@ -0,0 +1,479 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define WIN32_LEAN_AND_MEAN 1
+#include <windows.h>
+
+#define NARRAY(Array) (int)(sizeof(Array) / sizeof(Array[0]))
+
+typedef uint8_t uint8;
+typedef uintptr_t uintptr;
+
+struct ServerEntry{
+	ServerEntry *Next;
+	int Version;
+	char Alias[100];
+	char HostName[100];
+	int Port;
+	char RsaModulus[1024];
+};
+
+struct TibiaVersion{
+	int Version;
+	const char *VersionString;
+	int NumLoginEndpoints;
+	int LoginEndpointStride;
+	int MaxHostNameSize;
+	int MaxRsaModulusSize;
+	uintptr VersionStringAddr;
+	uintptr FirstLoginHostNameAddr;
+	uintptr FirstLoginPortAddr;
+	uintptr RsaModulusAddr;
+};
+
+struct AutoHandleClose{
+private:
+	HANDLE m_Handle;
+
+public:
+	AutoHandleClose(HANDLE Handle){
+		m_Handle = Handle;
+	}
+
+	~AutoHandleClose(void){
+		if(m_Handle != NULL){
+			CloseHandle(m_Handle);
+		}
+	}
+};
+
+bool StringEqN(const char *A, const char *B, int N){
+	int Index = 0;
+	while(true){
+		if(Index >= N){
+			return true;
+		}else if(A[Index] != B[Index] || A[Index] == 0){
+			return false;
+		}
+		Index += 1;
+	}
+}
+
+bool StringEqCI(const char *A, const char *B){
+	int Index = 0;
+	while(true){
+		if(tolower(A[Index]) != tolower(B[Index])){
+			return false;
+		}else if(A[Index] == 0){
+			return true;
+		}
+		Index += 1;
+	}
+}
+
+void PrintLastError(const char *Context){
+	DWORD ErrorCode = GetLastError();
+	char ErrorString[256];
+	DWORD Ret = FormatMessageA(
+		FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+		NULL, ErrorCode, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+		ErrorString, sizeof(ErrorString), NULL);
+	if(Ret == 0){
+		strcpy(ErrorString, "unknown error");
+	}
+	printf("%s | error(%d): %s\n", Context, ErrorCode, ErrorString);
+}
+
+void DebugPrintBuf(uintptr Address, const uint8 *Buffer, int Count){
+	const int BytesPerLine = 16;
+	int FullLines = Count / BytesPerLine;
+	int Remainder = Count % BytesPerLine;
+
+	for(int i = 0; i < FullLines; i += 1){
+		printf("%16llX | ", (Address + i * BytesPerLine));
+
+		for(int j = 0; j < BytesPerLine; j += 1){
+			if(j > 0) putchar(' ');
+			printf("%02X", Buffer[i * BytesPerLine + j]);
+		}
+
+		printf(" | ");
+
+		for(int j = 0; j < BytesPerLine; j += 1){
+			int ch = Buffer[i * BytesPerLine + j];
+			printf("%c", isprint(ch) ? ch : '.');
+		}
+
+		putchar('\n');
+	}
+
+	if(Remainder > 0){
+		printf("%16llX | ", (Address + FullLines * BytesPerLine));
+
+		for(int j = 0; j < BytesPerLine; j += 1){
+			if(j > 0) putchar(' ');
+			if(j < Remainder){
+				printf("%02X", Buffer[FullLines * BytesPerLine + j]);
+			}else{
+				printf("  ");
+			}
+		}
+
+		printf(" | ");
+
+		for(int j = 0; j < BytesPerLine; j += 1){
+			if(j < Remainder){
+				int ch = Buffer[FullLines * BytesPerLine + j];
+				printf("%c", isprint(ch) ? ch : '.');
+			}else{
+				printf(" ");
+			}
+		}
+
+		putchar('\n');
+	}
+}
+
+bool ChangeIP(const TibiaVersion *V, const char *HostName, int Port, const char *RsaModulus){
+	int HostNameSize = (int)strlen(HostName) + 1;
+	if(HostNameSize > V->MaxHostNameSize){
+		printf("ChangeIP: HostName size exceeds limit for version %d (%d > %d).\n",
+				V->Version, HostNameSize, V->MaxHostNameSize);
+		return false;
+	}
+
+	if(Port <= 0 || Port > 0xFFFF){
+		printf("ChangeIP: Invalid port number %d.\n", Port);
+		return false;
+	}
+
+	HWND Window = FindWindowA("TibiaClient", NULL);
+	if(Window == NULL){
+		printf("ChangeIP: No client running.\n");
+		return false;
+	}
+
+	DWORD ProcessID;
+	GetWindowThreadProcessId(Window, &ProcessID);
+
+	HANDLE Process = OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_READ | PROCESS_VM_WRITE, FALSE, ProcessID);
+	if(Process == NULL){
+		PrintLastError("OpenProcess");
+		return false;
+	}
+
+	AutoHandleClose HandleClose(Process);
+	if(V->VersionString != NULL && V->VersionStringAddr != 0){
+		uint8 VersionString[128];
+		if(!ReadProcessMemory(Process, (void*)V->VersionStringAddr,
+				VersionString, sizeof(VersionString), NULL)){
+			PrintLastError("ReadProcessMemory(VersionString)");
+			return false;
+		}
+
+		int VersionStringLen = (int)strlen(V->VersionString);
+		if(!StringEqN(V->VersionString, (char*)VersionString, VersionStringLen)){
+			printf("ChangeIP: Invalid client version.\n");
+			return false;
+		}
+	}
+
+	if(V->FirstLoginHostNameAddr != 0 && V->FirstLoginPortAddr != 0){
+		uint8 HelpPort[4];
+		HelpPort[0] = (uint8)(Port >>  0);
+		HelpPort[1] = (uint8)(Port >>  8);
+		HelpPort[2] = (uint8)(Port >> 16);
+		HelpPort[3] = (uint8)(Port >> 24);
+
+		for(int i = 0; i < V->NumLoginEndpoints; i += 1){
+			uintptr HostNameAddr = V->FirstLoginHostNameAddr + i * V->LoginEndpointStride;
+			uintptr PortAddr     = V->FirstLoginPortAddr     + i * V->LoginEndpointStride;
+
+			if(!WriteProcessMemory(Process, (void*)HostNameAddr, HostName, HostNameSize, NULL)){
+				PrintLastError("WriteProcessMemory(HostName)");
+				return false;
+			}
+
+			if(!WriteProcessMemory(Process, (void*)PortAddr, HelpPort, sizeof(HelpPort), NULL)){
+				PrintLastError("WriteProcessMemory(Port)");
+				return false;
+			}
+		}
+	}
+
+	if(RsaModulus != NULL && V->RsaModulusAddr != 0){
+		int RsaModulusSize = (int)strlen(RsaModulus) + 1;
+		if(RsaModulusSize > V->MaxRsaModulusSize){
+			printf("ChangeIP: RsaModulus size exceeds limit for version %d (%d > %d).\n",
+					V->Version, RsaModulusSize, V->MaxRsaModulusSize);
+			return false;
+		}
+
+		// NOTE(fusion): The RSA modulus lives in READONLY memory.
+		DWORD OldProtection;
+		if(!VirtualProtectEx(Process, (void*)V->RsaModulusAddr,
+				V->MaxRsaModulusSize, PAGE_READWRITE, &OldProtection)){
+			PrintLastError("VirtualProtectEx(RsaModulus, READWRITE)");
+			return false;
+		}
+
+		if(!WriteProcessMemory(Process, (void*)V->RsaModulusAddr, RsaModulus, RsaModulusSize, NULL)){
+			PrintLastError("WriteProcessMemory(RsaModulus)");
+			return false;
+		}
+
+		DWORD Dummy;
+		if(!VirtualProtectEx(Process, (void*)V->RsaModulusAddr,
+				V->MaxRsaModulusSize, OldProtection, &Dummy)){
+			PrintLastError("VirtualProtectEx(RsaModulus, OldProtection)");
+			return false;
+		}
+	}
+
+	return true;
+}
+
+int ReadLine(FILE *File, char *Buffer, int BufferSize, bool *OutEndOfFile, bool *OutClamped){
+	int LineSize = 0;
+	bool EndOfFile = false;
+	bool Clamped = false;
+	while(true){
+		int ch = fgetc(File);
+		if(ch == EOF || ch == '\n'){
+			EndOfFile = (ch == EOF);
+			break;
+		}
+
+		if(LineSize < BufferSize){
+			Buffer[LineSize] = (char)ch;
+		}
+
+		LineSize += 1;
+	}
+
+	if(LineSize >= BufferSize){
+		LineSize = BufferSize - 1;
+		Clamped = true;
+	}
+
+	if(!EndOfFile && LineSize > 0 && Buffer[LineSize - 1] == '\r'){
+		LineSize -= 1;
+	}
+
+	Buffer[LineSize] = 0;
+	if(OutEndOfFile) *OutEndOfFile = EndOfFile;
+	if(OutClamped) *OutClamped = Clamped;
+	return LineSize;
+}
+
+void NextValue(const char *Line, int Delim, int *Cursor, char *Buffer, int BufferSize){
+	int Size = 0;
+	while(Line[*Cursor] != 0 && Line[*Cursor] != Delim){
+		if(Size < BufferSize){
+			Buffer[Size] = Line[*Cursor];
+		}
+
+		*Cursor += 1;
+		Size += 1;
+	}
+
+	if(Line[*Cursor] != 0){
+		*Cursor += 1;
+	}
+
+	if(Size >= BufferSize){
+		Size = BufferSize - 1;
+	}
+
+	Buffer[Size] = 0;
+}
+
+ServerEntry *ParseServerEntry(const char *Line, int LineNumber){
+	int LineStart = 0;
+	while(Line[LineStart] != 0 && isspace(Line[LineStart])){
+		LineStart += 1;
+	}
+
+	if(Line[LineStart] == 0 || Line[LineStart] == '#'){
+		return NULL;
+	}
+
+	char HelpVersion[16];
+	char HelpPort[16];
+	int Cursor = LineStart;
+	ServerEntry *Server = (ServerEntry*)calloc(1, sizeof(ServerEntry));
+	NextValue(Line, ';', &Cursor, HelpVersion, sizeof(HelpVersion));
+	NextValue(Line, ';', &Cursor, Server->Alias, sizeof(Server->Alias));
+	NextValue(Line, ';', &Cursor, Server->HostName, sizeof(Server->HostName));
+	NextValue(Line, ';', &Cursor, HelpPort, sizeof(HelpPort));
+	NextValue(Line, ';', &Cursor, Server->RsaModulus, sizeof(Server->RsaModulus));
+	Server->Version = atoi(HelpVersion);
+	Server->Port = atoi(HelpPort);
+	return Server;
+}
+
+ServerEntry *ReadServerList(const char *FileName){
+	FILE *File = fopen(FileName, "r");
+	if(File == NULL){
+		printf("ReadServerList: Failed to open \"%s\" for reading.\n", FileName);
+		return NULL;
+	}
+
+	ServerEntry *ServerList = NULL;
+	for(int LineNumber = 1; true; LineNumber += 1){
+		char Line[4096];
+		bool EndOfFile;
+		bool Clamped;
+		int LineSize = ReadLine(File, Line, sizeof(Line), &EndOfFile, &Clamped);
+		if(LineSize > 0){
+			ServerEntry *Server = ParseServerEntry(Line, LineNumber);
+			if(Server){
+				Server->Next = ServerList;
+				ServerList = Server;
+			}
+		}
+
+		if(EndOfFile){
+			break;
+		}
+	}
+
+	fclose(File);
+	return ServerList;
+}
+
+void CreateSampleServerList(const char *FileName){
+	FILE *File = fopen(FileName, "w");
+	if(File == NULL){
+		printf("CreateSampleServerList: Failed to open \"%s\" for writing.\n", FileName);
+		return;
+	}
+
+	fprintf(File,
+		"# Each server entry should be in a SINGLE line and have the\n"
+		"# format \"VERSION;ALIAS;HOSTNAME;PORT;RSAMODULUS\". Empty\n"
+		"# lines and lines starting with # are discarded. The server\n"
+		"# alias may be empty, meaning you'll need to specify its\n"
+		"# host name instead. For versions without RSA encryption,\n"
+		"# the RSA modulus is ignored.\n"
+		"\n"
+		"# Example for the default 7.7 tibia login server:\n"
+		"770;tibia;server.tibia.com;7171;"
+			"1429962396241639952007017738289889555079540334546615321747051608"
+			"2934737582776038882967213386204600674145392845853859217990626450"
+			"9724520840657286865659265687630979195970404721891201847792002125"
+			"5354012927791239372074475745966927885136471792353355293072513505"
+			"70728407373705564708871762033017096809910315212883967\n"
+		"\n"
+		"# Example for a regular 8.6 otserv:\n"
+		"860;otserv;server.otserv.com;7171;"
+			"1091201329673994292788609605089955415282375029027981291234687579"
+			"3726629149257644633073969600111060390723088861007265581882535850"
+			"3429057592827629436413108566029093628212635953836686562675849720"
+			"6207862794310902180176810615217550567108238764764442605581471797"
+			"07119674283982419152118103759076030616683978566631413\n");
+
+	fclose(File);
+}
+
+int main(int argc, char **argv){
+	// TODO(fusion): This could be loaded at runtime from some `versions.txt` file.
+	static const TibiaVersion Versions[] = {
+		{
+			770,				// Version
+			"Version 7.7",		// VersionString
+			5,					// NumLoginEndpoints
+			112,				// LoginEndpointStride
+			100,				// MaxHostNameSize
+			312,				// MaxRsaModulusSize
+			0x51765D,			// VersionStringAddr
+			0x6BB2F0,			// FirstLoginHostNameAddr
+			0x6BB354,			// FirstLoginPortAddr
+			0x516620,			// RsaModulusAddr
+		},
+		{
+			810,				// Version
+			"Version 8.10",		// VersionString
+			10,					// NumLoginEndpoints
+			112,				// LoginEndpointStride
+			100,				// MaxHostNameSize
+			312,				// MaxRsaModulusSize
+			0x61B64D,			// VersionStringAddr
+			0x763BB8,			// FirstLoginHostNameAddr
+			0x763C1C,			// FirstLoginPortAddr
+			0x597610,			// RsaModulusAddr
+		},
+		{
+			860,				// Version
+			"Version 8.60",		// VersionString
+			10,					// NumLoginEndpoints
+			112,				// LoginEndpointStride
+			100,				// MaxHostNameSize
+			312,				// MaxRsaModulusSize
+			0x64C2AD,			// VersionStringAddr
+			0x7947F8,			// FirstLoginHostNameAddr
+			0x79485C,			// FirstLoginPortAddr
+			0x5B8980,			// RsaModulusAddr
+		},
+	};
+
+	if(argc <= 1 || argv[1][0] == 0 || argv[1][0] == '-'){
+		if(argc > 1 && StringEqCI(argv[1], "-sample")){
+			CreateSampleServerList("servers.txt");
+			printf("The file `server.txt` was created/rewritten with"
+					" instructions on how to add or modify servers.\n");
+		}else{
+			printf(
+				"USAGE: ipchanger.exe ALIAS|HOSTNAME    # modify client\n"
+				"       ipchanger.exe -sample           # create/reset `servers.txt`\n"
+				"       ipchanger.exe -help             # print this message\n");
+		}
+		return EXIT_FAILURE;
+	}
+
+	ServerEntry *ServerList = ReadServerList("servers.txt");
+	if(ServerList == NULL){
+		printf("No server information was found.\n");
+		return EXIT_FAILURE;
+	}
+
+	ServerEntry *Server = ServerList;
+	const char *AliasOrHostName = argv[1];
+	while(Server != NULL){
+		if(StringEqCI(Server->Alias, AliasOrHostName)
+		|| StringEqCI(Server->HostName, AliasOrHostName)){
+			break;
+		}
+
+		Server = Server->Next;
+	}
+
+	if(Server == NULL){
+		printf("No server with alias or hostname \"%s\" found.\n", AliasOrHostName);
+		return EXIT_FAILURE;
+	}
+
+	const TibiaVersion *Version = NULL;
+	for(int i = 0; i < NARRAY(Versions); i += 1){
+		if(Versions[i].Version == Server->Version){
+			Version = &Versions[i];
+			break;
+		}
+	}
+
+	if(Version == NULL){
+		printf("Server \"%s\" is defined with version %d which is not"
+				" currently supported.\n", AliasOrHostName, Version->Version);
+		return EXIT_FAILURE;
+	}
+
+	if(!ChangeIP(Version, Server->HostName, Server->Port, Server->RsaModulus)){
+		printf("There was a problem with changing the client's IP.\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("Client is now configured to connect to %s:%d.\n", Server->HostName, Server->Port);
+	return EXIT_SUCCESS;
+}