implement `crypto.cc` with OpenSSL + fix config loading

  I considered reversing the original `vlong` implementation but
OpenSSL is just simpler, more secure, and most importantly, is
already there. I also made it so the key is now stored in a PEM
file (`tibia.pem`) so it can be easily swapped without re-compiling.

  This was the last piece to build and run a working executable,
except that we now need to implement a query manager for the server
to communicate with. I was able to fix a small problem with loading
the config before hitting the problem with the query manager, which
was expected.

  The next task should be getting a query manager up and running
before starting phase two of upgrading and fixing the server itself.

6 files changed, 120 insertions, 49 deletions

diff --git a/src/communication.cc b/src/communication.cc
index 9f0e6e5..a15e20a 100644
--- a/src/communication.cc
+++ b/src/communication.cc
@@ -23,16 +23,6 @@
 #define MAX_COMMUNICATION_THREADS 1100
 #define COMMUNICATION_THREAD_STACK_SIZE ((int)KB(64))
 
-static const char RSA_PRIME_P[] =
-		"1201758001370723323398753778257470257713354828752713123415294815"
-		"0506251412291888866940292054989907714155267326586216043845592229"
-		"084368540020196135619327879";
-
-static const char RSA_PRIME_Q[] =
-		"1189892136861686835188050824611210139447876026576932541274639840"
-		"5473436969889506919017477758618276066588858607419440134394668095"
-		"105156501566867770737187273";
-
 static int TERMINALVERSION[3] = {770, 770, 770};
 static int TCPSocket;
 static ThreadHandle AcceptorThread;
@@ -1533,7 +1523,9 @@ void InitCommunication(void){
 	AcceptorThreadPID = 0;
 	ActiveConnections = 0;
 	QueryManagerConnectionPool.init();
-	PrivateKey.init(RSA_PRIME_P, RSA_PRIME_Q);
+
+	// TODO(fusion): This is arbitrary, should probably be set in the config.
+	PrivateKey.initFromFile("tibia.pem");
 
 	OpenSocket();
 	if(TCPSocket == -1){
diff --git a/src/config.cc b/src/config.cc
index 257985b..b9c33bc 100644
--- a/src/config.cc
+++ b/src/config.cc
@@ -106,6 +106,7 @@ void ReadConfig(void){
 	MANAGER_DATABASE.Database[0] = 0;
 
 	char FileName[4096];
+#if 0
 	if(const char *Home = getenv("home")){
 		snprintf(FileName, sizeof(FileName), "%s/.tibia", Home);
 	}else if(const char *Home = getenv("HOME")){
@@ -113,6 +114,9 @@ void ReadConfig(void){
 	}else{
 		snprintf(FileName, sizeof(FileName), ".tibia");
 	}
+#else
+	snprintf(FileName, sizeof(FileName), ".tibia");
+#endif
 
 	if(!FileExists(FileName)){
 		throw "cannot find config-file";
@@ -130,7 +134,7 @@ void ReadConfig(void){
 		}
 
 		char Identifier[MAX_IDENT_LENGTH];
-		strcpy(Identifier, Script.readIdentifier());
+		strcpy(Identifier, Script.getIdentifier());
 		Script.readSymbol('=');
 
 		// TODO(fusion): Ughh... Get rid of all `strcpy`s. A malicious configuration
diff --git a/src/crypto.cc b/src/crypto.cc
index b6df866..aa53dc3 100644
--- a/src/crypto.cc
+++ b/src/crypto.cc
@@ -1,3 +1,108 @@
 #include "crypto.hh"
 
-// TODO
+#include <openssl/err.h>
+#include <openssl/pem.h>
+
+static void DumpOpenSSLErrors(const char *Where, const char *What){
+	error("OpenSSL error(s) while executing %s at %s:\n", What, Where);
+	ERR_print_errors_cb(
+		[](const char *str, usize len, void *u) -> int {
+			// NOTE(fusion): These error strings already have trailing newlines,
+			// for whatever reason.
+			error("> %s", str);
+			return 1;
+		}, NULL);
+}
+
+// TRSAPrivateKey
+// =============================================================================
+TRSAPrivateKey::TRSAPrivateKey(void){
+	m_RSA = NULL;
+}
+
+TRSAPrivateKey::~TRSAPrivateKey(void){
+	if(m_RSA){
+		RSA_free(m_RSA);
+		m_RSA = NULL;
+	}
+}
+
+void TRSAPrivateKey::initFromFile(const char *FileName){
+	if(m_RSA != NULL){
+		error("TRSAPrivateKey::init: Key already initialized.\n");
+		return;
+	}
+
+	FILE *File = fopen(FileName, "rb");
+	if(File == NULL){
+		error("TRSAPrivateKey::initFromFile: Failed to open \"%s\".\n", FileName);
+		return;
+	}
+
+	m_RSA = PEM_read_RSAPrivateKey(File, NULL, NULL, NULL);
+	fclose(File);
+
+	if(m_RSA == NULL){
+		error("TRSAPrivateKey::initFromFile: Failed to read key from \"%s\".\n", FileName);
+		DumpOpenSSLErrors("TRSAPrivateKey::initFromFile", "PEM_read_RSAPrivateKey");
+	}else if(RSA_size(m_RSA) != 128){
+		error("TRSAPrivateKey::initFromFile: File \"%s\" doesn't contain a 1024-bit key", FileName);
+		RSA_free(m_RSA);
+		m_RSA = NULL;
+	}
+}
+
+void TRSAPrivateKey::decrypt(uint8 *Data){
+	if(m_RSA == NULL){
+		error("TRSAPrivateKey::decrypt: Key not initialized.\n");
+		return;
+	}
+
+	// TODO(fusion): Pass in the length of `Data` for checking.
+	ASSERT(RSA_size(m_RSA) == 128);
+
+	if(RSA_private_decrypt(128, Data, Data, m_RSA, RSA_NO_PADDING) == -1){
+		DumpOpenSSLErrors("TRSAPrivateKey::decrypt", "RSA_private_decrypt");
+	}
+}
+
+// TXTEASymmetricKey
+// =============================================================================
+void TXTEASymmetricKey::init(TReadBuffer *Buffer){
+	m_SymmetricKey[0] = Buffer->readQuad();
+	m_SymmetricKey[1] = Buffer->readQuad();
+	m_SymmetricKey[2] = Buffer->readQuad();
+	m_SymmetricKey[3] = Buffer->readQuad();
+}
+
+void TXTEASymmetricKey::encrypt(uint8 *Data){
+	// TODO(fusion): This assumes both data endpoints have the same byte order.
+	// It's unlikely that there is anything other than little-endian but we
+	// should use a few helping functions to ensure compatibility.
+	uint32 Sum = 0x00000000UL;
+	uint32 Delta = 0x9E3779B9UL;
+	uint32 V0 = *(uint32*)(&Data[0]);
+	uint32 V1 = *(uint32*)(&Data[4]);
+	for(int i = 0; i < 32; i += 1){
+		V0 += (((V1 << 4) ^ (V1 >> 5)) + V1) ^ (Sum + m_SymmetricKey[Sum & 3]);
+		Sum += Delta;
+		V1 += (((V0 << 4) ^ (V0 >> 5)) + V0) ^ (Sum + m_SymmetricKey[(Sum >> 11) & 3]);
+	}
+	*(uint32*)(&Data[0]) = V0;
+	*(uint32*)(&Data[4]) = V1;
+}
+
+void TXTEASymmetricKey::decrypt(uint8 *Data){
+	// TODO(fusion): Same as above.
+	uint32 Sum = 0xC6EF3720UL;
+	uint32 Delta = 0x9E3779B9UL;
+	uint32 V0 = *(uint32*)(&Data[0]);
+	uint32 V1 = *(uint32*)(&Data[4]);
+	for(int i = 0; i < 32; i += 1){
+		V1 -= (((V0 << 4) ^ (V0 >> 5)) + V0) ^ (Sum + m_SymmetricKey[(Sum >> 11) & 3]);
+		Sum -= Delta;
+		V0 -= (((V1 << 4) ^ (V1 >> 5)) + V1) ^ (Sum + m_SymmetricKey[Sum & 3]);
+	}
+	*(uint32*)(&Data[0]) = V0;
+	*(uint32*)(&Data[4]) = V1;
+}
diff --git a/src/crypto.hh b/src/crypto.hh
index 7159a37..b649ad8 100644
--- a/src/crypto.hh
+++ b/src/crypto.hh
@@ -2,52 +2,20 @@
 #define TIBIA_CRYPTO_HH_ 1
 
 #include "common.hh"
-
-// TODO(fusion): We might want to scrap this implementation and use OpenSSL instead.
-
-struct vlong_flex_unit{
-	uint32 n;
-	uint32 *a;
-	uint32 z;
-};
-
-struct vlong_value: vlong_flex_unit {
-	uint32 share;
-};
-
-struct vlong{
-	vlong_value *value;
-	int negative;
-};
-
-struct vlong_montgomery{
-	vlong R;
-	vlong R1;
-	vlong m;
-	vlong n1;
-	vlong T;
-	vlong k;
-	uint32 N;
-};
+#include <openssl/rsa.h>
 
 struct TRSAPrivateKey{
 	TRSAPrivateKey(void);
 	~TRSAPrivateKey(void);
-	void init(const char *PrimeP, const char *PrimeQ);
+	void initFromFile(const char *FileName);
 	void decrypt(uint8 *Data); // single 128 bytes block
 
 	// DATA
 	// =================
-	vlong m_PrimeP;
-	vlong m_PrimeQ;
-	vlong m_U;
-	vlong m_DP;
-	vlong m_DQ;
+	RSA *m_RSA;
 };
 
 struct TXTEASymmetricKey{
-	TXTEASymmetricKey(void);
-	~TXTEASymmetricKey(void);
 	void init(TReadBuffer *Buffer);
 	void encrypt(uint8 *Data); // single 8 bytes block
 	void decrypt(uint8 *Data); // single 8 bytes block
diff --git a/src/main.cc b/src/main.cc
index 92e7e73..2089641 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -216,7 +216,7 @@ void LoadWorldConfig(void){
 static void InitAll(void){
 	try{
 		ReadConfig();
-		//SetQueryManagerLoginData(1, WorldName);
+		SetQueryManagerLoginData(1, WorldName);
 		LoadWorldConfig();
 		InitSHM(!BeADaemon);
 		LockGame();
diff --git a/src/query.hh b/src/query.hh
index dbba9dc..6ac6afb 100644
--- a/src/query.hh
+++ b/src/query.hh
@@ -187,4 +187,6 @@ struct TQueryManagerPoolConnection{
 	TQueryManagerConnection *QueryManagerConnection;
 };
 
+void SetQueryManagerLoginData(int Type, const char *Data);
+
 #endif //TIBIA_QUERY_HH_