/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */
#include "q_shared.h"
#include "qcommon.h"

#define MD5_BLOCK_SIZE 64
#define MD5_DIGEST_SIZE 16

typedef struct MD5Context {
	uint32_t buf[4];
	uint32_t bits[2];
	union {
		unsigned char b[ MD5_BLOCK_SIZE ];
		uint32_t u32[ MD5_BLOCK_SIZE / 4 ];
	} in;
} MD5_CTX;

#ifndef Q3_BIG_ENDIAN
	#define byteReverse(buf, len)	/* Nothing */
#else
	static void byteReverse(unsigned char *buf, unsigned longs);

	/*
	* Note: this code is harmless on little-endian machines.
	*/
	static void byteReverse(unsigned char *buf, unsigned longs)
	{
		uint32_t t;
		do {
			t = (uint32_t)
				((unsigned) buf[3] << 8 | buf[2]) << 16 |
				((unsigned) buf[1] << 8 | buf[0]);
				*(uint32_t *) buf = t;
				buf += 4;
		} while (--longs);
	}
#endif // Q3_BIG_ENDIAN

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
static void MD5Init(struct MD5Context *ctx)
{
	ctx->buf[0] = 0x67452301;
	ctx->buf[1] = 0xefcdab89;
	ctx->buf[2] = 0x98badcfe;
	ctx->buf[3] = 0x10325476;

	ctx->bits[0] = 0;
	ctx->bits[1] = 0;
}

static void MD5Copy( struct MD5Context *to, const struct MD5Context *from )
{
	memcpy( to, from, sizeof( *to ) );
}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void MD5Transform( uint32_t buf[4], uint32_t const in[16] )
{
	uint32_t a, b, c, d;

	a = buf[0];
	b = buf[1];
	c = buf[2];
	d = buf[3];

	MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
	MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
	MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
	MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
	MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
	MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
	MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
	MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
	MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
	MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
	MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
	MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
	MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
	MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
	MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
	MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

	MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
	MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
	MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
	MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
	MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
	MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
	MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
	MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
	MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
	MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
	MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
	MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
	MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
	MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
	MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
	MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

	MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
	MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
	MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
	MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
	MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
	MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
	MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
	MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
	MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
	MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
	MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
	MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
	MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
	MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
	MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
	MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

	MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
	MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
	MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
	MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
	MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
	MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
	MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
	MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
	MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
	MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
	MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
	MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
	MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
	MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
	MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
	MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

	buf[0] += a;
	buf[1] += b;
	buf[2] += c;
	buf[3] += d;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
static void MD5Update(struct MD5Context *ctx, unsigned char const *buf,
	unsigned len)
{
	uint32_t t;

	/* Update bitcount */

	t = ctx->bits[0];
	if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
		ctx->bits[1]++;		/* Carry from low to high */
	ctx->bits[1] += len >> 29;

	t = (t >> 3) & 0x3f;	/* Bytes already in shsInfo->data */

	/* Handle any leading odd-sized chunks */

	if (t) {
		unsigned char *p = ctx->in.b + t;

		t = 64 - t;
		if (len < t) {
			memcpy(p, buf, len);
			return;
		}
		memcpy(p, buf, t);
		byteReverse(ctx->in.b, 16);
		MD5Transform(ctx->buf, ctx->in.u32);
		buf += t;
		len -= t;
	}
	/* Process data in 64-byte chunks */

	while (len >= MD5_BLOCK_SIZE) {
		memcpy(ctx->in.b, buf, MD5_BLOCK_SIZE);
		byteReverse(ctx->in.b, 16);
		MD5Transform(ctx->buf, ctx->in.u32);
		buf += MD5_BLOCK_SIZE;
		len -= MD5_BLOCK_SIZE;
	}

	/* Handle any remaining bytes of data. */

	memcpy(ctx->in.b, buf, len);
}


/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
static void MD5Final(struct MD5Context *ctx, unsigned char *digest)
{
	unsigned count;
	unsigned char *p;

	/* Compute number of bytes mod 64 */
	count = (ctx->bits[0] >> 3) & 0x3F;

	/* Set the first char of padding to 0x80.  This is safe since there is
		always at least one byte free */
	p = ctx->in.b + count;
	*p++ = 0x80;

	/* Bytes of padding needed to make 64 bytes */
	count = 64 - 1 - count;

	/* Pad out to 56 mod 64 */
	if (count < 8) {
		/* Two lots of padding:  Pad the first block to 64 bytes */
		memset(p, 0, count);
		byteReverse(ctx->in.b, 16);
		MD5Transform(ctx->buf, ctx->in.u32);

		/* Now fill the next block with 56 bytes */
		memset(ctx->in.b, 0, 56);
	} else {
		/* Pad block to 56 bytes */
		memset(p, 0, count - 8);
	}
	byteReverse(ctx->in.b, 14);

	/* Append length in bits and transform */
	ctx->in.u32[14] = ctx->bits[0];
	ctx->in.u32[15] = ctx->bits[1];

	MD5Transform(ctx->buf, ctx->in.u32);
	byteReverse((unsigned char *) ctx->buf, 4);

	if (digest!=NULL)
		memcpy( digest, ctx->buf, MD5_DIGEST_SIZE );

	memset(ctx, 0, sizeof(*ctx));	/* In case it's sensitive */
}


char *Com_MD5File( const char *fn, int length, const char *prefix, int prefix_len )
{
	static char final[MD5_DIGEST_SIZE*2+1];
	unsigned char digest[MD5_DIGEST_SIZE];
	fileHandle_t f;
	MD5_CTX md5;
	byte buffer[2048];
	int i;
	int filelen = 0;
	int r;
	int total = 0;

	final[0] = '\0';

	filelen = FS_SV_FOpenFileRead( fn, &f );

	if ( f == FS_INVALID_HANDLE ) {
		return final;
	}

	if ( filelen < 1 ) {
		FS_FCloseFile( f );
		return final;
	}

	if ( filelen < length || !length ) {
		length = filelen;
	}

	MD5Init( &md5 );

	if ( prefix_len && *prefix )
		MD5Update( &md5, (unsigned char *)prefix, prefix_len );

	for ( ;; ) {
		r = FS_Read( buffer, sizeof( buffer ), f );
		if ( r < 1 )
			break;
		if ( r + total > length )
			r = length - total;
		total += r;
		MD5Update( &md5 , buffer, r );
		if ( r < sizeof( buffer ) || total >= length )
			break;
	}
	FS_FCloseFile( f );
	MD5Final( &md5, digest );

	final[0] = '\0';
	for ( i = 0; i < sizeof( digest ); i++ ) {
		Q_strcat( final, sizeof( final ), va( "%02X", digest[i] & 0xFF ) );
	}

	return final;
}


char *Com_MD5Buf( const char *data, int length, const char *data2, int length2 )
{
	static char final_buf[MD5_DIGEST_SIZE*2+1];
	unsigned char digest[MD5_DIGEST_SIZE];
	unsigned i;
	MD5_CTX md5;

	MD5Init( &md5 );

	if ( data && length > 0 )
		MD5Update( &md5 , (unsigned char *)data, length );

	if (data2 && length2 > 0)
		MD5Update( &md5 , (unsigned char *)data2, length2 );

	MD5Final( &md5, digest );

	final_buf[0] = '\0';
	for ( i = 0; i < sizeof( digest ); i++ ) {
		Q_strcat( final_buf, sizeof( final_buf ), va( "%02X", digest[i] & 0xFF ) );
	}

	return final_buf;
}


// stateless challenges

static struct MD5Context hmac_ctx_in;
static struct MD5Context hmac_ctx_out;

void Com_MD5Init( void )
{
	struct {
		byte key1[MD5_BLOCK_SIZE];
		byte key2[MD5_BLOCK_SIZE];
	} secret;

	Sys_RandomBytes( (byte*)&secret, sizeof( secret ) );

	// initialize inner context
	MD5Init( &hmac_ctx_in );
	MD5Update( &hmac_ctx_in, secret.key1, sizeof( secret.key1 ) );

	// initialize outer context
	MD5Init( &hmac_ctx_out );
	MD5Update( &hmac_ctx_out, secret.key2, sizeof( secret.key2 ) );
}


int Com_MD5Addr( const netadr_t *addr, int timestamp )
{
	struct MD5Context ctx_in;
	struct MD5Context ctx_out;
	union {
		byte b[MD5_DIGEST_SIZE];
		int i[MD5_DIGEST_SIZE/sizeof(int)];
	} digest;

	MD5Copy( &ctx_in, &hmac_ctx_in );
	MD5Copy( &ctx_out, &hmac_ctx_out );

	// inner_hash = MD5( key1 | address | port | timestamp )
	switch ( addr->type ) {
		case NA_BROADCAST:
		case NA_IP: 
			MD5Update( &ctx_in, addr->ipv._4, 4 ); 
				break;
#ifdef USE_IPV6
		case NA_IP6:
		case NA_MULTICAST6:
			MD5Update( &ctx_in, addr->ipv._6, 16 ); 
			break;
#endif
		default:
			break;
	}

	MD5Update( &ctx_in, (byte*)&addr->port, sizeof( addr->port ) );
	MD5Update( &ctx_in, (byte*)&timestamp, sizeof( timestamp ) );
	MD5Final( &ctx_in, digest.b );

	// MD5( key2 | inner_hash )
	MD5Update( &ctx_out, digest.b, sizeof( digest.b ) );
	MD5Final( &ctx_out, digest.b );

	return digest.i[0];
}
