/* Prosody IM
-- Copyright (C) 2009-2010 Matthew Wild
-- Copyright (C) 2009-2010 Waqas Hussain
-- 
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
*/


/*
* hashes.c
* Lua library for sha1, sha256 and md5 hashes
*/

#include <string.h>

#include "lua.h"
#include "lauxlib.h"
#include <openssl/sha.h>
#include <openssl/md5.h>

#define HMAC_IPAD 0x36363636
#define HMAC_OPAD 0x5c5c5c5c

const char *hex_tab = "0123456789abcdef";
void toHex(const unsigned char *in, int length, unsigned char *out) {
	int i;
	for (i = 0; i < length; i++) {
		out[i*2] = hex_tab[(in[i] >> 4) & 0xF];
		out[i*2+1] = hex_tab[(in[i]) & 0xF];
	}
}

#define MAKE_HASH_FUNCTION(myFunc, func, size) \
static int myFunc(lua_State *L) { \
	size_t len; \
	const char *s = luaL_checklstring(L, 1, &len); \
	int hex_out = lua_toboolean(L, 2); \
	unsigned char hash[size], result[size*2]; \
	func((const unsigned char*)s, len, hash);  \
	if (hex_out) { \
		toHex(hash, size, result); \
		lua_pushlstring(L, (char*)result, size*2); \
	} else { \
		lua_pushlstring(L, (char*)hash, size);\
	} \
	return 1; \
}

MAKE_HASH_FUNCTION(Lsha1, SHA1, SHA_DIGEST_LENGTH)
MAKE_HASH_FUNCTION(Lsha224, SHA224, SHA224_DIGEST_LENGTH)
MAKE_HASH_FUNCTION(Lsha256, SHA256, SHA256_DIGEST_LENGTH)
MAKE_HASH_FUNCTION(Lsha384, SHA384, SHA384_DIGEST_LENGTH)
MAKE_HASH_FUNCTION(Lsha512, SHA512, SHA512_DIGEST_LENGTH)
MAKE_HASH_FUNCTION(Lmd5, MD5, MD5_DIGEST_LENGTH)

struct hash_desc {
	int (*Init)(void*);
	int (*Update)(void*, const void *, size_t);
	int (*Final)(unsigned char*, void*);
	size_t digestLength;
	void *ctx, *ctxo;
};

static void hmac(struct hash_desc *desc, const char *key, size_t key_len,
    const char *msg, size_t msg_len, unsigned char *result)
{
	union xory {
		unsigned char bytes[64];
		uint32_t quadbytes[16];
	};

	int i;
	char hashedKey[64]; /* Maximum used digest length */
	union xory k_ipad, k_opad;

	if (key_len > 64) {
		desc->Init(desc->ctx);
		desc->Update(desc->ctx, key, key_len);
		desc->Final(desc->ctx, hashedKey);
		key = (const char*)hashedKey;
		key_len = desc->digestLength;
	}

	memcpy(k_ipad.bytes, key, key_len);
	memset(k_ipad.bytes + key_len, 0, 64 - key_len);
	memcpy(k_opad.bytes, k_ipad.bytes, 64);

	for (i = 0; i < 16; i++) {
		k_ipad.quadbytes[i] ^= HMAC_IPAD;
		k_opad.quadbytes[i] ^= HMAC_OPAD;
	}

	desc->Init(desc->ctx);
	desc->Update(desc->ctx, k_ipad.bytes, 64);
	desc->Init(desc->ctxo);
	desc->Update(desc->ctxo, k_opad.bytes, 64);
	desc->Update(desc->ctx, msg, msg_len);
	desc->Final(result, desc->ctx);
	desc->Update(desc->ctxo, result, desc->digestLength);
	desc->Final(result, desc->ctxo);
}

#define MAKE_HMAC_FUNCTION(myFunc, func, size, type) \
static int myFunc(lua_State *L) { \
	type ctx, ctxo; \
	unsigned char hash[size], result[2*size]; \
	size_t key_len, msg_len; \
	const char *key = luaL_checklstring(L, 1, &key_len); \
	const char *msg = luaL_checklstring(L, 2, &msg_len); \
	const int hex_out = lua_toboolean(L, 3); \
	struct hash_desc desc; \
	desc.Init = (int (*)(void*))func##_Init; \
	desc.Update = (int (*)(void*, const void *, size_t))func##_Update; \
	desc.Final = (int (*)(unsigned char*, void*))func##_Final; \
	desc.digestLength = size; \
	desc.ctx = &ctx; \
	desc.ctxo = &ctxo; \
	hmac(&desc, key, key_len, msg, msg_len, hash); \
	if (hex_out) { \
		toHex(hash, size, result); \
		lua_pushlstring(L, (char*)result, size*2); \
	} else { \
		lua_pushlstring(L, (char*)hash, size); \
	} \
	return 1; \
}

MAKE_HMAC_FUNCTION(Lhmac_sha1, SHA1, SHA_DIGEST_LENGTH, SHA_CTX)
MAKE_HMAC_FUNCTION(Lhmac_sha256, SHA256, SHA256_DIGEST_LENGTH, SHA256_CTX)
MAKE_HMAC_FUNCTION(Lhmac_sha512, SHA512, SHA512_DIGEST_LENGTH, SHA512_CTX)
MAKE_HMAC_FUNCTION(Lhmac_md5, MD5, MD5_DIGEST_LENGTH, MD5_CTX)

static const luaL_Reg Reg[] =
{
	{ "sha1",		Lsha1		},
	{ "sha224",		Lsha224		},
	{ "sha256",		Lsha256		},
	{ "sha384",		Lsha384		},
	{ "sha512",		Lsha512		},
	{ "md5",		Lmd5		},
	{ "hmac_sha1",		Lhmac_sha1	},
	{ "hmac_sha256",	Lhmac_sha256	},
	{ "hmac_sha512",	Lhmac_sha512	},
	{ "hmac_md5",		Lhmac_md5	},
	{ NULL,			NULL		}
};

LUALIB_API int luaopen_util_hashes(lua_State *L)
{
	luaL_register(L, "hashes", Reg);
	lua_pushliteral(L, "version");			/** version */
	lua_pushliteral(L, "-3.14");
	lua_settable(L,-3);
	return 1;
}