/* Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- Copyright (C) 1994-2015 Lua.org, PUC-Rio.

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

*/

/*

* encodings.c

* Lua library for base64, stringprep and idna encodings

*/

/* Newer MSVC compilers deprecate strcpy as unsafe, but we use it in a safe way */

#define _CRT_SECURE_NO_DEPRECATE

#include <string.h>

#include <stdlib.h>

#include "lua.h"

#include "lauxlib.h"

#if (LUA_VERSION_NUM < 504)

#define luaL_pushfail lua_pushnil

#endif

/***************** BASE64 *****************/

static const char code[] =

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static void base64_encode(luaL_Buffer *b, unsigned int c1, unsigned int c2, unsigned int c3, int n) {

	unsigned long tuple = c3 + 256UL * (c2 + 256UL * c1);

	int i;

	char s[4];

	for(i = 0; i < 4; i++) {

		s[3 - i] = code[tuple % 64];

		tuple /= 64;

	}

	for(i = n + 1; i < 4; i++) {

		s[i] = '=';

	}

	luaL_addlstring(b, s, 4);

}

static int Lbase64_encode(lua_State *L) {	/** encode(s) */

	size_t l;

	const unsigned char *s = (const unsigned char *)luaL_checklstring(L, 1, &l);

	luaL_Buffer b;

	int n;

	luaL_buffinit(L, &b);

	for(n = l / 3; n--; s += 3) {

		base64_encode(&b, s[0], s[1], s[2], 3);

	}

	switch(l % 3) {

		case 1:

			base64_encode(&b, s[0], 0, 0, 1);

			break;

		case 2:

			base64_encode(&b, s[0], s[1], 0, 2);

			break;

	}

	luaL_pushresult(&b);

	return 1;

}

static void base64_decode(luaL_Buffer *b, int c1, int c2, int c3, int c4, int n) {

	unsigned long tuple = c4 + 64L * (c3 + 64L * (c2 + 64L * c1));

	char s[3];

	switch(--n) {

		case 3:

			s[2] = (char) tuple;

			/* Falls through. */

		case 2:

			s[1] = (char)(tuple >> 8);

			/* Falls through. */

		case 1:

			s[0] = (char)(tuple >> 16);

	}

	luaL_addlstring(b, s, n);

}

static int Lbase64_decode(lua_State *L) {	/** decode(s) */

	size_t l;

	const char *s = luaL_checklstring(L, 1, &l);

	luaL_Buffer b;

	int n = 0;

	char t[4];

	luaL_buffinit(L, &b);

	for(;;) {

		int c = *s++;

		switch(c) {

				const char *p;

			default:

				p = strchr(code, c);

				if(p == NULL) {

					return 0;

				}

				t[n++] = (char)(p - code);

				if(n == 4) {

					base64_decode(&b, t[0], t[1], t[2], t[3], 4);

					n = 0;

				}

				break;

			case '=':

				switch(n) {

					case 1:

						base64_decode(&b, t[0], 0, 0, 0, 1);

						break;

					case 2:

						base64_decode(&b, t[0], t[1], 0, 0, 2);

						break;

					case 3:

						base64_decode(&b, t[0], t[1], t[2], 0, 3);

						break;

				}

				n = 0;

				break;

			case 0:

				luaL_pushresult(&b);

				return 1;

			case '\n':

			case '\r':

			case '\t':

			case ' ':

			case '\f':

			case '\b':

				break;

		}

	}

}

static const luaL_Reg Reg_base64[] = {

	{ "encode",	Lbase64_encode	},

	{ "decode",	Lbase64_decode	},

	{ NULL,		NULL	}

};

/******************* UTF-8 ********************/

/*

 * Adapted from Lua 5.3

 * Needed because libidn does not validate that input is valid UTF-8

 */

#define MAXUNICODE	0x10FFFF

/*

 * Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.

 */

static const char *utf8_decode(const char *o, int *val) {

	static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF};

	const unsigned char *s = (const unsigned char *)o;

	unsigned int c = s[0];

	unsigned int res = 0;  /* final result */

	if(c < 0x80) { /* ascii? */

		res = c;

	} else {

		int count = 0;  /* to count number of continuation bytes */

		while(c & 0x40) {   /* still have continuation bytes? */

			int cc = s[++count];  /* read next byte */

			if((cc & 0xC0) != 0x80) { /* not a continuation byte? */

				return NULL;    /* invalid byte sequence */

			}

			res = (res << 6) | (cc & 0x3F);  /* add lower 6 bits from cont. byte */

			c <<= 1;  /* to test next bit */

		}

		res |= ((c & 0x7F) << (count * 5));  /* add first byte */

		if(count > 3 || res > MAXUNICODE || res <= limits[count] || (0xd800 <= res && res <= 0xdfff)) {

			return NULL;    /* invalid byte sequence */

		}

		s += count;  /* skip continuation bytes read */

	}

	if(val) {

		*val = res;

	}

	return (const char *)s + 1;  /* +1 to include first byte */

}

/*

 * Check that a string is valid UTF-8

 * Returns NULL if not

 */

static const char *check_utf8(lua_State *L, int idx, size_t *l) {

	size_t pos, len;

	const char *s = luaL_checklstring(L, idx, &len);

	pos = 0;

	while(pos <= len) {

		const char *s1 = utf8_decode(s + pos, NULL);

		if(s1 == NULL) {   /* conversion error? */

			return NULL;

		}

		pos = s1 - s;

	}

	if(l != NULL) {

		*l = len;

	}

	return s;

}

static int Lutf8_valid(lua_State *L) {

	lua_pushboolean(L, check_utf8(L, 1, NULL) != NULL);

	return 1;

}

static int Lutf8_length(lua_State *L) {

	size_t len;

	if(!check_utf8(L, 1, &len)) {

		luaL_pushfail(L);

		lua_pushliteral(L, "invalid utf8");

		return 2;

	}

	lua_pushinteger(L, len);

	return 1;

}

static const luaL_Reg Reg_utf8[] = {

	{ "valid",	Lutf8_valid	},

	{ "length",	Lutf8_length	},

	{ NULL,		NULL	}

};

/***************** STRINGPREP *****************/

#ifdef USE_STRINGPREP_ICU

#include <unicode/usprep.h>

#include <unicode/ustring.h>

#include <unicode/utrace.h>

#include <unicode/uspoof.h>

#include <unicode/uidna.h>

static int icu_stringprep_prep(lua_State *L, const UStringPrepProfile *profile) {

	size_t input_len;

	int32_t unprepped_len, prepped_len, output_len;

	const char *input;

	char output[1024];

	int flags = USPREP_ALLOW_UNASSIGNED;

	UChar unprepped[1024]; /* Temporary unicode buffer (1024 characters) */

	UChar prepped[1024];

	UErrorCode err = U_ZERO_ERROR;

	input = luaL_checklstring(L, 1, &input_len);

	if(input_len >= 1024) {

		luaL_pushfail(L);

		return 1;

	}

	/* strict */

	if(!lua_isnoneornil(L, 2)) {

		luaL_checktype(L, 2, LUA_TBOOLEAN);

		if(lua_toboolean(L, 2)) {

			flags = 0;

		}

	}

	u_strFromUTF8(unprepped, 1024, &unprepped_len, input, input_len, &err);

	if(U_FAILURE(err)) {

		luaL_pushfail(L);

		return 1;

	}

	prepped_len = usprep_prepare(profile, unprepped, unprepped_len, prepped, 1024, flags, NULL, &err);

	if(U_FAILURE(err)) {

		luaL_pushfail(L);

		return 1;

	} else {

		u_strToUTF8(output, 1024, &output_len, prepped, prepped_len, &err);

		if(U_SUCCESS(err) && output_len < 1024) {

			lua_pushlstring(L, output, output_len);

		} else {

			luaL_pushfail(L);

		}

		return 1;

	}

}

static UStringPrepProfile *icu_nameprep;

static UStringPrepProfile *icu_nodeprep;

static UStringPrepProfile *icu_resourceprep;

static UStringPrepProfile *icu_saslprep;

static USpoofChecker *icu_spoofcheck;

static UIDNA *icu_idna2008;

#if (U_ICU_VERSION_MAJOR_NUM < 58)

/* COMPAT */

#define USPOOF_CONFUSABLE (USPOOF_SINGLE_SCRIPT_CONFUSABLE | USPOOF_MIXED_SCRIPT_CONFUSABLE | USPOOF_WHOLE_SCRIPT_CONFUSABLE)

#endif

/* initialize global ICU stringprep profiles */

static void init_icu(void) {

	UErrorCode err = U_ZERO_ERROR;

	utrace_setLevel(UTRACE_VERBOSE);

	icu_nameprep = usprep_openByType(USPREP_RFC3491_NAMEPREP, &err);

	icu_nodeprep = usprep_openByType(USPREP_RFC3920_NODEPREP, &err);

	icu_resourceprep = usprep_openByType(USPREP_RFC3920_RESOURCEPREP, &err);

	icu_saslprep = usprep_openByType(USPREP_RFC4013_SASLPREP, &err);

	icu_spoofcheck = uspoof_open(&err);

	uspoof_setChecks(icu_spoofcheck, USPOOF_CONFUSABLE, &err);

	int options = UIDNA_DEFAULT;

#if 0

	/* COMPAT with future Unicode versions */

	options |= UIDNA_ALLOW_UNASSIGNED;

#endif

#if 1

	/* Forbid eg labels starting with _ */

	options |= UIDNA_USE_STD3_RULES;

#endif

#if 0

	/* TODO determine if we need this */

	options |= UIDNA_CHECK_BIDI;

#endif

#if 0

	/* UTS46 makes it sound like these are the responsibility of registrars */

	options |= UIDNA_CHECK_CONTEXTJ;

	options |= UIDNA_CHECK_CONTEXTO;

#endif

#if 0

	/* This disables COMPAT with IDNA 2003 */

	options |= UIDNA_NONTRANSITIONAL_TO_ASCII;

	options |= UIDNA_NONTRANSITIONAL_TO_UNICODE;

#endif

	icu_idna2008 = uidna_openUTS46(options, &err);

	if(U_FAILURE(err)) {

		fprintf(stderr, "[c] util.encodings: error: %s\n", u_errorName(err));

	}

}

#define MAKE_PREP_FUNC(myFunc, prep) \

static int myFunc(lua_State *L) { return icu_stringprep_prep(L, prep); }

MAKE_PREP_FUNC(Lstringprep_nameprep, icu_nameprep)		/** stringprep.nameprep(s) */

MAKE_PREP_FUNC(Lstringprep_nodeprep, icu_nodeprep)		/** stringprep.nodeprep(s) */

MAKE_PREP_FUNC(Lstringprep_resourceprep, icu_resourceprep)		/** stringprep.resourceprep(s) */

MAKE_PREP_FUNC(Lstringprep_saslprep, icu_saslprep)		/** stringprep.saslprep(s) */

static const luaL_Reg Reg_stringprep[] = {

	{ "nameprep",	Lstringprep_nameprep	},