rizin/librz/util/hex.c

// SPDX-FileCopyrightText: 2007-2020 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: LGPL-3.0-only

#include "rz_types.h"
#include "rz_util.h"
#include <stdio.h>
#include <ctype.h>

/* int c = 0; ret = hex_to_byte(&c, 'c'); */
RZ_API bool rz_hex_to_byte(ut8 *val, ut8 c) {
	if (IS_DIGIT(c)) {
		*val = (ut8)(*val) * 16 + (c - '0');
	} else if (c >= 'A' && c <= 'F') {
		*val = (ut8)(*val) * 16 + (c - 'A' + 10);
	} else if (c >= 'a' && c <= 'f') {
		*val = (ut8)(*val) * 16 + (c - 'a' + 10);
	} else {
		return 1;
	}
	return 0;
}

RZ_API char *rz_hex_from_py_str(char *out, const char *code) {
	if (!strncmp(code, "'''", 3)) {
		const char *s = code + 2;
		return rz_hex_from_c_str(out, &s);
	}
	return rz_hex_from_c_str(out, &code);
}

static const char *skip_comment_py(const char *code) {
	if (*code != '#') {
		return code;
	}
	char *end = strchr(code, '\n');
	if (end) {
		code = end;
	}
	return code + 1;
}

RZ_API char *rz_hex_from_py_array(char *out, const char *code) {
	const char abc[] = "0123456789abcdef";
	if (*code != '[' || !strchr(code, ']')) {
		return NULL;
	}
	code++;
	for (; *code; code++) {
		char *comma = strchr(code, ',');
		if (!comma) {
			comma = strchr(code, ']');
		}
		if (!comma) {
			break;
		}
		char *_word = rz_str_ndup(code, comma - code);
		const char *word = _word;
		while (*word == ' ' || *word == '\t' || *word == '\n') {
			word++;
			word = skip_comment_py(word);
		}
		if (IS_DIGIT(*word)) {
			ut8 n = (ut8)rz_num_math(NULL, word);
			*out++ = abc[(n >> 4) & 0xf];
			*out++ = abc[n & 0xf];
		}
		free(_word);
		code = comma;
		if (*code == ']') {
			break;
		}
	}
	return out;
}

RZ_API char *rz_hex_from_py(const char *code) {
	if (!code) {
		return NULL;
	}
	char *const ret = malloc(strlen(code) * 3);
	if (!ret) {
		return NULL;
	}
	*ret = '\0';
	char *out = ret;
	const char *tmp_code = strchr(code, '=');
	if (tmp_code) {
		code = tmp_code;
	}
	for (; *code && *code != '[' && *code != '\'' && *code != '"'; code++) {
		code = skip_comment_py(code);
	}
	if (*code == '[') {
		out = rz_hex_from_py_array(out, code);
	} else if (*code == '"' || *code == '\'') {
		out = rz_hex_from_py_str(out, code);
	}
	if (!out) {
		free(ret);
		return NULL;
	}
	*out = '\0';
	return ret;
}

RZ_API char *rz_hex_from_c_str(char *out, const char **code) {
	const char abc[] = "0123456789abcdefABCDEF";
	const char *iter = *code;
	if (*iter != '\'' && *iter != '"') {
		return NULL;
	}
	const char end_char = *iter;
	iter++;
	for (; *iter && *iter != end_char; iter++) {
		if (*iter == '\\') {
			iter++;
			switch (iter[0]) {
			case 'e':
				*out++ = '1';
				*out++ = 'b';
				break;
			case 'r':
				*out++ = '0';
				*out++ = 'd';
				break;
			case 'n':
				*out++ = '0';
				*out++ = 'a';
				break;
			case 'x': {
				ut8 c1 = iter[1];
				ut8 c2 = iter[2];
				iter += 2;
				if (c1 == '\0' || c2 == '\0') {
					return NULL;
				} else if (strchr(abc, c1) && strchr(abc, c2)) {
					*out++ = tolower(c1);
					*out++ = tolower(c2);
				} else {
					return NULL;
				}
				break;
			}
			default:
				if (iter[0] == end_char) {
					ut8 x = *iter;
					*out++ = abc[x >> 4];
					*out++ = abc[x & 0xf];
				}
				return NULL;
			}
		} else {
			ut8 x = *iter;
			*out++ = abc[x >> 4];
			*out++ = abc[x & 0xf];
		}
	}
	*code = iter;
	return out;
}

const char *skip_comment_c(const char *code) {
	if (!strncmp(code, "/*", 2)) {
		char *end = strstr(code, "*/");
		if (end) {
			code = end + 2;
		} else {
			eprintf("Missing closing comment\n");
		}
	} else if (!strncmp(code, "//", 2)) {
		char *end = strchr(code, '\n');
		if (end) {
			code = end + 2;
		}
	}
	return code;
}

RZ_API char *rz_hex_from_c_array(char *out, const char *code) {
	if (!code) {
		return NULL;
	}
	const char abc[] = "0123456789abcdef";
	if (*code != '{' || !strchr(code, '}')) {
		return NULL;
	}
	code++;
	for (; *code; code++) {
		const char *comma = strchr(code, ',');
		if (!comma) {
			comma = strchr(code, '}');
		}
		char *_word = rz_str_ndup(code, comma - code);
		const char *word = _word;
		word = skip_comment_c(word);
		while (*word == ' ' || *word == '\t' || *word == '\n') {
			word++;
			word = skip_comment_c(word);
		}
		if (IS_DIGIT(*word)) {
			ut8 n = (ut8)rz_num_math(NULL, word);
			*out++ = abc[(n >> 4) & 0xf];
			*out++ = abc[n & 0xf];
		}
		free(_word);
		code = comma;
		if (code && *code == '}') {
			break;
		}
	}
	return out;
}

/* convert:
 *    char *foo = "\x41\x23\x42\x1b";
 * into:
 *    4123421b
 */
RZ_API char *rz_hex_from_c(const char *code) {
	if (!code) {
		return NULL;
	}
	char *const ret = malloc(strlen(code) * 3);
	if (!ret) {
		return NULL;
	}
	*ret = '\0';
	char *out = ret;
	const char *tmp_code = strchr(code, '=');
	if (tmp_code) {
		code = tmp_code;
	}
	for (; *code != '\0' && *code != '{' && *code != '"'; code++) {
		code = skip_comment_c(code);
	}
	if (*code == '{') {
		out = rz_hex_from_c_array(out, code);
	} else if (*code == '"') {
		const char *s1, *s2;
		s1 = code;
		do {
			code = s1;
			out = rz_hex_from_c_str(out, &code);
			if (!out) {
				break;
			}
			s1 = strchr(code + 1, '"');
			s2 = strchr(code + 1, ';');
		} while (s1 && s2 && (s1 <= s2));
	}
	if (!out) {
		free(ret);
		return NULL;
	}
	*out = '\0';
	return ret;
}

RZ_API char *rz_hex_from_js(const char *code) {
	char *s1 = strchr(code, '\'');
	char *s2 = strchr(code, '"');

	/* there are no strings in the input */
	if (!(s1 || s2)) {
		return NULL;
	}

	char *start, *end;
	if (s1 < s2) {
		start = s1;
		end = strchr(start + 1, '\'');
	} else {
		start = s2;
		end = strchr(start + 1, '"');
	}

	/* the string isn't properly terminated */
	if (!end) {
		return NULL;
	}

	char *str = rz_str_ndup(start + 1, end - start - 1);

	/* assuming base64 input, output will always be shorter */
	ut8 *b64d = malloc(end - start);
	if (!b64d) {
		free(str);
		return NULL;
	}

	rz_base64_decode(b64d, str, end - start - 1);
	if (!b64d) {
		free(str);
		free(b64d);
		return NULL;
	}

	// TODO: use rz_str_bin2hex
	int i, len = strlen((const char *)b64d);
	char *out = malloc(len * 2 + 1);
	if (!out) {
		free(str);
		free(b64d);
		return NULL;
	}
	for (i = 0; i < len; i++) {
		sprintf(&out[i * 2], "%02x", b64d[i]);
	}
	out[len * 2] = '\0';

	free(str);
	free(b64d);
	return out;
}

/* convert
 * "\x41\x23\x42\x1b"
 * "\x41\x23\x42\x1b"
 * into
 * 4123421b4123421b
 */
RZ_API char *rz_hex_no_code(const char *code) {
	if (!code) {
		return NULL;
	}
	char *const ret = calloc(1, strlen(code) * 3);
	if (!ret) {
		return NULL;
	}
	*ret = '\0';
	char *out = ret;
	out = rz_hex_from_c_str(out, &code);
	code = strchr(code + 1, '"');
	if (!out) {
		free(ret);
		return NULL;
	}
	*out = '\0';
	while (out && code) {
		*out = '\0';
		out = rz_hex_from_c_str(out, &code);
		code = strchr(code + 1, '"');
	}
	return ret;
}

RZ_API char *rz_hex_from_code(const char *code) {
	if (!strchr(code, '=')) {
		return rz_hex_no_code(code);
	}
	/* C language */
	if (strstr(code, "char") || strstr(code, "int")) {
		return rz_hex_from_c(code);
	}
	/* JavaScript */
	if (strstr(code, "var")) {
		return rz_hex_from_js(code);
	}
	/* Python */
	return rz_hex_from_py(code);
}

/* int byte = hexpair2bin("A0"); */
// (0A) => 10 || -1 (on error)
RZ_API int rz_hex_pair2bin(const char *arg) {
	ut8 *ptr, c = 0, d = 0;
	ut32 j = 0;

	for (ptr = (ut8 *)arg;; ptr = ptr + 1) {
		if (!*ptr || *ptr == ' ' || j == 2) {
			break;
		}
		d = c;
		if (*ptr != '.' && rz_hex_to_byte(&c, *ptr)) {
			eprintf("Invalid hexa string at char '%c' (%s).\n",
				*ptr, arg);
			return -1;
		}
		c |= d;
		if (j++ == 0) {
			c <<= 4;
		}
	}
	return (int)c;
}

RZ_API int rz_hex_bin2str(const ut8 *in, int len, char *out) {
	int i, idx;
	char tmp[8];
	if (len < 0) {
		return 0;
	}
	for (idx = i = 0; i < len; i++, idx += 2) {
		snprintf(tmp, sizeof(tmp), "%02x", in[i]);
		memcpy(out + idx, tmp, 2);
	}
	out[idx] = 0;
	return len;
}

/**
 * \brief Takes an unsigned 32bit integer with MSB set to 1 and returns the signed integer in hex format as string.
 * E.g.: 0xffffffff -> "-0x1"
 *
 * \param in The integer to convert to the signed string.
 * \param out The buffer to write the signed hex string to.
 * \param len Length of the out buffer.
 * \return char* The signed integer as hex string.
 */
RZ_API void rz_hex_ut2st_str(const ut32 in, RZ_INOUT char *out, const int len) {
	char tmp[12];
	if (len < sizeof(tmp)) {
		RZ_LOG_FATAL("Output buffer too small for negative 32bit value.\n");
	}
	snprintf(tmp, sizeof(tmp), "-0x%" PFMT32x, ~in + 1);
	memcpy(out, tmp, sizeof(tmp));
	return;
}

RZ_API char *rz_hex_bin2strdup(const ut8 *in, int len) {
	int i, idx;
	char tmp[5], *out;

	if ((len + 1) * 2 < len) {
		return NULL;
	}
	out = malloc((len + 1) * 2);
	if (!out) {
		return NULL;
	}
	for (i = idx = 0; i < len; i++, idx += 2) {
		snprintf(tmp, sizeof(tmp), "%02x", in[i]);
		memcpy(out + idx, tmp, 2);
	}
	out[idx] = 0;
	return out;
}

/**
 * \brief Convert an input string \p in into the binary form in \p out
 *
 * Convert an input string in the hexadecimal form (e.g. "41424344") into the
 * raw binary form (e.g. "ABCD")
 *
 * \param in Input string in hexadecimal form. An optional "0x" prefix may be present.
 * \param out Output buffer having at least strlen(in) / 2 bytes available
 * \return number of bytes written into \p out
 */
RZ_API int rz_hex_str2bin(const char *in, ut8 *out) {
	long nibbles = 0;

	while (in && *in) {
		ut8 tmp;
		/* skip hex prefix */
		if (*in == '0' && in[1] == 'x') {
			in += 2;
		}
		/* read hex digits */
		while (!rz_hex_to_byte(out ? &out[nibbles / 2] : &tmp, *in)) {
			nibbles++;
			in++;
		}
		if (*in == '\0') {
			break;
		}
		/* comments */
		if (*in == '#' || (*in == '/' && in[1] == '/')) {
			if ((in = strchr(in, '\n'))) {
				in++;
			}
			continue;
		} else if (*in == '/' && in[1] == '*') {
			if ((in = strstr(in, "*/"))) {
				in += 2;
			}
			continue;
		} else if (!IS_WHITESPACE(*in) && *in != '\n') {
			/* this is not a valid string */
			return 0;
		}
		/* ignore character */
		in++;
	}

	if (nibbles % 2) {
		if (out) {
			rz_hex_to_byte(&out[nibbles / 2], '0');
		}
		return -(nibbles + 1) / 2;
	}

	return nibbles / 2;
}

RZ_API int rz_hex_str2binmask(const char *in, ut8 *out, ut8 *mask) {
	ut8 *ptr;
	int len, ilen = strlen(in) + 1;
	int has_nibble = 0;
	memcpy(out, in, ilen);
	for (ptr = out; *ptr; ptr++) {
		if (*ptr == '.') {
			*ptr = '0';
		}
	}
	len = rz_hex_str2bin((char *)out, out);
	if (len < 0) {
		has_nibble = 1;
		len = -(len + 1);
	}
	if (len != -1) {
		memcpy(mask, in, ilen);
		if (has_nibble) {
			memcpy(mask + ilen, "f0", 3);
		}
		for (ptr = mask; *ptr; ptr++) {
			if (IS_HEXCHAR(*ptr)) {
				*ptr = 'f';
			} else if (*ptr == '.') {
				*ptr = '0';
			}
		}
		len = rz_hex_str2bin((char *)mask, mask);
		if (len < 0) {
			len++;
		}
	}
	return len;
}

RZ_API st64 rz_hex_bin_truncate(ut64 in, int n) {
	switch (n) {
	case 1:
		if ((in & UT8_GT0)) {
			return UT64_8U | in;
		}
		return in & UT8_MAX;
	case 2:
		if ((in & UT16_GT0)) {
			return UT64_16U | in;
		}
		return in & UT16_MAX;
	case 4:
		if ((in & UT32_GT0)) {
			return UT64_32U | in;
		}
		return in & UT32_MAX;
	case 8:
		return in & UT64_MAX;
	}
	return in;
}

/**
 * \brief Check if \p str contains only hexadecimal characters
 *
 * Check that the input string is in the hexadecimal form (e.g. "41424344", with whitespace ignored), and return the number of bytes of its raw binary form (4 for the previous example), or an error if non-hexadecimal characters were found
 *
 * \param str Input string in hexadecimal form.
 * \param allow_prefix Whether an optional "0x" prefix may be present at the start of \p str.
 * \return number of bytes in the raw binary form of \p str, or -1 if invalid characters were found
 */
RZ_API int rz_hex_str_is_valid(const char *str, bool allow_prefix) {
	int i;
	int len = 0;
	if (allow_prefix && !strncmp(str, "0x", 2)) {
		str += 2;
	}
	for (i = 0; str[i] != '\0'; i++) {
		if (IS_HEXCHAR(str[i])) {
			len++;
		}
		if (IS_HEXCHAR(str[i]) || IS_WHITESPACE(str[i])) {
			continue;
		}
		return -1; // if we're here, then str isn't valid
	}
	return len;
}