SlunkCrypt/frontend/src/main.c

/******************************************************************************/
/* SlunkCrypt, by LoRd_MuldeR <MuldeR2@GMX.de>                                */
/* This work has been released under the CC0 1.0 Universal license!           */
/******************************************************************************/

#ifdef _WIN32
#	define _CRT_SECURE_NO_WARNINGS 1
#else
#	define _GNU_SOURCE 1
#endif

/* Internal */
#include <slunkcrypt.h>
#include "utils.h"
#include "crypt.h"
#include "selftest.h"

/* CRT */
#include <string.h>
#include <time.h>
#include <inttypes.h>
#include <ctype.h>
#include <signal.h>

// ==========================================================================
// Constants
// ==========================================================================

#define MODE_HELP 0
#define MODE_VERS 1
#define MODE_ENCR 2
#define MODE_DECR 3
#define MODE_PASS 4
#define MODE_TEST 5

#define PW_FROM_ENV (!(argc > 4))

static const CHR* const ENV_PASSWORD = T("SLUNK_PASSPHRASE");
static const CHR* const ENV_KEEPFILE = T("SLUNK_KEEP_INCOMPLETE");

static const CHR* const PREFIX_PASS = T("pass:");
static const CHR* const PREFIX_FILE = T("file:");

static const char PASSWD_SYMBOLS[] =
{
	'!', '#', '$', '%', '&', '(', ')', '*', '+', ',', '-', '.', '/', '0', '1',
	'2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@',
	'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
	'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', ']', '^', '_',
	'a', 'b', 'c', 'd',	'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
	'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~'
};

static const size_t RCMD_PWDLEN_LENGTH = 12U;
static const size_t DFLT_PWDLEN_LENGTH = 20U;

// ==========================================================================
// Auxiliary functions
// ==========================================================================

static int parse_slunk_mode(const CHR* const command)
{
	if ((!STRICMP(command, T("-h"))) || (!STRICMP(command, T("/?"))) || (!STRICMP(command, T("--help"))))
	{
		return MODE_HELP;
	}
	else if ((!STRICMP(command, T("-v"))) || (!STRICMP(command, T("--version"))))
	{
		return MODE_VERS;
	}
	else if ((!STRICMP(command, T("-e"))) || (!STRICMP(command, T("--encrypt"))))
	{
		return MODE_ENCR;
	}
	else if ((!STRICMP(command, T("-d"))) || (!STRICMP(command, T("--decrypt"))))
	{
		return MODE_DECR;
	}
	else if ((!STRICMP(command, T("-p"))) || (!STRICMP(command, T("--make-pw"))))
	{
		return MODE_PASS;
	}
	else if ((!STRICMP(command, T("-t"))) || (!STRICMP(command, T("--self-test"))))
	{
		return MODE_TEST;
	}
	else
	{
		return -1; /*invalid command*/
	}
}

static void print_manpage(const CHR *const program)
{
	FPUTS(T("====================================================================\n"), stderr);
	FPUTS(T("This software has been released under the CC0 1.0 Universal license:\n"), stderr);
	FPUTS(T("https://creativecommons.org/publicdomain/zero/1.0/legalcode\n"), stderr);
	FPUTS(T("====================================================================\n\n"), stderr);
	FPUTS(T("Usage:\n"), stderr);
	FPRINTF(stderr, T("  %") T(PRISTR) T(" --encrypt [pass:<pass>|file:<file>] <input.txt> <output.enc>\n"), program);
	FPRINTF(stderr, T("  %") T(PRISTR) T(" --decrypt [pass:<pass>|file:<file>] <input.enc> <output.txt>\n"), program);
	FPRINTF(stderr, T("  %") T(PRISTR) T(" --make-pw [<length>]\n\n"), program);
	FPRINTF(stderr, T("Optionally, reads passphrase from the %") T(PRISTR) T(" environment variable.\n\n"), ENV_PASSWORD);
}

static char *copy_passphrase(const CHR *const passphrase)
{
	if ((!passphrase) || (!passphrase[0U]))
	{
		FPUTS(T("Error: The passphrase input string must not be empty!\n\n"), stderr);
		return NULL;
	}

	char *const buffer = CHR_to_utf8(passphrase);
	if (!buffer)
	{
		FPUTS(T("Error: Failed to allocate the string buffer!\n\n"), stderr);
	}

	return buffer;
}

static char *read_passphrase(const CHR *const file_name)
{
	if ((!file_name) || (!file_name[0U]))
	{
		FPUTS(T("Error: The passphrase input file name must not be empty!\n\n"), stderr);
		return NULL;
	}

	const size_t max_len = SLUNKCRYPT_PWDLEN_MAX + 2U;
	char *const buffer = (char*) malloc(max_len * sizeof(char));
	if (!buffer)
	{
		FPUTS(T("Error: Failed to allocate the passphrase buffer!\n\n"), stderr);
		return NULL;
	}

	const int use_stdin = (!file_name) || (!STRICMP(file_name, T("-")));
	FILE *const file_in = use_stdin ? stdin : FOPEN(file_name, T("rb"));
	if (!file_in)
	{
		FPRINTF(stderr, T("Error: Failed to open input file \"%") T(PRISTR) T("\" for reading!\n\n"), file_name);
		free(buffer);
		return NULL;
	}

	do
	{
		if (!fgets(buffer, (int)max_len, file_in))
		{
			buffer[0U] = '\0';
			goto finish;
		}
		size_t length = strlen(buffer);
		while ((length > 0U) && ((buffer[length - 1U] == '\r') || (buffer[length - 1U] == '\n')))
		{
			buffer[--length] = '\0';
		}
	}
	while (!buffer[0U]);

finish:

	if ((!use_stdin) && file_in)
	{
		fclose(file_in);
	}

	return buffer;
}

static int weak_passphrase(const char *str)
{
	int flags[4U] = { 0, 0, 0, 0 };
	while (*str)
	{
		const int c = *str++;
		if (isalpha(c))
		{
			flags[isupper(c) ? 0U : 1U] = 1;
		}
		else 
		{
			flags[isdigit(c) ? 2U : 3U] = 1;
		}
	}
	const int strong = flags[0U] && flags[1U] && flags[2U] && flags[3U];
	return !strong;
}

static int generate_passphrase(const size_t length)
{
	int result = EXIT_FAILURE;
	const size_t passwd_len = BOUND(SLUNKCRYPT_PWDLEN_MIN, length, SLUNKCRYPT_PWDLEN_MAX);

	char *const buffer = (char*) malloc((passwd_len + 1U) * sizeof(char));
	if (!buffer)
	{
		FPUTS(T("Error: Failed to allocate memory buffer!\n\n"), stderr);
		return EXIT_FAILURE;
	}

	do
	{
		for (size_t i = 0U; i < passwd_len; ++i)
		{
			uint64_t value;
			if (slunkcrypt_generate_nonce(&value) != SLUNKCRYPT_SUCCESS)
			{
				FPUTS(T("Error: Failed to generate next random number!\n\n"), stderr);
				goto clean_up;
			}
			buffer[i] = PASSWD_SYMBOLS[value % ARRAY_SIZE(PASSWD_SYMBOLS)];
		}
		buffer[passwd_len] = '\0';
	}
	while ((!isalpha((int)buffer[0U])) || (!isalnum((int)buffer[passwd_len - 1U])) || weak_passphrase(buffer));

	FPRINTF(stdout, T("%") T(PRIstr) T("\n\n"), buffer);
	fflush(stdout);
	result = EXIT_SUCCESS;

clean_up:

	if (buffer)
	{
		slunkcrypt_bzero(buffer, passwd_len * sizeof(char));
		free(buffer);
	}

	return result;
}

static int keep_incomplete_files(void)
{
	const CHR *const keep_files = GETENV(ENV_KEEPFILE);
	if (keep_files)
	{
		return BOOLIFY(STRTOUL(keep_files));
	}
	return 0;
}

static void check_excess_arguments(const int argc, int maximum)
{
	if (argc > maximum)
	{
		FPUTS(T("Warning: Excess command-line argument(s) will be ignored!\n\n"), stderr);
		fflush(stderr);
	}
}

static void sigint_handler(const int sig)
{
	if (sig == SIGINT)
	{
		g_slunkcrypt_abort_flag = 1;
	}
}

// ==========================================================================
// Main function
// ==========================================================================

int MAIN(const int argc, CHR *const argv[])
{
	init_terminal();
	setup_signal_handler(SIGINT, sigint_handler);
	int result = EXIT_FAILURE;
	char *passphrase_buffer = NULL;

	FPRINTF(stderr, T("SlunkCrypt Utility (%") T(PRIstr) T("-%") T(PRIstr) T("), by LoRd_MuldeR <MuldeR2@GMX.de>\n"), OS_TYPE, CPU_ARCH);
	FPRINTF(stderr, T("Using libSlunkCrypt v%u.%u.%u [%") T(PRIstr) T("]\n\n"), SLUNKCRYPT_VERSION_MAJOR, SLUNKCRYPT_VERSION_MINOR, SLUNKCRYPT_VERSION_PATCH, SLUNKCRYPT_BUILD);

	fflush(stderr);

	/* ----------------------------------------------------- */
	/* Parse arguments                                       */
	/* ----------------------------------------------------- */

	if (argc < 2)
	{
		FPRINTF(stderr, T("Error: Nothing to do. Please type '%") T(PRISTR) T(" --help' for details!\n\n"), get_file_name(argv[0U]));
		goto clean_up;
	}

	const int slunk_mode = parse_slunk_mode(argv[1U]);
	switch (slunk_mode)
	{
	case MODE_HELP:
		print_manpage(get_file_name(argv[0U]));
	case MODE_VERS:
		result = EXIT_SUCCESS;
		goto clean_up;
	case MODE_ENCR:
	case MODE_DECR:
		break; /*fallthrough*/
	case MODE_PASS:
		check_excess_arguments(argc, 3);
		result = generate_passphrase((argc > 2) ? STRTOUL(argv[2U]) : DFLT_PWDLEN_LENGTH);
		goto clean_up;
	case MODE_TEST:
		check_excess_arguments(argc, 2);
		result = run_selftest_routine();
		goto clean_up;
	default:
		FPRINTF(stderr, T("Error: The specified command \"%") T(PRISTR) T("\" is unknown!\n\n"), argv[1U]);
		goto clean_up;
	}

	if (argc < 4)
	{
		FPRINTF(stderr, T("Error: Required argument is missing. Please type '%") T(PRISTR) T(" --help' for details!\n\n"), get_file_name(argv[0U]));
		goto clean_up;
	}

	check_excess_arguments(argc, 5);
	
	const CHR *const passphrase = PW_FROM_ENV ? GETENV(ENV_PASSWORD) : argv[2U];
	const CHR *const input_file = argv[PW_FROM_ENV ? 2U : 3U], *const output_file = argv[PW_FROM_ENV ? 3U : 4U];

	if ((!passphrase) || (!passphrase[0U]))
	{
		FPUTS(T("Error: The passphrase must be specified, directly or indirectly!\n\n"), stderr);
		goto clean_up;
	}

	if ((!PW_FROM_ENV) && STRICMP(passphrase, T("-")))
	{
		if ((!STARTS_WITH(passphrase, PREFIX_PASS)) && (!STARTS_WITH(passphrase, PREFIX_FILE)))
		{
			FPRINTF(stderr, T("Error: The passphrase must start with a '%") T(PRISTR) T("' or '%") T(PRISTR) T("' prefix!\n\n"), PREFIX_PASS, PREFIX_FILE);
			goto clean_up;
		}
	}

	if ((!input_file[0U]) || (!output_file[0U]))
	{
		FPUTS(T("Error: The input file and/or output file must not be empty!\n\n"), stderr);
		goto clean_up;
	}

	/* ----------------------------------------------------- */
	/* Initialize passphrase                                 */
	/* ----------------------------------------------------- */

	if (!(passphrase_buffer = PW_FROM_ENV ? copy_passphrase(passphrase) :
			(STARTS_WITH(passphrase, PREFIX_PASS) ? copy_passphrase(passphrase + STRLEN(PREFIX_PASS)) :
			(STARTS_WITH(passphrase, PREFIX_FILE) ? read_passphrase(passphrase + STRLEN(PREFIX_FILE)) : read_passphrase(T("-"))))))
	{
		goto clean_up;
	}

	slunkcrypt_bzero((CHR*)passphrase, STRLEN(passphrase) * sizeof(CHR));

	const size_t passphrase_len = strlen(passphrase_buffer);
	if (passphrase_len < SLUNKCRYPT_PWDLEN_MIN)
	{
		FPRINTF(stderr, T("Error: Passphrase must be at least %u characters in length!\n\n"), (unsigned)SLUNKCRYPT_PWDLEN_MIN);
		goto clean_up;
	}
	else if (passphrase_len > SLUNKCRYPT_PWDLEN_MAX)
	{
		FPRINTF(stderr, T("Error: Passphrase must be at most %u characters in length!\n\n"),  (unsigned)SLUNKCRYPT_PWDLEN_MAX);
		goto clean_up;
	}

	if (passphrase_len < RCMD_PWDLEN_LENGTH)
	{
		FPRINTF(stderr, T("Warning: Using a *short* passphrase; a length of %u characters or more is recommended!\n\n"), (unsigned)RCMD_PWDLEN_LENGTH);
	}
	else if (weak_passphrase(passphrase_buffer))
	{
		FPUTS(T("Warning: Using a *weak* passphrase; a mix of upper-case letters, lower-case letters, digits and 'special' characters is recommended!\n\n"), stderr);
	}

	fflush(stderr);

	/* ----------------------------------------------------- */
	/* Encrypt or decrypt                                    */
	/* ----------------------------------------------------- */

	const clock_t clk_start = clock();
	const int keep_incomplete = keep_incomplete_files();

	switch (slunk_mode)
	{
	case MODE_ENCR:
		result = encrypt(passphrase_buffer, input_file, output_file, keep_incomplete);
		break;
	case MODE_DECR:
		result = decrypt(passphrase_buffer, input_file, output_file, keep_incomplete);
		break;
	default:
		FPUTS(T("Unexpected mode encountered!\n\n"), stderr);
	}

	if (!g_slunkcrypt_abort_flag)
	{
		const clock_t clk_end = clock();
		FPRINTF(stderr, T("--------\n\nOperation completed after %.1f seconds.\n\n"), (clk_end - clk_start) / ((double)CLOCKS_PER_SEC));
	}

	/* ----------------------------------------------------- */
	/* Final clean-up                                        */
	/* ----------------------------------------------------- */

clean_up:

	fflush(stderr);

	if (passphrase_buffer)
	{
		slunkcrypt_bzero(passphrase_buffer, strlen(passphrase_buffer));
		free(passphrase_buffer);
	}

	return result;
}

#if defined(_WIN32) && defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR)
void __wgetmainargs(int*, wchar_t***, wchar_t***, int, int*);
int main()
{
	wchar_t** enpv, ** argv;
	int argc, si = 0;
	__wgetmainargs(&argc, &argv, &enpv, 1, &si);
	return wmain(argc, argv);
}
#endif