control.h

#include <string.h>

char *DATABASE_PATH;
char *DNS_SERVER_IP;
int DEBUG_LEVEL;

void DEBUG0(const char *info, ...)
{
	if (DEBUG_LEVEL < 0)
		return;
	printf("[FATAL]");
	va_list args;
	va_start(args, info);
	vprintf(info, args);
	va_end(args);
	puts("");
}

void DEBUG1(const char *info, ...)
{
	if (DEBUG_LEVEL < 1)
		return;
	printf("[ERROR]");
	va_list args;
	va_start(args, info);
	vprintf(info, args);
	va_end(args);
	puts("");
}

void DEBUG2(const char *info, ...)
{
	if (DEBUG_LEVEL < 2)
		return;
	printf("[INFO]");
	va_list args;
	va_start(args, info);
	vprintf(info, args);
	va_end(args);
	puts("");
}

void DEBUG3(const char *info, ...)
{
	if (DEBUG_LEVEL < 3)
		return;
	printf("[DETAIL]");
	va_list args;
	va_start(args, info);
	vprintf(info, args);
	va_end(args);
	puts("");
}

/*
* init_opt
* initialize options
*/
int init_opt(int argc, char *argv[])
{
	// default
	DEBUG_LEVEL = 0;
	DNS_SERVER_IP = "114.114.114.114";
	DATABASE_PATH = "dnsrelay-edit.txt";

	for (int i = 1; i < argc; i++) {
		// debug level
		if (!strcmp(argv[i], "-d")) {
			DEBUG_LEVEL = 1;
			continue;
		}
		if (!strcmp(argv[i], "-dd")) {
			DEBUG_LEVEL = 2;
			continue;
		}
		if (!strcmp(argv[i], "-ddd")) {
			DEBUG_LEVEL = 3;
			continue;
		}

		if (argv[i][0] >= '0' && argv[i][0] <= '9') {
			// ip address
			free(DNS_SERVER_IP);
			DNS_SERVER_IP = (char *)malloc(
				strlen(argv[i]) * sizeof(char) + 1);
			memcpy(DNS_SERVER_IP, argv[i], strlen(argv[i]));
			DNS_SERVER_IP[strlen(argv[i])] = 0;
			continue;
		}

		// filename
		free(DATABASE_PATH);
		DATABASE_PATH =
			(char *)malloc(strlen(argv[i]) * sizeof(char) + 1);
		memcpy(DATABASE_PATH, argv[i], strlen(argv[i]));
		DATABASE_PATH[strlen(argv[i])] = 0;
	}
}