/* Truncate str at the first occurrence of delimiter and return the first
 * non-whitespace character after that point. */
static char *
delimit(char *str, char delimiter)
{
	while (*str != '\0' && *str != delimiter)
		str++;
	if (*str != '\0')
		*str++ = '\0';
	return skip_whitespace(str);
}

/*
 * loads the configuration file
 * this is called while having a mutex lock on the mechanism list
 * entries for libraries that have been loaded can't be modified
 * mechNameStr and mech_type fields are not updated during updates
 */
static void
loadConfigFile(const char *fileName)
{
	char *sharedLib, *kernMod, *modOptions, *modType, *oid, *next;
	char buffer[BUFSIZ], *oidStr;
	FILE *confFile;

	if ((confFile = fopen(fileName, "r")) == NULL) {
		return;
	}

	(void) memset(buffer, 0, sizeof (buffer));
	while (fgets(buffer, BUFSIZ, confFile) != NULL) {

		/* ignore lines beginning with # */
		if (*buffer == '#')
			continue;

		/* Parse out the name, oid, and shared library path. */
		oidStr = buffer;
		oid = delimit_ws(oidStr);
		if (*oid == '\0')
			continue;
		sharedLib = delimit_ws(oid);
		if (*sharedLib == '\0')
			continue;
		next = delimit_ws(sharedLib);

		/* Parse out the kernel module name if present. */
		if (*next != '\0' && *next != '[' && *next != '<') {
			kernMod = next;
			next = delimit_ws(kernMod);
		} else {
			kernMod = NULL;
		}

		/* Parse out the module options if present. */
		if (*next == '[') {
			modOptions = next + 1;
			next = delimit(modOptions, ']');
		} else {
			modOptions = NULL;
		}

		/* Parse out the module type if present. */
		if (*next == '<') {
			modType = next + 1;
			(void)delimit(modType, '>');
		} else {
			modType = NULL;
		}

		addConfigEntry(oidStr, oid, sharedLib, kernMod, modOptions,
			       modType);
	} /* while */
	(void) fclose(confFile);
} /* loadConfigFile */

#if defined(_WIN32)

static time_t
filetimeToTimet(const FILETIME *ft)
{
	ULARGE_INTEGER ull;

	ull.LowPart = ft->dwLowDateTime;
	ull.HighPart = ft->dwHighDateTime;
	return (time_t)(ull.QuadPart / 10000000ULL - 11644473600ULL);
}

static time_t
getRegConfigModTime(const char *keyPath)
{
	time_t currentUserModTime = getRegKeyModTime(HKEY_CURRENT_USER,
						     keyPath);
	time_t localMachineModTime = getRegKeyModTime(HKEY_LOCAL_MACHINE,
						      keyPath);

	return currentUserModTime > localMachineModTime ? currentUserModTime :
		localMachineModTime;
}

static time_t
getRegKeyModTime(HKEY hBaseKey, const char *keyPath)
{
	HKEY hConfigKey;
	HRESULT rc;
	int iSubKey = 0;
	time_t modTime = 0, keyModTime;
	FILETIME keyLastWriteTime;
	char subKeyName[256];

	if ((rc = RegOpenKeyEx(hBaseKey, keyPath, 0, KEY_ENUMERATE_SUB_KEYS,
			       &hConfigKey)) != ERROR_SUCCESS) {
		/* TODO: log error message */
		return 0;
	}
	do {
		int subKeyNameSize=sizeof(subKeyName)/sizeof(subKeyName[0]);
		if ((rc = RegEnumKeyEx(hConfigKey, iSubKey++, subKeyName,
				       &subKeyNameSize, NULL, NULL, NULL,
				       &keyLastWriteTime)) != ERROR_SUCCESS) {
			break;
		}
		keyModTime = filetimeToTimet(&keyLastWriteTime);
		if (modTime < keyModTime) {
			modTime = keyModTime;
		}
	} while (1);
	RegCloseKey(hConfigKey);
	return modTime;
}

static void
getRegKeyValue(HKEY hKey, const char *keyPath, const char *valueName,
	       void **data, DWORD* dataLen)
{
	DWORD sizeRequired=*dataLen;
	HRESULT hr;
	/* Get data length required */
	if ((hr = RegGetValue(hKey, keyPath, valueName, RRF_RT_REG_SZ, NULL,
			      NULL, &sizeRequired)) != ERROR_SUCCESS) {
		/* TODO: LOG registry error */
		return;
	}
	/* adjust data buffer size if necessary */
	if (*dataLen < sizeRequired) {
		*dataLen = sizeRequired;
		*data = realloc(*data, sizeRequired);
		if (!*data) {
			*dataLen = 0;
			/* TODO: LOG OOM ERROR! */
			return;
		}
	}
	/* get data */
	if ((hr = RegGetValue(hKey, keyPath, valueName, RRF_RT_REG_SZ, NULL,
			      *data, &sizeRequired)) != ERROR_SUCCESS) {
		/* LOG registry error */
		return;
	}
}

static void
loadConfigFromRegistry(HKEY hBaseKey, const char *keyPath)
{
	HKEY hConfigKey;
	DWORD iSubKey, nSubKeys, maxSubKeyNameLen, modTypeLen;
	char *oidStr = NULL, *oid = NULL, *sharedLib = NULL, *kernMod = NULL;
	char *modOptions = NULL, *modType = NULL;
	DWORD oidStrLen = 0, oidLen = 0, sharedLibLen = 0, kernModLen = 0;
	DWORD modOptionsLen = 0;
	HRESULT rc;

	if ((rc = RegOpenKeyEx(hBaseKey, keyPath, 0,
			       KEY_ENUMERATE_SUB_KEYS|KEY_QUERY_VALUE,
			       &hConfigKey)) != ERROR_SUCCESS) {
		/* TODO: log registry error */
		return;
	}

	if ((rc = RegQueryInfoKey(hConfigKey,
		NULL, /* lpClass */
		NULL, /* lpcClass */
		NULL, /* lpReserved */
		&nSubKeys,
		&maxSubKeyNameLen,
		NULL, /* lpcMaxClassLen */
		NULL, /* lpcValues */
		NULL, /* lpcMaxValueNameLen */
		NULL, /* lpcMaxValueLen */
		NULL, /* lpcbSecurityDescriptor */
		NULL  /* lpftLastWriteTime */ )) != ERROR_SUCCESS) {
		goto cleanup;
	}
	oidStr = malloc(++maxSubKeyNameLen);
	if (!oidStr) {
		goto cleanup;
	}
	for (iSubKey=0; iSubKey<nSubKeys; iSubKey++) {
		oidStrLen = maxSubKeyNameLen;
		if ((rc = RegEnumKeyEx(hConfigKey, iSubKey, oidStr, &oidStrLen,
				       NULL, NULL, NULL, NULL)) !=
		    ERROR_SUCCESS) {
			/* TODO: log registry error */
			continue;
		}
		getRegKeyValue(hConfigKey, oidStr, "OID", &oid, &oidLen);
		getRegKeyValue(hConfigKey, oidStr, "Shared Library",
			       &sharedLib, &sharedLibLen);
		getRegKeyValue(hConfigKey, oidStr, "Kernel Module", &kernMod,
			       &kernModLen);
		getRegKeyValue(hConfigKey, oidStr, "Options", &modOptions,
			       &modOptionsLen);
		getRegKeyValue(hConfigKey, oidStr, "Type", &modType,
			       &modTypeLen);
		addConfigEntry(oidStr, oid, sharedLib, kernMod, modOptions,
			       modType);
	}
cleanup:
	RegCloseKey(hConfigKey);
	if (oidStr) {
		free(oidStr);
	}
	if (oid) {
		free(oid);
	}
	if (sharedLib) {
		free(sharedLib);
	}
	if (kernMod) {
		free(kernMod);
	}
	if (modOptions) {
		free(modOptions);
	}
}
#endif

static void
addConfigEntry(const char *oidStr, const char *oid, const char *sharedLib,
	       const char *kernMod, const char *modOptions,
	       const char *modType)
{
#if defined(_WIN32)
	const char *sharedPath;
#else
	char sharedPath[sizeof (MECH_LIB_PREFIX) + BUFSIZ];
#endif
	char *tmpStr;
	gss_OID mechOid;
	gss_mech_info aMech, tmp;
	OM_uint32 minor;
	gss_buffer_desc oidBuf;

	if ((!oid) || (!oidStr)) {
		return;
	}
	/*
	 * check if an entry for this oid already exists
	 * if it does, and the library is already loaded then
	 * we can't modify it, so skip it
	 */
	oidBuf.value = (void *)oid;
	oidBuf.length = strlen(oid);
	if (generic_gss_str_to_oid(&minor, &oidBuf, &mechOid)
		!= GSS_S_COMPLETE) {
#if 0
		(void) syslog(LOG_INFO, "invalid mechanism oid"
				" [%s] in configuration file", oid);
#endif
		return;
	}

	aMech = searchMechList(mechOid);
	if (aMech && aMech->mech) {
		generic_gss_release_oid(&minor, &mechOid);
		return;
	}

	/*
	 * If that's all, then this is a corrupt entry. Skip it.
	 */
	if (! *sharedLib) {
		generic_gss_release_oid(&minor, &mechOid);
		return;
	}
#if defined(_WIN32)
	sharedPath = sharedLib;
#else
	if (sharedLib[0] == '/')
		snprintf(sharedPath, sizeof(sharedPath), "%s", sharedLib);
	else
		snprintf(sharedPath, sizeof(sharedPath), "%s%s",
			 MECH_LIB_PREFIX, sharedLib);
#endif
	/*
	 * are we creating a new mechanism entry or
	 * just modifying existing (non loaded) mechanism entry
	 */
	if (aMech) {
		/*
		 * delete any old values and set new
		 * mechNameStr and mech_type are not modified
		 */
		if (aMech->kmodName) {
			free(aMech->kmodName);
			aMech->kmodName = NULL;
		}

		if (aMech->optionStr) {
			free(aMech->optionStr);
			aMech->optionStr = NULL;
		}

		if ((tmpStr = strdup(sharedPath)) != NULL) {
			if (aMech->uLibName)
				free(aMech->uLibName);
			aMech->uLibName = tmpStr;
		}

		if (kernMod) /* this is an optional parameter */
			aMech->kmodName = strdup(kernMod);

		if (modOptions) /* optional module options */
			aMech->optionStr = strdup(modOptions);

		/* the oid is already set */
		generic_gss_release_oid(&minor, &mechOid);
		return;
	}

	/* adding a new entry */
	aMech = calloc(1, sizeof (struct gss_mech_config));
	if (aMech == NULL) {
		generic_gss_release_oid(&minor, &mechOid);
		return;
	}
	aMech->mech_type = mechOid;
	aMech->uLibName = strdup(sharedPath);
	aMech->mechNameStr = strdup(oidStr);
	aMech->freeMech = 0;

	/* check if any memory allocations failed - bad news */
	if (aMech->uLibName == NULL || aMech->mechNameStr == NULL) {
		if (aMech->uLibName)
			free(aMech->uLibName);
		if (aMech->mechNameStr)
			free(aMech->mechNameStr);
		generic_gss_release_oid(&minor, &mechOid);
		free(aMech);
		return;
	}
	if (kernMod)	/* this is an optional parameter */
		aMech->kmodName = strdup(kernMod);

	if (modOptions)
		aMech->optionStr = strdup(modOptions);

	if (modType && strcmp(modType, "interposer") == 0)
		aMech->is_interposer = 1;

	/*
	 * add the new entry to the end of the list - make sure
	 * that only complete entries are added because other
	 * threads might currently be searching the list.
	 */
	tmp = g_mechListTail;
	g_mechListTail = aMech;

	if (tmp != NULL)
		tmp->next = aMech;

	if (g_mechList == NULL)
		g_mechList = aMech;
}