enum: Add helper to parse enum flags from strings

Individual flag names are separated by |.

src/libstrongswan/utils/enum.c

@@ -17,6 +17,7 @@
 #include <stdio.h>
 
 #include <library.h>
+#include <collections/enumerator.h>
 #include <utils/utils.h>
 
 #include "enum.h"
@@ -135,6 +136,54 @@ char *enum_flags_to_string(enum_name_t *e, u_int val, char *buf, size_t len)
 	return buf;
 }
 
+/*
+ * Described in header
+ */
+bool enum_flags_from_string_as_int(enum_name_t *e, const char *str, u_int *val)
+{
+	enumerator_t *enumerator;
+	char *name;
+
+	*val = 0;
+
+	if (!str || !*str)
+	{
+		return TRUE;
+	}
+	else if (e->next != ENUM_FLAG_MAGIC)
+	{
+		return enum_from_name_as_int(e, str, val);
+	}
+
+	enumerator = enumerator_create_token(str, "|", " ");
+	while (enumerator->enumerate(enumerator, &name))
+	{
+		u_int flag, i;
+		bool found = FALSE;
+
+		if (strcaseeq(name, e->names[0]))
+		{	/* accept name used if no flags are set */
+			continue;
+		}
+		for (i = 1, flag = e->first; flag <= e->last; i++, flag <<= 1)
+		{
+			if (e->names[i] && strcaseeq(name, e->names[i]))
+			{
+				*val |= flag;
+				found = TRUE;
+				break;
+			}
+		}
+		if (!found)
+		{
+			enumerator->destroy(enumerator);
+			return FALSE;
+		}
+	}
+	enumerator->destroy(enumerator);
+	return TRUE;
+}
+
 /**
  * See header.
  */