The ovm_var_t universal type

The OrchIDS virtual machine only handles one data type, ovm_var_t.

This is defined in src/lang.h:

typedef struct ovm_var_s ovm_var_t;
struct ovm_var_s
{
  gc_header_t gc;
  uint8_t  data[STR_PAD_LEN];
};

The data array is just a stub. There is no ovm_var_t object per se in OrchIDS. All of them are of one of the standard data types, such as ovm_int_t. The list of standard data types used by the OrchIDS virtual machine is:

• ovm_int_t (machine integers)
• ovm_uint_t (unsigned machine integers)
• ovm_float_t (floating-point numbers)
• ovm_bstr_t (binary strings)
• ovm_vbstr_t (virtual binary strings)
• ovm_str_t (character strings)
• ovm_vstr_t (virtual character strings)
• ovm_ctime_t (times)
• ovm_timeval_t (durations and times)
• ovm_ipv4_t (IPv4 addresses)
• ovm_ipv6_t (IPv6 addresses)
• ovm_regex_t (regular expression matchers)
• ovm_snmpoid_t (SNMP object identifiers)
• ovm_extern_t (foreign data)

One point to be careful about is the following. An object of type ovm_var_t *, handled by OrchIDS, can be a pointer to an object of one of the above types, or the value NULL. The latter is usually indicative of a run-time error. One implication of this is that, when writing a function that works on objects of type ovm_var_t *, one should first check whether it is NULL before accessing it.