Provided by: wipl-daemon_20020601-10_i386
wipllang - Description of the wipl programming language
This manual page describes the wipl programming language as implemented
by the two programs wipld and wiplcExec. Look at the pages for these
programs for examples of programs usable in practice.
The programs always have access to the shared memory area maintained by
the wipld daemon and the purpose of the programs are to update and/or
print information about the counters in this area. Only a single
program at a time can access the shared memory area maintained by a
wipld daemon, so a program can assume that the counters are not changed
by others while it executes.
The following program will print the numbers from 1 to 10:
When executed by wiplcExec they will be printed on stdout. When
executed by wipld they will be written to the logfile. Note that the
language does not have traditional lexical scoping. So the following
program is not valid:
int a; // Error - variable a already declared
A variable of type int should be at least a 64 bit signed number and
thus has more bits than the C type int has on most current platforms.
An integer literal on more than 32 bits can be written in the form a:b.
This is equivalent to (but more efficient to evaluate than) the
The language has a bool type which can be either true or false. You
need an explicit cast to convert values between these two types. For
b=bool(a); // Ok, b will now be true
a=int(b); // Ok, a will now be 1
b=a; // Error
a=b; // Error
Besides the types int and bool the language also has the types maca and
ipa. A variable of type maca can contain a MAC address (like
11:22:33:44:55:66) and a variable of type ipa can contain an IP version
4 address (like 220.127.116.11).
With our new terminology we can say that wipld creates a shared memory
area. This area contains an array. Depending on the addressing mode
selected by wipld the array is indexed either by the maca or the ipa
type. Each element in this array has a list of counters of type int.
If the daemon is in MAC addressing mode you can access counter 2 of the
MAC address 11:22:33:44:55:66 by the expression 11:22:33:44:55:66.
To set the value of this counter to 10 use:
The following code will have the same effect:
If the daemon is in IP addressing mode you should use IP instead of MAC
A rich set of operators on int arguments is available. For example one
can use +, -, * and / for addition, subtraction, multiplication and
division respectively. The operators << and >> can be used for bitwise
left and right shifting.
Note that the / operator has a special meaning when used in the form
ip/number: it gives the network part of the IP address, with the
network mask given by the number. For example: 192.168.22.103/24 is
the same as 192.168.22.0, and 192.168.22.103/16 is the same as
For a complete reference of the grammar of the language look in the
module parseprg.y in the source code of wipl.
Several functions are available for the programs and these will will be
These functions can be used to print variables or strings as the
in the example above. print is defined for all build in types
described above. It can also be used to print strings, like:
print("Hello World"); The prints function is only defined for
integer arguments. On most platforms it will print the 64 bit
signed parameter as an unsigned 32 bit number.
The expression TBLcardcnt() evaluates to the number of entries
(i.e. MAC/IP addresses) in the table in the shared memory area.
These are numbered from 0.
The expression TBLcntcnt() evaluates to the number of counters
defined for each entry in the table.
The expression TBLidxget(a) will return the index the given
address has in the table. If the daemon is in MAC addressing
mode a must be a MAC address. If it is in IP addressing mode it
must be an IP address. If no entry in the table exists for the
given address an entry is created with all counters set to 0.
The expression MACgetmacaddr(i) will return the MAC address of
the i’th entry in the table.
The expression MACgetipaddr(i) will return the IP address of the
i’th entry in the table.
The expression TBLidxdel(i) will delete the i’th entry from the
All programs have access to the following predefined variables:
This is the current time in number of seconds since 1. January
hour, min, wday, mday
Evaluate to an integer representation of the hour, minute,
weekday and day in month.
Besides these variables programs executed from wipld have access other
variables reflecting the current packet being handled:
srcmac, srcip, srcport, dstmac, dstip, dstport
The source and destination of the packet. srcport and dstport
will evaluate to 0 if the packet is not a TCP or UDP packet.
The size of the IP part of the packet
The error messages for wrong programs are not always very informative.
wipl(1), wiplc(1), wipld(8)
June 2000 wipllang(5)