FREE ESSAY ON NETWORKING PRINCIPLES

NETWORKING PRINCIPLES

Dial-Up Scripting Command Language
For Dial-Up Networking Scripting Support
Copyright (c) 1995 Microsoft Corp.
Table of Contents
1.0 Overview
2.0 Basic Structure of a Script
3.0 Variables
3.1 System Variables
4.0 String Literals
5.0 Expressions
6.0 Comments
7.0 Keywords
8.0 Commands
9.0 Reserved Words
1.0 Overview
Many Internet service providers and online services require you to manually enter
information, such as your user name and password, to establish a connection. With
Scripting support for Dial-Up Networking, you can write a script to automate this
process. 
A script is a text file that contains a series of commands, parameters, and expressions
required by your Internet service provider or online service to establish the connection
and use the service. You can use any text editor, such as Microsoft Notepad, to create a
script file. Once you've created your script file, you can then assign it to a specific
Dial-Up Networking connection by running the Dial-Up Scripting Tool.
2.0 Basic Structure of a Script
A command is the basic instruction that a script file contains. Some commands require
parameters that further define what the command should do. An expression is a combination
of operators and arguments that create a result. Expressions can be used as values in any
command. Examples of expressions include arithmetic, relational comparisons, and string
concatenations.
The basic form of a script for Dial-Up Networking follows:
;
; A comment begins with a semi-colon and extends to 
; the end of the line.
;
proc main
; A script can have any number of variables 
; and commands
variable declarations
command block
endproc
A script must have a main procedure, specified by the proc keyword, and a matching
endproc keyword, indicating the end of the procedure. 
You must declare variables before you add commands. The first command in the main
procedure is executed, and then any subsequent commands are executed in the order they
appear in the script. The script ends when the end of the main procedure is reached.
3.0 Variables
Scripts may contain variables. Variable names must begin with a letter or an underscore
('_'), and may contain any sequence of upper- or lower-case letters, digits, and
underscores. You cannot use a reserved word as a variable name. For more information, see
the list of reserved words at the end of this document.
You must declare variables before you use them. When you declare a variable, you must
also define its type. A variable of a certain type may only contain values of that same
type. The following three types of variables are supported:
Type Description
integer A negative or positive number, such as 7, -12, or 5698.
string A series of characters enclosed in double-quotes; for example, Hello world! or
Enter password:.
boolean A logical boolean value of TRUE or FALSE.
Variables are assigned values using the following assignment statement:
variable = expression
The variable gets the evaluated expression. 
Examples:
integer count = 5
integer timeout = (4 * 3)
integer i
boolean bDone = FALSE
string szIP = (getip 2)
set ipaddr szIP
3.1 System Variables
System variables are set by scripting commands or are determined by the information your
enter when you set up a Dial-Up Networking connection. System variables are read-only,
which means they cannot be changed within the script. The system variables are:
Name Type Description 
$USERID String The user identification for the current connection. This variable is 
the value of the user name specified in the Dial-Up Networking 
Connect To dialog box. 
$PASSWORD String The password for the current connection. This variable is the 
value of the user name specified in the Dial-Up Networking 
Connect To dialog box. 
$SUCCESS Boolean This variable is set by certain commands to indicate whether or not the
command succeeded. A script can make 
decisions based upon the value of this variable. 
$FAILURE Boolean This variable is set by certain commands to indicate 
whether or not the command failed. A script can make decisions 
based upon the value of this variable. 
These variables may be used wherever an expression of a similar type is used. For
example, 
transmit $USERID
is a valid command because $USERID is a variable of type string.
4.0 String Literals
Scripting for Dial-Up Networking supports escape sequences and caret translations, as
described below.
String Literal Description
^char Caret translation
If char is a value between '@' and '_', the character sequence is translated into a
single-byte value between 0 and 31. For example, ^M is converted to a carriage return.
If char is a value between a and z, the character sequence is translated into a
single-byte value between 1 and 26.
If char is any other value, the character sequence is not specially treated.
*cr* Carriage return
*lf* Linefeed
\ Double-quote
\^ Single caret
\* Single '*'
\\ Backslash
Examples:
transmit ^M
transmit Joe^M
transmit *cr**lf*
waitfor *cr**lf*
5.0 Expressions
An expression is a combination of operators and arguments that evaluates to a result.
Expressions can be used as values in any command.
An expression can combine any variable, or integer, string, or boolean values with any of
the unary and binary operators in the following tables. All unary operators take the
highest precedence. The precedence of binary operators is indicated by their position in
the table. 
The unary operators are:
Operator Type of Operation 
- Unary minus 
! One's complement 
The binary operators are listed in the following table in their order of precedence.
Operators with higher precedence are listed first:
Operators Type of Operation Type Restrictions 
* / Multiplicative Integers 
+ - Additive integers Strings (+ only) 
* * *= *= Relational Integers 
== != Equality Integers, strings, booleans
and Logical AND Booleans 
or Logical OR Booleans 
Examples:
count = 3 + 5 * 40
transmit Hello +  there
delay 24 / (7 - 1)
6.0 Comments
All text on a line following a semicolon is ignored.
Examples:
; this is a comment
transmit hello ; transmit the string hello
7.0 Keywords
Keywords specify the structure of the script. Unlike commands, they do not perform an
action. The keywords are listed below.
proc name 
Indicates the beginning of a procedure. All scripts must have a main procedure (proc
main). Script execution starts at the main procedure and terminates at the end of the
main procedure.
endproc
Indicates the end of a procedure. When the script is executed to the endproc statement
for the main procedure, Dial-Up Networking will start PPP or SLIP. 
integer name [ = value ] 
Declares a variable of type integer. You can use any numerical expression or variable to
initialize the variable.
string name [ = value ] 
Declares a variable of type string. You can use any string literal or variable to
initialize the variable.
boolean name [ = value ] 
Declares a variable of type boolean. You can use any boolean expression or variable to
initialize the variable.
8.0 Commands
All commands are reserved words, which means you cannot declare variables that have the
same names as the commands. The commands are listed below:
delay nSeconds
Pauses for the number of seconds specified by nSeconds before executing the next command
in the script.
Examples:
delay 2 ; pauses for 2 seconds
delay x * 3 ; pauses for x * 3 seconds
getip value
Waits for an IP address to be received from the remote computer. If your Internet service
provider returns several IP addresses in a string, use the value parameter to specify
which IP address the script should use.
Examples:
; get the second IP address 
set ipaddr getip 2 
; assign the first received IP address to a variable
szAddress = getip
goto label
Jumps to the location in the script specified by label and continues executing the
commands following it.
Example:
waitfor Prompt* until 10
if !$SUCCESS then
goto BailOut ; jumps to BailOut and executes commands 
; following it
endif
transmit bbs^M
goto End
BailOut:
transmit ^M
halt
Stops the script. This command does not remove the terminal dialog window. You must click
Continue to establish the connection. You cannot restart the script.
if condition then
commands
endif
Executes the series of commands if condition is TRUE.
Example:
if $USERID == John then
transmit Johnny^M
endif
label :
Specifies the place in the script to jump to. A label must be a unique name and follow
the naming conventions of variables.
set port databits 5 | 6 | 7 | 8
Changes the number of bits in the bytes that are transmitted and received during the
session. The number of bits can be between 5 and 8. If you do not include this command,
Dial-Up Networking will use the properties settings specified for the connection.
Example:
set port databits 7
set port parity none | odd | even | mark | space
Changes the parity scheme for the port during the session. If you do not include this
command, Dial-Up Networking will use the properties settings specified for the
connection.
Example:
set port parity even
set port stopbits 1 | 2
Changes the number of stop bits for the port during the session. This number can be
either 1 or 2. If you do not include this command, Dial-Up Networking uses the properties
settings specified for the connection.
Example:
set port stopbits 2
set screen keyboard on | off
Enables or disables keyboard input in the scripting terminal window.
Example:
set screen keyboard on
set ipaddr string
Specifies the IP address of the workstation for the session. String must be in the form
of an IP address.
Examples:
szIPAddress = 11.543.23.13
set ipaddr szIPAddress
set ipaddr 11.543.23.13
set ipaddr getip
transmit string [ , raw ]
Sends the characters specified by string to the remote computer. 
The remote computer will recognize escape sequences and caret translations, unless you
include the raw parameter with the command. The raw parameter is useful when transmitting
$USERID and $PASSWORD system variables when the user name or password contains character
sequences that, without the raw parameter, would be interpreted as caret or escape
sequences.
Examples:
transmit slip + ^M
transmit $USERID, raw
waitfor string [ , matchcase ] [ then label 
{ , string [ , matchcase ] then label } ]
[ until time ]
Waits until your computer receives one or more of the specified strings from the remote
computer. The string parameter is case-insensitive, unless you include the matchcase
parameter.
If a matching string is received and the then label parameter is used, this command will
jump to the place in the script file designated by label.
The optional until time parameter defines the maximum number of seconds that your
computer will wait to receive the string before it execute the next command. Without
this
parameter, your computer will wait forever.
If your computer receives one of the specified strings, the system variable $SUCCESS is
set to TRUE. Otherwise, it is set to FALSE if the number of seconds specified by time
elapses before the string is received. 
Examples:
waitfor Login:
waitfor Password?, matchcase
waitfor prompt* until 10
waitfor
Login: then DoLogin,
Password: then DoPassword,
BBS: then DoBBS,
Other: then DoOther
until 10
while condition do
commands
endwhile
Executes the series of commands until condition is FALSE.
Example:
integer count = 0
while count * 4 do
transmit ^M
waitfor Login: until 10
if $SUCCESS then
goto DoLogin
endif
count = count + 1
endwhile
...
9.0 Reserved Words
The following words are reserved and may not be used as variable names.
and boolean databits delay 
do endif endproc endwhile 
even FALSE getip goto 
halt if integer ipaddr 
keyboard mark matchcase none 
odd off on or 
parity port proc raw 
screen set space stopbits 
string then transmit TRUE 
until waitfor while