Networking Principles Essay, Research Paper

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