data编程代写、代做c/c++，Java语言程序

日期：2024-11-13 08:53

Operating Systems and Systems

Programming

Semester 1, 2024

Eike Ritter, David Oswald

The University of Birmingham

30 September, 2024

Exercise 1

Deadline: 14 November, 4pm

The Task

Write a set of programs which maintains the firewall configuation.

1. One program is a server program. Once started, the server should run for ever. It waits for requests, process them and produce a specific response.

The server maintains a collection of firewall rules. For each rule in the

collection of rules, the server also maintains a list of pairs of IP addresses

and ports which have been queried and found to match this rule. The

server also maintains a list of all requests submitted to it. The server

program should accept and process requests and return a response as

follows:

❼ Listing all requests in the order they were given. The command for

this request is R

❼ Adding a rule to the stored rules. This request expects a string which

contains a firewall rule as specified below. If the rule is valid, the

rule is added the set of firewall rules. The response is Rule added

if the rule has been added, and Invalid rule if the string is not a

valid rule. The command for this request is

A <rule>

❼ Checking whether a given IP address and port are allowed according

to the rules. If this is the case, the IP address and port are added

to list of matched queries for this rule. If the given address and port

are allowed according to several rules, you should add the IP address

and port to only one rule. If the given IP address and port is checked

again, they may be added to a different rule. If the input does not

provide a valid IP address and a valid port, the response should be

Illegal IP address or port specified. If the IP address and

port are valid and should be accepted according to the rules, the

response should be Connection accepted. If the IP address and

port are valid and should be rejected according to the rules, the

response should be Connection rejected. The command for this

request is

C <IPAddress> <port>

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❼ Delete a valid rule from the stored rules. This should also delete the

list of IP addresses and ports stored for this rule. The rule should

only be deleted if the server stores exactly the same rule. In all

other cases, no action should be taken except returning a suitable

message. If the specification of the rule is invalid, the response should

be Rule invalid. If the rule is successfully deleted, the response

should be Rule deleted. If the rule is valid but not found on the

server, the response should be Rule not found. The command for

this request is

D <rule>

❼ Return all rules and for each rule list all IP addresses and ports

which are stored with it. More precisely, for each rule, the response

should be

Rule: <rule>

where <rule> is the specification of the rule as given below, followed

by

Query: <IPaddress> <port>

for each query stored with this firewall rule. The command for this

request is L

❼ For any other request, the response should be Illegal request.

There are two ways of interacting with the server program.

❼ The first one is to start the server with

<ServerProgram> -i

where <ServerProgram> is the way to call the server program, typ ically ./server. In this mode the server reads an command from

standard input, prints the response and waits for the next input.

❼ The second way of running the server is

<ServerProgram> <port>

where <ServerProgram> is the way to call the server program, typ ically ./server, and <port> is the port on which the server listens

for incoming connections. A client program, which you will have to

write as well, makes it possible to send commands to the server pro gram and display the results on standard output. The client should

be called with

<ClientProgram> <serverHost> <serverPort> <command>

without any quotes, e.g.

./client localhost 2200 A 147.188.193.15 22

All other ways of calling the client program should return an error

message.

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The specification of a firewall rule is below.

A rule is of the form

<IPAddresses> <ports>

where <IPAddresses> is either a single IP address, which has the form xxx.xxx.xxx.xxx,

where xxx is a number between 0 and 255, or <IPAddress1>-<IPAddress2>,

where <IPAddress1> and <IPaddress2> are IP addresses, and <IPAddress1> is

smaller than <IPaddress2>. Assume that IP addresses and ports are separated

by exactly one space character.

Similarly, <ports> is either a single port number, which is a number between

0 and 65535, or <port1>-<port2>, where <port1> and <port2> are ports and

<port1> is smaller than <port2>.

Examples of such rules would be

147.188.193.0-147.188.194.255 21-22

147.188.192.41 443

Your server program should maximise the degree of concurrency and not contain

any memory leaks.

Submission and Marking

❼ You should submit the file server.c and client.c on the appropriate

canvas-quiz. The marking scripts will execute the command make with

the Makefile provided in the archive on canvas to produce all required

binaries.

❼ The zip-archive on canvas contains a Makefile and a basic test script is

provided in the file test.sh. The Makefile and the test script will only

work if server.c and client.c are in the same directory as the Makefile

and the test script respectively. The test script tests the cases of adding

a rule both interactively and via sockets. It is run by changing into the

directory containing the binaries and then running

./test.sh

We will use more advanced scripts for marking which test all the specified

functionality, including concurrency and memory leaks. If the basic test

script does not work, all other scripts are likely to fail as well.

❼ Code which does not compile on the virtual machine provided will be

awarded 0 marks.

Hints

❼ You should start by implementing the interactive version of the server

(the version running with server -i) and the R-command. Sockets and

concurrency will be explained in later lectures.

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❼ You may use the code provided in the lectures in your assignments as you

see fit.

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