Description
This is a team-based (max. 2) assignment. We want to build a “Chatting Remotely over the Internet” (CRI) server. The protocol is similar to a nearly unknown chat server from decades ago known as IRC. Our CRI server must support an arbitrary number of users and channels. Each user can be a member of zero or more channels. Channel names should always be prefixed with a hash (#). All commands, users, and channel names are case-sensitive. See the slides from Lecture 12. Output your randomly chosen port Implement the following commands: • USER • LIST • JOIN • PART • OPERATOR • KICK • PRIVMSG • QUIT USER The USER command must be the first command sent to the server immediately following a connection from a client. Otherwise, the server MUST disconnect. Users cannot change their nickname at a later time. User names should be at most 20 characters and should adhere to the following regular expression: [a-zA-Z][_0-9a-zA-Z]* LIST [#channel] The LIST command should output the current count and list all of the channels currently available on the server. If a valid channel is supplied, LIST should output the current count and print the names of all users on channel #channel. 1 JOIN <#channel> The JOIN command must add the current user to the named channel. If the named channel does not exist, it must be created. Channel names not starting with a # should not be created. Users currently on the channel should receive a message that USER has joined. Channel names should be at most 20 characters and should adhere to the following regular expression: #[a-zA-Z][_0-9a-zA-Z]* PART [#channel] The PART command must remove the current user from the named channel. Users currently on the channel should receive a message that USER has left. PARTing from a channel the user is not a member of should produce an error message and not modify the user’s current channel list. With no arguments, this command should remove the current user from all channels. OPERATOR The OPERATOR command must make the current user an operator of the server if and only if the given password matches the password supplied on the server’s command line. When starting the CRI server, an optional flag –opt-pass= may be supplied. If no such flag is passed then no users can be promoted to operator status. If the password is incorrect (or none was given on the command line) the server should print an error message but not disconnect the user. Passwords should be at most 20 characters and should adhere to the following regular expression: [a-zA-Z][_0-9a-zA-Z]* KICK <#channel> The KICK command must remove the named user from the named channel if and only if the current user is an operator of the server. PRIVMSG ( <#channel> | ) The PRIVMSG command will send the specified message to either all members of the named channel, or to the named user alone. Messages can be any printable ASCII character strings at most 512 characters in length. QUIT The QUIT command will remove the current user from all channels and disconnect from the server. Example output below. User input is in bold. $ ./cri.out –opt-pass=netprog 35232 On another terminal, use netcat to connect to the CRI server: $ nc localhost 35232 JOIN #programming Invalid command, please identify yourself with USER. $ nc localhost 35232 OPERATOR foobar Invalid command, please identify yourself with USER. 2 $ nc localhost 35232 USERblah Invalid command. USER justin Welcome, justin LIST There are currently 3 channels. * netprog * llvm * csci4220 LIST #netProg There are currently 3 channels. * netprog * llvm * csci4220 LIST #netprog There are currently 3 members. #netprog members: Alice Bob grace JOIN #netprog Joined channel #netprog #netprog> Alice: Hi Justin! #netprog> Bob: what’s up man? Bob> I need some help on the llvm channel when you get a minute! #netprog> Alice left the channel. PRIVMSG #netprog Hey guys how’s it going? #netprog> justin: Hey guys how’s it going? #netprog> grace: Hey you guys should install some backdoors in this service OPERATOR NetProg Invalid OPERATOR command. OPERATOR netprog OPERATOR status bestowed. KICK #netprog grace #netprog> grace has been kicked from the channel. PART #NetProg You are not currently in #NetProg. PART #netprog #netprog> justin left the channel. Meanwhile, on grace’s terminal: … #llvm> Bob: I have a question about how to access instruction dependencies in LLVM #llvm> Bob: hmm I wish Justin would log on #netprog> justin joined the channel. #netprog> Alice: Hi Justin! #netprog> Bob: what’s up man? #netprog> Alice left the channel. PRIVMSG #netprog Hey you guys should install some backdoors in this service #netprog> grace: Hey you guys should install some backdoors in this service #netprog> grace has been kicked from the channel. QUIT $ 3