first mostly working draft

client.go

@@ -0,0 +1,313 @@
+// =============================================================================
+// Auth: alex
+// File: client.go
+// Revn: 10-02-2023  1.0
+// Func: ask server for a message of the day quote
+//
+// TODO: document
+//       add more flags?
+//       log errors in logfile
+// =============================================================================
+// CHANGE LOG
+// -----------------------------------------------------------------------------
+// 05-11-2022: init
+// 05-17-2022: changed an entry in the response table
+// 08-16-2023: copied from speak.go
+//             gutted, rewrote
+// 09-12-2023: added size conversation
+//             added -d, -l, and -dest flags
+//             commented
+// 09-21-2023: began complete-ass overhaul of handle() system
+//             wrote draft of draw()
+// 09-26-2023: made draw return size and reference globals
+//             imported check() from soary
+// 09-29-2023: commented handle()
+//*10-02-2023: commented main(), and friends
+//
+// =============================================================================
+
+package main
+
+import ( 
+    "io"        // io.EOF
+    "flag"      // BoolVar, StringVar, Parse
+    "fmt"       // Println
+    "math/rand" // NewSource, New, Intn, *rand.Rand
+    "net"       // ResolveTCPAddr, DialTCP, conn.Write,Read
+    "os"        // Exit
+    "strconv"   // Atoi, Itoa
+    "strings"   // Split
+    "time"      // Now, UnixNano
+)
+
+
+
+// print errors if they occur, quit
+func check( err error ) {
+
+    var errep string    // declare error report string
+    switch err {        // switch case over error input
+        case nil:       // if there was no error
+            // then there was no error
+            errep = "err is nil"
+        case io.EOF:    // if there was an End Of File error
+            errep = "Error: " + err.Error()     // document error
+            conn.Close()    // close connection
+        default:    // anything besides those are a big deal
+            errep = "Fatal: " + err.Error()
+    }
+
+    var critical bool   // declare critical error flag
+    // must be neither nil nor EOF
+    critical = err != nil && err != io.EOF
+    if critical {   // XXX critical print
+        // TODO at some point, critical should be logging instead of
+        // printing, only verbose should print
+        fmt.Println( "check() -> ", errep )
+    }
+    
+    if critical {       // if there was a critical error
+        os.Exit( 1 )    // cut and run
+    }
+}
+
+
+// seed and get a new rng
+func seed() *rand.Rand {
+    // use current time to seed random number
+    s := rand.NewSource( time.Now().UnixNano() )
+    r := rand.New( s )  // create new random number from seed
+    return r    // return random number
+}
+
+
+// get a random number
+func draw() string {
+    rn := seed()            // get a random seed
+    r := rn.Intn( qsize )   // get a random number using seed
+    if debug {      // XXX debug print
+        fmt.Println( "random number: ", r )
+    }
+    // convert random number to ascii, because converting
+    // ints to bytes ( for networking ) and back is obnoxious
+    rsz := strconv.Itoa( r )
+    if debug {      // XXX debug print
+        fmt.Println( "converted size var" )
+        fmt.Printf( rsz + ": %T\n", rsz )
+    }
+    return rsz      // return rand size
+}
+
+
+// get server response and print
+func handle( conn net.Conn ) {
+
+    var buffer [512]byte    // create buffer to hold response
+    // read n bytes from server into buffer ( byte slice )
+    n, err := conn.Read( buffer[:] )
+    check( err )    // check for errors
+
+    // split recv'd message over @, separate header from message
+    msg := strings.Split( string( buffer[:n] ), "@" )
+
+    var resp string     // declare response variable
+    switch msg[0] {     // switch/case over the header
+        // if message is...
+        case "sa":      // /sa/, size answer
+            // convert back half to int, catch error
+            size, nerr := strconv.Atoi( msg[1] )
+            if nerr == nil {    // if there was no error
+                qsize = size    // set size global to recv'd size
+            } else {
+                // if int conversion failed, just quit
+                // TODO make more robust
+                os.Exit( 1 )
+            }
+            req := draw()           // draw a random number
+            resp = "qr@" + req      // create quote query with rng
+        case "ba":      // /ba/, bad answer
+            // TODO create server-side, and handle client-side
+            fmt.Println( "error in " + msg[1] + ": " + msg[2] )
+            resp = "te@error"   // set transaction end message
+        case "qa":      // /qa/, quote answer
+            fmt.Println( msg[1] )   // whole-ass just print quote
+            resp = "te@success"     // set transaction end message
+        case "la":      // /la/, list answer
+            // split recv'd message over newline to create quote list
+            quotes := strings.Split( msg[1], "\n" )
+            for p, v := range quotes {      // iterate over quotes
+                // print num of quote, followed by that quote
+                fmt.Println( p+1, "\t", v )
+            }
+            resp = "te@success"     // set transaction end message
+        case "aa":      // /aa/, add answer
+            // if server says add succeeded
+            if msg[1] == "success" {
+                fmt.Println( "Add successful" )     // print success
+                resp = "te@success" // set transaction end message
+            // if server says add failed
+            } else if msg[1] == "error" {
+                fmt.Println( "Add failed" )     // print fail
+                resp = "te@error"   // set transaction end message
+            // unknown status message
+            } else {
+                // print unknown status
+                fmt.Println( "Unknown status code: " + msg[1] )
+                // TODO should this be unknown instead of error?
+                resp = "te@error"   // set transaction end message
+            }
+        case "r1":      // /r1/, remove ( first transaction )
+        // the idea is that if the user doesn't specify which quote to
+        // remove, list all quotes and let the user choose the quote
+        // to remove. There was probably a way to handle this a little
+        // more simply, but this, I feel, has some nuance to it that I
+        // actually like
+            // redo /la/, list all quotes
+            quotes := strings.Split( msg[1], "\n" )
+            for p, v := range quotes {
+                fmt.Println( p+1, "\t", v )
+            }
+            // TODO get user input
+        case "r2":      // /r2/, remove ( second transaction )
+            // if server says remove succeeded
+            if msg[1] == "success" {
+                fmt.Println( "Remove successful" )  // print success
+                // list all quotes to validate remove succeeded
+                // TODO should /aa/ also make /lr/ before /te/?
+                resp = "lr@dumvar"  // set transaction end message
+            // if server says remove failed
+            } else if msg[1] == "error" {
+                fmt.Println( "Remove failed" )      // print failure
+                resp = "te@error"   // set transaction end message
+            // if unknown status message
+            } else {
+                // print unknown status
+                fmt.Println( "Unknown error code: " + msg[1] )
+                // TODO should this be unknown instead of error?
+                resp = "te@error"   // set transaction end message
+            }
+        case "br":      // /br/, bad request
+        // client has asked for something nonsensical
+            // TODO write out to file
+            fmt.Println( "Client sent a bad request" )
+            resp = "te@error"       // set transaction end message
+        default:        // something undefined entirely
+            // TODO write out to file
+            fmt.Println( "Message header not recognized" )
+            fmt.Println( msg )
+            conn.Close()    // TODO how important is this line
+            return      // dead return, essentially lets program quit
+    }
+
+    if debug {      // XXX debug print
+        fmt.Print( "raw read: " + strconv.Itoa( n ) + " bytes " )
+        fmt.Println( buffer[:n] )
+    }
+
+    // send formulated response back to server
+    _, err = conn.Write( []byte( resp ) )
+    check( err )    // make sure write worked
+
+    handle( conn )  // call handle again
+}
+
+
+// globals
+var qsize int       // keep track of num of quotes
+var conn net.Conn   // keep track of connection
+
+
+// global flag variables
+var debug bool      // debug prints useful information
+var add bool        // add new quotes to quote file ( on server )
+var remove bool     // remove quotes from quote file ( on server )
+var list bool       // request entire quote file from server
+var dest string     // provide a new destination ip and port
+
+
+func main() {
+
+    // define flags
+    flag.BoolVar( &debug, "d", false, "print debug info" )
+    flag.BoolVar( &add, "a", false, "add quote to list" )
+    flag.BoolVar( &remove, "r", false, "remove quote from list" )
+    flag.BoolVar( &list, "l", false, "print quote list" )
+    flag.StringVar( &dest, "ip", ":1300", "ip:port of server" )
+    flag.Parse()    // process flags
+
+    if debug {      // XXX debug print
+        fmt.Println( "ip:port = ", dest )
+    }
+
+    service := dest     // declare server ip:port
+
+    // create address object
+    addr, err := net.ResolveTCPAddr( "tcp", service )
+    check( err )    // check for errors
+
+    // make connection with object
+    conn, err = net.DialTCP( "tcp", nil, addr )
+    check( err )    // check for errors
+
+    // block for all flags
+    var command string
+    switch {        // empty switch statement is basically an if
+        case list:  // if list flag is active
+            command = "lr@dumvar"   // list request
+            // TODO come up with a useful argument, instead of dumvar
+        case add:   // if add flag is active
+            // if arguments were specified
+            if len( flag.Args() ) != 0 {
+                command = "ar@"     // preface command w/ add request
+                // need to concat flag.args
+                for _, v := range flag.Args() {
+                    // add the string and a space to command
+                    command = command + v + " "
+                }
+                // remove the trailing space
+                command = command[:len( command ) - 1]
+            } else {    // if no arguments were specified
+                // print that you need args and bail
+                fmt.Println( "/a/ flag must be used with an arugment" )
+                os.Exit( 1 )
+            }
+        case remove:    // if remove flag is active
+            // if arguments were specified
+            if len( flag.Args() ) >= 0 {
+                // argument is supposed to the number of the quote to
+                // be removed, get first arg
+                // cast to int just to make sure it's a valid number
+                // assuming the user knows what they're doing
+                _, rerr := strconv.Atoi( flag.Args()[0] )
+                // if there was an error, just pretend there's no args
+                if rerr != nil {
+                    command = "r1@dumvar"   // remove request 1
+                    // TODO come up w/ useful argument, replace dumvar
+                } else {
+                    // if user knows the number, take care of it
+                    // arg[0] is a string, so concat is cool
+                    // jump right into remove request 2
+                    command = "r2@" + flag.Args()[0]
+                }
+            } else {    // if no argument was specified for remove
+                // jump right into remove request 1
+                command = "r1@dumvar"
+            }
+        default:    // if no flag was specified
+            // begin transaction for quote request
+            command = "sr@please"   // size request
+    }
+
+    // write command to server, beginning transaction
+    _, err = conn.Write( []byte( command ) )
+    check( err )    // make sure write worked
+
+    handle( conn )  // handle response
+    // TODO stack trace when handle returns, should probably be
+    // updated
+    conn.Close()    // close connection when finished
+
+    os.Exit( 0 )    // exit
+
+}
+

server.go

@@ -0,0 +1,238 @@
+// =============================================================================
+// Auth: Alex Celani
+// File: server.go
+// Revn: 10-02-2023  1.0
+// Func: host connection, reply to speak.go
+//
+// TODO: fix remove
+//       write back to file, re-read file
+//       add more /codes/ to handle
+//       add flags
+// =============================================================================
+// CHANGE LOG
+// -----------------------------------------------------------------------------
+// 05-13-2022: init
+// 08-29-2023: gutted and rewrote
+//             commented
+// 09-12-2023: imported io/ioutil, strings, strconv
+//             added size conversation
+//             added file read function, fread()
+//             commented
+// 09-21-2023: began rewrite of handle()
+// 09-26-2023: got /list/ command working
+//             got /add/ command (mostly) working
+//*10-02-2023: commented handle()
+//             added checks to /qr/ and /r2/ to make sure recv'd
+//              length is valid
+// =============================================================================
+
+package main
+
+import (
+    "fmt"       // Println
+    "io/ioutil" // ReadFile
+    "net"       // ResovleTCPAddr, ListenTCP, listener.Accept
+                // conn.Read,Write
+    "os"        // Exit
+    "strconv"   // Itoa
+    "strings"   // Split
+)
+
+
+// handle errors catastrophically
+func check( err error ) {
+    if err != nil {    // error is not nil on error
+        // print error
+        fmt.Println( "Fatal: ", err.Error() )
+        os.Exit( 1 )    // bail
+    }
+}
+
+
+// read file and create quote list
+func fread() string {
+    // open file "quotes", read entire file as bytes into qfile
+    qfile, err := ioutil.ReadFile( "quotes" )
+    check( err )    // make sure read works
+    // cast bytes to string, split string over newline into array
+    qlist = strings.Split( string( qfile ), "\n" )
+    // remove last item in list ( trailing newline leaves empty item )
+    qlist = qlist[:len( qlist ) - 1]
+    if false {      // XXX debug print ( next )
+        for _, q := range qlist {   // iterate over all quotes in list
+            fmt.Println( q )        // print quote
+        }
+    }
+    return string( qfile )      // return file as string
+}
+
+
+// write qfile back to file
+func writeFile( f string ) {
+    file, err := os.Create( "quotes" )
+    check( err )
+    _, err = file.WriteString( f )
+    check( err )
+}
+
+
+// handle connections ( new and improved )
+func handle( conn net.Conn ) {
+
+    // create buffer to hold read message
+    var buffer [256]byte
+    // read n bytes from client
+    n, err := conn.Read( buffer[:] )
+    check( err )    // make sure read worked
+
+    // cast message to string, take first n bytes, split over @
+    command := strings.Split( string( buffer[:n] ), "@" )
+
+    // declare response string
+    var resp string
+    switch command[0] {     // switch/case over opcode
+        case "sr":      // /sr/, size request
+            // get length of list, convert to string
+            // XXX probably no reason to have this declaration scheme
+            var num string = strconv.Itoa( len( qlist ) )
+            // concat and send
+            resp = "sa@" + num      // size answer
+        case "qr":      // /qr/, quote request
+            // convert message argument to string to make sure it's a
+            // valid number
+            num, nerr := strconv.Atoi( command[1] )
+            // nerr will not be nil if comm[1] is not a number
+            if nerr != nil {
+                // formulate an error message
+                // TODO flesh this out more
+                resp = "ba@Number not understood"   // bad answer
+            } else {        // comm[1] was a number, but...
+                switch {    // how do we know it's a valid number
+                    case num > len( qlist ):
+                        // bad answer in quote request
+                        resp = "ba@qr@>"
+                        // why bad? num is >
+                    case num < 0:
+                        // bad answer in quote request
+                        resp = "bad@qr@-"
+                        // why bad? num is -
+                    default:
+                        // good num, get quote, send off
+                        resp = "qa@" + qlist[num]   // quote answer
+                }
+            }
+        case "lr":      // /lr/, list request
+            // just concat entire list to send
+            resp = "la@" + qfile[:len( qfile ) - 1]     // list answer
+            // TODO what happens if this is longer than 256 char?
+        case "ar":      // /ar/, add request
+            // append new quote to list
+            qlist = append( qlist, command[1] )
+            // also append new quote to file variable
+            qfile = qfile + command[1] + "\n"
+            writeFile( qfile )
+            resp = "aa@success"     // add answer
+            // TODO write to file
+        case "r1":      // /r1/, remove request 1
+            // same as list, just send whole file
+            resp = "r1@" + qfile    // remove request 1
+        case "r2":      // /r2/, remove request 2
+            // convert message argument to string to make sure it's a
+            // valid number
+            num, nerr := strconv.Atoi( command[1] )
+            // nerr will not be nil if comm[1] is not a number
+            if nerr != nil {
+                // formulate an error message
+                // TODO flesh this out more
+                resp = "ba@Number not understood"   // bad answer
+            } else {        // comm[1] was a number, but...
+                switch {    // how do we know it's a valid number
+                    case num > len( qlist ):
+                        // bad answer in quote request
+                        resp = "ba@r2@>"
+                        // why bad? num is >
+                    case num < 0:
+                        // bad answer in quote request
+                        resp = "ba@r2@-"
+                        // why bad? num is -
+                    default:
+                        qlist[num + 1] = qlist[len( qlist ) - 1]
+                        qlist = qlist[:len( qlist ) - 1]
+                        var f string = ""
+                        for _, v := range qlist {
+                            f = f + v + "\n"
+                        }
+                        f = f[:len( f ) - 1]
+                        qfile = f
+                        writeFile( qfile )
+                        resp = "r2@" + qfile
+                }
+            }
+            /*
+            resp = "r2@"    // remove request 2
+            // 
+            index, nerr := strconv.Atoi( command[1] )
+            if nerr == nil {
+                if index < len( qlist ) {
+                    qlist[index] = qlist[len( qlist ) - 1]
+                    qlist = qlist[:len( qlist ) - 1]
+                    //writeFile() //TODO
+                    resp = resp + "success"
+                } else {
+                    resp = resp + "error"
+                }
+            } else {
+                resp = resp + "error"
+            }
+            */
+        case "te":      // /te/, transaction end
+            // TODO should I be sending something?
+            // TODO is it better to close now or outside of handle()
+            conn.Close()    // close connection and leave
+            return          // return from handle(), finish connection
+        default:        // opcode not recognized
+            // TODO there should be more being down, here, right?
+            return          // return from handle(), finish connection
+    }
+
+    // write response to client
+    _, err = conn.Write( []byte( resp ) )
+    check( err )    // make sure write worked
+
+    handle( conn )  // call handle() again to get response from client
+
+}
+
+
+// globals
+var qlist []string      // list of quotes
+var qfile string        // file object
+var quit bool
+
+
+// main, create port and wait for connection
+func main() {
+
+    qfile = fread() // read quote file, init ( global ) list of quotes
+
+    service := ":1300"  // create service on ip and port
+
+    // resolve ip address and port
+    addr, err := net.ResolveTCPAddr( "tcp", service )
+    check( err )    // make sure ip resolves
+
+    // create listener object from ip:port
+    listener, err := net.ListenTCP( "tcp", addr )
+
+    for {
+        // wait, create connection when found
+        conn, err := listener.Accept()
+        check( err )    // make sure connection works
+    
+        go handle( conn )  // handle connection
+    }
+
+    os.Exit( 0 )    // exeunt
+
+}
+