282 lines
10 KiB
Go
282 lines
10 KiB
Go
// =============================================================================
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// Auth: Alex Celani
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// File: server.go
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// Revn: 10-17-2023 3.0
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// Func: host connection, reply to speak.go
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//
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// TODO: add more /codes/ to handle
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// add flags?
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// write usage and errors to logfile
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// send logfile to client on request
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// =============================================================================
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// CHANGE LOG
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// -----------------------------------------------------------------------------
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// 05-13-2022: init
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// 08-29-2023: gutted and rewrote
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// commented
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// 09-12-2023: imported io/ioutil, strings, strconv
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// added size conversation
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// added file read function, fread()
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// commented
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// 09-21-2023: began rewrite of handle()
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// 09-26-2023: got /list/ command working
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// got /add/ command (mostly) working
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//*10-02-2023: commented handle()
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// added checks to /qr/ and /r2/ to make sure recv'd
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// length is valid
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// wrote writeFile()
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//*10-05-2023: commented
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// imported check() to ignore EOF
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// fixed bug in /r2/ where removing quote at final
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// position would break
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// removed deadcode from /r2/, unused "quit" bool?
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//*10-17-2023: fixed bug where quotes are read from and saved to two
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// different files
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// removed implicit newline at end of qfile to stop ghost
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// line bug in /la/
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// removed dead debug print in fread()
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//
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// =============================================================================
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package main
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import (
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"fmt" // Println
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"io" // io.EOF
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"io/ioutil" // ReadFile
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"net" // ResovleTCPAddr, ListenTCP, listener.Accept
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// conn.Read,Write
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"os" // Exit
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"strconv" // Itoa
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"strings" // Split
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)
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// handle errors catastrophically
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func check( err error ) {
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if err != nil { // error is not nil on error
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// print error
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fmt.Println( "Fatal: ", err.Error() )
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os.Exit( 1 ) // bail
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}
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}
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// FIXME clean this two check() shit up
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// print errors if they occur, quit
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func checkN( err error, conn net.Conn ) {
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var errep string // declare error report string
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switch err { // switch case over error input
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case nil: // if there was no error
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// then there was no error
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errep = "err is nil"
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case io.EOF: // if there was an End Of File error
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errep = "Error: " + err.Error() // document error
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conn.Close() // close connection
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default: // anything besides those are a big deal
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errep = "Fatal: " + err.Error()
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}
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var critical bool // declare critical error flag
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// must be neither nil nor EOF
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critical = err != nil && err != io.EOF
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if critical { // XXX critical print
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// TODO at some point, critical should be logging instead of
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// printing, only verbose should print
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fmt.Println( "check() -> ", errep )
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}
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if critical { // if there was a critical error
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os.Exit( 1 ) // cut and run
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}
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}
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// read file and create quote list
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func fread() string {
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// open file "quotes", read entire file as bytes into qfile
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qfile, err := ioutil.ReadFile( "list.q" )
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check( err ) // make sure read works
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// there is a trailing newline in the file, not removing it caused
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// bugs where a blank item was introduced into qlist and calling
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// /la/ would produce a blank line on the client side that didn't
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// really exist
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qfile = qfile[:len( qfile ) - 1]
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// cast bytes to string, split string over newline into array
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qlist = strings.Split( string( qfile ), "\n" )
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// deal with the trailing
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return string( qfile ) // return file as string
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}
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// write qfile back to file
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func writeFile( f string ) {
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// open file list.q as variable file
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file, err := os.Create( "list.q" )
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check( err ) // make sure open worked
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// write input string ( quote file ) back to file
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_, err = file.WriteString( f )
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check( err ) // make sure writeback worked
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}
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// handle connections ( new and improved )
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func handle( conn net.Conn ) {
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// create buffer to hold read message
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var buffer [256]byte
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// read n bytes from client
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n, err := conn.Read( buffer[:] )
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checkN( err, conn ) // make sure read worked
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// cast message to string, take first n bytes, split over @
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command := strings.Split( string( buffer[:n] ), "@" )
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// declare response string
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var resp string
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switch command[0] { // switch/case over opcode
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case "sr": // /sr/, size request
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// get length of list, convert to string
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// XXX probably no reason to have this declaration scheme
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var num string = strconv.Itoa( len( qlist ) )
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// concat and send
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resp = "sa@" + num // size answer
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case "qr": // /qr/, quote request
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// convert message argument to string to make sure it's a
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// valid number
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num, nerr := strconv.Atoi( command[1] )
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// nerr will not be nil if comm[1] is not a number
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if nerr != nil {
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// formulate an error message
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// TODO flesh this out more
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resp = "ba@qr@!" // bad answer
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} else { // comm[1] was a number, but...
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switch { // how do we know it's a valid number
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case num > len( qlist ):
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// bad answer in quote request
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resp = "ba@qr@>"
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// why bad? num is >
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case num < 0:
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// bad answer in quote request
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resp = "ba@qr@-"
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// why bad? num is -
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default:
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// good num, get quote, send off
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resp = "qa@" + qlist[num] // quote answer
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}
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}
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case "lr": // /lr/, list request
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// just concat entire list to send
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//resp = "la@" + qfile[:len( qfile ) - 1] // list answer
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resp = "la@" + qfile // list answer
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// TODO what happens if this is longer than 256 char?
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case "ar": // /ar/, add request
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// append new quote to list
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qlist = append( qlist, command[1] )
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// also append new quote to file variable
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qfile = qfile + "\n" + command[1]
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writeFile( qfile )
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resp = "aa@success" // add answer
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// TODO write to file
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case "r1": // /r1/, remove request 1
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// same as list, just send whole file
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resp = "r1@" + qfile // remove request 1
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case "r2": // /r2/, remove request 2
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// convert message argument to string to make sure it's a
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// valid number
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num, nerr := strconv.Atoi( command[1] )
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// nerr will not be nil if comm[1] is not a number
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if nerr != nil {
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// formulate an error message
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// TODO flesh this out more
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resp = "ba@r2@!" // bad answer
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} else { // comm[1] was a number, but...
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num = num - 1
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switch { // how do we know it's a valid number
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// valid numbers are from 0 - len-1
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case num > len( qlist ):
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// bad answer in quote request
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resp = "ba@r2@>"
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// why bad? num is >
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case num < 0:
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// bad answer in quote request
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resp = "ba@r2@-"
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// why bad? num is -
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// if num is not OUT OF RANGE, must be in range
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default:
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// replace the quote at that position with
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// final quote
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qlist[num] = qlist[len( qlist ) - 1]
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// remove second copy of quote
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qlist = qlist[:len( qlist ) - 1]
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// O(1) remove from list at any position
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// must entirely recreate quote string
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var f string = "" // init empty string
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// iterate over list, disregard index
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for _, v := range qlist {
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// add next quote to file and separate
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// quotes with newline
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f = f + v + "\n"
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}
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// remove trailing newline, to prevent ghost
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f = f[:len( f ) - 1] // quote in lr
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// reassign global string variable to
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// recreated quote string
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qfile = f
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writeFile( qfile ) // write back to file
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// let client know remove was successful
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resp = "r2@success"
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}
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}
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case "te": // /te/, transaction end
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// TODO should I be sending something?
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// TODO is it better to close now or outside of handle()
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conn.Close() // close connection and leave
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return // return from handle(), finish connection
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default: // opcode not recognized
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// TODO there should be more being down, here, right?
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return // return from handle(), finish connection
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}
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// write response to client
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_, err = conn.Write( []byte( resp ) )
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checkN( err, conn ) // make sure write worked
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handle( conn ) // call handle() again to get response from client
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}
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// globals
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var qlist []string // list of quotes
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var qfile string // file object
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// main, create port and wait for connection
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func main() {
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qfile = fread() // read quote file, init ( global ) list of quotes
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service := ":1300" // create service on ip and port
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// resolve ip address and port
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addr, err := net.ResolveTCPAddr( "tcp", service )
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check( err ) // make sure ip resolves
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// create listener object from ip:port
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listener, err := net.ListenTCP( "tcp", addr )
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for {
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// wait, create connection when found
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conn, err := listener.Accept()
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check( err ) // make sure connection works
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go handle( conn ) // handle connection
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}
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os.Exit( 0 ) // exeunt
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}
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