97 lines
3.0 KiB
Go
97 lines
3.0 KiB
Go
|
// =============================================================================
|
||
|
|
// Auth: Alex Celani
|
||
|
|
// File: colonel.go
|
||
|
|
// Revn: 06-20-2022 1.0
|
||
|
|
// Func: Send message to another machine and then receive a single
|
||
|
|
// response. Extremely tight bounds, not robust at all
|
||
|
|
//
|
||
|
|
// TODO: comment
|
||
|
|
// =============================================================================
|
||
|
|
// CHANGE LOG
|
||
|
|
// -----------------------------------------------------------------------------
|
||
|
|
// 05-04-2022: init
|
||
|
|
//*06-20-2022: changed name to reflect first draft of colonel.go
|
||
|
|
//
|
||
|
|
// =============================================================================
|
||
|
|
|
||
|
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"net" // ResolveTCPAddr, DialTCP, conn.Write,Read
|
||
|
|
"os" // Exit, Stdin, Stderr, Args
|
||
|
|
"fmt" // Println, Print, Fprintf
|
||
|
|
"bufio" // NewScanner, NewScanner.Scan,Text
|
||
|
|
"strings" // ToLower
|
||
|
|
"time" // Now, Sub
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
// quick function to take user input
|
||
|
|
func input( ps1 string ) string {
|
||
|
|
fmt.Print( ps1 ) // print prompt
|
||
|
|
scanner := bufio.NewScanner( os.Stdin ) // link to stdin
|
||
|
|
scanner.Scan() // pull data
|
||
|
|
return strings.ToLower( scanner.Text() ) // return lower text
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// quick error checking
|
||
|
|
func check( err error ) {
|
||
|
|
// if user checks an error, it better be nil
|
||
|
|
if err != nil {
|
||
|
|
// put error in string, print in stderr
|
||
|
|
fmt.Fprintf( os.Stderr, "Fatal error: %s", err.Error() )
|
||
|
|
os.Exit( 2 ) // quit
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
|
||
|
|
// if len is not 2 ( ./name host:port ), print usage and quit
|
||
|
|
if len( os.Args ) != 2 {
|
||
|
|
fmt.Fprintf( os.Stderr, "Usage: %s host:port", os.Args[0] )
|
||
|
|
os.Exit( 1 )
|
||
|
|
}
|
||
|
|
|
||
|
|
service := os.Args[1] // capture ip address and host
|
||
|
|
|
||
|
|
// "resolve" ip & host according to TCP rules
|
||
|
|
tcpAddr, err := net.ResolveTCPAddr( "tcp", service )
|
||
|
|
check( err ) // check error
|
||
|
|
|
||
|
|
// "dial" ( establish connection ) to destination ip & port
|
||
|
|
// according to TCP rules
|
||
|
|
// laddr = nil -> local address is localhost
|
||
|
|
conn, err := net.DialTCP( "tcp", nil, tcpAddr )
|
||
|
|
check( err ) // check error
|
||
|
|
|
||
|
|
var in string = input( ">> " ) // get user input
|
||
|
|
|
||
|
|
start := time.Now() // start round trip timer
|
||
|
|
|
||
|
|
// convert user input to bytes and send over connection
|
||
|
|
_, err = conn.Write( []byte( in ) )
|
||
|
|
check( err ) // check error
|
||
|
|
|
||
|
|
var buf [512]byte // init byte array
|
||
|
|
// read from connection into byte array
|
||
|
|
// amount of bytes read stored in n
|
||
|
|
//n, err := conn.Read( buf[0:] )
|
||
|
|
n, err := conn.Read( buf[:] )
|
||
|
|
check( err ) // check error
|
||
|
|
|
||
|
|
t := time.Now() // stop round trip timer
|
||
|
|
|
||
|
|
// convert read bytes into string and print
|
||
|
|
fmt.Println( string( buf[:n] ) )
|
||
|
|
|
||
|
|
fmt.Println() // newline to clean up a little
|
||
|
|
fmt.Println( "rtt: ", t.Sub( start ) ) // print elapsed time
|
||
|
|
|
||
|
|
|
||
|
|
os.Exit( 0 ) // exeunt
|
||
|
|
|
||
|
|
}
|
||
|
|
|