init

draft3_pinroute/colonel.go

@@ -0,0 +1,100 @@
+// =============================================================================
+// Auth: Alex Celani
+// File: colonel.go
+// Revn: 06-23-2022  1.1
+// 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
+// 06-23-2022: made input an infinite loop
+//
+// =============================================================================
+
+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
+
+    for {       // loop forever
+
+        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 time
+
+    }
+
+    os.Exit( 0 )        // exeunt
+
+}
+