means (#3)

Co-authored-by: Evan Burkey <dev@fputs.com>
Reviewed-on: https://git.fputs.com/fputs/protohackers/pulls/3

pkg/conn/conn.go

@@ -1,6 +1,7 @@
 package conn
 
 import (
+	"bufio"
 	"fmt"
 	"net"
 )
@@ -30,3 +31,19 @@ func StartSimple(handler func(conn net.Conn)) error {
 		}
 	}
 }
+
+func ReadAndRespond(c net.Conn, process func([]byte) []byte) error {
+	defer c.Close()
+	sc := bufio.NewScanner(c)
+	for sc.Scan() {
+		response := process(sc.Bytes())
+		_, err := c.Write(response)
+		if err != nil {
+			return err
+		}
+	}
+	if err := sc.Err(); err != nil {
+		return err
+	}
+	return nil
+}