Fail fast on connection errors.

The fix for #4 in f221c3c was still not right.

It worked I think for the pure go backends, but for the nfdump backend
that uses exec, it was triggering the error inside of exec before the
flush even happened.

flowindexer/flowindexer.go

@@ -12,6 +12,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"sort"
+	"strings"
 	"sync"
 	"time"
 
@@ -410,6 +411,9 @@ func (i *Indexer) Dump(query string, writer io.Writer) error {
 		}
 		if err != nil {
 			log.Printf("Error dumping %q: %q", fn, err)
+			if isBrokenPipe(err) {
+				return err
+			}
 		}
 	}
 	return err
@@ -460,3 +464,9 @@ func RunDaemon(config string) {
 	}
 
 }
+
+//isBrokenPipe determines if an error was a broken pipe or connection reset error
+//This is really the wrong way to do this, but the right way was not working either.
+func isBrokenPipe(err error) bool {
+	return strings.Contains(err.Error(), "broken pipe") || strings.Contains(err.Error(), "connection")
+}