From b77abf480b8e45a6cda1600cb3516208bc687db0 Mon Sep 17 00:00:00 2001
From: David Wragg <david@wragg.org>
Date: Mon, 25 May 2015 20:45:29 +0100
Subject: [PATCH] Move DF indication into LogFrame

---
 router/ethernet_decoder.go |  4 ++++
 router/router.go           | 19 +++++--------------
 weaver/main.go             | 14 ++++++++++----
 3 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/router/ethernet_decoder.go b/router/ethernet_decoder.go
index 8fe65ebb..555ce033 100644
--- a/router/ethernet_decoder.go
+++ b/router/ethernet_decoder.go
@@ -74,3 +74,7 @@ func (dec *EthernetDecoder) IsSpecial() bool {
 	return dec.Eth.Length == 0 && dec.Eth.EthernetType == layers.EthernetTypeLLC &&
 		bytes.Equal(zeroMAC, dec.Eth.SrcMAC) && bytes.Equal(zeroMAC, dec.Eth.DstMAC)
 }
+
+func (dec *EthernetDecoder) DF() bool {
+	return len(dec.decoded) == 2 && (dec.IP.Flags&layers.IPv4DontFragment != 0)
+}
diff --git a/router/router.go b/router/router.go
index 339c20fb..11cc3038 100644
--- a/router/router.go
+++ b/router/router.go
@@ -2,7 +2,6 @@ package router
 
 import (
 	"bytes"
-	"code.google.com/p/gopacket/layers"
 	"encoding/binary"
 	"fmt"
 	"io"
@@ -155,12 +154,9 @@ func (router *Router) handleCapturedPacket(frameData []byte, dec *EthernetDecode
 	if found && dstPeer == router.Ourself.Peer {
 		return
 	}
-	df := decodedLen == 2 && (dec.IP.Flags&layers.IPv4DontFragment != 0)
-	if df {
-		router.LogFrame("Forwarding DF", frameData, dec)
-	} else {
-		router.LogFrame("Forwarding", frameData, dec)
-	}
+	df := dec.DF()
+	router.LogFrame("Forwarding", frameData, dec)
+
 	// at this point we are handing over the frame to forwarders, so
 	// we need to make a copy of it in order to prevent the next
 	// capture from overwriting the data
@@ -300,16 +296,11 @@ func (router *Router) handleUDPPacketFunc(relayConn *LocalConnection, dec *Ether
 			return
 		}
 
-		df := decodedLen == 2 && (dec.IP.Flags&layers.IPv4DontFragment != 0)
+		df := dec.DF()
 
 		if dstPeer != router.Ourself.Peer {
 			// it's not for us, we're just relaying it
-			if df {
-				router.LogFrame("Relaying DF", frame, dec)
-			} else {
-				router.LogFrame("Relaying", frame, dec)
-			}
-
+			router.LogFrame("Relaying", frame, dec)
 			err := router.Ourself.Relay(srcPeer, dstPeer, df, frame, dec)
 			if ftbe, ok := err.(FrameTooBigError); ok {
 				err = dec.sendICMPFragNeeded(ftbe.EPMTU, func(icmpFrame []byte) error {
diff --git a/weaver/main.go b/weaver/main.go
index 9b2f9f39..7f1bb896 100644
--- a/weaver/main.go
+++ b/weaver/main.go
@@ -172,11 +172,17 @@ func logFrameFunc(debug bool) weave.LogFrameFunc {
 	}
 	return func(prefix string, frame []byte, dec *weave.EthernetDecoder) {
 		h := fmt.Sprintf("%x", sha256.Sum256(frame))
-		if dec == nil {
-			log.Println(prefix, len(frame), "bytes (", h, ")")
-		} else {
-			log.Println(prefix, len(frame), "bytes (", h, "):", dec.Eth.SrcMAC, "->", dec.Eth.DstMAC)
+		parts := []interface{}{prefix, len(frame), "bytes (", h, ")"}
+
+		if dec != nil {
+			parts = append(parts, dec.Eth.SrcMAC, "->", dec.Eth.DstMAC)
+
+			if dec.DF() {
+				parts = append(parts, "(DF)")
+			}
 		}
+
+		log.Println(parts...)
 	}
 }