From be983931fc890b6ffc3194e310b0b1158f16963e Mon Sep 17 00:00:00 2001
From: David Wragg <david@wragg.org>
Date: Fri, 1 May 2015 21:40:53 +0100
Subject: [PATCH 1/2] Produce a better error message when there is no real
 SetImmediateMode

If gopacket is compiled against an older pcap.h that doesn't have
pcap_set_immediate_mode, it supplies a dummy definition that
always returns PCAP_ERROR.  That becomes "Generic error", which
is not very helpful.  The real pcap_set_set_immediate never
returns PCAP_ERROR, so this turns it into a more informative
message.
---
 router/pcap.go | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/router/pcap.go b/router/pcap.go
index e8594ecd..c3cd96d0 100644
--- a/router/pcap.go
+++ b/router/pcap.go
@@ -2,6 +2,7 @@ package router
 
 import (
 	"code.google.com/p/gopacket/pcap"
+	"fmt"
 )
 
 type PcapIO struct {
@@ -44,6 +45,17 @@ func newPcapIO(ifName string, promisc bool, snaplen int, bufSz int) (handle *Pca
 		return
 	}
 	if err = inactive.SetImmediateMode(true); err != nil {
+		// If gopacket is compiled against an older pcap.h
+		// that doesn't have pcap_set_immediate_mode, it
+		// supplies a dummy definition that always returns
+		// PCAP_ERROR.  That becomes "Generic error", which is
+		// not very helpful.  The real pcap_set_set_immediate
+		// never returns PCAP_ERROR, so this turns it into a
+		// more informative message.
+		if fmt.Sprint(err) == "Generic error" {
+			err = fmt.Errorf("compiled against an old version of libpcap; please compile against libpcap-1.5.0 or later")
+		}
+
 		return
 	}
 	if err = inactive.SetBufferSize(bufSz); err != nil {

From e40f1fe9a72fe0419689dad5e82a1fe988255549 Mon Sep 17 00:00:00 2001
From: Matthias Radestock <matthias.radestock@gmail.com>
Date: Sat, 2 May 2015 17:46:21 +0100
Subject: [PATCH 2/2] fix typo and reformat

---
 router/pcap.go | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/router/pcap.go b/router/pcap.go
index c3cd96d0..b7365f68 100644
--- a/router/pcap.go
+++ b/router/pcap.go
@@ -45,13 +45,12 @@ func newPcapIO(ifName string, promisc bool, snaplen int, bufSz int) (handle *Pca
 		return
 	}
 	if err = inactive.SetImmediateMode(true); err != nil {
-		// If gopacket is compiled against an older pcap.h
-		// that doesn't have pcap_set_immediate_mode, it
-		// supplies a dummy definition that always returns
-		// PCAP_ERROR.  That becomes "Generic error", which is
-		// not very helpful.  The real pcap_set_set_immediate
-		// never returns PCAP_ERROR, so this turns it into a
-		// more informative message.
+		// If gopacket is compiled against an older pcap.h that
+		// doesn't have pcap_set_immediate_mode, it supplies a dummy
+		// definition that always returns PCAP_ERROR.  That becomes
+		// "Generic error", which is not very helpful.  The real
+		// pcap_set_immediate_mode never returns PCAP_ERROR, so this
+		// turns it into a more informative message.
 		if fmt.Sprint(err) == "Generic error" {
 			err = fmt.Errorf("compiled against an old version of libpcap; please compile against libpcap-1.5.0 or later")
 		}