From 716eadcd8f8277ec85fe3b5c4314d3288ffc0924 Mon Sep 17 00:00:00 2001
From: Anton Skorokhod <anton@nsl.cz>
Date: Mon, 17 Aug 2015 19:56:48 +0200
Subject: [PATCH] Fix setting IPv6 source address

---
 fastping.go | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/fastping.go b/fastping.go
index b2bb348..96950ca 100644
--- a/fastping.go
+++ b/fastping.go
@@ -131,6 +131,7 @@ type Pinger struct {
 	addrs   map[string]*net.IPAddr
 	network string
 	source  string
+	source6 string
 	hasIPv4 bool
 	hasIPv6 bool
 	ctx     *context
@@ -160,6 +161,7 @@ func NewPinger() *Pinger {
 		addrs:   make(map[string]*net.IPAddr),
 		network: "ip",
 		source:  "",
+		source6: "",
 		hasIPv4: false,
 		hasIPv6: false,
 		Size:    TimeSliceLength,
@@ -187,25 +189,36 @@ func (p *Pinger) Network(network string) (string, error) {
 	return origNet, nil
 }
 
-// Source sets source IP for sending ICMP packets and returns the previous
-// setting. Empty value indicates to use system default one.
+// Source sets ipv4/ipv6 source IP for sending ICMP packets and returns the previous
+// setting. Empty value indicates to use system default one (for both ipv4 and ipv6).
 func (p *Pinger) Source(source string) (string, error) {
+	// using ipv4 previous value for new empty one
 	origSource := p.source
 	if "" == source {
 		p.mu.Lock()
-		p.source = source
+		p.source = ""
+		p.source6 = ""
 		p.mu.Unlock()
 		return origSource, nil
 	}
 
 	addr := net.ParseIP(source)
 	if addr == nil {
-		return origSource, errors.New(source + " is not a valid textual representation of an IP address")
+		return origSource, errors.New(source + " is not a valid textual representation of an IPv4/IPv6 address")
 	}
 
-	p.mu.Lock()
-	p.source = source
-	p.mu.Unlock()
+	if isIPv4(addr) {
+		p.mu.Lock()
+		p.source = source
+		p.mu.Unlock()
+	} else if isIPv6(addr) {
+		origSource = p.source6
+		p.mu.Lock()
+		p.source6 = source
+		p.mu.Unlock()
+	} else {
+		return origSource, errors.New(source + " is not a valid textual representation of an IPv4/IPv6 address")
+	}
 
 	return origSource, nil
 }
@@ -396,7 +409,7 @@ func (p *Pinger) run(once bool) {
 	}
 
 	if p.hasIPv6 {
-		if conn6 = p.listen(ipv6Proto[p.network], p.source); conn6 == nil {
+		if conn6 = p.listen(ipv6Proto[p.network], p.source6); conn6 == nil {
 			return
 		}
 		defer conn6.Close()