From 4d3f1b83a62c8c7bd4b828336efb4ca7ae536c9e Mon Sep 17 00:00:00 2001
From: Eugene Bujak <hmage@hmage.net>
Date: Sat, 29 Dec 2018 19:13:00 +0300
Subject: [PATCH] Fix race conditions found by -race

---
 dhcpd/dhcpd.go      | 9 ++++++++-
 dnsforward/stats.go | 8 ++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/dhcpd/dhcpd.go b/dhcpd/dhcpd.go
index 2b1198e4..deeaac02 100644
--- a/dhcpd/dhcpd.go
+++ b/dhcpd/dhcpd.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"net"
+	"sync"
 	"time"
 
 	"github.com/hmage/golibs/log"
@@ -47,6 +48,7 @@ type Server struct {
 	IPpool map[[4]byte]net.HardwareAddr
 
 	ServerConfig
+	sync.RWMutex
 }
 
 // Start will listen on port 67 and serve DHCP requests.
@@ -179,7 +181,9 @@ func (s *Server) reserveLease(p dhcp4.Packet) (*Lease, error) {
 	log.Tracef("Assigning to %s IP address %s", hwaddr, ip.String())
 	hostname := p.ParseOptions()[dhcp4.OptionHostName]
 	lease := &Lease{HWAddr: hwaddr, IP: ip, Hostname: string(hostname)}
+	s.Lock()
 	s.leases = append(s.leases, lease)
+	s.Unlock()
 	return lease, nil
 }
 
@@ -387,5 +391,8 @@ func (s *Server) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dh
 }
 
 func (s *Server) Leases() []*Lease {
-	return s.leases
+	s.RLock()
+	result := s.leases
+	s.RUnlock()
+	return result
 }
diff --git a/dnsforward/stats.go b/dnsforward/stats.go
index 5791e1dc..9d11504b 100644
--- a/dnsforward/stats.go
+++ b/dnsforward/stats.go
@@ -142,6 +142,8 @@ func statsRotator() {
 type counter struct {
 	name  string // used as key in periodic stats
 	value int64
+
+	sync.Mutex
 }
 
 func newDNSCounter(name string) *counter {
@@ -156,7 +158,9 @@ func (c *counter) IncWithTime(when time.Time) {
 	statistics.PerMinute.Inc(c.name, when)
 	statistics.PerHour.Inc(c.name, when)
 	statistics.PerDay.Inc(c.name, when)
+	c.Lock()
 	c.value++
+	c.Unlock()
 }
 
 func (c *counter) Inc() {
@@ -167,6 +171,8 @@ type histogram struct {
 	name  string // used as key in periodic stats
 	count int64
 	total float64
+
+	sync.Mutex
 }
 
 func newDNSHistogram(name string) *histogram {
@@ -180,8 +186,10 @@ func (h *histogram) ObserveWithTime(value float64, when time.Time) {
 	statistics.PerMinute.Observe(h.name, when, value)
 	statistics.PerHour.Observe(h.name, when, value)
 	statistics.PerDay.Observe(h.name, when, value)
+	h.Lock()
 	h.count++
 	h.total += value
+	h.Unlock()
 }
 
 func (h *histogram) Observe(value float64) {