From 5abd03e241c373fa06b60c3848ef0104ef503190 Mon Sep 17 00:00:00 2001
From: yaling888 <73897884+yaling888@users.noreply.github.com>
Date: Tue, 15 Mar 2022 02:43:40 +0800
Subject: [PATCH] Fix: exclude the broadcast address to fake ip pool

---
 component/fakeip/pool.go       | 35 ++++++++++++++++++++--------------
 component/resolver/enhancer.go |  9 +++++++++
 dns/enhancer.go                | 14 +++++++++++++-
 3 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/component/fakeip/pool.go b/component/fakeip/pool.go
index 925882bb..43b9cee1 100644
--- a/component/fakeip/pool.go
+++ b/component/fakeip/pool.go
@@ -22,14 +22,15 @@ type store interface {
 
 // Pool is a implementation about fake ip generator without storage
 type Pool struct {
-	max     uint32
-	min     uint32
-	gateway uint32
-	offset  uint32
-	mux     sync.Mutex
-	host    *trie.DomainTrie
-	ipnet   *net.IPNet
-	store   store
+	max       uint32
+	min       uint32
+	gateway   uint32
+	broadcast uint32
+	offset    uint32
+	mux       sync.Mutex
+	host      *trie.DomainTrie
+	ipnet     *net.IPNet
+	store     store
 }
 
 // Lookup return a fake ip with host
@@ -82,6 +83,11 @@ func (p *Pool) Gateway() net.IP {
 	return uintToIP(p.gateway)
 }
 
+// Broadcast return broadcast ip
+func (p *Pool) Broadcast() net.IP {
+	return uintToIP(p.broadcast)
+}
+
 // IPNet return raw ipnet
 func (p *Pool) IPNet() *net.IPNet {
 	return p.ipnet
@@ -144,7 +150,7 @@ func New(options Options) (*Pool, error) {
 	min := ipToUint(options.IPNet.IP) + 2
 
 	ones, bits := options.IPNet.Mask.Size()
-	total := 1<<uint(bits-ones) - 2
+	total := 1<<uint(bits-ones) - 3
 
 	if total <= 0 {
 		return nil, errors.New("ipnet don't have valid ip")
@@ -152,11 +158,12 @@ func New(options Options) (*Pool, error) {
 
 	max := min + uint32(total) - 1
 	pool := &Pool{
-		min:     min,
-		max:     max,
-		gateway: min - 1,
-		host:    options.Host,
-		ipnet:   options.IPNet,
+		min:       min,
+		max:       max,
+		gateway:   min - 1,
+		broadcast: max + 1,
+		host:      options.Host,
+		ipnet:     options.IPNet,
 	}
 	if options.Persistence {
 		pool.store = &cachefileStore{
diff --git a/component/resolver/enhancer.go b/component/resolver/enhancer.go
index c096f87a..68f1d5d1 100644
--- a/component/resolver/enhancer.go
+++ b/component/resolver/enhancer.go
@@ -10,6 +10,7 @@ type Enhancer interface {
 	FakeIPEnabled() bool
 	MappingEnabled() bool
 	IsFakeIP(net.IP) bool
+	IsFakeBroadcastIP(net.IP) bool
 	IsExistFakeIP(net.IP) bool
 	FindHostByIP(net.IP) (string, bool)
 }
@@ -38,6 +39,14 @@ func IsFakeIP(ip net.IP) bool {
 	return false
 }
 
+func IsFakeBroadcastIP(ip net.IP) bool {
+	if mapper := DefaultHostMapper; mapper != nil {
+		return mapper.IsFakeBroadcastIP(ip)
+	}
+
+	return false
+}
+
 func IsExistFakeIP(ip net.IP) bool {
 	if mapper := DefaultHostMapper; mapper != nil {
 		return mapper.IsExistFakeIP(ip)
diff --git a/dns/enhancer.go b/dns/enhancer.go
index 76f0f262..f42fa268 100644
--- a/dns/enhancer.go
+++ b/dns/enhancer.go
@@ -40,7 +40,19 @@ func (h *ResolverEnhancer) IsFakeIP(ip net.IP) bool {
 	}
 
 	if pool := h.fakePool; pool != nil {
-		return pool.IPNet().Contains(ip) && !pool.Gateway().Equal(ip)
+		return pool.IPNet().Contains(ip) && !pool.Gateway().Equal(ip) && !pool.Broadcast().Equal(ip)
+	}
+
+	return false
+}
+
+func (h *ResolverEnhancer) IsFakeBroadcastIP(ip net.IP) bool {
+	if !h.FakeIPEnabled() {
+		return false
+	}
+
+	if pool := h.fakePool; pool != nil {
+		return pool.Broadcast().Equal(ip)
 	}
 
 	return false