From d22574a627d6b4d6964cb0c2be52f2831ea14945 Mon Sep 17 00:00:00 2001
From: louisehong <louisehong4168@gmail.com>
Date: Mon, 7 Sep 2020 19:00:32 +0800
Subject: [PATCH] Optimized ip checking algorithm for ipv6

IPv6 parser should fail with 8 groups plus one blank
---
 internal/tools/ipparser.go     | 70 ++++++++++++++++++++++++++++------
 internal/tools/iptools_test.go | 43 +++++++++++++++++++++
 2 files changed, 101 insertions(+), 12 deletions(-)

diff --git a/internal/tools/ipparser.go b/internal/tools/ipparser.go
index 602ffd2..b39c473 100644
--- a/internal/tools/ipparser.go
+++ b/internal/tools/ipparser.go
@@ -46,7 +46,7 @@ func ValidIP4(IP string) bool {
 	return true
 }
 
-func ValidIP6(str string) bool {
+func ValidIP6Re(str string) bool {
 	str = strings.Trim(str, " ")
 	return ipv6re0.MatchString(str)
 
@@ -67,24 +67,70 @@ func GetIP6FromString(str string) []string {
 //1. 用“：”分割字符串，若长度不等于8，则return Neither
 //2. 遍历每一个数组的每一个元素，若元素的长度大于4，则return Neither
 //3. 判断每一个元素的字符，若出现非0-9，A-F的字符，则return Neither
-func isIPV6(IP string) bool {
+func ValidIP6(IP string) bool {
 	IP = strings.ToUpper(IP)
-	arr := strings.Split(IP, ":")
-	if len(arr) != 8 {
+	n := len(IP)
+	if n > 39 || n == 0 {
 		return false
 	}
-	for _, elem := range arr {
-		if elem == "" || len(elem) > 4 {
-			return false
-		}
 
-		for _, c := range elem {
-			if (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') {
+	// 以 ":" 结尾 但是只有一个
+	if strings.HasSuffix(IP, ":") && !strings.HasSuffix(IP, "::") {
+		return false
+	}
+	// 如果"::" 有两个以上
+	if strings.Count(IP, "::") > 1 {
+		return false
+	}
+	// 如果 ":" 有8个以上
+	if strings.Count(IP, ":") > 8 {
+		return false
+	}
+	tmp := strings.Split(IP, ":")
+	// 如果有ipv4， 则返回真， 前面的部分未校验。
+	if ValidIP4(tmp[len(tmp)-1]) {
+		return true
+	}
+	if strings.Contains(IP,"::") {
+		var count int
+		for _, v := range tmp {
+			if v != "" {
+				count++
 				continue
-			} else {
-				return false
 			}
 		}
+		if count == 8 {
+			return false
+		}
 	}
+
+	// 对每个元素进行遍历
+	for k := 0; k < n-1; {
+		if IP[k] == ':' {
+			k++
+			continue
+		} else if valid(IP[k]) {
+			var bits int
+			for valid(IP[k]) {
+				k++
+				bits++
+				if bits > 4 {
+					return false
+				}
+				if k == n {
+					break
+				}
+			}
+
+		} else {
+			return false
+		}
+	}
+
+	// 到了这一步， 可以确定是ipv6
 	return true
 }
+
+func valid(i uint8) bool {
+	return (i >= 'A' && i <= 'F') || (i >= '0' && i <= '9')
+}
\ No newline at end of file
diff --git a/internal/tools/iptools_test.go b/internal/tools/iptools_test.go
index d6fc8af..04a2961 100644
--- a/internal/tools/iptools_test.go
+++ b/internal/tools/iptools_test.go
@@ -42,6 +42,7 @@ func TestValidIP6(t *testing.T) {
 		"::4:5:6:7:8",
 		"::3:4:5:6:7:8",
 		"::2:3:4:5:6:7:8",
+		"2001:0db8:85a3:0000:0000:8a2e:0370:7334",
 
 		"::192.168.1.1",
 		"::ffff:135.75.43.52",
@@ -52,6 +53,8 @@ func TestValidIP6(t *testing.T) {
 		"A:0f:0F:FFFF1:5:6:7:8",
 		"G:0f:0F:FFFF:5:6:7:8",
 		"2001::25de::cade",
+		"2001:0db8:85a3:0:0:8A2E:0370:73341",
+		"a1:a2:a3:a4::b1:b2:b3:b4",
 	}
 
 	for _, i := range ipv6Valid {
@@ -66,3 +69,43 @@ func TestValidIP6(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkValidIP6Re(b *testing.B) {
+	b.ResetTimer()
+	origin := "::ffff:135.75.43.52"
+	for i:=0; i<b.N;i++ {
+		ValidIP6Re(origin)
+	}
+}
+
+func BenchmarkValidIP6(b *testing.B) {
+	b.ResetTimer()
+	origin := "::ffff:135.75.43.52"
+	for i:=0; i<b.N;i++ {
+		ValidIP6(origin)
+	}
+}
+
+/*
+
+   IPv6-addr      = IPv6-full / IPv6-comp / IPv6v4-full / IPv6v4-comp
+
+   IPv6-hex       = 1*4HEXDIG
+
+   IPv6-full      = IPv6-hex 7(":" IPv6-hex)
+
+   IPv6-comp      = [IPv6-hex *5(":" IPv6-hex)] "::"
+                  [IPv6-hex *5(":" IPv6-hex)]
+                  ; The "::" represents at least 2 16-bit groups of
+                  ; zeros.  No more than 6 groups in addition to the
+                  ; "::" may be present.
+
+   IPv6v4-full    = IPv6-hex 5(":" IPv6-hex) ":" IPv4-address-literal
+
+   IPv6v4-comp    = [IPv6-hex *3(":" IPv6-hex)] "::"
+                  [IPv6-hex *3(":" IPv6-hex) ":"]
+                  IPv4-address-literal
+                  ; The "::" represents at least 2 16-bit groups of
+                  ; zeros.  No more than 4 groups in addition to the
+                  ; "::" and IPv4-address-literal may be present.
+*/
\ No newline at end of file