From efdfd9d612e68863972611e985fad2cf84ea90f0 Mon Sep 17 00:00:00 2001
From: sjlleo <sjlleo001@gmail.com>
Date: Fri, 3 Jun 2022 16:26:01 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20=E4=BF=AE=E5=A4=8D=E4=B8=80=E4=B8=AA?=
 =?UTF-8?q?=E5=A4=9A=E7=BA=BF=E7=A8=8B=E8=B7=AF=E7=94=B1=E8=B7=9F=E8=B8=AA?=
 =?UTF-8?q?=E9=94=99=E4=B9=B1=E7=9A=84=E9=97=AE=E9=A2=98?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 trace/icmp_ipv4.go | 31 +++++++++++++++++++------------
 trace/tcp_ipv4.go  | 27 +++++++++++++++------------
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/trace/icmp_ipv4.go b/trace/icmp_ipv4.go
index 0d79688..62c0a76 100644
--- a/trace/icmp_ipv4.go
+++ b/trace/icmp_ipv4.go
@@ -74,19 +74,26 @@ func (t *ICMPTracer) listenICMP() {
 			if msg.N == nil {
 				continue
 			}
-			rm, err := icmp.ParseMessage(1, msg.Msg[:*msg.N])
-			if err != nil {
-				log.Println(err)
-				continue
-			}
-			switch rm.Type {
-			case ipv4.ICMPTypeTimeExceeded:
-				t.handleICMPMessage(msg, 0, rm.Body.(*icmp.TimeExceeded).Data)
-			case ipv4.ICMPTypeEchoReply:
-				t.handleICMPMessage(msg, 1, rm.Body.(*icmp.Echo).Data)
-			default:
-				// log.Println("received icmp message of unknown type", rm.Type)
+			// 抢在ICMP解析包之前先判断是否和目的地IP一致
+			// Leo 注释：我是伞兵，traceroute 居然忘了做包校验...
+			dstip := net.IP(msg.Msg[24:28])
+			if dstip.Equal(t.DestIP) || dstip.Equal(net.IPv4zero) {
+				// 匹配再继续解析包，否则直接丢弃
+				rm, err := icmp.ParseMessage(1, msg.Msg[:*msg.N])
+				if err != nil {
+					log.Println(err)
+					continue
+				}
+				switch rm.Type {
+				case ipv4.ICMPTypeTimeExceeded:
+					t.handleICMPMessage(msg, 0, rm.Body.(*icmp.TimeExceeded).Data)
+				case ipv4.ICMPTypeEchoReply:
+					t.handleICMPMessage(msg, 1, rm.Body.(*icmp.Echo).Data)
+				default:
+					// log.Println("received icmp message of unknown type", rm.Type)
+				}
 			}
+
 		}
 	}
 
diff --git a/trace/tcp_ipv4.go b/trace/tcp_ipv4.go
index be7ced1..4bb62e6 100644
--- a/trace/tcp_ipv4.go
+++ b/trace/tcp_ipv4.go
@@ -88,18 +88,21 @@ func (t *TCPTracer) listenICMP() {
 			if msg.N == nil {
 				continue
 			}
-			rm, err := icmp.ParseMessage(1, msg.Msg[:*msg.N])
-			if err != nil {
-				log.Println(err)
-				continue
-			}
-			switch rm.Type {
-			case ipv4.ICMPTypeTimeExceeded:
-				t.handleICMPMessage(msg, rm.Body.(*icmp.TimeExceeded).Data)
-			case ipv4.ICMPTypeDestinationUnreachable:
-				t.handleICMPMessage(msg, rm.Body.(*icmp.DstUnreach).Data)
-			default:
-				//log.Println("received icmp message of unknown type", rm.Type)
+			dstip := net.IP(msg.Msg[24:28])
+			if dstip.Equal(t.DestIP) {
+				rm, err := icmp.ParseMessage(1, msg.Msg[:*msg.N])
+				if err != nil {
+					log.Println(err)
+					continue
+				}
+				switch rm.Type {
+				case ipv4.ICMPTypeTimeExceeded:
+					t.handleICMPMessage(msg, rm.Body.(*icmp.TimeExceeded).Data)
+				case ipv4.ICMPTypeDestinationUnreachable:
+					t.handleICMPMessage(msg, rm.Body.(*icmp.DstUnreach).Data)
+				default:
+					//log.Println("received icmp message of unknown type", rm.Type)
+				}
 			}
 		}
 	}