From b4bffa978cd323777ebd599c22c4f15641d6c1e2 Mon Sep 17 00:00:00 2001
From: Starainrt <i@b612,me>
Date: Fri, 4 Jun 2021 10:49:23 +0800
Subject: [PATCH] add ping functions

---
 ping.go      | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 ping_test.go | 11 ++++++
 2 files changed, 108 insertions(+)
 create mode 100644 ping.go
 create mode 100644 ping_test.go

diff --git a/ping.go b/ping.go
new file mode 100644
index 0000000..efbd183
--- /dev/null
+++ b/ping.go
@@ -0,0 +1,97 @@
+package starnet
+
+import (
+	"bytes"
+	"encoding/binary"
+	"net"
+	"time"
+)
+
+type ICMP struct {
+	Type        uint8
+	Code        uint8
+	CheckSum    uint16
+	Identifier  uint16
+	SequenceNum uint16
+}
+
+func getICMP(seq uint16) ICMP {
+	icmp := ICMP{
+		Type:        8,
+		Code:        0,
+		CheckSum:    0,
+		Identifier:  0,
+		SequenceNum: seq,
+	}
+	var buffer bytes.Buffer
+	binary.Write(&buffer, binary.BigEndian, icmp)
+	icmp.CheckSum = checkSum(buffer.Bytes())
+	buffer.Reset()
+
+	return icmp
+}
+
+func sendICMPRequest(icmp ICMP, destAddr *net.IPAddr, timeout time.Duration) (PingResult, error) {
+	var res PingResult
+	conn, err := net.DialIP("ip:icmp", nil, destAddr)
+	if err != nil {
+		return res, err
+	}
+	defer conn.Close()
+	var buffer bytes.Buffer
+	binary.Write(&buffer, binary.BigEndian, icmp)
+
+	if _, err := conn.Write(buffer.Bytes()); err != nil {
+		return res, err
+	}
+
+	tStart := time.Now()
+
+	conn.SetReadDeadline((time.Now().Add(timeout)))
+
+	recv := make([]byte, 1024)
+	res.RecvCount, err = conn.Read(recv)
+
+	if err != nil {
+		return res, err
+	}
+
+	tEnd := time.Now()
+	res.Duration = tEnd.Sub(tStart)
+
+	return res, err
+}
+
+func checkSum(data []byte) uint16 {
+	var (
+		sum    uint32
+		length int = len(data)
+		index  int
+	)
+	for length > 1 {
+		sum += uint32(data[index])<<8 + uint32(data[index+1])
+		index += 2
+		length -= 2
+	}
+	if length > 0 {
+		sum += uint32(data[index])
+	}
+	sum += (sum >> 16)
+
+	return uint16(^sum)
+}
+
+type PingResult struct {
+	Duration  time.Duration
+	RecvCount int
+}
+
+func Ping(ip string, seq int, timeout time.Duration) (PingResult, error) {
+	var res PingResult
+	ipAddr, err := net.ResolveIPAddr("ip", ip)
+	if err != nil {
+		return res, err
+	}
+	icmp := getICMP(uint16(seq))
+	return sendICMPRequest(icmp, ipAddr, timeout)
+}
diff --git a/ping_test.go b/ping_test.go
new file mode 100644
index 0000000..66ea297
--- /dev/null
+++ b/ping_test.go
@@ -0,0 +1,11 @@
+package starnet
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func Test_Ping(t *testing.T) {
+	fmt.Println(Ping("baidu.com", 0, time.Second*2))
+}