[ADD]supplemental readme

README.md

@@ -1,6 +1,6 @@
 # nmap-parser
 
-Convert nmap's nmap-service-probes files to go structs and support output as JSON format files
+Convert nmap's nmap-service-probe file into a go structure for service probing.
 
 ## Usage
 
@@ -10,7 +10,7 @@ go get "github.com/randolphcyg/nmap-parser"
 
 you can download the latest nmap probe file: [nmap-service-probes](https://github.com/nmap/nmap/blob/master/nmap-service-probes)
 
-and in the same directory, you can write the main func: 
+### 1. Convert the NMAP probe file to JSON format and save it as a JSON file
 
 ```go
 package main
@@ -59,4 +59,151 @@ func main() {
 
 	fmt.Println("Done")
 }
+```
+
+### 2. Perform service probe on local port 3306
+
+```go
+package main
+
+import (
+	"fmt"
+	"net"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	parser "github.com/randolphcyg/nmap-parser"
+)
+
+var (
+	ErrConn       = errors.New("Error connecting")
+	ErrSetTimeout = errors.New("Failed to set deadline")
+	ErrSendCmd    = errors.New("Error sending command")
+	ErrRecRsp     = errors.New("Error receiving response")
+)
+
+func GetLocalIP() (string, error) {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return "", err
+	}
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if ok && !ipNet.IP.IsLoopback() {
+			if ipNet.IP.To4() != nil {
+				return ipNet.IP.String(), nil
+			}
+		}
+	}
+
+	return "", errors.New("no IPv4 address found")
+}
+
+func ServiceDetect(host string, port int, probe parser.Probe) (serviceName string, info parser.VInfo, err error) {
+	addr := net.JoinHostPort(host, strconv.Itoa(port))
+	conn, err := net.Dial(strings.ToLower(probe.Protocol), addr)
+	if err != nil {
+		err = errors.WithMessage(err, ErrConn.Error())
+		return
+	}
+
+	// set connect timeout
+	timeout := time.Millisecond * 10
+	if probe.TcpWrappedMs != "" {
+		timeoutCount, _ := strconv.Atoi(probe.TcpWrappedMs)
+		timeout = time.Duration(timeoutCount)
+	}
+	err = conn.SetDeadline(time.Now().Add(timeout))
+	if err != nil {
+		err = errors.WithMessage(err, ErrSetTimeout.Error())
+		return
+	}
+
+	defer conn.Close()
+
+	// send request
+	probeStringCMD, _ := parser.UnquoteRawString(probe.ProbeString)
+	_, err = conn.Write([]byte(probeStringCMD))
+	if err != nil {
+		err = errors.WithMessage(err, ErrSendCmd.Error())
+		return
+	}
+
+	// read respond
+	resp := make([]byte, 4096)
+	n, err := conn.Read(resp)
+	if err != nil {
+		err = errors.WithMessage(err, ErrRecRsp.Error())
+		return
+	}
+
+	for _, match := range probe.Matches {
+		pattern := match.Pattern
+		re, errRgx := regexp.Compile(pattern)
+		if errRgx != nil {
+			continue
+		}
+		// Use regular expressions for matching
+		srcByte := re.FindSubmatch(resp[:n])
+
+		// find the match rule
+		if len(srcByte) > 1 {
+			serviceName = match.Name
+			info = parser.FillVersionInfoFields(srcByte, match)
+
+			return
+		}
+
+	}
+
+	return
+}
+
+func main() {
+	srcFilePath := "nmap-service-probes"
+	probes, err := parser.ParseNmap(srcFilePath)
+	if err != nil {
+		panic(err)
+	}
+
+	localIP, err := GetLocalIP()
+	if err != nil {
+		panic(err)
+	}
+
+	isLocal := false
+	var host string
+	if isLocal {
+		host = localIP
+	} else {
+		host = "127.0.0.1"
+	}
+
+	port := 6379
+
+	serviceName := ""
+	info := parser.VInfo{}
+	for _, probe := range probes {
+		serviceNameTmp, infoTmp, err := ServiceDetect(host, port, probe)
+		if err != nil {
+			continue
+		}
+
+		if serviceNameTmp != "" && !infoTmp.IsVInfoEmpty() {
+			serviceName = serviceNameTmp
+			info = infoTmp
+		}
+
+	}
+
+	if serviceName != "" && !info.IsVInfoEmpty() {
+		fmt.Println(serviceName, info) // redis {Redis key-value store 7.0.8     [{ redislabs redis 7.0.8       }]}
+	} else {
+		fmt.Println("no match service!")
+	}
+
+}
 ```