Golang: Undefined Field in Struct Error

[Chris_S]

I am trying to parse an xml file using golang. I have created my structs needed but when I try to compile the go file, I get an error saying the following:

./main_v4.go:146: aggInfoXml.IpAddr.Hports undefined (type []Addr has no field or method Hports)

I am stumped on this problem. Here is my code:

package main

import (

	"net/http"
	"html/template"
	"os/exec"
	"io/ioutil"
	"os"
	"encoding/xml"
    "encoding/json"
	"fmt"
	"bufio"
	"github.com/gorilla/websocket"
	"time"
	"log"

)

type PercentInfo struct {
    Percent IntPercent `xml:"taskprogress,omitempty"`
} 

type AggInfoXml struct {
    Percent     IntPercent  `xml:"taskprogress,omitempty"`
    IpAddr      []Addr      `xml:"host>address,omitempty"`
}

type IntPercent struct {
    Value float64 `xml:"percent,attr,omitempty"` // works
}


type Addr struct {
    Ip      string   `xml:"addr,attr"`
    Hports  []Ports  `xml:"host>ports>port,omitempty"` //failing to be recognized
}

type Ports struct {
    Port string `xml:"portid,attr"`
}

func (p *Addr) ipaddr() string {
     return p.Ip
}

func (p *Ports) ports() string {
     return p.Port
}

func (p *IntPercent) percent() float64 {
    return p.Value
}

func (f *Test) Name() string {
    return f.Value

}

var upgrader = websocket.Upgrader{
    ReadBufferSize: 1024,
    WriteBufferSize: 1024,
}

type Test struct {
    Value string    
}


func wsHandler(w http.ResponseWriter, r *http.Request) {

    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        fmt.Println(err)
    }

    cmd := exec.Command("nmap", "-F", "-sS", "172.16.2.0/24", "-oX", "output.xml", "--stats-every", "1s")

    if err := cmd.Start(); err != nil {
        log.Fatal(err)
    }

    time.Sleep( 1000 * time.Millisecond) 

    fp, err := os.Open("output.xml")
    if err != nil {
        log.Fatal(err)
    }


    // create scanner on the output.xml file
    in := bufio.NewScanner(fp)

    // change this loop to buffer read the xml file...
    aggInfoXml  := AggInfoXml{}


//    pInfo := IntPercent{} //go hates us Thiago   LOL

    fmt.Printf("hello")

    for in.Scan() {

        err = xml.Unmarshal([]byte(in.Text()), &aggInfoXml.Percent) // this is not working..
        if err != nil {
            fmt.Printf("Could not unmarshal the line <%v>", in.Text())
        } else {
            fmt.Printf("%+v\n", aggInfoXml.Percent.Value) // this is not working? why .percent()
        }

        // bail out of slow loop if 100% reached
        if aggInfoXml.Percent.Value == 100 {
            break
        }

        time.Sleep(1000*time.Millisecond)

        bytesArray, err := json.Marshal(aggInfoXml.Percent)

        err = conn.WriteMessage(websocket.TextMessage, bytesArray)  // send JSON over
        if err != nil {
            panic(err)
        }

    }//this is the end of the in.Scan loop now

    fmt.Println("After loop")
    // out here... we just need to Wait on the cmd... then when cmd is finish
    // open the file (with differnet file handle) and unmarshal the host parts
    // agree? yes

    // open the file AGAIN (so the pointer restarts at to of file)
    /*
    fp2, err := os.Open("output.xml")
    if err != nil {
        log.Fatal(err)
    }
    */

    if err := cmd.Wait(); err != nil {  
        log.Fatal(err)
    }
    
    data, err := ioutil.ReadFile("output.xml")

    if err != nil {
        panic(err)
    }

    err = xml.Unmarshal(data, &aggInfoXml.IpAddr)
    if err != nil {
        log.Fatal("Could not unmarshal host")
    }

    for _, port := range aggInfoXml.IpAddr.Hports {
        fmt.Printf("Port: %s\n", port.ports())
    }

    for _, ip := range aggInfoXml.IpAddr {
        fmt.Printf("IpAdd: %s\n", ip.ipaddr())
    }

    conn.Close()
    fp.Close()
}

func handler(w http.ResponseWriter, r *http.Request) {
    
    t, _ := template.ParseFiles("index.html")
    t.Execute(w,nil)
}

func main() {

    http.HandleFunc("/", handler)
    http.Handle("/layout/", http.StripPrefix("/layout/", http.FileServer(http.Dir("layout"))))
    http.HandleFunc("/websocket", wsHandler)
    http.ListenAndServe(":8080", nil)

}

Any suggestions would be appreciated.

[airomega (Steve McC)]

aggInfoXml.IpAddr isn’t an instance of Addr - it’s an []Addr. Your going to have to range over aggInfoXml.IpAddr first to get a single Addr then range over Addr.HPorts to get a single port.

 for _, addr := range aggInfoXml.IpAddr{
        for _, port := range addr.Hports  {
            fmt.Printf("Port: %s\n", port.ports())
        }
    }