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package main
import (
"encoding/json"
"flag"
"fmt"
"io"
"net/http"
"os"
"strings"
"time"
"gopkg.in/h2non/gentleman.v2"
"gopkg.in/h2non/gentleman.v2/plugins/timeout"
)
var session = flag.String("session", "9e8831af-ce30-48c3-8663-4b27262f43f1.pjKPVCYufDhuA9GPJAlc_xh45M8", "The session (the value of the cookie named 'session')")
var rootURL = flag.String("url", "https://ctf.example.com", "The root URL of the CTFd instance")
var outputFolder = flag.String("out", "challdump", "The name of the folder to dump the files to")
func main() {
flag.Parse()
// fetch the list of all challenges
challs, err := fetchAllChallenges()
if err != nil {
panic(err)
}
// iterate over all challenges downloading all files
fmt.Println("Downloading the files included in the challenges")
for _, chall := range challs.Data {
// define where to store the challenge
filepath := fmt.Sprintf("%s/%s/%s", *outputFolder, chall.Category, chall.Name)
fmt.Printf("→ %s\n", filepath)
err := os.MkdirAll(filepath, os.ModePerm) // create the directory
if err != nil {
fmt.Println(err)
}
// fetch the challenge information
challenge, err := fetchChallenge(chall.ID)
if err != nil {
fmt.Println(err)
}
// download all files
for _, file := range challenge.Data.Files {
err := Download(file, filepath)
if err != nil {
fmt.Println(err)
}
}
// store the description of the challenge in a README.md file
err = saveDescription(challenge, filepath)
if err != nil {
fmt.Println(err)
}
}
}
// fetchAllChallenges fetches the list of all challs using the ctfs api.
func fetchAllChallenges() (Challenges, error) {
fmt.Println("Fetching all challenges using the ctf api...")
cli := gentleman.New()
cli.URL(*rootURL)
// define the timeouts outrageously long, as some CTFs hosted using CTFd are incredibly inresponsive.
cli.Use(timeout.Request(1000 * time.Second))
cli.Use(timeout.Dial(1000 * time.Second, 2000 * time.Second))
req := cli.Request()
req.Path("/api/v1/challenges")
req.SetHeader("Cookie", fmt.Sprintf("session=%s", *session))
// Perform the request
res, err := req.Send()
if err != nil {
fmt.Printf("Request error: %s\n", err)
return Challenges{}, err
}
if !res.Ok {
fmt.Printf("Invalid server response: %d\n", res.StatusCode)
return Challenges{}, err
}
// unmarshal the resulting json into a Challenges struct
var challenges Challenges
if err := json.Unmarshal(res.Bytes(), &challenges); err != nil {
fmt.Printf("Challenge unmarshal error: %d\n", res.StatusCode)
fmt.Println(res.String())
return Challenges{}, err
}
fmt.Println("Done fetching all challenges")
return challenges, nil
}
// fetchChallenge fetches a single challenge
func fetchChallenge(id int) (Challenge, error) {
cli := gentleman.New()
cli.URL(*rootURL)
req := cli.Request()
req.Path(fmt.Sprintf("/api/v1/challenges/%d", id))
req.SetHeader("Cookie", fmt.Sprintf("session=%s", *session))
// Perform the request
res, err := req.Send()
if err != nil {
fmt.Printf("Request error: %s\n", err)
return Challenge{}, err
}
if !res.Ok {
fmt.Printf("Invalid server response: %d\n", res.StatusCode)
return Challenge{}, err
}
var challenge Challenge
if err := json.Unmarshal(res.Bytes(), &challenge); err != nil {
return Challenge{}, err
}
return challenge, nil
}
// Download downloads a file from the given URL and stores it at the given
// filepath
func Download(url string, filepath string) error {
// So what the code below does, is it extracts the filename from the url by
// first splitting the url at slashed and then at questionmarks (could have
// used regex, but this is CTF code ¯\_(ツ)_/¯)
a := strings.Split(url, "/")
b := strings.Split(a[len(a)-1], "?")
filename := b[0]
prefix := *rootURL
fullurl := fmt.Sprintf("%s%s", prefix, url)
client := &http.Client{}
req, err := http.NewRequest("GET", fullurl, nil)
req.Header.Add("Cookie", fmt.Sprintf("session=%s", *session))
resp, err := client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
// Create the file
out, err := os.Create(fmt.Sprintf("%s/%s", filepath, filename))
if err != nil {
return err
}
defer out.Close()
// Write the body to file
_, err = io.Copy(out, resp.Body)
if err != nil {
return err
}
return nil
}
func saveDescription(challenge Challenge, filepath string) error {
path := fmt.Sprintf("%s/README.md", filepath)
f, err := os.Create(path)
if err != nil {
return err
}
// fill the readme with some content
f.WriteString(fmt.Sprintf("# %s\n\n", challenge.Data.Name))
f.WriteString(fmt.Sprintf("Category: %s\n\n", challenge.Data.Category))
f.WriteString("Files:\n")
for _, file := range challenge.Data.Files {
// So what the code below does, is it extracts the filename from the url by
// first splitting the url at slashed and then at questionmarks (could have
// used regex, but this is CTF code ¯\_(ツ)_/¯)
a := strings.Split(file, "/")
b := strings.Split(a[len(a)-1], "?")
filename := b[0]
f.WriteString(fmt.Sprintf("- %s\n", filename))
}
f.WriteString("\n")
f.WriteString("## Description\n\n")
f.WriteString(fmt.Sprintf("%s\n\n", challenge.Data.Description))
f.WriteString("## Writeup")
return nil
}
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