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package devianter
import (
"encoding/json"
"errors"
"io"
"net/http"
"strconv"
"strings"
"time"
)
// функция для высера ошибки в stderr
func try(txt error) {
if txt != nil {
println(txt.Error())
}
}
func ujson(data string, output any) Error {
input, err := puppy(data)
if err == nil {
try(json.Unmarshal([]byte(input), output))
}
return APIError(err)
}
type Error struct {
Reason string `json:"error"`
Error string `json:"errorDescription"`
RAW []byte `json:"-"`
}
func APIError(inputError error) (err Error) {
if inputError != nil {
err.RAW = []byte(inputError.Error())
// DA's API errors are JSON. Anything else (CDN block pages, transport
// failures) is surfaced as-is rather than spamming a JSON parse error —
// this is what used to print `invalid character '<'` on every page.
if json.Unmarshal(err.RAW, &err) != nil {
err.Reason = "request_failed"
err.Error = inputError.Error()
}
}
return
}
/* REQUEST SECTION */
// структура для ответа сервера
type reqrt struct {
Body string
Status int
Cookies []*http.Cookie
Headers http.Header
// Err is set when the request never completed (transport error). Status is 0.
Err error
}
// функция для совершения запроса
var UserAgent string
// Timeout bounds a single request end-to-end (dial, response, body read).
// Without it, a hung connection blocks its caller forever.
var Timeout = 30 * time.Second
func request(uri string, other ...string) reqrt {
var r reqrt
// создаём новый запрос
// Transport is deliberately left nil so http.DefaultTransport applies: that
// keeps HTTPS_PROXY support and lets callers wrap it (e.g. to rate-limit).
cli := &http.Client{Timeout: Timeout}
req, e := http.NewRequest("GET", uri, nil)
if e != nil {
try(e)
r.Err = e
return r
}
req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64; rv:123.0) Gecko/20100101 Firefox/123.0.0")
// куки и UA-шник
if UserAgent != "" {
req.Header.Set("User-Agent", UserAgent)
}
if len(other) != 0 {
req.Header.Set("Cookie", other[0])
}
resp, e := cli.Do(req)
if e != nil {
// resp is nil on error: returning here avoids dereferencing it, which
// used to panic and (from UpdateCSRF's goroutine) kill the process.
try(e)
r.Err = e
return r
}
defer resp.Body.Close()
body, e := io.ReadAll(resp.Body)
if e != nil {
try(e)
r.Err = e
}
// заполняем структуру
r.Body = string(body)
r.Cookies = resp.Cookies()
r.Headers = resp.Header
r.Status = resp.StatusCode
return r
}
// looksLikeJSON reports whether a response is actually JSON, so an HTML page from
// a CDN/edge never reaches json.Unmarshal.
func looksLikeJSON(r reqrt) bool {
if ct := r.Headers.Get("Content-Type"); ct != "" && !strings.Contains(ct, "json") {
return false
}
b := strings.TrimSpace(r.Body)
return len(b) > 0 && (b[0] == '{' || b[0] == '[')
}
// describe renders a failed response as a readable message, instead of the opaque
// `invalid character '<'` you get from json.Unmarshal on an HTML error page.
func describe(r reqrt) string {
body := strings.TrimSpace(r.Body)
if looksLikeJSON(r) {
return body // DA's own JSON error; callers unmarshal it into Error
}
msg := "devianter: HTTP " + strconv.Itoa(r.Status) + " non-JSON response from DeviantArt"
if strings.Contains(body, "Generated by cloudfront") || strings.Contains(body, "Request blocked") {
msg += ": blocked by CloudFront/WAF — this egress IP is likely banned"
}
if len(body) > 200 {
body = body[:200] + "..."
}
return msg + " — " + body
}
/* PUPPY aka DeviantArt API */
// получение или обновление токена
var cookie string
var token string
const (
csrfPrefix = "window.__CSRF_TOKEN__ = '"
xhrMarker = "window.__XHR_LOCAL__"
)
func UpdateCSRF() error {
if cookie == "" {
req := request("https://www.deviantart.com/_puppy")
for _, content := range req.Cookies {
cookie = content.Raw
}
}
req := request("https://www.deviantart.com", cookie)
if req.Err != nil {
return req.Err
}
if req.Status != 200 {
return errors.New(describe(req))
}
// Bounds-check the markers. On a block/challenge page they are absent, and the
// old arithmetic sliced Body[24:-4] — a panic that killed the whole process.
start, end := strings.Index(req.Body, csrfPrefix), strings.Index(req.Body, xhrMarker)
if start < 0 || end < 0 {
return errors.New("devianter: CSRF token not found in homepage (blocked, challenged, or markup changed)")
}
start += len(csrfPrefix)
end -= 3
if end <= start || end > len(req.Body) {
return errors.New("devianter: CSRF token markers out of order (markup changed)")
}
token = req.Body[start:end]
return nil
}
func puppy(data string) (string, error) {
var url strings.Builder
url.WriteString("https://www.deviantart.com/_puppy/")
url.WriteString(data)
url.WriteString("&csrf_token=")
url.WriteString(token)
url.WriteString("&da_minor_version=20230710")
body := request(url.String(), cookie)
if body.Err != nil {
return "", body.Err
}
// если код ответа не 200, возвращается ошибка
if body.Status != 200 {
return "", errors.New(describe(body))
}
// A 200 that isn't JSON means an edge/CDN page slipped through.
if !looksLikeJSON(body) {
return "", errors.New(describe(body))
}
return body.Body, nil
}
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