wayback/wayback.go
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package wayback
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"regexp"
)
type Client struct {
httpClient *http.Client
}
const userAgent = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"
var (
host = "archive.org"
dest = "https://web." + host
base = "https://web.archive.org/save/"
endpoint = "https://archive.org/wayback/available"
)
// Wayback is the handle of saving webpages to archive.org
func (wbrc *Client) Archive(ctx context.Context, u string) (result string, err error) {
if wbrc.httpClient == nil {
wbrc.httpClient = &http.Client{
CheckRedirect: noRedirect,
}
}
result, err = wbrc.archive(ctx, u)
if err != nil {
return
}
return
}
func (wbrc *Client) archive(ctx context.Context, uri string) (string, error) {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, base+uri, nil)
if err != nil {
return "", err
}
req.Header.Add("User-Agent", userAgent)
resp, err := wbrc.httpClient.Do(req)
if err != nil {
return "", err
}
defer resp.Body.Close()
var loc string
loc = resp.Header.Get("Content-Location")
if len(loc) > 0 {
return loc, nil
}
loc = resp.Header.Get("Location")
if len(loc) > 0 {
return loc, nil
}
links := resp.Header.Get("Link")
re := regexp.MustCompile(`(?m)http[s]?:\/\/web\.archive\.org/web/[-a-zA-Z0-9@:%_\+.~#?&//=]*`)
if match := re.FindAllString(links, -1); len(match) > 0 {
loc = match[len(match)-1]
return fmt.Sprintf("%v", loc), nil
}
loc = resp.Request.URL.String()
if match := re.FindAllString(loc, -1); len(match) > 0 {
return fmt.Sprintf("%v", loc), nil
}
loc, err = wbrc.latest(ctx, uri)
if err != nil {
loc = base + uri
}
// HTTP 509 Bandwidth Limit Exceeded
if resp.StatusCode == 509 {
return fmt.Sprint(loc), nil
}
if resp.StatusCode != 200 {
return fmt.Sprint(loc), nil
}
return loc, nil
}
func (wbrc *Client) latest(_ context.Context, u string) (string, error) {
// https://web.archive.org/*/https://example.org
result := fmt.Sprintf("%s/*/%s", dest, u)
uri := endpoint + "?url=" + u
resp, err := wbrc.httpClient.Get(uri)
if err != nil {
return "", err
}
defer resp.Body.Close()
data, err := io.ReadAll(resp.Body)
if err != nil {
return "", err
}
var dat map[string]interface{}
if err := json.Unmarshal(data, &dat); err != nil {
return "", err
}
if archived, ok := dat["archived_snapshots"].(map[string]interface{}); ok {
if closest, ok := archived["closest"].(map[string]interface{}); ok {
if closest["available"].(bool) && closest["status"] == "200" {
return closest["url"].(string), nil
}
}
}
return result, fmt.Errorf("Not found")
}
func noRedirect(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
}