archiveis - fix panic from closing a closed channel

If one of the recursive calls encounters an error, it was closing the channel without setting the closed flag. This change moves the channel close outside enumerate() so there's only one place that needs to close it.

Also removed the loop in enumerate() which wasn't necessary.

pkg/subscraping/sources/archiveis/archiveis.go

@@ -13,54 +13,40 @@ import (
 type ArchiveIs struct {
 	Results chan subscraping.Result
 	Session *subscraping.Session
-
-	closed bool
 }
 
 var reNext = regexp.MustCompile("<a id=\"next\" style=\".*\" href=\"(.*)\">&rarr;</a>")
 
 func (a *ArchiveIs) enumerate(ctx context.Context, baseURL string) {
-	for {
-		select {
-		case <-ctx.Done():
-			close(a.Results)
-			return
-		default:
-			resp, err := a.Session.NormalGetWithContext(ctx, baseURL)
-			if err != nil {
-				a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Error, Error: err}
-				close(a.Results)
-				return
-			}
+	select {
+	case <-ctx.Done():
+		return
+	default:
+	}
 
-			// Get the response body
-			body, err := ioutil.ReadAll(resp.Body)
-			if err != nil {
-				a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Error, Error: err}
-				resp.Body.Close()
-				close(a.Results)
-				return
-			}
-			resp.Body.Close()
+	resp, err := a.Session.NormalGetWithContext(ctx, baseURL)
+	if err != nil {
+		a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Error, Error: err}
+		return
+	}
 
-			src := string(body)
+	// Get the response body
+	body, err := ioutil.ReadAll(resp.Body)
+	resp.Body.Close()
+	if err != nil {
+		a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Error, Error: err}
+		return
+	}
 
-			for _, subdomain := range a.Session.Extractor.FindAllString(src, -1) {
-				a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Subdomain, Value: subdomain}
-			}
+	src := string(body)
 
-			match1 := reNext.FindStringSubmatch(src)
-			if len(match1) > 0 {
-				a.enumerate(ctx, match1[1])
-			}
+	for _, subdomain := range a.Session.Extractor.FindAllString(src, -1) {
+		a.Results <- subscraping.Result{Source: "archiveis", Type: subscraping.Subdomain, Value: subdomain}
+	}
 
-			// Guard channel closing during recursion
-			if !a.closed {
-				close(a.Results)
-				a.closed = true
-			}
-			return
-		}
+	match1 := reNext.FindStringSubmatch(src)
+	if len(match1) > 0 {
+		a.enumerate(ctx, match1[1])
 	}
 }
 
@@ -76,7 +62,10 @@ func (s *Source) Run(ctx context.Context, domain string, session *subscraping.Se
 		Results: results,
 	}
 
-	go aInstance.enumerate(ctx, "http://archive.is/*."+domain)
+	go func() {
+		aInstance.enumerate(ctx, "http://archive.is/*."+domain)
+		close(aInstance.Results)
+	}()
 
 	return aInstance.Results
 }