fetch favicon

server/crawler.go

@@ -1,7 +1,9 @@
 package server
 
 import (
+	"fmt"
 	"github.com/PuerkitoBio/goquery"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 )
@@ -32,3 +34,60 @@ func FindFeeds(r *http.Response) ([]FeedSource, error) {
 	})
 	return sources, nil
 }
+
+func findFavicon(websiteUrl, feedUrl string) (*[]byte, error) {
+	candidateUrls := make([]string, 0)
+
+	favicon := func(link string) string {
+		u, err := url.Parse(link)
+		if err != nil {
+			return ""
+		}
+		return fmt.Sprintf("%s://%s/favicon.ico", u.Scheme, u.Host)
+	}
+
+	if len(websiteUrl) != 0 {
+		doc, err := goquery.NewDocument(websiteUrl)
+		if err != nil {
+			return nil, err
+		}
+		doc.Find(`link[rel=icon]`).EachWithBreak(func(i int, s *goquery.Selection) bool {
+			if href, ok := s.Attr("href"); ok {
+				if hrefUrl, err := url.Parse(href); err == nil {
+					faviconUrl := doc.Url.ResolveReference(hrefUrl).String()
+					candidateUrls = append(candidateUrls, faviconUrl)
+				}
+			}
+			return true
+		})
+
+		if c := favicon(websiteUrl); len(c) != 0 {
+			candidateUrls = append(candidateUrls, c)
+		}
+	}
+	if c := favicon(feedUrl); len(c) != 0 {
+		candidateUrls = append(candidateUrls, c)
+	}
+
+	client := http.Client{}
+
+	imageTypes := [4]string{
+		"image/x-icon",
+		"image/png",
+		"image/jpeg",
+		"image/gif",
+	}
+	for _, url := range candidateUrls {
+		if res, err := client.Get(url); err == nil && res.StatusCode == 200 {
+			if content, err := ioutil.ReadAll(res.Body); err == nil {
+				ctype := http.DetectContentType(content)
+				for _, itype := range imageTypes {
+					if ctype == itype {
+						return &content, nil
+					}
+				}
+			}
+		}
+	}
+	return nil, nil
+}