1 files changed, 75 insertions, 0 deletions
diff --git a/cmd/links/links.go b/cmd/links/links.go
new file mode 100644
index 0000000..3ba63be
--- /dev/null
+++ b/cmd/links/links.go
@@ -0,0 +1,75 @@
+// A restartable crawler that extracts links from HTML pages and
+// simply prints them.
+//
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"git.autistici.org/ale/crawl"
+	"github.com/PuerkitoBio/goquery"
+)
+
+var (
+	dbPath       = flag.String("state", "crawldb", "crawl state database path")
+	concurrency  = flag.Int("c", 10, "concurrent workers")
+	depth        = flag.Int("depth", 10, "maximum link depth")
+	validSchemes = flag.String("schemes", "http,https", "comma-separated list of allowed protocols")
+)
+
+var linkMatches = []struct {
+	tag  string
+	attr string
+}{
+	{"a", "href"},
+	{"link", "href"},
+	{"img", "src"},
+	{"script", "src"},
+}
+
+func extractLinks(c *crawl.Crawler, u string, depth int, resp *http.Response, err error) error {
+	if !strings.HasPrefix(resp.Header.Get("Content-Type"), "text/html") {
+		return nil
+	}
+
+	doc, err := goquery.NewDocumentFromResponse(resp)
+	if err != nil {
+		return err
+	}
+
+	links := make(map[string]*url.URL)
+
+	for _, lm := range linkMatches {
+		doc.Find(fmt.Sprintf("%s[%s]", lm.tag, lm.attr)).Each(func(i int, s *goquery.Selection) {
+			val, _ := s.Attr(lm.attr)
+			if linkurl, err := resp.Request.URL.Parse(val); err == nil {
+				links[linkurl.String()] = linkurl
+			}
+		})
+	}
+
+	for _, link := range links {
+		//log.Printf("%s -> %s", u, link.String())
+		c.Enqueue(link, depth+1)
+	}
+	return nil
+}
+
+func main() {
+	flag.Parse()
+
+	seeds := crawl.MustParseURLs(flag.Args())
+	scope := crawl.NewSeedScope(seeds, *depth, strings.Split(*validSchemes, ","))
+
+	crawler, err := crawl.NewCrawler("crawldb", seeds, scope, crawl.FetcherFunc(http.Get), crawl.HandlerFunc(extractLinks))
+	if err != nil {
+		log.Fatal(err)
+	}
+	crawler.Run()
+}