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// 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()
}
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