use io.Reader when parsing urls

cmd/crawl/main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"fmt"
+	"io"
+	"io/ioutil"
 	"net/http"
 	"os"
 
@@ -20,9 +22,14 @@ func main() {
 	for p := range spider.Pages(os.Args[1]) {
 		resp, err := http.Get(p.To)
 		if err != nil {
+			p.Err = err
 			failures = append(failures, p)
+			continue
 		}
+		io.Copy(ioutil.Discard, resp.Body)
+		resp.Body.Close()
 		if resp.StatusCode != http.StatusOK {
+			p.Err = fmt.Errorf("http status; got %s, want %s", http.StatusText(resp.StatusCode), http.StatusText(http.StatusOK))
 			failures = append(failures, p)
 		}
 	}

cmd/lnks/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"net/http"
 	"os"
 
 	"mcquay.me/spider"
@@ -14,7 +15,15 @@ func main() {
 		fmt.Fprintf(os.Stderr, "%s\n", usage)
 		os.Exit(1)
 	}
-	for _, l := range spider.URLs(os.Args[1]) {
+	resp, err := http.Get(os.Args[1])
+	if err != nil {
+		panic(err)
+	}
+	links, err := spider.URLs(resp.Body)
+	if err != nil {
+		panic(err)
+	}
+	for _, l := range links {
 		fmt.Println(l)
 	}
 }

spider.go

@@ -2,33 +2,27 @@ package spider
 
 import (
 	"fmt"
+	"io"
 	"net/http"
-	"os"
 	"strings"
 
 	"golang.org/x/net/html"
 )
 
 // URLs returns all links on a page
-func URLs(url string) []Link {
-	resp, err := http.Get(url)
+func URLs(page io.Reader) ([]string, error) {
+	doc, err := html.Parse(page)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
+		return nil, fmt.Errorf("parsing html: %v", err)
 	}
-	doc, err := html.Parse(resp.Body)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
-	}
-	paths := []Link{}
+	paths := []string{}
 	var f func(*html.Node)
 	f = func(n *html.Node) {
 		if n.Type == html.ElementNode {
 			for _, a := range n.Attr {
 				switch a.Key {
 				case "href", "src":
-					paths = append(paths, Link{From: url, To: a.Val})
+					paths = append(paths, a.Val)
 					break
 				}
 			}
@@ -38,25 +32,52 @@ func URLs(url string) []Link {
 		}
 	}
 	f(doc)
-	return paths
+	return paths, nil
 }
 
 type Link struct {
 	From string
 	To   string
+
+	Err error
 }
 
 func (l Link) String() string {
-	return fmt.Sprintf("%s > %s", l.From, l.To)
+	r := fmt.Sprintf("%s > %s", l.From, l.To)
+	if l.Err != nil {
+		r = fmt.Sprintf("%v (%v)", r, l.Err)
+	}
+	return r
 }
 
 // Pages returns a stream of full urls starting at a given base page.
 func Pages(base string) <-chan Link {
+	r := make(chan Link)
+
 	base = strings.TrimRight(base, "/")
 	visited := map[string]bool{base: true}
-	links := URLs(base)
+	links := []Link{}
 
-	r := make(chan Link)
+	resp, err := http.Get(base)
+	if err != nil {
+		go func() {
+			r <- Link{To: base, From: "start", Err: err}
+			close(r)
+		}()
+		return r
+	}
+	lks, err := URLs(resp.Body)
+	if err != nil {
+		go func() {
+			r <- Link{To: base, From: "start", Err: err}
+			close(r)
+		}()
+		return r
+	}
+
+	for _, l := range lks {
+		links = append(links, Link{From: base, To: l})
+	}
 
 	go func() {
 		for len(links) > 0 {
@@ -77,8 +98,18 @@ func Pages(base string) <-chan Link {
 
 			if _, ok := visited[l.To]; !ok {
 				r <- l
-				for _, lk := range URLs(l.To) {
-					links = append(links, lk)
+
+				resp, err := http.Get(l.To)
+				if err != nil {
+					panic(err)
+				}
+				lks, err := URLs(resp.Body)
+				if err != nil {
+					panic(err)
+				}
+
+				for _, lk := range lks {
+					links = append(links, Link{From: l.From, To: lk})
 				}
 			}
 			visited[l.To] = true