initial commit

default.go

@@ -0,0 +1,173 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"github.com/PuerkitoBio/goquery"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"path"
+	"strconv"
+	"strings"
+)
+
+const (
+	ContentTypeHtml = "text/html"
+)
+
+func defaultLinkHandler(link string) (*LinkInfo, error) {
+	redirects := make([]string, 0)
+
+	u, err := url.Parse(link)
+
+	if err != nil {
+		return nil, err
+	}
+
+	var res *http.Response
+
+	for i := 0; i < 10; i++ {
+		res, err = client.Head(link)
+
+		if err != nil {
+			return nil, err
+		}
+
+		if (res.StatusCode == 301 || res.StatusCode == 302) && res.Header.Get("Location") != "" {
+			link = res.Header.Get("Location")
+			redirects = append(redirects, link)
+		} else {
+			break
+		}
+	}
+
+	if res != nil && res.StatusCode != 200 {
+		return nil, errors.New("invalid response, expected 200, got " + strconv.Itoa(res.StatusCode))
+	}
+
+	contentType := res.Header.Get("Content-Type")
+
+	if contentType == "" {
+		contentType = detectContentType(link, "application/octet-stream")
+	}
+
+	if idx := strings.Index(contentType, ";"); idx != -1 {
+		contentType = contentType[:idx]
+	}
+
+	var contentLength int64
+
+	if contentLengthStr := res.Header.Get("Content-Length"); contentLengthStr != "" {
+		contentLength, err = strconv.ParseInt(contentLengthStr, 10, 64)
+	}
+
+	ret := &LinkInfo{
+		ContentType: contentType,
+		ContentLength: contentLength,
+	}
+
+	switch contentType {
+	case ContentTypeHtml:
+		err = retrieveHtmlLinkTitle(ret, link)
+	default:
+		ret.Title = fmt.Sprintf("%s (%s, %s)", path.Base(u.Path), contentType, ByteCountDecimal(contentLength))
+	}
+
+	return ret, err
+}
+
+func detectContentType(link, defaultType string) string {
+	req, err := http.NewRequest("GET", link, nil)
+
+	if err != nil {
+		return defaultType
+	}
+
+	req.Header.Set("Range", "bytes=0-512")
+
+	res, err := client.Do(req)
+
+	if err != nil {
+		return defaultType
+	}
+
+	defer res.Body.Close()
+
+	b, err := ioutil.ReadAll(io.LimitReader(res.Body, 512))
+
+	if err != nil {
+		return defaultType
+	}
+
+	t := http.DetectContentType(b)
+
+	if t == "" {
+		t = defaultType
+	}
+
+	return t
+}
+
+var (
+	attrKeys = []string{"property", "name", "itemprop"}
+)
+
+func retrieveHtmlLinkTitle(i *LinkInfo, link string) error {
+	res, err := client.Get(link)
+
+	if err != nil {
+		return err
+	}
+
+	defer res.Body.Close()
+
+	q, err := goquery.NewDocumentFromReader(res.Body)
+
+	if err != nil {
+		return err
+	}
+
+	meta := q.Find("meta")
+
+	metaTags := make(map[string]string)
+
+	meta.Each(func(_ int, s *goquery.Selection) {
+		var key string
+		var exists bool
+
+		for _, k := range attrKeys {
+			key, exists = s.Attr(k)
+
+			if exists {
+				break
+			}
+		}
+
+		if key == "" {
+			return
+		}
+	})
+
+	var attr string
+	var exists bool
+
+	if attr, exists = metaTags["og:title"]; exists {
+		i.Title = attr
+	} else if tag := q.Find("title"); tag.Length() > 0 {
+		i.Title = tag.Text()
+	}
+
+	if attr, exists = metaTags["og:description"]; exists {
+		i.Description = attr
+	} else if attr, exists = metaTags["description"]; exists {
+		i.Description = attr
+	}
+
+	if attr, exists = metaTags["duration"]; exists {
+		i.Duration = attr
+	}
+
+	return nil
+}

default_test.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"net/http"
+	"testing"
+	"time"
+)
+
+func Test_DefaultLinkHandler(t *testing.T) {
+	client = &http.Client{
+		Timeout: 10 * time.Second,
+	}
+
+	type expectedData struct {
+		Link string
+		Title string
+		Type string
+	}
+
+	testLinks := []expectedData{
+		{"https://paste.ee", "Paste.ee", "text/html"},
+		{"http://techslides.com/demos/sample-videos/small.mp4", "", "video/mp4"},
+	}
+
+	for _, link := range testLinks {
+		l, err := defaultLinkHandler(link.Link)
+
+		if err != nil {
+			t.Fatal("Unable to retrieve link info:", err)
+		}
+
+		if link.Title != "" && link.Title != l.Title {
+			t.Fatal("Unexpected title, expected:", link.Title, "got:", l.Title)
+		}
+
+		if link.Type != "" && link.Type != l.ContentType {
+			t.Fatal("Unexpected content type, expected:", link.Type, "got:", l.ContentType)
+		}
+	}
+}

go.mod

@@ -0,0 +1,5 @@
+module meow.tf/go/linkinfo
+
+go 1.12
+
+require github.com/PuerkitoBio/goquery v1.5.0

go.sum

@@ -0,0 +1,7 @@
+github.com/PuerkitoBio/goquery v1.5.0 h1:uGvmFXOA73IKluu/F84Xd1tt/z07GYm8X49XKHP7EJk=
+github.com/PuerkitoBio/goquery v1.5.0/go.mod h1:qD2PgZ9lccMbQlc7eEOjaeRlFQON7xY8kdmcsrnKqMg=
+github.com/andybalholm/cascadia v1.0.0 h1:hOCXnnZ5A+3eVDX8pvgl4kofXv2ELss0bKcqRySc45o=
+github.com/andybalholm/cascadia v1.0.0/go.mod h1:GsXiBklL0woXo1j/WYWtSYYC4ouU9PqHO0sqidkEA4Y=
+golang.org/x/net v0.0.0-20180218175443-cbe0f9307d01/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20181114220301-adae6a3d119a h1:gOpx8G595UYyvj8UK4+OFyY4rx037g3fmfhe5SasG3U=
+golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=

main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"net/http"
+	"time"
+)
+
+var (
+	client *http.Client
+)
+
+type LinkInfo struct {
+	Title string `json:"title"`
+	Description string `json:"description"`
+	ContentType string `json:"type"`
+	ContentLength int64 `json:"contentLength"`
+	Duration string `json:"duration,omitempty"`
+	Redirects []string `json:"redirects,omitempty"`
+}
+
+func main() {
+	client = &http.Client{
+		Timeout: 10 * time.Second,
+	}
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/info", handleInfoRequest)
+	http.ListenAndServe(":8080", mux)
+}
+
+func handleInfoRequest(w http.ResponseWriter, r *http.Request) {
+
+}

util.go

@@ -0,0 +1,29 @@
+package main
+
+import "fmt"
+
+func ByteCountDecimal(b int64) string {
+	const unit = 1000
+	if b < unit {
+		return fmt.Sprintf("%d B", b)
+	}
+	div, exp := int64(unit), 0
+	for n := b / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "kMGTPE"[exp])
+}
+
+func ByteCountBinary(b int64) string {
+	const unit = 1024
+	if b < unit {
+		return fmt.Sprintf("%d B", b)
+	}
+	div, exp := int64(unit), 0
+	for n := b / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %ciB", float64(b)/float64(div), "KMGTPE"[exp])
+}