Merge pull request #4 from dborzov/master

Add tests for ParseMagnetURI

magnet.go

@@ -30,6 +30,7 @@ func (m *Magnet) String() (ret string) {
 	return
 }
 
+// ParseMagnetURI parses Magnet-formatted URIs into a Magnet instance
 func ParseMagnetURI(uri string) (m Magnet, err error) {
 	u, err := url.Parse(uri)
 	if err != nil {
@@ -45,22 +46,23 @@ func ParseMagnetURI(uri string) (m Magnet, err error) {
 		err = fmt.Errorf("bad xt parameter")
 		return
 	}
-	xt = xt[len(xtPrefix):]
-	decode := func() func(dst, src []byte) (int, error) {
-		switch len(xt) {
-		case 40:
-			return hex.Decode
-		case 32:
-			return base32.StdEncoding.Decode
-		default:
-			return nil
-		}
-	}()
+	infoHash := xt[len(xtPrefix):]
+
+	// BTIH hash can be in HEX or BASE32 encoding
+	// will assign apropriate func judging from symbol length
+	var decode func(dst, src []byte) (int, error)
+	switch len(infoHash) {
+	case 40:
+		decode = hex.Decode
+	case 32:
+		decode = base32.StdEncoding.Decode
+	}
+
 	if decode == nil {
-		err = fmt.Errorf("unhandled xt parameter encoding: encoded length %d", len(xt))
+		err = fmt.Errorf("unhandled xt parameter encoding: encoded length %d", len(infoHash))
 		return
 	}
-	n, err := decode(m.InfoHash[:], []byte(xt))
+	n, err := decode(m.InfoHash[:], []byte(infoHash))
 	if err != nil {
 		err = fmt.Errorf("error decoding xt: %s", err)
 		return

magnet_test.go

@@ -2,22 +2,67 @@ package torrent
 
 import (
 	"encoding/hex"
+	"reflect"
 	"testing"
 )
 
-// Converting from our Magnet type to URL string.
-func TestMagnetString(t *testing.T) {
-	m := Magnet{
+var (
+	exampleMagnetURI = `magnet:?xt=urn:btih:51340689c960f0778a4387aef9b4b52fd08390cd&dn=Shit+Movie+%281985%29+1337p+-+Eru&tr=http%3A%2F%2Fhttp.was.great%21&tr=udp%3A%2F%2Fanti.piracy.honeypot%3A6969`
+	exampleMagnet    = Magnet{
 		DisplayName: "Shit Movie (1985) 1337p - Eru",
 		Trackers: []string{
 			"http://http.was.great!",
 			"udp://anti.piracy.honeypot:6969",
 		},
 	}
-	hex.Decode(m.InfoHash[:], []byte("51340689c960f0778a4387aef9b4b52fd08390cd"))
-	s := m.String()
-	const e = `magnet:?xt=urn:btih:51340689c960f0778a4387aef9b4b52fd08390cd&dn=Shit+Movie+%281985%29+1337p+-+Eru&tr=http%3A%2F%2Fhttp.was.great%21&tr=udp%3A%2F%2Fanti.piracy.honeypot%3A6969`
-	if s != e {
-		t.Fatalf("\nexpected:\n\t%q\nactual\n\t%q", e, s)
+)
+
+// Converting from our Magnet type to URL string.
+func TestMagnetString(t *testing.T) {
+	hex.Decode(exampleMagnet.InfoHash[:], []byte("51340689c960f0778a4387aef9b4b52fd08390cd"))
+	s := exampleMagnet.String()
+	if s != exampleMagnetURI {
+		t.Fatalf("\nexpected:\n\t%q\nactual\n\t%q", exampleMagnetURI, s)
 	}
 }
+
+func TestParseMagnetURI(t *testing.T) {
+	var uri string
+	var m Magnet
+	var err error
+
+	// parsing the legit Magnet URI with btih-formatted xt should not return errors
+	uri = "magnet:?xt=urn:btih:ZOCMZQIPFFW7OLLMIC5HUB6BPCSDEOQU"
+	_, err = ParseMagnetURI(uri)
+	if err != nil {
+		t.Errorf("Attempting parsing the proper Magnet btih URI:\"%v\" failed with err: %v", uri, err)
+	}
+
+	// Checking if the magnet instance struct is built correctly from parsing
+	m, err = ParseMagnetURI(exampleMagnetURI)
+	if err != nil || !reflect.DeepEqual(exampleMagnet, m) {
+		t.Errorf("ParseMagnetURI(%e) returned %v, expected %v", uri, m, exampleMagnet)
+	}
+
+	// empty string URI case
+	_, err = ParseMagnetURI("")
+	if err == nil {
+		t.Errorf("Parsing empty string as URI should have returned an error but didn't")
+	}
+
+	// only BTIH (BitTorrent info hash)-formatted magnet links are currently supported
+	// must return error correctly when encountering other URN formats
+	uri = "magnet:?xt=urn:sha1:YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C"
+	_, err = ParseMagnetURI(uri)
+	if err == nil {
+		t.Errorf("Magnet URI with non-BTIH URNs (like \"%v\") are not supported and should return an error", uri)
+	}
+
+	// resilience to the broken hash
+	uri = "magnet:?xt=urn:btih:this hash is really broken"
+	_, err = ParseMagnetURI(uri)
+	if err == nil {
+		t.Errorf("Failed to detect broken Magnet URI: %v", uri)
+	}
+
+}