Fix sitemap (#22272)

Fix #22270.

Related to #18407.

The old code treated both sitemap and sitemap index as the format like:

```xml
...
<url>
  <loc>http://localhost:3000/explore/users/sitemap-1.xml</loc>
</url>
...
```

Actually, it's incorrect for sitemap index, it should be:

```xml
...
<sitemap>
  <loc>http://localhost:3000/explore/users/sitemap-1.xml</loc>
</sitemap>
...
```

See https://www.sitemaps.org/protocol.html

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: delvh <dev.lh@web.de>

2 files changed, 170 insertions, 66 deletions

diff --git a/modules/sitemap/sitemap.go b/modules/sitemap/sitemap.go
index ceb65c1c8d..280ca1d710 100644
--- a/modules/sitemap/sitemap.go
+++ b/modules/sitemap/sitemap.go
@@ -11,48 +11,62 @@ import (
 	"time"
 )
 
-// sitemapFileLimit contains the maximum size of a sitemap file
-const sitemapFileLimit = 50 * 1024 * 1024
+const (
+	sitemapFileLimit = 50 * 1024 * 1024 // the maximum size of a sitemap file
+	urlsLimit        = 50000
 
-// Url represents a single sitemap entry
+	schemaURL        = "http://www.sitemaps.org/schemas/sitemap/0.9"
+	urlsetName       = "urlset"
+	sitemapindexName = "sitemapindex"
+)
+
+// URL represents a single sitemap entry
 type URL struct {
 	URL     string     `xml:"loc"`
 	LastMod *time.Time `xml:"lastmod,omitempty"`
 }
 
-// SitemapUrl represents a sitemap
+// Sitemap represents a sitemap
 type Sitemap struct {
 	XMLName   xml.Name
 	Namespace string `xml:"xmlns,attr"`
 
-	URLs []URL `xml:"url"`
+	URLs     []URL `xml:"url"`
+	Sitemaps []URL `xml:"sitemap"`
 }
 
 // NewSitemap creates a sitemap
 func NewSitemap() *Sitemap {
 	return &Sitemap{
-		XMLName:   xml.Name{Local: "urlset"},
-		Namespace: "http://www.sitemaps.org/schemas/sitemap/0.9",
+		XMLName:   xml.Name{Local: urlsetName},
+		Namespace: schemaURL,
 	}
 }
 
-// NewSitemap creates a sitemap index.
+// NewSitemapIndex creates a sitemap index.
 func NewSitemapIndex() *Sitemap {
 	return &Sitemap{
-		XMLName:   xml.Name{Local: "sitemapindex"},
-		Namespace: "http://www.sitemaps.org/schemas/sitemap/0.9",
+		XMLName:   xml.Name{Local: sitemapindexName},
+		Namespace: schemaURL,
 	}
 }
 
 // Add adds a URL to the sitemap
 func (s *Sitemap) Add(u URL) {
-	s.URLs = append(s.URLs, u)
+	if s.XMLName.Local == sitemapindexName {
+		s.Sitemaps = append(s.Sitemaps, u)
+	} else {
+		s.URLs = append(s.URLs, u)
+	}
 }
 
-// Write writes the sitemap to a response
+// WriteTo writes the sitemap to a response
 func (s *Sitemap) WriteTo(w io.Writer) (int64, error) {
-	if len(s.URLs) > 50000 {
-		return 0, fmt.Errorf("The sitemap contains too many URLs: %d", len(s.URLs))
+	if l := len(s.URLs); l > urlsLimit {
+		return 0, fmt.Errorf("The sitemap contains %d URLs, but only %d are allowed", l, urlsLimit)
+	}
+	if l := len(s.Sitemaps); l > urlsLimit {
+		return 0, fmt.Errorf("The sitemap contains %d sub-sitemaps, but only %d are allowed", l, urlsLimit)
 	}
 	buf := bytes.NewBufferString(xml.Header)
 	if err := xml.NewEncoder(buf).Encode(s); err != nil {
@@ -62,7 +76,7 @@ func (s *Sitemap) WriteTo(w io.Writer) (int64, error) {
 		return 0, err
 	}
 	if buf.Len() > sitemapFileLimit {
-		return 0, fmt.Errorf("The sitemap is too big: %d", buf.Len())
+		return 0, fmt.Errorf("The sitemap has %d bytes, but only %d are allowed", buf.Len(), sitemapFileLimit)
 	}
 	return buf.WriteTo(w)
 }
diff --git a/modules/sitemap/sitemap_test.go b/modules/sitemap/sitemap_test.go
index ab879b272e..1180463cd7 100644
--- a/modules/sitemap/sitemap_test.go
+++ b/modules/sitemap/sitemap_test.go
@@ -6,7 +6,6 @@ package sitemap
 import (
 	"bytes"
 	"encoding/xml"
-	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -14,63 +13,154 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestOk(t *testing.T) {
-	testReal := func(s *Sitemap, name string, urls []URL, expected string) {
-		for _, url := range urls {
-			s.Add(url)
-		}
-		buf := &bytes.Buffer{}
-		_, err := s.WriteTo(buf)
-		assert.NoError(t, nil, err)
-		assert.Equal(t, xml.Header+"<"+name+" xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\">"+expected+"</"+name+">\n", buf.String())
+func TestNewSitemap(t *testing.T) {
+	ts := time.Unix(1651322008, 0).UTC()
+
+	tests := []struct {
+		name    string
+		urls    []URL
+		want    string
+		wantErr string
+	}{
+		{
+			name: "empty",
+			urls: []URL{},
+			want: xml.Header + `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"" +
+				"</urlset>\n",
+		},
+		{
+			name: "regular",
+			urls: []URL{
+				{URL: "https://gitea.io/test1", LastMod: &ts},
+			},
+			want: xml.Header + `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<url><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></url>" +
+				"</urlset>\n",
+		},
+		{
+			name: "without lastmod",
+			urls: []URL{
+				{URL: "https://gitea.io/test1"},
+			},
+			want: xml.Header + `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<url><loc>https://gitea.io/test1</loc></url>" +
+				"</urlset>\n",
+		},
+		{
+			name: "multiple",
+			urls: []URL{
+				{URL: "https://gitea.io/test1", LastMod: &ts},
+				{URL: "https://gitea.io/test2", LastMod: nil},
+			},
+			want: xml.Header + `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<url><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></url>" +
+				"<url><loc>https://gitea.io/test2</loc></url>" +
+				"</urlset>\n",
+		},
+		{
+			name:    "too many urls",
+			urls:    make([]URL, 50001),
+			wantErr: "The sitemap contains 50001 URLs, but only 50000 are allowed",
+		},
+		{
+			name: "too big file",
+			urls: []URL{
+				{URL: strings.Repeat("b", 50*1024*1024+1)},
+			},
+			wantErr: "The sitemap has 52428932 bytes, but only 52428800 are allowed",
+		},
 	}
-	test := func(urls []URL, expected string) {
-		testReal(NewSitemap(), "urlset", urls, expected)
-		testReal(NewSitemapIndex(), "sitemapindex", urls, expected)
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := NewSitemap()
+			for _, url := range tt.urls {
+				s.Add(url)
+			}
+			buf := &bytes.Buffer{}
+			_, err := s.WriteTo(buf)
+			if tt.wantErr != "" {
+				assert.EqualError(t, err, tt.wantErr)
+			} else {
+				assert.NoError(t, err)
+				assert.Equalf(t, tt.want, buf.String(), "NewSitemap()")
+			}
+		})
 	}
+}
 
+func TestNewSitemapIndex(t *testing.T) {
 	ts := time.Unix(1651322008, 0).UTC()
 
-	test(
-		[]URL{},
-		"",
-	)
-	test(
-		[]URL{
-			{URL: "https://gitea.io/test1", LastMod: &ts},
+	tests := []struct {
+		name    string
+		urls    []URL
+		want    string
+		wantErr string
+	}{
+		{
+			name: "empty",
+			urls: []URL{},
+			want: xml.Header + `<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"" +
+				"</sitemapindex>\n",
 		},
-		"<url><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></url>",
-	)
-	test(
-		[]URL{
-			{URL: "https://gitea.io/test2", LastMod: nil},
+		{
+			name: "regular",
+			urls: []URL{
+				{URL: "https://gitea.io/test1", LastMod: &ts},
+			},
+			want: xml.Header + `<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<sitemap><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></sitemap>" +
+				"</sitemapindex>\n",
 		},
-		"<url><loc>https://gitea.io/test2</loc></url>",
-	)
-	test(
-		[]URL{
-			{URL: "https://gitea.io/test1", LastMod: &ts},
-			{URL: "https://gitea.io/test2", LastMod: nil},
+		{
+			name: "without lastmod",
+			urls: []URL{
+				{URL: "https://gitea.io/test1"},
+			},
+			want: xml.Header + `<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<sitemap><loc>https://gitea.io/test1</loc></sitemap>" +
+				"</sitemapindex>\n",
+		},
+		{
+			name: "multiple",
+			urls: []URL{
+				{URL: "https://gitea.io/test1", LastMod: &ts},
+				{URL: "https://gitea.io/test2", LastMod: nil},
+			},
+			want: xml.Header + `<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">` +
+				"<sitemap><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></sitemap>" +
+				"<sitemap><loc>https://gitea.io/test2</loc></sitemap>" +
+				"</sitemapindex>\n",
+		},
+		{
+			name:    "too many sitemaps",
+			urls:    make([]URL, 50001),
+			wantErr: "The sitemap contains 50001 sub-sitemaps, but only 50000 are allowed",
+		},
+		{
+			name: "too big file",
+			urls: []URL{
+				{URL: strings.Repeat("b", 50*1024*1024+1)},
+			},
+			wantErr: "The sitemap has 52428952 bytes, but only 52428800 are allowed",
 		},
-		"<url><loc>https://gitea.io/test1</loc><lastmod>2022-04-30T12:33:28Z</lastmod></url>"+
-			"<url><loc>https://gitea.io/test2</loc></url>",
-	)
-}
-
-func TestTooManyURLs(t *testing.T) {
-	s := NewSitemap()
-	for i := 0; i < 50001; i++ {
-		s.Add(URL{URL: fmt.Sprintf("https://gitea.io/test%d", i)})
 	}
-	buf := &bytes.Buffer{}
-	_, err := s.WriteTo(buf)
-	assert.EqualError(t, err, "The sitemap contains too many URLs: 50001")
-}
-
-func TestSitemapTooBig(t *testing.T) {
-	s := NewSitemap()
-	s.Add(URL{URL: strings.Repeat("b", sitemapFileLimit)})
-	buf := &bytes.Buffer{}
-	_, err := s.WriteTo(buf)
-	assert.EqualError(t, err, "The sitemap is too big: 52428931")
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := NewSitemapIndex()
+			for _, url := range tt.urls {
+				s.Add(url)
+			}
+			buf := &bytes.Buffer{}
+			_, err := s.WriteTo(buf)
+			if tt.wantErr != "" {
+				assert.EqualError(t, err, tt.wantErr)
+			} else {
+				assert.NoError(t, err)
+				assert.Equalf(t, tt.want, buf.String(), "NewSitemapIndex()")
+			}
+		})
+	}
 }