2 files changed, 43 insertions, 1 deletions
diff --git a/app/post.go b/app/post.go
index 41139da63..bc31aee44 100644
--- a/app/post.go
+++ b/app/post.go
@@ -9,6 +9,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 	"regexp"
@@ -19,6 +20,7 @@ import (
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/store"
 	"github.com/mattermost/mattermost-server/utils"
+	"golang.org/x/net/html/charset"
 )
 
 var linkWithTextRegex = regexp.MustCompile(`<([^<\|]+)\|([^>]+)>`)
@@ -726,7 +728,10 @@ func (a *App) GetOpenGraphMetadata(requestURL string) *opengraph.OpenGraph {
 	}
 	defer consumeAndClose(res)
 
-	if err := og.ProcessHTML(res.Body); err != nil {
+	contentType := res.Header.Get("Content-Type")
+	body := forceHTMLEncodingToUTF8(res.Body, contentType)
+
+	if err := og.ProcessHTML(body); err != nil {
 		mlog.Error(fmt.Sprintf("GetOpenGraphMetadata processing failed for url=%v with err=%v", requestURL, err.Error()))
 	}
 
@@ -735,6 +740,15 @@ func (a *App) GetOpenGraphMetadata(requestURL string) *opengraph.OpenGraph {
 	return og
 }
 
+func forceHTMLEncodingToUTF8(body io.Reader, contentType string) io.Reader {
+	r, err := charset.NewReader(body, contentType)
+	if err != nil {
+		mlog.Error(fmt.Sprintf("forceHTMLEncodingToUTF8 failed to convert for contentType=%v with err=%v", contentType, err.Error()))
+		return body
+	}
+	return r
+}
+
 func makeOpenGraphURLsAbsolute(og *opengraph.OpenGraph, requestURL string) {
 	parsedRequestURL, err := url.Parse(requestURL)
 	if err != nil {
diff --git a/app/post_test.go b/app/post_test.go
index 10b957751..aefc0ea35 100644
--- a/app/post_test.go
+++ b/app/post_test.go
@@ -297,6 +297,34 @@ func TestImageProxy(t *testing.T) {
 	}
 }
 
+func BenchmarkForceHTMLEncodingToUTF8(b *testing.B) {
+	HTML := `
+		<html>
+			<head>
+				<meta property="og:url" content="https://example.com/apps/mattermost">
+				<meta property="og:image" content="https://images.example.com/image.png">
+			</head>
+		</html>
+	`
+	ContentType := "text/html; utf-8"
+
+	b.Run("with converting", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			r := forceHTMLEncodingToUTF8(strings.NewReader(HTML), ContentType)
+
+			og := opengraph.NewOpenGraph()
+			og.ProcessHTML(r)
+		}
+	})
+
+	b.Run("without converting", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			og := opengraph.NewOpenGraph()
+			og.ProcessHTML(strings.NewReader(HTML))
+		}
+	})
+}
+
 func TestMakeOpenGraphURLsAbsolute(t *testing.T) {
 	for name, tc := range map[string]struct {
 		HTML       string