[PLT-7574] Update and Simplify Compatibility Check and Replace UA Dependency (#7427)

* Add fix to not run browser check on Mobile Browsers or the App

* remove non safari and IE checks

* Replace useragent checking dependency and update UA tests

* change some wording

* change dependancy again to one with compatible licence

* Fix typos and clarify wording

* fix typo and comvert tests to use array

2 files changed, 44 insertions, 12 deletions

diff --git a/web/web.go b/web/web.go
index e0edd1b7a..22fe43923 100644
--- a/web/web.go
+++ b/web/web.go
@@ -8,12 +8,12 @@ import (
 	"strings"
 
 	"github.com/NYTimes/gziphandler"
+	"github.com/avct/uasurfer"
 
 	l4g "github.com/alecthomas/log4go"
 	"github.com/mattermost/mattermost-server/api"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
-	"github.com/mssola/user_agent"
 )
 
 func Init(api3 *api.API) {
@@ -65,26 +65,27 @@ func pluginHandler(config model.ConfigFunc, handler http.Handler) http.Handler {
 	})
 }
 
-var browsersNotSupported string = "MSIE/8;MSIE/9;MSIE/10;Internet Explorer/8;Internet Explorer/9;Internet Explorer/10;Safari/7;Safari/8"
+// Due to the complexities of UA detection and the ramifications of a misdetection only older Safari and IE browsers throw incompatibility errors.
 
-func CheckBrowserCompatability(c *api.Context, r *http.Request) bool {
-	ua := user_agent.New(r.UserAgent())
-	bname, bversion := ua.Browser()
+// Map should be of minimum required browser version.
+var browserMinimumSupported = map[string]int{
+	"BrowserIE":     11,
+	"BrowserSafari": 9,
+}
 
-	browsers := strings.Split(browsersNotSupported, ";")
-	for _, browser := range browsers {
-		version := strings.Split(browser, "/")
+func CheckClientCompatability(agentString string) bool {
+	ua := uasurfer.Parse(agentString)
 
-		if strings.HasPrefix(bname, version[0]) && strings.HasPrefix(bversion, version[1]) {
-			return false
-		}
+	if version, exist := browserMinimumSupported[ua.Browser.Name.String()]; exist && ua.Browser.Version.Major < version {
+		return false
 	}
 
 	return true
 }
 
 func root(c *api.Context, w http.ResponseWriter, r *http.Request) {
-	if !CheckBrowserCompatability(c, r) {
+
+	if !CheckClientCompatability(r.UserAgent()) {
 		w.Header().Set("Cache-Control", "no-store")
 		page := utils.NewHTMLTemplate(c.App.HTMLTemplates(), "unsupported_browser")
 		page.Props["Title"] = c.T("web.error.unsupported_browser.title")
diff --git a/web/web_test.go b/web/web_test.go
index 373d47103..890b1ba58 100644
--- a/web/web_test.go
+++ b/web/web_test.go
@@ -166,4 +166,35 @@ func TestMain(m *testing.M) {
 	}()
 
 	status = m.Run()
+
+}
+
+func TestCheckClientCompatability(t *testing.T) {
+	//Browser Name, UA String, expected result (if the browser should fail the test false and if it should pass the true)
+	type uaTest struct {
+		Name      string // Name of Browser
+		UserAgent string // Useragent of Browser
+		Result    bool   // Expected result (true if browser should be compatible, false if browser shouldn't be compatible)
+	}
+	var uaTestParameters = []uaTest{
+		{"Mozilla 40.1", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1", true},
+		{"Chrome 60", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36", true},
+		{"Chrome Mobile", "Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Mobile Safari/537.36", true},
+		{"MM Classic App", "Mozilla/5.0 (Linux; Android 8.0.0; Nexus 5X Build/OPR6.170623.013; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/61.0.3163.81 Mobile Safari/537.36 Web-Atoms-Mobile-WebView", true},
+		{"MM App 3.7.1", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Mattermost/3.7.1 Chrome/56.0.2924.87 Electron/1.6.11 Safari/537.36", true},
+		{"Franz 4.0.4", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Franz/4.0.4 Chrome/52.0.2743.82 Electron/1.3.1 Safari/537.36", true},
+		{"Edge 14", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393", true},
+		{"Internet Explorer 11", "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko", true},
+		{"Internet Explorer 9", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 7.1; Trident/5.0", false},
+		{"Safari 9", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Safari/604.1.38", true},
+		{"Safari 8", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_4) AppleWebKit/600.7.12 (KHTML, like Gecko) Version/8.0.7 Safari/600.7.12", false},
+		{"Safari Mobile", "Mozilla/5.0 (iPhone; CPU iPhone OS 9_1 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13B137 Safari/601.1", true},
+	}
+	for _, browser := range uaTestParameters {
+		if result := CheckClientCompatability(browser.UserAgent); result == browser.Result {
+			t.Logf("Pass: %s passed browser test.", browser.Name)
+		} else {
+			t.Errorf("Fail: %s User Agent Test failed!", browser.Name)
+		}
+	}
 }