Use CNAME for SNI check on host header

Co-authored-by: Julien Salleyron <julien.salleyron@gmail.com>

pkg/middlewares/snicheck/snicheck_test.go

@@ -0,0 +1,60 @@
+package snicheck
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSNICheck_ServeHTTP(t *testing.T) {
+	testCases := []struct {
+		desc              string
+		tlsOptionsForHost map[string]string
+		host              string
+		expected          int
+	}{
+		{
+			desc:     "no TLS options",
+			expected: http.StatusOK,
+		},
+		{
+			desc: "with TLS options",
+			tlsOptionsForHost: map[string]string{
+				"example.com": "foo",
+			},
+			expected: http.StatusOK,
+		},
+		{
+			desc: "server name and host doesn't have the same TLS configuration",
+			tlsOptionsForHost: map[string]string{
+				"example.com": "foo",
+			},
+			host:     "example.com",
+			expected: http.StatusMisdirectedRequest,
+		},
+	}
+
+	for _, test := range testCases {
+		test := test
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			next := http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {})
+
+			sniCheck := New(test.tlsOptionsForHost, next)
+
+			req := httptest.NewRequest(http.MethodGet, "https://localhost", nil)
+			if test.host != "" {
+				req.Host = test.host
+			}
+
+			recorder := httptest.NewRecorder()
+
+			sniCheck.ServeHTTP(recorder, req)
+
+			assert.Equal(t, test.expected, recorder.Code)
+		})
+	}
+}