Fix http.Cookie SameSite is not copied. (#450)

* fix: http.Cookie SameSite is not copied.

* Update CHANGELOG.md

CHANGELOG.md

@@ -9,6 +9,7 @@
 
 ## Changes since v5.0.0
 
+- [#450](https://github.com/pusher/oauth2_proxy/pull/450) Fix http.Cookie SameSite is not copied (@johejo)
 - [#445](https://github.com/pusher/oauth2_proxy/pull/445) Expose `acr_values` to all providers (@holyjak)
 - [#419](https://github.com/pusher/oauth2_proxy/pull/419) Support Go 1.14, upgrade dependencies, upgrade golangci-lint to 1.23.6 (@johejo)
 - [#444](https://github.com/pusher/oauth2_proxy/pull/444) Support prompt in addition to approval-prompt (@holyjak)

pkg/sessions/cookie/session_store.go

@@ -207,5 +207,6 @@ func copyCookie(c *http.Cookie) *http.Cookie {
 		HttpOnly:   c.HttpOnly,
 		Raw:        c.Raw,
 		Unparsed:   c.Unparsed,
+		SameSite:   c.SameSite,
 	}
 }

pkg/sessions/cookie/session_store_test.go

@@ -0,0 +1,30 @@
+package cookie
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_copyCookie(t *testing.T) {
+	expire, _ := time.Parse(time.RFC3339, "2020-03-17T00:00:00Z")
+	c := &http.Cookie{
+		Name:       "name",
+		Value:      "value",
+		Path:       "/path",
+		Domain:     "x.y.z",
+		Expires:    expire,
+		RawExpires: "rawExpire",
+		MaxAge:     1,
+		Secure:     true,
+		HttpOnly:   true,
+		Raw:        "raw",
+		Unparsed:   []string{"unparsed"},
+		SameSite:   http.SameSiteLaxMode,
+	}
+
+	got := copyCookie(c)
+	assert.Equal(t, c, got)
+}