Add p2c load-balancing strategy for servers load-balancer

Co-authored-by: Ian Ross <ifross@gmail.com>
Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

pkg/server/service/loadbalancer/sticky_test.go

@@ -0,0 +1,138 @@
+package loadbalancer
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/traefik/traefik/v3/pkg/config/dynamic"
+)
+
+func pointer[T any](v T) *T { return &v }
+
+func TestSticky_StickyHandler(t *testing.T) {
+	testCases := []struct {
+		desc        string
+		handlers    []string
+		cookies     []*http.Cookie
+		wantHandler string
+		wantRewrite bool
+	}{
+		{
+			desc:        "No previous cookie",
+			handlers:    []string{"first"},
+			wantHandler: "",
+			wantRewrite: false,
+		},
+		{
+			desc:     "Wrong previous cookie",
+			handlers: []string{"first"},
+			cookies: []*http.Cookie{
+				{Name: "test", Value: sha256Hash("foo")},
+			},
+			wantHandler: "",
+			wantRewrite: false,
+		},
+		{
+			desc:     "Sha256 previous cookie",
+			handlers: []string{"first", "second"},
+			cookies: []*http.Cookie{
+				{Name: "test", Value: sha256Hash("first")},
+			},
+			wantHandler: "first",
+			wantRewrite: false,
+		},
+		{
+			desc:     "Raw previous cookie",
+			handlers: []string{"first", "second"},
+			cookies: []*http.Cookie{
+				{Name: "test", Value: "first"},
+			},
+			wantHandler: "first",
+			wantRewrite: true,
+		},
+		{
+			desc:     "Fnv previous cookie",
+			handlers: []string{"first", "second"},
+			cookies: []*http.Cookie{
+				{Name: "test", Value: fnvHash("first")},
+			},
+			wantHandler: "first",
+			wantRewrite: true,
+		},
+		{
+			desc:     "Double fnv previous cookie",
+			handlers: []string{"first", "second"},
+			cookies: []*http.Cookie{
+				{Name: "test", Value: fnvHash("first")},
+			},
+			wantHandler: "first",
+			wantRewrite: true,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			sticky := NewSticky(dynamic.Cookie{Name: "test"})
+
+			for _, handler := range test.handlers {
+				sticky.AddHandler(handler, http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {}))
+			}
+
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			for _, cookie := range test.cookies {
+				req.AddCookie(cookie)
+			}
+
+			h, rewrite, err := sticky.StickyHandler(req)
+			require.NoError(t, err)
+
+			if test.wantHandler != "" {
+				assert.NotNil(t, h)
+				assert.Equal(t, test.wantHandler, h.Name)
+			} else {
+				assert.Nil(t, h)
+			}
+			assert.Equal(t, test.wantRewrite, rewrite)
+		})
+	}
+}
+
+func TestSticky_WriteStickyCookie(t *testing.T) {
+	sticky := NewSticky(dynamic.Cookie{
+		Name:     "test",
+		Secure:   true,
+		HTTPOnly: true,
+		SameSite: "none",
+		MaxAge:   42,
+		Path:     pointer("/foo"),
+		Domain:   "foo.com",
+	})
+
+	// Should return an error if the handler does not exist.
+	res := httptest.NewRecorder()
+	require.Error(t, sticky.WriteStickyCookie(res, "first"))
+
+	// Should write the sticky cookie and use the sha256 hash.
+	sticky.AddHandler("first", http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {}))
+
+	res = httptest.NewRecorder()
+	require.NoError(t, sticky.WriteStickyCookie(res, "first"))
+
+	assert.Len(t, res.Result().Cookies(), 1)
+
+	cookie := res.Result().Cookies()[0]
+
+	assert.Equal(t, sha256Hash("first"), cookie.Value)
+	assert.Equal(t, "test", cookie.Name)
+	assert.True(t, cookie.Secure)
+	assert.True(t, cookie.HttpOnly)
+	assert.Equal(t, http.SameSiteNoneMode, cookie.SameSite)
+	assert.Equal(t, 42, cookie.MaxAge)
+	assert.Equal(t, "/foo", cookie.Path)
+	assert.Equal(t, "foo.com", cookie.Domain)
+}