fix: data race with trustedCIDRs (#2674) (#2675)

Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

context_test.go

@@ -1388,10 +1388,14 @@ func TestContextAbortWithError(t *testing.T) {
 	assert.True(t, c.IsAborted())
 }
 
+func resetTrustedCIDRs(c *Context) {
+	c.engine.trustedCIDRs, _ = c.engine.prepareTrustedCIDRs()
+}
+
 func TestContextClientIP(t *testing.T) {
 	c, _ := CreateTestContext(httptest.NewRecorder())
 	c.Request, _ = http.NewRequest("POST", "/", nil)
-
+	resetTrustedCIDRs(c)
 	resetContextForClientIPTests(c)
 
 	// Legacy tests (validating that the defaults don't break the
@@ -1421,35 +1425,43 @@ func TestContextClientIP(t *testing.T) {
 
 	// No trusted proxies
 	c.engine.TrustedProxies = []string{}
+	resetTrustedCIDRs(c)
 	c.engine.RemoteIPHeaders = []string{"X-Forwarded-For"}
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
 	// Last proxy is trusted, but the RemoteAddr is not
 	c.engine.TrustedProxies = []string{"30.30.30.30"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
 	// Only trust RemoteAddr
 	c.engine.TrustedProxies = []string{"40.40.40.40"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "20.20.20.20", c.ClientIP())
 
 	// All steps are trusted
 	c.engine.TrustedProxies = []string{"40.40.40.40", "30.30.30.30", "20.20.20.20"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "20.20.20.20", c.ClientIP())
 
 	// Use CIDR
 	c.engine.TrustedProxies = []string{"40.40.25.25/16", "30.30.30.30"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "20.20.20.20", c.ClientIP())
 
 	// Use hostname that resolves to all the proxies
 	c.engine.TrustedProxies = []string{"foo"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
 	// Use hostname that returns an error
 	c.engine.TrustedProxies = []string{"bar"}
+	resetTrustedCIDRs(c)
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
 	// X-Forwarded-For has a non-IP element
 	c.engine.TrustedProxies = []string{"40.40.40.40"}
+	resetTrustedCIDRs(c)
 	c.Request.Header.Set("X-Forwarded-For", " blah ")
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
@@ -1457,10 +1469,12 @@ func TestContextClientIP(t *testing.T) {
 	// happen, but we should test it to make sure we handle it
 	// gracefully.
 	c.engine.TrustedProxies = []string{"baz"}
+	resetTrustedCIDRs(c)
 	c.Request.Header.Set("X-Forwarded-For", " 30.30.30.30 ")
 	assert.Equal(t, "40.40.40.40", c.ClientIP())
 
 	c.engine.TrustedProxies = []string{"40.40.40.40"}
+	resetTrustedCIDRs(c)
 	c.Request.Header.Del("X-Forwarded-For")
 	c.engine.RemoteIPHeaders = []string{"X-Forwarded-For", "X-Real-IP"}
 	assert.Equal(t, "10.10.10.10", c.ClientIP())