Setting trusted platform using an enum-like (#2739)

context_appengine.go

@@ -8,5 +8,5 @@
 package gin
 
 func init() {
-	defaultAppEngine = true
+	defaultPlatform = PlatformGoogleAppEngine
 }

context_test.go

@@ -1406,7 +1406,7 @@ func TestContextClientIP(t *testing.T) {
 
 	c.Request.Header.Del("X-Forwarded-For")
 	c.Request.Header.Del("X-Real-IP")
-	c.engine.AppEngine = true
+	c.engine.TrustedPlatform = PlatformGoogleAppEngine
 	assert.Equal(t, "50.50.50.50", c.ClientIP())
 
 	c.Request.Header.Del("X-Appengine-Remote-Addr")
@@ -1470,8 +1470,15 @@ func TestContextClientIP(t *testing.T) {
 	assert.Equal(t, "10.10.10.10", c.ClientIP())
 
 	c.engine.RemoteIPHeaders = []string{}
+	c.engine.TrustedPlatform = PlatformGoogleAppEngine
+	assert.Equal(t, "50.50.50.50", c.ClientIP())
+
+	// Test the legacy flag
+	c.engine.TrustedPlatform = ""
 	c.engine.AppEngine = true
 	assert.Equal(t, "50.50.50.50", c.ClientIP())
+	c.engine.AppEngine = false
+	c.engine.TrustedPlatform = PlatformGoogleAppEngine
 
 	c.Request.Header.Del("X-Appengine-Remote-Addr")
 	assert.Equal(t, "40.40.40.40", c.ClientIP())

gin.go

@@ -55,6 +55,16 @@ type RouteInfo struct {
 // RoutesInfo defines a RouteInfo array.
 type RoutesInfo []RouteInfo
 
+// Trusted platforms
+const (
+	// When running on Google App Engine. Trust X-Appengine-Remote-Addr
+	// for determining the client's IP
+	PlatformGoogleAppEngine = "google-app-engine"
+	// When using Cloudflare's CDN. Trust CF-Connecting-IP for determining
+	// the client's IP
+	PlatformCloudflare = "cloudflare"
+)
+
 // Engine is the framework's instance, it contains the muxer, middleware and configuration settings.
 // Create an instance of Engine, by using New() or Default()
 type Engine struct {