add remote proto mechanism

context.go

@@ -814,6 +814,30 @@ func (c *Context) RemoteIP() string {
 	return ip
 }
 
+func (c *Context) ClientProto() string {
+	var isTls = c.Request.TLS != nil
+	remoteIP := net.ParseIP(c.RemoteIP())
+	if remoteIP == nil {
+		return ""
+	}
+	trusted := c.engine.isTrustedProxy(remoteIP)
+
+	if trusted && c.engine.ForwardedByClientProto && c.engine.RemoteProtoHeaders != nil {
+		for _, headerName := range c.engine.RemoteProtoHeaders {
+			proto, valid := c.engine.validateHeader(c.requestHeader(headerName))
+			if valid {
+				return proto
+			}
+		}
+	}
+
+	if isTls {
+		return "https"
+	} else {
+		return "http"
+	}
+}
+
 // ContentType returns the Content-Type header of the request.
 func (c *Context) ContentType() string {
 	return filterFlags(c.requestHeader("Content-Type"))

gin.go

@@ -112,6 +112,8 @@ type Engine struct {
 	// `(*gin.Context).Request.RemoteAddr`.
 	ForwardedByClientIP bool
 
+	ForwardedByClientProto bool
+
 	// AppEngine was deprecated.
 	// Deprecated: USE `TrustedPlatform` WITH VALUE `gin.PlatformGoogleAppEngine` INSTEAD
 	// #726 #755 If enabled, it will trust some headers starting with
@@ -136,6 +138,8 @@ type Engine struct {
 	// network origins of list defined by `(*gin.Engine).SetTrustedProxies()`.
 	RemoteIPHeaders []string
 
+	RemoteProtoHeaders []string
+
 	// TrustedPlatform if set to a constant of value gin.Platform*, trusts the headers set by
 	// that platform, for example to determine the client IP
 	TrustedPlatform string
@@ -189,7 +193,9 @@ func New() *Engine {
 		RedirectFixedPath:      false,
 		HandleMethodNotAllowed: false,
 		ForwardedByClientIP:    true,
+		ForwardedByClientProto: true,
 		RemoteIPHeaders:        []string{"X-Forwarded-For", "X-Real-IP"},
+		RemoteProtoHeaders:     []string{"X-Forwarded-Proto"},
 		TrustedPlatform:        defaultPlatform,
 		UseRawPath:             false,
 		RemoveExtraSlash:       false,