Handle incoming proxy requests ip, scheme (#5591)

This PR implements functions to get the right ip, scheme
from the incoming proxied requests.

cmd/auth-handler.go

@@ -22,6 +22,8 @@ import (
 	"io/ioutil"
 	"net/http"
 	"strings"
+
+	"github.com/minio/minio/pkg/handlers"
 )
 
 // Verify if request has JWT.
@@ -136,13 +138,12 @@ func checkRequestAuthType(r *http.Request, bucket, policyAction, region string)
 
 	if reqAuthType == authTypeAnonymous && policyAction != "" {
 		// http://docs.aws.amazon.com/AmazonS3/latest/dev/using-with-s3-actions.html
-		sourceIP := getSourceIPAddress(r)
 		resource, err := getResource(r.URL.Path, r.Host, globalDomainName)
 		if err != nil {
 			return ErrInternalError
 		}
 		return enforceBucketPolicy(bucket, policyAction, resource,
-			r.Referer(), sourceIP, r.URL.Query())
+			r.Referer(), handlers.GetSourceIP(r), r.URL.Query())
 	}
 
 	// By default return ErrAccessDenied