Add rate limiter, rename maxConn into inFlightReq

Co-authored-by: Julien Salleyron <julien.salleyron@gmail.com>
Co-authored-by: Jean-Baptiste Doumenjou <jb.doumenjou@gmail.com>

pkg/middlewares/extractor.go

@@ -0,0 +1,49 @@
+package middlewares
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/containous/traefik/v2/pkg/config/dynamic"
+	"github.com/containous/traefik/v2/pkg/log"
+	"github.com/vulcand/oxy/utils"
+)
+
+// GetSourceExtractor returns the SourceExtractor function corresponding to the given sourceMatcher.
+// It defaults to a RemoteAddrStrategy IPStrategy if need be.
+func GetSourceExtractor(ctx context.Context, sourceMatcher *dynamic.SourceCriterion) (utils.SourceExtractor, error) {
+	if sourceMatcher == nil ||
+		sourceMatcher.IPStrategy == nil &&
+			sourceMatcher.RequestHeaderName == "" && !sourceMatcher.RequestHost {
+		sourceMatcher = &dynamic.SourceCriterion{
+			IPStrategy: &dynamic.IPStrategy{},
+		}
+	}
+
+	logger := log.FromContext(ctx)
+	if sourceMatcher.IPStrategy != nil {
+		strategy, err := sourceMatcher.IPStrategy.Get()
+		if err != nil {
+			return nil, err
+		}
+
+		logger.Debug("Using IPStrategy")
+		return utils.ExtractorFunc(func(req *http.Request) (string, int64, error) {
+			return strategy.GetIP(req), 1, nil
+		}), nil
+	}
+
+	if sourceMatcher.RequestHeaderName != "" {
+		logger.Debug("Using RequestHeaderName")
+		return utils.NewExtractor(fmt.Sprintf("request.header.%s", sourceMatcher.RequestHeaderName))
+	}
+
+	if sourceMatcher.RequestHost {
+		logger.Debug("Using RequestHost")
+		return utils.NewExtractor("request.host")
+	}
+
+	return nil, errors.New("no SourceCriterion criterion defined")
+}