Move code to pkg

pkg/ip/strategy.go

@@ -0,0 +1,63 @@
+package ip
+
+import (
+	"net/http"
+	"strings"
+)
+
+const (
+	xForwardedFor = "X-Forwarded-For"
+)
+
+// Strategy a strategy for IP selection
+type Strategy interface {
+	GetIP(req *http.Request) string
+}
+
+// RemoteAddrStrategy a strategy that always return the remote address
+type RemoteAddrStrategy struct{}
+
+// GetIP return the selected IP
+func (s *RemoteAddrStrategy) GetIP(req *http.Request) string {
+	return req.RemoteAddr
+}
+
+// DepthStrategy a strategy based on the depth inside the X-Forwarded-For from right to left
+type DepthStrategy struct {
+	Depth int
+}
+
+// GetIP return the selected IP
+func (s *DepthStrategy) GetIP(req *http.Request) string {
+	xff := req.Header.Get(xForwardedFor)
+	xffs := strings.Split(xff, ",")
+
+	if len(xffs) < s.Depth {
+		return ""
+	}
+	return strings.TrimSpace(xffs[len(xffs)-s.Depth])
+}
+
+// CheckerStrategy a strategy based on an IP Checker
+// allows to check that addresses are in a trusted IPs
+type CheckerStrategy struct {
+	Checker *Checker
+}
+
+// GetIP return the selected IP
+func (s *CheckerStrategy) GetIP(req *http.Request) string {
+	if s.Checker == nil {
+		return ""
+	}
+
+	xff := req.Header.Get(xForwardedFor)
+	xffs := strings.Split(xff, ",")
+
+	for i := len(xffs) - 1; i >= 0; i-- {
+		xffTrimmed := strings.TrimSpace(xffs[i])
+		if contain, _ := s.Checker.Contains(xffTrimmed); !contain {
+			return xffTrimmed
+		}
+	}
+	return ""
+}