useragent: include function for getting the real upstream requester

README.md

@@ -59,6 +59,18 @@ u := webtools.CreateURL("example.org", "/some/path", map[string]string {
 })
 ```
 
+There is also the `Origins` convenience function for parsing the user-agent
+of an `http.Request` and creating a struct of interesting values regarding the
+request.
+
+```go
+ua := webtools.Origins(r)
+
+fmt.Println(ua.String()) # e.g. curl/unknown
+fmt.Println(ua.Anchor()) # e.g. example.org/path/to/page
+fmt.Println(ua.From())   # e.g. 10.0.0.1
+```
+
 #### package webtools/middles
 
 Provides a generic sessions `http.Handler` which can be used to set and validate

useragent.go

@@ -17,9 +17,18 @@ type Origin struct {
 	UserAgent useragent.UserAgent
 }
 
-// From returns a parsed version of the Referer headers, including the domain
-// and path without the protocol or query.
+// From returns the value of the X-Forwarded-For if set, otherwise defaulting
+// to the Host header.
 func (o *Origin) From() string {
+	if o.Forward != "" {
+		return o.Forward
+	}
+	return o.Host
+}
+
+// Anchor returns a parsed version of the Referer headers, including the domain
+// and path without the protocol or query.
+func (o *Origin) Anchor() string {
 	if o.Reference == "" {
 		return "-"
 	}

useragent_test.go

@@ -12,6 +12,29 @@ import (
 func TestOrigin_From(t *testing.T) {
 	t.Parallel()
 
+	t.Run("forward set", func(t *testing.T) {
+		o := &Origin{
+			Host:    "10.0.0.1",
+			Forward: "example.com",
+		}
+
+		s := o.From()
+		must.Eq(t, "example.com", s)
+	})
+
+	t.Run("not set", func(t *testing.T) {
+		o := &Origin{
+			Host: "10.0.0.1",
+		}
+
+		s := o.From()
+		must.Eq(t, "10.0.0.1", s)
+	})
+}
+
+func TestOrigin_Anchor(t *testing.T) {
+	t.Parallel()
+
 	cases := []struct {
 		name      string
 		reference string
@@ -26,7 +49,7 @@ func TestOrigin_From(t *testing.T) {
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
 			o := &Origin{Reference: tc.reference}
-			must.Eq(t, tc.exp, o.From())
+			must.Eq(t, tc.exp, o.Anchor())
 		})
 	}
 }