read original addr from x-forwarded-for header if present

common/protocol/http/headers.go

@@ -0,0 +1,21 @@
+package http
+
+import (
+	"net/http"
+	"strings"
+
+	"v2ray.com/core/common/net"
+)
+
+func ParseXForwardedFor(header http.Header) []net.Address {
+	xff := header.Get("X-Forwarded-For")
+	if len(xff) == 0 {
+		return nil
+	}
+	list := strings.Split(xff, ",")
+	addrs := make([]net.Address, 0, len(list))
+	for _, proxy := range list {
+		addrs = append(addrs, net.ParseAddress(proxy))
+	}
+	return addrs
+}

common/protocol/http/headers_test.go

@@ -0,0 +1,20 @@
+package http_test
+
+import (
+	"net/http"
+	"testing"
+
+	. "v2ray.com/core/common/protocol/http"
+	. "v2ray.com/ext/assert"
+)
+
+func TestParseXForwardedFor(t *testing.T) {
+	assert := With(t)
+
+	header := http.Header{}
+	header.Add("X-Forwarded-For", "129.78.138.66, 129.78.64.103")
+	addrs := ParseXForwardedFor(header)
+	assert(len(addrs), Equals, 2)
+	assert(addrs[0].String(), Equals, "129.78.138.66")
+	assert(addrs[1].String(), Equals, "129.78.64.103")
+}