improve remote addr parsing as requested at: https://github.com/kataras/iris/issues/1453

Former-commit-id: e5fde988eda9bf582b04285a1c77ba123910a699

core/netutil/ip.go

@@ -0,0 +1,59 @@
+package netutil
+
+import (
+	"bytes"
+	"net"
+	"strings"
+)
+
+/* Based on:
+https://husobee.github.io/golang/ip-address/2015/12/17/remote-ip-go.html requested at:
+https://github.com/kataras/iris/issues/1453
+*/
+
+//IPRange is a structure that holds the start and end of a range of IP Addresses.
+type IPRange struct {
+	Start net.IP `json:"start" yaml:"Start" toml"Start"`
+	End   net.IP `json:"end" yaml:"End" toml"End"`
+}
+
+// IPInRange reports whether a given IP Address is within a range given.
+func IPInRange(r IPRange, ipAddress net.IP) bool {
+	return bytes.Compare(ipAddress, r.Start) >= 0 && bytes.Compare(ipAddress, r.End) < 0
+}
+
+// IPIsPrivateSubnet reports whether this "ipAddress" is in a private subnet.
+func IPIsPrivateSubnet(ipAddress net.IP, privateRanges []IPRange) bool {
+	// IPv4 for now.
+	if ipCheck := ipAddress.To4(); ipCheck != nil {
+		// iterate over all our ranges.
+		for _, r := range privateRanges {
+			// check if this ip is in a private range.
+			if IPInRange(r, ipAddress) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// GetIPAddress returns a valid public IP Address from a collection of IP Addresses
+// and a range of private subnets.
+//
+// Reports whether a valid IP was found.
+func GetIPAddress(ipAddresses []string, privateRanges []IPRange) (string, bool) {
+	// march from right to left until we get a public address
+	// that will be the address right before our proxy.
+	for i := len(ipAddresses) - 1; i >= 0; i-- {
+		ip := strings.TrimSpace(ipAddresses[i])
+		realIP := net.ParseIP(ip)
+		if !realIP.IsGlobalUnicast() || IPIsPrivateSubnet(realIP, privateRanges) {
+			// bad address, go to next
+			continue
+		}
+		return ip, true
+
+	}
+
+	return "", false
+}

core/netutil/ip_test.go

@@ -0,0 +1,62 @@
+package netutil
+
+import (
+	"net"
+	"testing"
+)
+
+func TestIP(t *testing.T) {
+	privateRanges := []IPRange{
+		{
+			Start: net.ParseIP("10.0.0.0"),
+			End:   net.ParseIP("10.255.255.255"),
+		},
+		{
+			Start: net.ParseIP("100.64.0.0"),
+			End:   net.ParseIP("100.127.255.255"),
+		},
+		{
+			Start: net.ParseIP("172.16.0.0"),
+			End:   net.ParseIP("172.31.255.255"),
+		},
+		{
+			Start: net.ParseIP("192.0.0.0"),
+			End:   net.ParseIP("192.0.0.255"),
+		},
+		{
+			Start: net.ParseIP("192.168.0.0"),
+			End:   net.ParseIP("192.168.255.255"),
+		},
+		{
+			Start: net.ParseIP("198.18.0.0"),
+			End:   net.ParseIP("198.19.255.255"),
+		},
+	}
+
+	addresses := []string{
+		"201.37.138.59",
+		"159.117.3.153",
+		"166.192.97.84",
+		"225.181.213.210",
+		"124.50.84.134",
+		"87.53.250.102",
+		"106.79.33.62",
+		"242.120.17.144",
+		"131.179.101.254",
+		"103.11.11.174",
+		"115.97.0.114",
+		"219.202.120.251",
+		"37.72.123.120",
+		"154.94.78.101",
+		"126.105.144.250",
+	}
+
+	got, ok := GetIPAddress(addresses, privateRanges)
+	if !ok {
+		t.Logf("expected addr to be matched")
+	}
+
+	if expected := "126.105.144.250"; expected != got {
+		t.Logf("expected addr to be found: %s but got: %s", expected, got)
+	}
+}