Merge pull request #46 from multiformats/feat/private-net

private networks and utility functions

private.go

+package manet
+
+import (
+	"net"
+
+	ma "github.com/multiformats/go-multiaddr"
+)
+
+// Private4 and Private6 are well-known private networks
+var Private4, Private6 []*net.IPNet
+var privateCIDR4 = []string{
+	// localhost
+	"127.0.0.0/8",
+	// private networks
+	"10.0.0.0/8",
+	"100.64.0.0/10",
+	"172.16.0.0/12",
+	"192.168.0.0/16",
+	// link local
+	"169.254.0.0/16",
+}
+var privateCIDR6 = []string{
+	// localhost
+	"::1/128",
+	// ULA reserved
+	"fc00::/7",
+	// link local
+	"fe80::/10",
+}
+
+// Unroutable4 and Unroutable6 are well known unroutable address ranges
+var Unroutable4, Unroutable6 []*net.IPNet
+var unroutableCIDR4 = []string{
+	"0.0.0.0/8",
+	"192.0.0.0/26",
+	"192.0.2.0/24",
+	"192.88.99.0/24",
+	"198.18.0.0/15",
+	"198.51.100.0/24",
+	"203.0.113.0/24",
+	"224.0.0.0/4",
+	"240.0.0.0/4",
+	"255.255.255.255/32",
+}
+var unroutableCIDR6 = []string{
+	"ff00::/8",
+}
+
+func init() {
+	Private4 = parseCIDR(privateCIDR4)
+	Private6 = parseCIDR(privateCIDR6)
+	Unroutable4 = parseCIDR(unroutableCIDR4)
+	Unroutable6 = parseCIDR(unroutableCIDR6)
+}
+
+func parseCIDR(cidrs []string) []*net.IPNet {
+	ipnets := make([]*net.IPNet, len(cidrs))
+	for i, cidr := range cidrs {
+		_, ipnet, err := net.ParseCIDR(cidr)
+		if err != nil {
+			panic(err)
+		}
+		ipnets[i] = ipnet
+	}
+	return ipnets
+}
+
+// IsPublicAddr retruns true if the IP part of the multiaddr is a publicly routable address
+func IsPublicAddr(a ma.Multiaddr) bool {
+	isPublic := false
+	ma.ForEach(a, func(c ma.Component) bool {
+		switch c.Protocol().Code {
+		case ma.P_IP6ZONE:
+			return true
+		default:
+			return false
+		case ma.P_IP4:
+			ip := net.IP(c.RawValue())
+			isPublic = !inAddrRange(ip, Private4) && !inAddrRange(ip, Unroutable4)
+		case ma.P_IP6:
+			ip := net.IP(c.RawValue())
+			isPublic = !inAddrRange(ip, Private6) && !inAddrRange(ip, Unroutable6)
+		}
+		return false
+	})
+	return isPublic
+}
+
+// IsPrivateAddr returns true if the IP part of the mutiaddr is in a private network
+func IsPrivateAddr(a ma.Multiaddr) bool {
+	isPrivate := false
+	ma.ForEach(a, func(c ma.Component) bool {
+		switch c.Protocol().Code {
+		case ma.P_IP6ZONE:
+			return true
+		default:
+			return false
+		case ma.P_IP4:
+			isPrivate = inAddrRange(net.IP(c.RawValue()), Private4)
+		case ma.P_IP6:
+			isPrivate = inAddrRange(net.IP(c.RawValue()), Private6)
+		}
+		return false
+	})
+	return isPrivate
+}
+
+func inAddrRange(ip net.IP, ipnets []*net.IPNet) bool {
+	for _, ipnet := range ipnets {
+		if ipnet.Contains(ip) {
+			return true
+		}
+	}
+
+	return false
+}

private_test.go

+package manet
+
+import (
+	"testing"
+
+	ma "github.com/multiformats/go-multiaddr"
+)
+
+func TestIsPublicAddr(t *testing.T) {
+	a, err := ma.NewMultiaddr("/ip4/192.168.1.1/tcp/80")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if IsPublicAddr(a) {
+		t.Fatal("192.168.1.1 is not a public address!")
+	}
+
+	if !IsPrivateAddr(a) {
+		t.Fatal("192.168.1.1 is a private address!")
+	}
+
+	a, err = ma.NewMultiaddr("/ip4/1.1.1.1/tcp/80")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !IsPublicAddr(a) {
+		t.Fatal("1.1.1.1 is a public address!")
+	}
+
+	if IsPrivateAddr(a) {
+		t.Fatal("1.1.1.1 is not a private address!")
+	}
+
+	a, err = ma.NewMultiaddr("/tcp/80/ip4/1.1.1.1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if IsPublicAddr(a) {
+		t.Fatal("shouldn't consider an address that starts with /tcp/ as *public*")
+	}
+
+	if IsPrivateAddr(a) {
+		t.Fatal("shouldn't consider an address that starts with /tcp/ as *private*")
+	}
+}