add ipcidr support (#177)

* Add support for ipcidr protocol

* Move test

* Fix gocheck

* PR comments

* Check byte slice len

multiaddr_test.go

@@ -27,6 +27,8 @@ func TestConstructFails(t *testing.T) {
 		"/ip4",
 		"/ip4/::1",
 		"/ip4/fdpsofodsajfdoisa",
+		"/ip4/::/ipcidr/256",
+		"/ip6/::/ipcidr/1026",
 		"/ip6",
 		"/ip6zone",
 		"/ip6zone/",
@@ -101,9 +103,11 @@ func TestConstructSucceeds(t *testing.T) {
 	cases := []string{
 		"/ip4/1.2.3.4",
 		"/ip4/0.0.0.0",
+		"/ip4/192.0.2.0/ipcidr/24",
 		"/ip6/::1",
 		"/ip6/2601:9:4f81:9700:803e:ca65:66e8:c21",
 		"/ip6/2601:9:4f81:9700:803e:ca65:66e8:c21/udp/1234/quic",
+		"/ip6/2001:db8::/ipcidr/32",
 		"/ip6zone/x/ip6/fe80::1",
 		"/ip6zone/x%y/ip6/fe80::1",
 		"/ip6zone/x%y/ip6/::",

net/convert.go

 package manet
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"path/filepath"
@@ -51,6 +52,33 @@ func (cm *CodecMap) ToNetAddr(maddr ma.Multiaddr) (net.Addr, error) {
 	return p(maddr)
 }
 
+// MultiaddrToIPNet converts a multiaddr to an IPNet. Useful for seeing if another IP address is contained within this multiaddr network+mask
+func MultiaddrToIPNet(m ma.Multiaddr) (*net.IPNet, error) {
+	var ipString string
+	var mask string
+
+	ma.ForEach(m, func(c ma.Component) bool {
+		if c.Protocol().Code == ma.P_IP4 || c.Protocol().Code == ma.P_IP6 {
+			ipString = c.Value()
+		}
+		if c.Protocol().Code == ma.P_IPCIDR {
+			mask = c.Value()
+		}
+		return ipString == "" || mask == ""
+	})
+
+	if ipString == "" {
+		return nil, errors.New("no ip protocol found")
+	}
+
+	if mask == "" {
+		return nil, errors.New("no mask found")
+	}
+
+	_, ipnet, err := net.ParseCIDR(ipString + "/" + string(mask))
+	return ipnet, err
+}
+
 func parseBasicNetMaddr(maddr ma.Multiaddr) (net.Addr, error) {
 	network, host, err := DialArgs(maddr)
 	if err != nil {

net/convert_test.go

@@ -202,3 +202,65 @@ func TestDialArgs(t *testing.T) {
 	test("/dns6/abc.com/udp/1234", "udp6", "abc.com:1234")          // DNS6:port
 	test("/dns6/abc.com", "ip6", "abc.com")                         // Just DNS6
 }
+
+func TestMultiaddrToIPNet(t *testing.T) {
+	type testCase struct {
+		name      string
+		ma        string
+		ips       []string
+		contained []bool
+	}
+
+	testCases := []testCase{
+		{
+			name:      "basic",
+			ma:        "/ip4/1.2.3.0/ipcidr/24",
+			ips:       []string{"1.2.3.4", "1.2.3.9", "2.1.1.1"},
+			contained: []bool{true, true, false},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			ma := ma.StringCast(tc.ma)
+
+			ipnet, err := MultiaddrToIPNet(ma)
+			if err != nil {
+				t.Fatalf("failed to parse multiaddr %v into ipnet", ma)
+			}
+			for i, ipString := range tc.ips {
+				ip := net.ParseIP(ipString)
+				if ip == nil {
+					t.Fatalf("failed to parse IP %s", ipString)
+				}
+				if ipnet.Contains(ip) != tc.contained[i] {
+					t.Fatalf("Contains check failed. Expected %v got %v", tc.contained[i], ipnet.Contains(ip))
+				}
+			}
+		})
+	}
+}
+
+func TestFailMultiaddrToIPNet(t *testing.T) {
+	type testCase struct {
+		name string
+		ma   string
+	}
+
+	testCases := []testCase{
+		{name: "missing ip addr", ma: "/ipcidr/24"},
+		{name: "wrong mask", ma: "/ip4/1.2.3.0/ipcidr/128"},
+		{name: "wrong mask", ma: "/ip6/::/ipcidr/255"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			ma := ma.StringCast(tc.ma)
+
+			_, err := MultiaddrToIPNet(ma)
+			if err == nil {
+				t.Fatalf("Expected error when parsing: %s", tc.ma)
+			}
+		})
+	}
+}

protocols.go

@@ -13,6 +13,7 @@ const (
 	P_DCCP              = 0x0021
 	P_IP6               = 0x0029
 	P_IP6ZONE           = 0x002A
+	P_IPCIDR            = 0x002B
 	P_QUIC              = 0x01CC
 	P_SCTP              = 0x0084
 	P_CIRCUIT           = 0x0122
@@ -103,6 +104,13 @@ var (
 		Size:       128,
 		Transcoder: TranscoderIP6,
 	}
+	protoIPCIDR = Protocol{
+		Name:       "ipcidr",
+		Code:       P_IPCIDR,
+		VCode:      CodeToVarint(P_IPCIDR),
+		Size:       8,
+		Transcoder: TranscoderIPCIDR,
+	}
 	// these require varint
 	protoIP6ZONE = Protocol{
 		Name:       "ip6zone",
@@ -239,6 +247,7 @@ func init() {
 		protoDCCP,
 		protoIP6,
 		protoIP6ZONE,
+		protoIPCIDR,
 		protoSCTP,
 		protoCIRCUIT,
 		protoONION2,

transcoders.go

@@ -54,6 +54,22 @@ func (t twrp) ValidateBytes(b []byte) error {
 var TranscoderIP4 = NewTranscoderFromFunctions(ip4StB, ip4BtS, nil)
 var TranscoderIP6 = NewTranscoderFromFunctions(ip6StB, ip6BtS, nil)
 var TranscoderIP6Zone = NewTranscoderFromFunctions(ip6zoneStB, ip6zoneBtS, ip6zoneVal)
+var TranscoderIPCIDR = NewTranscoderFromFunctions(ipcidrStB, ipcidrBtS, nil)
+
+func ipcidrBtS(b []byte) (string, error) {
+	if len(b) != 1 {
+		return "", fmt.Errorf("invalid length (should be == 1)")
+	}
+	return strconv.Itoa(int(b[0])), nil
+}
+
+func ipcidrStB(s string) ([]byte, error) {
+	ipMask, err := strconv.ParseUint(s, 10, 8)
+	if err != nil {
+		return nil, err
+	}
+	return []byte{byte(uint8(ipMask))}, nil
+}
 
 func ip4StB(s string) ([]byte, error) {
 	i := net.ParseIP(s).To4()