Fix crash on ListPathRequest with malformed prefix

When ListPathRequest is done by a gRPC client including a malformed prefix,
 the server would crash an invalid memory address reference.

This commit fixes the crash by checking whether the parseCIDR method returned
an error.

pkg/packet/bgp/bgp.go

@@ -9604,26 +9604,30 @@ func GetRouteFamily(name string) (RouteFamily, error) {
 func NewPrefixFromRouteFamily(afi uint16, safi uint8, prefixStr ...string) (prefix AddrPrefixInterface, err error) {
 	family := AfiSafiToRouteFamily(afi, safi)
 
-	f := func(s string) AddrPrefixInterface {
-		addr, net, _ := net.ParseCIDR(s)
+	f := func(s string) (AddrPrefixInterface, error) {
+		addr, net, err := net.ParseCIDR(s)
+		if err != nil {
+			fmt.Printf("Invalid CIDR: %v", s)
+			return nil, err
+		}
 		len, _ := net.Mask.Size()
 		switch family {
 		case RF_IPv4_UC, RF_IPv4_MC:
-			return NewIPAddrPrefix(uint8(len), addr.String())
+			return NewIPAddrPrefix(uint8(len), addr.String()), nil
 		}
-		return NewIPv6AddrPrefix(uint8(len), addr.String())
+		return NewIPv6AddrPrefix(uint8(len), addr.String()), nil
 	}
 
 	switch family {
 	case RF_IPv4_UC, RF_IPv4_MC:
 		if len(prefixStr) > 0 {
-			prefix = f(prefixStr[0])
+			prefix, err = f(prefixStr[0])
 		} else {
 			prefix = NewIPAddrPrefix(0, "")
 		}
 	case RF_IPv6_UC, RF_IPv6_MC:
 		if len(prefixStr) > 0 {
-			prefix = f(prefixStr[0])
+			prefix, err = f(prefixStr[0])
 		} else {
 			prefix = NewIPv6AddrPrefix(0, "")
 		}

pkg/packet/bgp/bgp_test.go

@@ -88,6 +88,33 @@ func Test_IPAddrPrefixString(t *testing.T) {
 	assert.Equal(t, "3343:faba:3903:128::/63", ipv6.String())
 }
 
+func Test_MalformedPrefixLookup(t *testing.T) {
+	assert := assert.New(t)
+
+	var tests = []struct {
+		inPrefix    string
+		routeFamily RouteFamily
+		want        AddrPrefixInterface
+		err         bool
+	}{
+		{"129.6.128/22", RF_IPv4_UC, nil, true},
+		{"foo", RF_IPv4_UC, nil, true},
+		{"3343:faba:3903:128::::/63", RF_IPv6_UC, nil, true},
+		{"foo", RF_IPv6_UC, nil, true},
+	}
+
+	for _, test := range tests {
+		afi, safi := RouteFamilyToAfiSafi(RF_IPv4_UC)
+		p, err := NewPrefixFromRouteFamily(afi, safi, test.inPrefix)
+		if test.err {
+			assert.Error(err)
+		} else {
+			assert.Equal(test.want, p)
+		}
+	}
+
+}
+
 func Test_IPAddrDecode(t *testing.T) {
 	r := IPAddrPrefixDefault{}
 	b := make([]byte, 16)