Add cidr groups support (#1341)

Signed-off-by: Artem Glazychev <artem.glazychev@xored.com>

Signed-off-by: Artem Glazychev <artem.glazychev@xored.com>

pkg/tools/cidr/group.go

@@ -0,0 +1,120 @@
+// Copyright (c) 2022 Cisco and/or its affiliates.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cidr
+
+import (
+	"net"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// Groups allows parsing cidr groups.
+// Example: [v1, v2, v3], [v4], v5 =>
+//  [][]*net.IPNet{
+//		{v1, v2, v3},
+//		{v4},
+//		{v5},
+//	}
+// Can be used for env configuration.
+// See at https://github.com/kelseyhightower/envconfig#custom-decoders
+type Groups [][]*net.IPNet
+
+const (
+	// inside - means that we are inside a group
+	inside int = iota
+
+	// outside - means that we are outside a group
+	outside
+)
+
+// Decode parses values from passed string.
+func (g *Groups) Decode(value string) error {
+	value = strings.ReplaceAll(value, " ", "")
+	if value == "" {
+		return nil
+	}
+	if err := validateParentheses(value); err != nil {
+		return err
+	}
+
+	list := strings.Split(value, ",")
+	var groups [][]*net.IPNet
+
+	state := outside
+
+	for _, item := range list {
+		if state == outside {
+			groups = append(groups, []*net.IPNet{})
+		}
+		toAdd := strings.Trim(item, "[]")
+		if toAdd == "" {
+			return errors.New("empty value")
+		}
+		_, ipNet, parseErr := net.ParseCIDR(strings.TrimSpace(toAdd))
+		if parseErr != nil {
+			return errors.Errorf("сould not parse CIDR %s; %+v", item, parseErr)
+		}
+
+		groups[len(groups)-1] = append(groups[len(groups)-1], ipNet)
+
+		if strings.HasSuffix(item, "]") {
+			state = outside
+		} else if strings.HasPrefix(item, "[") {
+			state = inside
+		}
+	}
+	*g = groups
+	return nil
+}
+
+func validateParentheses(value string) error {
+	i := 0
+	length := len(value)
+	if length < 2 {
+		return errors.New("value is too short")
+	}
+
+	parenthesesCounter := 0
+	for ; i < length; i++ {
+		if value[i] == '[' {
+			if parenthesesCounter == 1 {
+				return errors.Errorf("unexpected character: %c", value[i])
+			}
+			parenthesesCounter++
+		} else if value[i] == ']' {
+			if parenthesesCounter == 0 {
+				return errors.Errorf("unexpected character: %c", value[i])
+			}
+			if i+1 == length {
+				return nil
+			}
+			if i+2 == length {
+				return errors.New("unexpected end of value")
+			}
+			if value[i+1] != ',' {
+				return errors.Errorf("unexpected character: %c", value[i+1])
+			}
+			parenthesesCounter--
+		}
+	}
+
+	if parenthesesCounter != 0 {
+		return errors.New("parenteses are not balanced")
+	}
+	return nil
+}

pkg/tools/cidr/group_test.go

@@ -0,0 +1,84 @@
+// Copyright (c) 2022 Cisco and/or its affiliates.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cidr_test
+
+import (
+	"fmt"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/networkservicemesh/sdk/pkg/tools/cidr"
+)
+
+func Test_CidrGroupsDecoder_EmptyInput(t *testing.T) {
+	var expected [][]*net.IPNet
+	var groups cidr.Groups
+	err := groups.Decode(``)
+	require.NoError(t, err)
+	require.Equal(t, expected, [][]*net.IPNet(groups))
+}
+
+func Test_CidrGroupsDecoder_CorrectInput(t *testing.T) {
+	_, cidr1, err := net.ParseCIDR("172.168.1.0/24")
+	require.NoError(t, err)
+	_, cidr2, err := net.ParseCIDR("172.168.2.0/24")
+	require.NoError(t, err)
+	_, cidr3, err := net.ParseCIDR("172.168.3.0/24")
+	require.NoError(t, err)
+
+	var expected = [][]*net.IPNet{
+		{cidr1},
+		{cidr1, cidr2},
+		{cidr1},
+		{cidr1, cidr2, cidr3},
+	}
+	var groups cidr.Groups
+	err = groups.Decode(fmt.Sprintf("[%v], [%v, %v], %v, [%v, %v , %v]",
+		cidr1.String(),
+		cidr1.String(), cidr2.String(),
+		cidr1.String(),
+		cidr1.String(), cidr2.String(), cidr3.String()))
+	require.NoError(t, err)
+	require.Equal(t, expected, [][]*net.IPNet(groups))
+}
+
+func Test_CidrGroupsDecoder_WrongInput(t *testing.T) {
+	cidr1 := "172.168.1.0/24"
+	var groups cidr.Groups
+	err := groups.Decode(fmt.Sprintf("[%[1]v, %[1]v], [[%[1]v],,[%[1]v]", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v, %[1]v", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v, %[1]v],", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v, %[1]v][%[1]v]", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v, %[1]v],[]", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v,, %[1]v]", cidr1))
+	require.Error(t, err)
+
+	err = groups.Decode(fmt.Sprintf("[%[1]v, %[1]v]", "172.168.1./24"))
+	require.Error(t, err)
+}