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| 1 | +/* |
| 2 | +Copyright 2021 The Kubernetes Authors All rights reserved. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +package network |
| 18 | + |
| 19 | +import ( |
| 20 | + "encoding/binary" |
| 21 | + "fmt" |
| 22 | + "net" |
| 23 | + |
| 24 | + "github.com/pkg/errors" |
| 25 | + "k8s.io/klog/v2" |
| 26 | +) |
| 27 | + |
| 28 | +var ( |
| 29 | + // valid private network subnets (RFC1918) |
| 30 | + privateSubnets = []net.IPNet{ |
| 31 | + // 10.0.0.0/8 |
| 32 | + { |
| 33 | + IP: []byte{10, 0, 0, 0}, |
| 34 | + Mask: []byte{255, 0, 0, 0}, |
| 35 | + }, |
| 36 | + // 172.16.0.0/12 |
| 37 | + { |
| 38 | + IP: []byte{172, 16, 0, 0}, |
| 39 | + Mask: []byte{255, 240, 0, 0}, |
| 40 | + }, |
| 41 | + // 192.168.0.0/16 |
| 42 | + { |
| 43 | + IP: []byte{192, 168, 0, 0}, |
| 44 | + Mask: []byte{255, 255, 0, 0}, |
| 45 | + }, |
| 46 | + } |
| 47 | +) |
| 48 | + |
| 49 | +// Parameters contains main network parameters. |
| 50 | +type Parameters struct { |
| 51 | + IP string // IP address of the network |
| 52 | + Netmask string // form: 4-byte ('a.b.c.d') |
| 53 | + CIDR string // form: CIDR |
| 54 | + Gateway string // first IP address (assumed, not checked !) |
| 55 | + ClientMin string // second IP address |
| 56 | + ClientMax string // last IP address before broadcastS |
| 57 | + Broadcast string // last IP address |
| 58 | + Interface |
| 59 | +} |
| 60 | + |
| 61 | +// Interface contains main network interface parameters. |
| 62 | +type Interface struct { |
| 63 | + IfaceName string |
| 64 | + IfaceIPv4 string |
| 65 | + IfaceMTU int |
| 66 | + IfaceMAC string |
| 67 | +} |
| 68 | + |
| 69 | +// inspect initialises IPv4 network parameters struct from given address. |
| 70 | +// address can be single address (like "192.168.17.42"), network address (like "192.168.17.0"), or in cidr form (like "192.168.17.42/24 or "192.168.17.0/24"). |
| 71 | +// If addr is valid existsing interface address, network struct will also contain info about the respective interface. |
| 72 | +func inspect(addr string) (*Parameters, error) { |
| 73 | + n := &Parameters{} |
| 74 | + |
| 75 | + // extract ip from addr |
| 76 | + ip, network, err := net.ParseCIDR(addr) |
| 77 | + if err != nil { |
| 78 | + ip = net.ParseIP(addr) |
| 79 | + if ip == nil { |
| 80 | + return nil, errors.Wrapf(err, "parsing address %q", addr) |
| 81 | + } |
| 82 | + } |
| 83 | + |
| 84 | + // check local interfaces |
| 85 | + ifaces, _ := net.Interfaces() |
| 86 | + for _, iface := range ifaces { |
| 87 | + ifAddrs, err := iface.Addrs() |
| 88 | + if err != nil { |
| 89 | + return nil, errors.Wrapf(err, "listing addresses of network interface %+v", iface) |
| 90 | + } |
| 91 | + for _, ifAddr := range ifAddrs { |
| 92 | + ifip, lan, err := net.ParseCIDR(ifAddr.String()) |
| 93 | + if err != nil { |
| 94 | + return nil, errors.Wrapf(err, "parsing address of network iface %+v", ifAddr) |
| 95 | + } |
| 96 | + if lan.Contains(ip) { |
| 97 | + n.IfaceName = iface.Name |
| 98 | + n.IfaceIPv4 = ifip.To4().String() |
| 99 | + n.IfaceMTU = iface.MTU |
| 100 | + n.IfaceMAC = iface.HardwareAddr.String() |
| 101 | + n.Gateway = n.IfaceIPv4 |
| 102 | + network = lan |
| 103 | + break |
| 104 | + } |
| 105 | + } |
| 106 | + } |
| 107 | + |
| 108 | + if network == nil { |
| 109 | + ipnet := &net.IPNet{ |
| 110 | + IP: ip, |
| 111 | + Mask: ip.DefaultMask(), // assume default network mask |
| 112 | + } |
| 113 | + _, network, err = net.ParseCIDR(ipnet.String()) |
| 114 | + if err != nil { |
| 115 | + return nil, errors.Wrapf(err, "determining network address from %q", addr) |
| 116 | + } |
| 117 | + } |
| 118 | + |
| 119 | + n.IP = network.IP.String() |
| 120 | + n.Netmask = net.IP(network.Mask).String() // form: 4-byte ('a.b.c.d') |
| 121 | + n.CIDR = network.String() |
| 122 | + |
| 123 | + networkIP := binary.BigEndian.Uint32(network.IP) // IP address of the network |
| 124 | + networkMask := binary.BigEndian.Uint32(network.Mask) // network mask |
| 125 | + broadcastIP := (networkIP & networkMask) | (networkMask ^ 0xffffffff) // last network IP address |
| 126 | + |
| 127 | + broadcast := make(net.IP, 4) |
| 128 | + binary.BigEndian.PutUint32(broadcast, broadcastIP) |
| 129 | + n.Broadcast = broadcast.String() |
| 130 | + |
| 131 | + gateway := net.ParseIP(n.Gateway).To4() // has to be converted to 4-byte representation! |
| 132 | + if gateway == nil { |
| 133 | + gateway = make(net.IP, 4) |
| 134 | + binary.BigEndian.PutUint32(gateway, networkIP+1) // assume first network IP address |
| 135 | + n.Gateway = gateway.String() |
| 136 | + } |
| 137 | + gatewayIP := binary.BigEndian.Uint32(gateway) |
| 138 | + |
| 139 | + min := make(net.IP, 4) |
| 140 | + binary.BigEndian.PutUint32(min, gatewayIP+1) // clients-from: first network IP address after gateway |
| 141 | + n.ClientMin = min.String() |
| 142 | + |
| 143 | + max := make(net.IP, 4) |
| 144 | + binary.BigEndian.PutUint32(max, broadcastIP-1) // clients-from: last network IP address before broadcast |
| 145 | + n.ClientMax = max.String() |
| 146 | + |
| 147 | + return n, nil |
| 148 | +} |
| 149 | + |
| 150 | +// isSubnetTaken returns if local network subnet exists and any error occurred. |
| 151 | +// If will return false in case of an error. |
| 152 | +func isSubnetTaken(subnet string) (bool, error) { |
| 153 | + ips, err := net.InterfaceAddrs() |
| 154 | + if err != nil { |
| 155 | + return false, errors.Wrap(err, "listing local networks") |
| 156 | + } |
| 157 | + for _, ip := range ips { |
| 158 | + _, lan, err := net.ParseCIDR(ip.String()) |
| 159 | + if err != nil { |
| 160 | + return false, errors.Wrapf(err, "parsing network iface address %q", ip) |
| 161 | + } |
| 162 | + if lan.Contains(net.ParseIP(subnet)) { |
| 163 | + return true, nil |
| 164 | + } |
| 165 | + } |
| 166 | + return false, nil |
| 167 | +} |
| 168 | + |
| 169 | +// isSubnetPrivate returns if subnet is a private network. |
| 170 | +func isSubnetPrivate(subnet string) bool { |
| 171 | + for _, ipnet := range privateSubnets { |
| 172 | + if ipnet.Contains(net.ParseIP(subnet)) { |
| 173 | + return true |
| 174 | + } |
| 175 | + } |
| 176 | + return false |
| 177 | +} |
| 178 | + |
| 179 | +// FreeSubnet will try to find free private network beginning with startSubnet, incrementing it in steps up to number of tries. |
| 180 | +func FreeSubnet(startSubnet string, step, tries int) (*Parameters, error) { |
| 181 | + for try := 0; try < tries; try++ { |
| 182 | + n, err := inspect(startSubnet) |
| 183 | + if err != nil { |
| 184 | + return nil, err |
| 185 | + } |
| 186 | + startSubnet = n.IP |
| 187 | + if isSubnetPrivate(startSubnet) { |
| 188 | + taken, err := isSubnetTaken(startSubnet) |
| 189 | + if err != nil { |
| 190 | + return nil, err |
| 191 | + } |
| 192 | + if !taken { |
| 193 | + klog.Infof("using free private subnet %s: %+v", n.CIDR, n) |
| 194 | + return n, nil |
| 195 | + } |
| 196 | + klog.Infof("skipping subnet %s that is taken: %+v", n.CIDR, n) |
| 197 | + } else { |
| 198 | + klog.Infof("skipping subnet %s that is not private", n.CIDR) |
| 199 | + } |
| 200 | + ones, _ := net.ParseIP(n.IP).DefaultMask().Size() |
| 201 | + nextSubnet := net.ParseIP(startSubnet).To4() |
| 202 | + if ones <= 16 { |
| 203 | + nextSubnet[1] += byte(step) |
| 204 | + } else { |
| 205 | + nextSubnet[2] += byte(step) |
| 206 | + } |
| 207 | + startSubnet = nextSubnet.String() |
| 208 | + } |
| 209 | + return nil, fmt.Errorf("no free private network subnets found with given parameters (start: %q, step: %d, tries: %d)", startSubnet, step, tries) |
| 210 | +} |
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