Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 1 | /* |
| 2 | Copyright 2016 The Kubernetes Authors. |
| 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 net |
| 18 | |
| 19 | import ( |
| 20 | "bufio" |
| 21 | "encoding/hex" |
| 22 | "fmt" |
| 23 | "io" |
| 24 | "net" |
| 25 | "os" |
| 26 | |
| 27 | "strings" |
| 28 | |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 29 | "k8s.io/klog" |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 30 | ) |
| 31 | |
| 32 | type AddressFamily uint |
| 33 | |
| 34 | const ( |
| 35 | familyIPv4 AddressFamily = 4 |
| 36 | familyIPv6 AddressFamily = 6 |
| 37 | ) |
| 38 | |
| 39 | const ( |
| 40 | ipv4RouteFile = "/proc/net/route" |
| 41 | ipv6RouteFile = "/proc/net/ipv6_route" |
| 42 | ) |
| 43 | |
| 44 | type Route struct { |
| 45 | Interface string |
| 46 | Destination net.IP |
| 47 | Gateway net.IP |
| 48 | Family AddressFamily |
| 49 | } |
| 50 | |
| 51 | type RouteFile struct { |
| 52 | name string |
| 53 | parse func(input io.Reader) ([]Route, error) |
| 54 | } |
| 55 | |
| 56 | // noRoutesError can be returned by ChooseBindAddress() in case of no routes |
| 57 | type noRoutesError struct { |
| 58 | message string |
| 59 | } |
| 60 | |
| 61 | func (e noRoutesError) Error() string { |
| 62 | return e.message |
| 63 | } |
| 64 | |
| 65 | // IsNoRoutesError checks if an error is of type noRoutesError |
| 66 | func IsNoRoutesError(err error) bool { |
| 67 | if err == nil { |
| 68 | return false |
| 69 | } |
| 70 | switch err.(type) { |
| 71 | case noRoutesError: |
| 72 | return true |
| 73 | default: |
| 74 | return false |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | var ( |
| 79 | v4File = RouteFile{name: ipv4RouteFile, parse: getIPv4DefaultRoutes} |
| 80 | v6File = RouteFile{name: ipv6RouteFile, parse: getIPv6DefaultRoutes} |
| 81 | ) |
| 82 | |
| 83 | func (rf RouteFile) extract() ([]Route, error) { |
| 84 | file, err := os.Open(rf.name) |
| 85 | if err != nil { |
| 86 | return nil, err |
| 87 | } |
| 88 | defer file.Close() |
| 89 | return rf.parse(file) |
| 90 | } |
| 91 | |
| 92 | // getIPv4DefaultRoutes obtains the IPv4 routes, and filters out non-default routes. |
| 93 | func getIPv4DefaultRoutes(input io.Reader) ([]Route, error) { |
| 94 | routes := []Route{} |
| 95 | scanner := bufio.NewReader(input) |
| 96 | for { |
| 97 | line, err := scanner.ReadString('\n') |
| 98 | if err == io.EOF { |
| 99 | break |
| 100 | } |
| 101 | //ignore the headers in the route info |
| 102 | if strings.HasPrefix(line, "Iface") { |
| 103 | continue |
| 104 | } |
| 105 | fields := strings.Fields(line) |
| 106 | // Interested in fields: |
| 107 | // 0 - interface name |
| 108 | // 1 - destination address |
| 109 | // 2 - gateway |
| 110 | dest, err := parseIP(fields[1], familyIPv4) |
| 111 | if err != nil { |
| 112 | return nil, err |
| 113 | } |
| 114 | gw, err := parseIP(fields[2], familyIPv4) |
| 115 | if err != nil { |
| 116 | return nil, err |
| 117 | } |
| 118 | if !dest.Equal(net.IPv4zero) { |
| 119 | continue |
| 120 | } |
| 121 | routes = append(routes, Route{ |
| 122 | Interface: fields[0], |
| 123 | Destination: dest, |
| 124 | Gateway: gw, |
| 125 | Family: familyIPv4, |
| 126 | }) |
| 127 | } |
| 128 | return routes, nil |
| 129 | } |
| 130 | |
| 131 | func getIPv6DefaultRoutes(input io.Reader) ([]Route, error) { |
| 132 | routes := []Route{} |
| 133 | scanner := bufio.NewReader(input) |
| 134 | for { |
| 135 | line, err := scanner.ReadString('\n') |
| 136 | if err == io.EOF { |
| 137 | break |
| 138 | } |
| 139 | fields := strings.Fields(line) |
| 140 | // Interested in fields: |
| 141 | // 0 - destination address |
| 142 | // 4 - gateway |
| 143 | // 9 - interface name |
| 144 | dest, err := parseIP(fields[0], familyIPv6) |
| 145 | if err != nil { |
| 146 | return nil, err |
| 147 | } |
| 148 | gw, err := parseIP(fields[4], familyIPv6) |
| 149 | if err != nil { |
| 150 | return nil, err |
| 151 | } |
| 152 | if !dest.Equal(net.IPv6zero) { |
| 153 | continue |
| 154 | } |
| 155 | if gw.Equal(net.IPv6zero) { |
| 156 | continue // loopback |
| 157 | } |
| 158 | routes = append(routes, Route{ |
| 159 | Interface: fields[9], |
| 160 | Destination: dest, |
| 161 | Gateway: gw, |
| 162 | Family: familyIPv6, |
| 163 | }) |
| 164 | } |
| 165 | return routes, nil |
| 166 | } |
| 167 | |
| 168 | // parseIP takes the hex IP address string from route file and converts it |
| 169 | // to a net.IP address. For IPv4, the value must be converted to big endian. |
| 170 | func parseIP(str string, family AddressFamily) (net.IP, error) { |
| 171 | if str == "" { |
| 172 | return nil, fmt.Errorf("input is nil") |
| 173 | } |
| 174 | bytes, err := hex.DecodeString(str) |
| 175 | if err != nil { |
| 176 | return nil, err |
| 177 | } |
| 178 | if family == familyIPv4 { |
| 179 | if len(bytes) != net.IPv4len { |
| 180 | return nil, fmt.Errorf("invalid IPv4 address in route") |
| 181 | } |
| 182 | return net.IP([]byte{bytes[3], bytes[2], bytes[1], bytes[0]}), nil |
| 183 | } |
| 184 | // Must be IPv6 |
| 185 | if len(bytes) != net.IPv6len { |
| 186 | return nil, fmt.Errorf("invalid IPv6 address in route") |
| 187 | } |
| 188 | return net.IP(bytes), nil |
| 189 | } |
| 190 | |
| 191 | func isInterfaceUp(intf *net.Interface) bool { |
| 192 | if intf == nil { |
| 193 | return false |
| 194 | } |
| 195 | if intf.Flags&net.FlagUp != 0 { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 196 | klog.V(4).Infof("Interface %v is up", intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 197 | return true |
| 198 | } |
| 199 | return false |
| 200 | } |
| 201 | |
| 202 | func isLoopbackOrPointToPoint(intf *net.Interface) bool { |
| 203 | return intf.Flags&(net.FlagLoopback|net.FlagPointToPoint) != 0 |
| 204 | } |
| 205 | |
| 206 | // getMatchingGlobalIP returns the first valid global unicast address of the given |
| 207 | // 'family' from the list of 'addrs'. |
| 208 | func getMatchingGlobalIP(addrs []net.Addr, family AddressFamily) (net.IP, error) { |
| 209 | if len(addrs) > 0 { |
| 210 | for i := range addrs { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 211 | klog.V(4).Infof("Checking addr %s.", addrs[i].String()) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 212 | ip, _, err := net.ParseCIDR(addrs[i].String()) |
| 213 | if err != nil { |
| 214 | return nil, err |
| 215 | } |
| 216 | if memberOf(ip, family) { |
| 217 | if ip.IsGlobalUnicast() { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 218 | klog.V(4).Infof("IP found %v", ip) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 219 | return ip, nil |
| 220 | } else { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 221 | klog.V(4).Infof("Non-global unicast address found %v", ip) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 222 | } |
| 223 | } else { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 224 | klog.V(4).Infof("%v is not an IPv%d address", ip, int(family)) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 225 | } |
| 226 | |
| 227 | } |
| 228 | } |
| 229 | return nil, nil |
| 230 | } |
| 231 | |
| 232 | // getIPFromInterface gets the IPs on an interface and returns a global unicast address, if any. The |
| 233 | // interface must be up, the IP must in the family requested, and the IP must be a global unicast address. |
| 234 | func getIPFromInterface(intfName string, forFamily AddressFamily, nw networkInterfacer) (net.IP, error) { |
| 235 | intf, err := nw.InterfaceByName(intfName) |
| 236 | if err != nil { |
| 237 | return nil, err |
| 238 | } |
| 239 | if isInterfaceUp(intf) { |
| 240 | addrs, err := nw.Addrs(intf) |
| 241 | if err != nil { |
| 242 | return nil, err |
| 243 | } |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 244 | klog.V(4).Infof("Interface %q has %d addresses :%v.", intfName, len(addrs), addrs) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 245 | matchingIP, err := getMatchingGlobalIP(addrs, forFamily) |
| 246 | if err != nil { |
| 247 | return nil, err |
| 248 | } |
| 249 | if matchingIP != nil { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 250 | klog.V(4).Infof("Found valid IPv%d address %v for interface %q.", int(forFamily), matchingIP, intfName) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 251 | return matchingIP, nil |
| 252 | } |
| 253 | } |
| 254 | return nil, nil |
| 255 | } |
| 256 | |
| 257 | // memberOF tells if the IP is of the desired family. Used for checking interface addresses. |
| 258 | func memberOf(ip net.IP, family AddressFamily) bool { |
| 259 | if ip.To4() != nil { |
| 260 | return family == familyIPv4 |
| 261 | } else { |
| 262 | return family == familyIPv6 |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | // chooseIPFromHostInterfaces looks at all system interfaces, trying to find one that is up that |
| 267 | // has a global unicast address (non-loopback, non-link local, non-point2point), and returns the IP. |
| 268 | // Searches for IPv4 addresses, and then IPv6 addresses. |
| 269 | func chooseIPFromHostInterfaces(nw networkInterfacer) (net.IP, error) { |
| 270 | intfs, err := nw.Interfaces() |
| 271 | if err != nil { |
| 272 | return nil, err |
| 273 | } |
| 274 | if len(intfs) == 0 { |
| 275 | return nil, fmt.Errorf("no interfaces found on host.") |
| 276 | } |
| 277 | for _, family := range []AddressFamily{familyIPv4, familyIPv6} { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 278 | klog.V(4).Infof("Looking for system interface with a global IPv%d address", uint(family)) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 279 | for _, intf := range intfs { |
| 280 | if !isInterfaceUp(&intf) { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 281 | klog.V(4).Infof("Skipping: down interface %q", intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 282 | continue |
| 283 | } |
| 284 | if isLoopbackOrPointToPoint(&intf) { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 285 | klog.V(4).Infof("Skipping: LB or P2P interface %q", intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 286 | continue |
| 287 | } |
| 288 | addrs, err := nw.Addrs(&intf) |
| 289 | if err != nil { |
| 290 | return nil, err |
| 291 | } |
| 292 | if len(addrs) == 0 { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 293 | klog.V(4).Infof("Skipping: no addresses on interface %q", intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 294 | continue |
| 295 | } |
| 296 | for _, addr := range addrs { |
| 297 | ip, _, err := net.ParseCIDR(addr.String()) |
| 298 | if err != nil { |
| 299 | return nil, fmt.Errorf("Unable to parse CIDR for interface %q: %s", intf.Name, err) |
| 300 | } |
| 301 | if !memberOf(ip, family) { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 302 | klog.V(4).Infof("Skipping: no address family match for %q on interface %q.", ip, intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 303 | continue |
| 304 | } |
| 305 | // TODO: Decide if should open up to allow IPv6 LLAs in future. |
| 306 | if !ip.IsGlobalUnicast() { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 307 | klog.V(4).Infof("Skipping: non-global address %q on interface %q.", ip, intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 308 | continue |
| 309 | } |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 310 | klog.V(4).Infof("Found global unicast address %q on interface %q.", ip, intf.Name) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 311 | return ip, nil |
| 312 | } |
| 313 | } |
| 314 | } |
| 315 | return nil, fmt.Errorf("no acceptable interface with global unicast address found on host") |
| 316 | } |
| 317 | |
| 318 | // ChooseHostInterface is a method used fetch an IP for a daemon. |
| 319 | // If there is no routing info file, it will choose a global IP from the system |
| 320 | // interfaces. Otherwise, it will use IPv4 and IPv6 route information to return the |
| 321 | // IP of the interface with a gateway on it (with priority given to IPv4). For a node |
| 322 | // with no internet connection, it returns error. |
| 323 | func ChooseHostInterface() (net.IP, error) { |
| 324 | var nw networkInterfacer = networkInterface{} |
| 325 | if _, err := os.Stat(ipv4RouteFile); os.IsNotExist(err) { |
| 326 | return chooseIPFromHostInterfaces(nw) |
| 327 | } |
| 328 | routes, err := getAllDefaultRoutes() |
| 329 | if err != nil { |
| 330 | return nil, err |
| 331 | } |
| 332 | return chooseHostInterfaceFromRoute(routes, nw) |
| 333 | } |
| 334 | |
| 335 | // networkInterfacer defines an interface for several net library functions. Production |
| 336 | // code will forward to net library functions, and unit tests will override the methods |
| 337 | // for testing purposes. |
| 338 | type networkInterfacer interface { |
| 339 | InterfaceByName(intfName string) (*net.Interface, error) |
| 340 | Addrs(intf *net.Interface) ([]net.Addr, error) |
| 341 | Interfaces() ([]net.Interface, error) |
| 342 | } |
| 343 | |
| 344 | // networkInterface implements the networkInterfacer interface for production code, just |
| 345 | // wrapping the underlying net library function calls. |
| 346 | type networkInterface struct{} |
| 347 | |
| 348 | func (_ networkInterface) InterfaceByName(intfName string) (*net.Interface, error) { |
| 349 | return net.InterfaceByName(intfName) |
| 350 | } |
| 351 | |
| 352 | func (_ networkInterface) Addrs(intf *net.Interface) ([]net.Addr, error) { |
| 353 | return intf.Addrs() |
| 354 | } |
| 355 | |
| 356 | func (_ networkInterface) Interfaces() ([]net.Interface, error) { |
| 357 | return net.Interfaces() |
| 358 | } |
| 359 | |
| 360 | // getAllDefaultRoutes obtains IPv4 and IPv6 default routes on the node. If unable |
| 361 | // to read the IPv4 routing info file, we return an error. If unable to read the IPv6 |
| 362 | // routing info file (which is optional), we'll just use the IPv4 route information. |
| 363 | // Using all the routing info, if no default routes are found, an error is returned. |
| 364 | func getAllDefaultRoutes() ([]Route, error) { |
| 365 | routes, err := v4File.extract() |
| 366 | if err != nil { |
| 367 | return nil, err |
| 368 | } |
| 369 | v6Routes, _ := v6File.extract() |
| 370 | routes = append(routes, v6Routes...) |
| 371 | if len(routes) == 0 { |
| 372 | return nil, noRoutesError{ |
| 373 | message: fmt.Sprintf("no default routes found in %q or %q", v4File.name, v6File.name), |
| 374 | } |
| 375 | } |
| 376 | return routes, nil |
| 377 | } |
| 378 | |
| 379 | // chooseHostInterfaceFromRoute cycles through each default route provided, looking for a |
| 380 | // global IP address from the interface for the route. Will first look all each IPv4 route for |
| 381 | // an IPv4 IP, and then will look at each IPv6 route for an IPv6 IP. |
| 382 | func chooseHostInterfaceFromRoute(routes []Route, nw networkInterfacer) (net.IP, error) { |
| 383 | for _, family := range []AddressFamily{familyIPv4, familyIPv6} { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 384 | klog.V(4).Infof("Looking for default routes with IPv%d addresses", uint(family)) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 385 | for _, route := range routes { |
| 386 | if route.Family != family { |
| 387 | continue |
| 388 | } |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 389 | klog.V(4).Infof("Default route transits interface %q", route.Interface) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 390 | finalIP, err := getIPFromInterface(route.Interface, family, nw) |
| 391 | if err != nil { |
| 392 | return nil, err |
| 393 | } |
| 394 | if finalIP != nil { |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 395 | klog.V(4).Infof("Found active IP %v ", finalIP) |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 396 | return finalIP, nil |
| 397 | } |
| 398 | } |
| 399 | } |
David Bainbridge | 8697152 | 2019-09-26 22:09:39 +0000 | [diff] [blame^] | 400 | klog.V(4).Infof("No active IP found by looking at default routes") |
Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 401 | return nil, fmt.Errorf("unable to select an IP from default routes.") |
| 402 | } |
| 403 | |
| 404 | // If bind-address is usable, return it directly |
| 405 | // If bind-address is not usable (unset, 0.0.0.0, or loopback), we will use the host's default |
| 406 | // interface. |
| 407 | func ChooseBindAddress(bindAddress net.IP) (net.IP, error) { |
| 408 | if bindAddress == nil || bindAddress.IsUnspecified() || bindAddress.IsLoopback() { |
| 409 | hostIP, err := ChooseHostInterface() |
| 410 | if err != nil { |
| 411 | return nil, err |
| 412 | } |
| 413 | bindAddress = hostIP |
| 414 | } |
| 415 | return bindAddress, nil |
| 416 | } |