Matthias Andreas Benkard | 832a54e | 2019-01-29 09:27:38 +0100 | [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 | |
| 29 | "github.com/golang/glog" |
| 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 | var ( |
| 57 | v4File = RouteFile{name: ipv4RouteFile, parse: getIPv4DefaultRoutes} |
| 58 | v6File = RouteFile{name: ipv6RouteFile, parse: getIPv6DefaultRoutes} |
| 59 | ) |
| 60 | |
| 61 | func (rf RouteFile) extract() ([]Route, error) { |
| 62 | file, err := os.Open(rf.name) |
| 63 | if err != nil { |
| 64 | return nil, err |
| 65 | } |
| 66 | defer file.Close() |
| 67 | return rf.parse(file) |
| 68 | } |
| 69 | |
| 70 | // getIPv4DefaultRoutes obtains the IPv4 routes, and filters out non-default routes. |
| 71 | func getIPv4DefaultRoutes(input io.Reader) ([]Route, error) { |
| 72 | routes := []Route{} |
| 73 | scanner := bufio.NewReader(input) |
| 74 | for { |
| 75 | line, err := scanner.ReadString('\n') |
| 76 | if err == io.EOF { |
| 77 | break |
| 78 | } |
| 79 | //ignore the headers in the route info |
| 80 | if strings.HasPrefix(line, "Iface") { |
| 81 | continue |
| 82 | } |
| 83 | fields := strings.Fields(line) |
| 84 | // Interested in fields: |
| 85 | // 0 - interface name |
| 86 | // 1 - destination address |
| 87 | // 2 - gateway |
| 88 | dest, err := parseIP(fields[1], familyIPv4) |
| 89 | if err != nil { |
| 90 | return nil, err |
| 91 | } |
| 92 | gw, err := parseIP(fields[2], familyIPv4) |
| 93 | if err != nil { |
| 94 | return nil, err |
| 95 | } |
| 96 | if !dest.Equal(net.IPv4zero) { |
| 97 | continue |
| 98 | } |
| 99 | routes = append(routes, Route{ |
| 100 | Interface: fields[0], |
| 101 | Destination: dest, |
| 102 | Gateway: gw, |
| 103 | Family: familyIPv4, |
| 104 | }) |
| 105 | } |
| 106 | return routes, nil |
| 107 | } |
| 108 | |
| 109 | func getIPv6DefaultRoutes(input io.Reader) ([]Route, error) { |
| 110 | routes := []Route{} |
| 111 | scanner := bufio.NewReader(input) |
| 112 | for { |
| 113 | line, err := scanner.ReadString('\n') |
| 114 | if err == io.EOF { |
| 115 | break |
| 116 | } |
| 117 | fields := strings.Fields(line) |
| 118 | // Interested in fields: |
| 119 | // 0 - destination address |
| 120 | // 4 - gateway |
| 121 | // 9 - interface name |
| 122 | dest, err := parseIP(fields[0], familyIPv6) |
| 123 | if err != nil { |
| 124 | return nil, err |
| 125 | } |
| 126 | gw, err := parseIP(fields[4], familyIPv6) |
| 127 | if err != nil { |
| 128 | return nil, err |
| 129 | } |
| 130 | if !dest.Equal(net.IPv6zero) { |
| 131 | continue |
| 132 | } |
| 133 | if gw.Equal(net.IPv6zero) { |
| 134 | continue // loopback |
| 135 | } |
| 136 | routes = append(routes, Route{ |
| 137 | Interface: fields[9], |
| 138 | Destination: dest, |
| 139 | Gateway: gw, |
| 140 | Family: familyIPv6, |
| 141 | }) |
| 142 | } |
| 143 | return routes, nil |
| 144 | } |
| 145 | |
| 146 | // parseIP takes the hex IP address string from route file and converts it |
| 147 | // to a net.IP address. For IPv4, the value must be converted to big endian. |
| 148 | func parseIP(str string, family AddressFamily) (net.IP, error) { |
| 149 | if str == "" { |
| 150 | return nil, fmt.Errorf("input is nil") |
| 151 | } |
| 152 | bytes, err := hex.DecodeString(str) |
| 153 | if err != nil { |
| 154 | return nil, err |
| 155 | } |
| 156 | if family == familyIPv4 { |
| 157 | if len(bytes) != net.IPv4len { |
| 158 | return nil, fmt.Errorf("invalid IPv4 address in route") |
| 159 | } |
| 160 | return net.IP([]byte{bytes[3], bytes[2], bytes[1], bytes[0]}), nil |
| 161 | } |
| 162 | // Must be IPv6 |
| 163 | if len(bytes) != net.IPv6len { |
| 164 | return nil, fmt.Errorf("invalid IPv6 address in route") |
| 165 | } |
| 166 | return net.IP(bytes), nil |
| 167 | } |
| 168 | |
| 169 | func isInterfaceUp(intf *net.Interface) bool { |
| 170 | if intf == nil { |
| 171 | return false |
| 172 | } |
| 173 | if intf.Flags&net.FlagUp != 0 { |
| 174 | glog.V(4).Infof("Interface %v is up", intf.Name) |
| 175 | return true |
| 176 | } |
| 177 | return false |
| 178 | } |
| 179 | |
| 180 | func isLoopbackOrPointToPoint(intf *net.Interface) bool { |
| 181 | return intf.Flags&(net.FlagLoopback|net.FlagPointToPoint) != 0 |
| 182 | } |
| 183 | |
| 184 | // getMatchingGlobalIP returns the first valid global unicast address of the given |
| 185 | // 'family' from the list of 'addrs'. |
| 186 | func getMatchingGlobalIP(addrs []net.Addr, family AddressFamily) (net.IP, error) { |
| 187 | if len(addrs) > 0 { |
| 188 | for i := range addrs { |
| 189 | glog.V(4).Infof("Checking addr %s.", addrs[i].String()) |
| 190 | ip, _, err := net.ParseCIDR(addrs[i].String()) |
| 191 | if err != nil { |
| 192 | return nil, err |
| 193 | } |
| 194 | if memberOf(ip, family) { |
| 195 | if ip.IsGlobalUnicast() { |
| 196 | glog.V(4).Infof("IP found %v", ip) |
| 197 | return ip, nil |
| 198 | } else { |
| 199 | glog.V(4).Infof("Non-global unicast address found %v", ip) |
| 200 | } |
| 201 | } else { |
| 202 | glog.V(4).Infof("%v is not an IPv%d address", ip, int(family)) |
| 203 | } |
| 204 | |
| 205 | } |
| 206 | } |
| 207 | return nil, nil |
| 208 | } |
| 209 | |
| 210 | // getIPFromInterface gets the IPs on an interface and returns a global unicast address, if any. The |
| 211 | // interface must be up, the IP must in the family requested, and the IP must be a global unicast address. |
| 212 | func getIPFromInterface(intfName string, forFamily AddressFamily, nw networkInterfacer) (net.IP, error) { |
| 213 | intf, err := nw.InterfaceByName(intfName) |
| 214 | if err != nil { |
| 215 | return nil, err |
| 216 | } |
| 217 | if isInterfaceUp(intf) { |
| 218 | addrs, err := nw.Addrs(intf) |
| 219 | if err != nil { |
| 220 | return nil, err |
| 221 | } |
| 222 | glog.V(4).Infof("Interface %q has %d addresses :%v.", intfName, len(addrs), addrs) |
| 223 | matchingIP, err := getMatchingGlobalIP(addrs, forFamily) |
| 224 | if err != nil { |
| 225 | return nil, err |
| 226 | } |
| 227 | if matchingIP != nil { |
| 228 | glog.V(4).Infof("Found valid IPv%d address %v for interface %q.", int(forFamily), matchingIP, intfName) |
| 229 | return matchingIP, nil |
| 230 | } |
| 231 | } |
| 232 | return nil, nil |
| 233 | } |
| 234 | |
| 235 | // memberOF tells if the IP is of the desired family. Used for checking interface addresses. |
| 236 | func memberOf(ip net.IP, family AddressFamily) bool { |
| 237 | if ip.To4() != nil { |
| 238 | return family == familyIPv4 |
| 239 | } else { |
| 240 | return family == familyIPv6 |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | // chooseIPFromHostInterfaces looks at all system interfaces, trying to find one that is up that |
| 245 | // has a global unicast address (non-loopback, non-link local, non-point2point), and returns the IP. |
| 246 | // Searches for IPv4 addresses, and then IPv6 addresses. |
| 247 | func chooseIPFromHostInterfaces(nw networkInterfacer) (net.IP, error) { |
| 248 | intfs, err := nw.Interfaces() |
| 249 | if err != nil { |
| 250 | return nil, err |
| 251 | } |
| 252 | if len(intfs) == 0 { |
| 253 | return nil, fmt.Errorf("no interfaces found on host.") |
| 254 | } |
| 255 | for _, family := range []AddressFamily{familyIPv4, familyIPv6} { |
| 256 | glog.V(4).Infof("Looking for system interface with a global IPv%d address", uint(family)) |
| 257 | for _, intf := range intfs { |
| 258 | if !isInterfaceUp(&intf) { |
| 259 | glog.V(4).Infof("Skipping: down interface %q", intf.Name) |
| 260 | continue |
| 261 | } |
| 262 | if isLoopbackOrPointToPoint(&intf) { |
| 263 | glog.V(4).Infof("Skipping: LB or P2P interface %q", intf.Name) |
| 264 | continue |
| 265 | } |
| 266 | addrs, err := nw.Addrs(&intf) |
| 267 | if err != nil { |
| 268 | return nil, err |
| 269 | } |
| 270 | if len(addrs) == 0 { |
| 271 | glog.V(4).Infof("Skipping: no addresses on interface %q", intf.Name) |
| 272 | continue |
| 273 | } |
| 274 | for _, addr := range addrs { |
| 275 | ip, _, err := net.ParseCIDR(addr.String()) |
| 276 | if err != nil { |
| 277 | return nil, fmt.Errorf("Unable to parse CIDR for interface %q: %s", intf.Name, err) |
| 278 | } |
| 279 | if !memberOf(ip, family) { |
| 280 | glog.V(4).Infof("Skipping: no address family match for %q on interface %q.", ip, intf.Name) |
| 281 | continue |
| 282 | } |
| 283 | // TODO: Decide if should open up to allow IPv6 LLAs in future. |
| 284 | if !ip.IsGlobalUnicast() { |
| 285 | glog.V(4).Infof("Skipping: non-global address %q on interface %q.", ip, intf.Name) |
| 286 | continue |
| 287 | } |
| 288 | glog.V(4).Infof("Found global unicast address %q on interface %q.", ip, intf.Name) |
| 289 | return ip, nil |
| 290 | } |
| 291 | } |
| 292 | } |
| 293 | return nil, fmt.Errorf("no acceptable interface with global unicast address found on host") |
| 294 | } |
| 295 | |
| 296 | // ChooseHostInterface is a method used fetch an IP for a daemon. |
| 297 | // If there is no routing info file, it will choose a global IP from the system |
| 298 | // interfaces. Otherwise, it will use IPv4 and IPv6 route information to return the |
| 299 | // IP of the interface with a gateway on it (with priority given to IPv4). For a node |
| 300 | // with no internet connection, it returns error. |
| 301 | func ChooseHostInterface() (net.IP, error) { |
| 302 | var nw networkInterfacer = networkInterface{} |
| 303 | if _, err := os.Stat(ipv4RouteFile); os.IsNotExist(err) { |
| 304 | return chooseIPFromHostInterfaces(nw) |
| 305 | } |
| 306 | routes, err := getAllDefaultRoutes() |
| 307 | if err != nil { |
| 308 | return nil, err |
| 309 | } |
| 310 | return chooseHostInterfaceFromRoute(routes, nw) |
| 311 | } |
| 312 | |
| 313 | // networkInterfacer defines an interface for several net library functions. Production |
| 314 | // code will forward to net library functions, and unit tests will override the methods |
| 315 | // for testing purposes. |
| 316 | type networkInterfacer interface { |
| 317 | InterfaceByName(intfName string) (*net.Interface, error) |
| 318 | Addrs(intf *net.Interface) ([]net.Addr, error) |
| 319 | Interfaces() ([]net.Interface, error) |
| 320 | } |
| 321 | |
| 322 | // networkInterface implements the networkInterfacer interface for production code, just |
| 323 | // wrapping the underlying net library function calls. |
| 324 | type networkInterface struct{} |
| 325 | |
| 326 | func (_ networkInterface) InterfaceByName(intfName string) (*net.Interface, error) { |
| 327 | return net.InterfaceByName(intfName) |
| 328 | } |
| 329 | |
| 330 | func (_ networkInterface) Addrs(intf *net.Interface) ([]net.Addr, error) { |
| 331 | return intf.Addrs() |
| 332 | } |
| 333 | |
| 334 | func (_ networkInterface) Interfaces() ([]net.Interface, error) { |
| 335 | return net.Interfaces() |
| 336 | } |
| 337 | |
| 338 | // getAllDefaultRoutes obtains IPv4 and IPv6 default routes on the node. If unable |
| 339 | // to read the IPv4 routing info file, we return an error. If unable to read the IPv6 |
| 340 | // routing info file (which is optional), we'll just use the IPv4 route information. |
| 341 | // Using all the routing info, if no default routes are found, an error is returned. |
| 342 | func getAllDefaultRoutes() ([]Route, error) { |
| 343 | routes, err := v4File.extract() |
| 344 | if err != nil { |
| 345 | return nil, err |
| 346 | } |
| 347 | v6Routes, _ := v6File.extract() |
| 348 | routes = append(routes, v6Routes...) |
| 349 | if len(routes) == 0 { |
| 350 | return nil, fmt.Errorf("No default routes.") |
| 351 | } |
| 352 | return routes, nil |
| 353 | } |
| 354 | |
| 355 | // chooseHostInterfaceFromRoute cycles through each default route provided, looking for a |
| 356 | // global IP address from the interface for the route. Will first look all each IPv4 route for |
| 357 | // an IPv4 IP, and then will look at each IPv6 route for an IPv6 IP. |
| 358 | func chooseHostInterfaceFromRoute(routes []Route, nw networkInterfacer) (net.IP, error) { |
| 359 | for _, family := range []AddressFamily{familyIPv4, familyIPv6} { |
| 360 | glog.V(4).Infof("Looking for default routes with IPv%d addresses", uint(family)) |
| 361 | for _, route := range routes { |
| 362 | if route.Family != family { |
| 363 | continue |
| 364 | } |
| 365 | glog.V(4).Infof("Default route transits interface %q", route.Interface) |
| 366 | finalIP, err := getIPFromInterface(route.Interface, family, nw) |
| 367 | if err != nil { |
| 368 | return nil, err |
| 369 | } |
| 370 | if finalIP != nil { |
| 371 | glog.V(4).Infof("Found active IP %v ", finalIP) |
| 372 | return finalIP, nil |
| 373 | } |
| 374 | } |
| 375 | } |
| 376 | glog.V(4).Infof("No active IP found by looking at default routes") |
| 377 | return nil, fmt.Errorf("unable to select an IP from default routes.") |
| 378 | } |
| 379 | |
| 380 | // If bind-address is usable, return it directly |
| 381 | // If bind-address is not usable (unset, 0.0.0.0, or loopback), we will use the host's default |
| 382 | // interface. |
| 383 | func ChooseBindAddress(bindAddress net.IP) (net.IP, error) { |
| 384 | if bindAddress == nil || bindAddress.IsUnspecified() || bindAddress.IsLoopback() { |
| 385 | hostIP, err := ChooseHostInterface() |
| 386 | if err != nil { |
| 387 | return nil, err |
| 388 | } |
| 389 | bindAddress = hostIP |
| 390 | } |
| 391 | return bindAddress, nil |
| 392 | } |