1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438
|
//go:build !windows
// +build !windows
package libnetwork
import (
"fmt"
"io/ioutil"
"os"
"path"
"path/filepath"
"strconv"
"strings"
"github.com/docker/libnetwork/etchosts"
"github.com/docker/libnetwork/resolvconf"
"github.com/docker/libnetwork/resolvconf/dns"
"github.com/docker/libnetwork/types"
"github.com/sirupsen/logrus"
)
const (
defaultPrefix = "/var/lib/docker/network/files"
dirPerm = 0755
filePerm = 0644
)
func (sb *sandbox) startResolver(restore bool) {
sb.resolverOnce.Do(func() {
var err error
sb.resolver = NewResolver(resolverIPSandbox, true, sb.Key(), sb)
defer func() {
if err != nil {
sb.resolver = nil
}
}()
// In the case of live restore container is already running with
// right resolv.conf contents created before. Just update the
// external DNS servers from the restored sandbox for embedded
// server to use.
if !restore {
err = sb.rebuildDNS()
if err != nil {
logrus.Errorf("Updating resolv.conf failed for container %s, %q", sb.ContainerID(), err)
return
}
}
sb.resolver.SetExtServers(sb.extDNS)
if err = sb.osSbox.InvokeFunc(sb.resolver.SetupFunc(0)); err != nil {
logrus.Errorf("Resolver Setup function failed for container %s, %q", sb.ContainerID(), err)
return
}
if err = sb.resolver.Start(); err != nil {
logrus.Errorf("Resolver Start failed for container %s, %q", sb.ContainerID(), err)
}
})
}
func (sb *sandbox) setupResolutionFiles() error {
if err := sb.buildHostsFile(); err != nil {
return err
}
if err := sb.updateParentHosts(); err != nil {
return err
}
return sb.setupDNS()
}
func (sb *sandbox) buildHostsFile() error {
if sb.config.hostsPath == "" {
sb.config.hostsPath = defaultPrefix + "/" + sb.id + "/hosts"
}
dir, _ := filepath.Split(sb.config.hostsPath)
if err := createBasePath(dir); err != nil {
return err
}
// This is for the host mode networking
if sb.config.useDefaultSandBox && len(sb.config.extraHosts) == 0 {
// We are working under the assumption that the origin file option had been properly expressed by the upper layer
// if not here we are going to error out
if err := copyFile(sb.config.originHostsPath, sb.config.hostsPath); err != nil && !os.IsNotExist(err) {
return types.InternalErrorf("could not copy source hosts file %s to %s: %v", sb.config.originHostsPath, sb.config.hostsPath, err)
}
return nil
}
extraContent := make([]etchosts.Record, 0, len(sb.config.extraHosts))
for _, extraHost := range sb.config.extraHosts {
extraContent = append(extraContent, etchosts.Record{Hosts: extraHost.name, IP: extraHost.IP})
}
return etchosts.Build(sb.config.hostsPath, "", sb.config.hostName, sb.config.domainName, extraContent)
}
func (sb *sandbox) updateHostsFile(ifaceIPs []string) error {
if ifaceIPs == nil || len(ifaceIPs) == 0 {
return nil
}
if sb.config.originHostsPath != "" {
return nil
}
// User might have provided a FQDN in hostname or split it across hostname
// and domainname. We want the FQDN and the bare hostname.
fqdn := sb.config.hostName
mhost := sb.config.hostName
if sb.config.domainName != "" {
fqdn = fmt.Sprintf("%s.%s", fqdn, sb.config.domainName)
}
parts := strings.SplitN(fqdn, ".", 2)
if len(parts) == 2 {
mhost = fmt.Sprintf("%s %s", fqdn, parts[0])
}
var extraContent []etchosts.Record
for _, ip := range ifaceIPs {
extraContent = append(extraContent, etchosts.Record{Hosts: mhost, IP: ip})
}
sb.addHostsEntries(extraContent)
return nil
}
func (sb *sandbox) addHostsEntries(recs []etchosts.Record) {
if err := etchosts.Add(sb.config.hostsPath, recs); err != nil {
logrus.Warnf("Failed adding service host entries to the running container: %v", err)
}
}
func (sb *sandbox) deleteHostsEntries(recs []etchosts.Record) {
if err := etchosts.Delete(sb.config.hostsPath, recs); err != nil {
logrus.Warnf("Failed deleting service host entries to the running container: %v", err)
}
}
func (sb *sandbox) updateParentHosts() error {
var pSb Sandbox
for _, update := range sb.config.parentUpdates {
sb.controller.WalkSandboxes(SandboxContainerWalker(&pSb, update.cid))
if pSb == nil {
continue
}
if err := etchosts.Update(pSb.(*sandbox).config.hostsPath, update.ip, update.name); err != nil {
return err
}
}
return nil
}
func (sb *sandbox) restorePath() {
if sb.config.resolvConfPath == "" {
sb.config.resolvConfPath = defaultPrefix + "/" + sb.id + "/resolv.conf"
}
sb.config.resolvConfHashFile = sb.config.resolvConfPath + ".hash"
if sb.config.hostsPath == "" {
sb.config.hostsPath = defaultPrefix + "/" + sb.id + "/hosts"
}
}
func (sb *sandbox) setExternalResolvers(content []byte, addrType int, checkLoopback bool) {
servers := resolvconf.GetNameservers(content, addrType)
for _, ip := range servers {
hostLoopback := false
if checkLoopback {
hostLoopback = dns.IsIPv4Localhost(ip)
}
sb.extDNS = append(sb.extDNS, extDNSEntry{
IPStr: ip,
HostLoopback: hostLoopback,
})
}
}
func (sb *sandbox) setupDNS() error {
var newRC *resolvconf.File
if sb.config.resolvConfPath == "" {
sb.config.resolvConfPath = defaultPrefix + "/" + sb.id + "/resolv.conf"
}
sb.config.resolvConfHashFile = sb.config.resolvConfPath + ".hash"
dir, _ := filepath.Split(sb.config.resolvConfPath)
if err := createBasePath(dir); err != nil {
return err
}
// When the user specify a conainter in the host namespace and do no have any dns option specified
// we just copy the host resolv.conf from the host itself
if sb.config.useDefaultSandBox &&
len(sb.config.dnsList) == 0 && len(sb.config.dnsSearchList) == 0 && len(sb.config.dnsOptionsList) == 0 {
// We are working under the assumption that the origin file option had been properly expressed by the upper layer
// if not here we are going to error out
if err := copyFile(sb.config.originResolvConfPath, sb.config.resolvConfPath); err != nil {
if !os.IsNotExist(err) {
return fmt.Errorf("could not copy source resolv.conf file %s to %s: %v", sb.config.originResolvConfPath, sb.config.resolvConfPath, err)
}
logrus.Infof("%s does not exist, we create an empty resolv.conf for container", sb.config.originResolvConfPath)
if err := createFile(sb.config.resolvConfPath); err != nil {
return err
}
}
return nil
}
originResolvConfPath := sb.config.originResolvConfPath
if originResolvConfPath == "" {
// fallback if not specified
originResolvConfPath = resolvconf.Path()
}
currRC, err := resolvconf.GetSpecific(originResolvConfPath)
if err != nil {
if !os.IsNotExist(err) {
return err
}
// it's ok to continue if /etc/resolv.conf doesn't exist, default resolvers (Google's Public DNS)
// will be used
currRC = &resolvconf.File{}
logrus.Infof("/etc/resolv.conf does not exist")
}
if len(sb.config.dnsList) > 0 || len(sb.config.dnsSearchList) > 0 || len(sb.config.dnsOptionsList) > 0 {
var (
err error
dnsList = resolvconf.GetNameservers(currRC.Content, types.IP)
dnsSearchList = resolvconf.GetSearchDomains(currRC.Content)
dnsOptionsList = resolvconf.GetOptions(currRC.Content)
)
if len(sb.config.dnsList) > 0 {
dnsList = sb.config.dnsList
}
if len(sb.config.dnsSearchList) > 0 {
dnsSearchList = sb.config.dnsSearchList
}
if len(sb.config.dnsOptionsList) > 0 {
dnsOptionsList = sb.config.dnsOptionsList
}
newRC, err = resolvconf.Build(sb.config.resolvConfPath, dnsList, dnsSearchList, dnsOptionsList)
if err != nil {
return err
}
// After building the resolv.conf from the user config save the
// external resolvers in the sandbox. Note that --dns 127.0.0.x
// config refers to the loopback in the container namespace
sb.setExternalResolvers(newRC.Content, types.IPv4, false)
} else {
// If the host resolv.conf file has 127.0.0.x container should
// use the host resolver for queries. This is supported by the
// docker embedded DNS server. Hence save the external resolvers
// before filtering it out.
sb.setExternalResolvers(currRC.Content, types.IPv4, true)
// Replace any localhost/127.* (at this point we have no info about ipv6, pass it as true)
if newRC, err = resolvconf.FilterResolvDNS(currRC.Content, true); err != nil {
return err
}
// No contention on container resolv.conf file at sandbox creation
if err := ioutil.WriteFile(sb.config.resolvConfPath, newRC.Content, filePerm); err != nil {
return types.InternalErrorf("failed to write unhaltered resolv.conf file content when setting up dns for sandbox %s: %v", sb.ID(), err)
}
}
// Write hash
if err := ioutil.WriteFile(sb.config.resolvConfHashFile, []byte(newRC.Hash), filePerm); err != nil {
return types.InternalErrorf("failed to write resolv.conf hash file when setting up dns for sandbox %s: %v", sb.ID(), err)
}
return nil
}
func (sb *sandbox) updateDNS(ipv6Enabled bool) error {
var (
currHash string
hashFile = sb.config.resolvConfHashFile
)
// This is for the host mode networking
if sb.config.useDefaultSandBox {
return nil
}
if len(sb.config.dnsList) > 0 || len(sb.config.dnsSearchList) > 0 || len(sb.config.dnsOptionsList) > 0 {
return nil
}
currRC, err := resolvconf.GetSpecific(sb.config.resolvConfPath)
if err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
h, err := ioutil.ReadFile(hashFile)
if err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
currHash = string(h)
}
}
if currHash != "" && currHash != currRC.Hash {
// Seems the user has changed the container resolv.conf since the last time
// we checked so return without doing anything.
//logrus.Infof("Skipping update of resolv.conf file with ipv6Enabled: %t because file was touched by user", ipv6Enabled)
return nil
}
// replace any localhost/127.* and remove IPv6 nameservers if IPv6 disabled.
newRC, err := resolvconf.FilterResolvDNS(currRC.Content, ipv6Enabled)
if err != nil {
return err
}
err = ioutil.WriteFile(sb.config.resolvConfPath, newRC.Content, 0644)
if err != nil {
return err
}
// write the new hash in a temp file and rename it to make the update atomic
dir := path.Dir(sb.config.resolvConfPath)
tmpHashFile, err := ioutil.TempFile(dir, "hash")
if err != nil {
return err
}
if err = tmpHashFile.Chmod(filePerm); err != nil {
tmpHashFile.Close()
return err
}
_, err = tmpHashFile.Write([]byte(newRC.Hash))
if err1 := tmpHashFile.Close(); err == nil {
err = err1
}
if err != nil {
return err
}
return os.Rename(tmpHashFile.Name(), hashFile)
}
// Embedded DNS server has to be enabled for this sandbox. Rebuild the container's
// resolv.conf by doing the following
// - Add only the embedded server's IP to container's resolv.conf
// - If the embedded server needs any resolv.conf options add it to the current list
func (sb *sandbox) rebuildDNS() error {
currRC, err := resolvconf.GetSpecific(sb.config.resolvConfPath)
if err != nil {
return err
}
if len(sb.extDNS) == 0 {
sb.setExternalResolvers(currRC.Content, types.IPv4, false)
}
var (
dnsList = []string{sb.resolver.NameServer()}
dnsOptionsList = resolvconf.GetOptions(currRC.Content)
dnsSearchList = resolvconf.GetSearchDomains(currRC.Content)
)
// external v6 DNS servers has to be listed in resolv.conf
dnsList = append(dnsList, resolvconf.GetNameservers(currRC.Content, types.IPv6)...)
// If the user config and embedded DNS server both have ndots option set,
// remember the user's config so that unqualified names not in the docker
// domain can be dropped.
resOptions := sb.resolver.ResolverOptions()
dnsOpt:
for _, resOpt := range resOptions {
if strings.Contains(resOpt, "ndots") {
for _, option := range dnsOptionsList {
if strings.Contains(option, "ndots") {
parts := strings.Split(option, ":")
if len(parts) != 2 {
return fmt.Errorf("invalid ndots option %v", option)
}
if num, err := strconv.Atoi(parts[1]); err != nil {
return fmt.Errorf("invalid number for ndots option: %v", parts[1])
} else if num >= 0 {
// if the user sets ndots, use the user setting
sb.ndotsSet = true
break dnsOpt
} else {
return fmt.Errorf("invalid number for ndots option: %v", num)
}
}
}
}
}
if !sb.ndotsSet {
// if the user did not set the ndots, set it to 0 to prioritize the service name resolution
// Ref: https://linux.die.net/man/5/resolv.conf
dnsOptionsList = append(dnsOptionsList, resOptions...)
}
_, err = resolvconf.Build(sb.config.resolvConfPath, dnsList, dnsSearchList, dnsOptionsList)
return err
}
func createBasePath(dir string) error {
return os.MkdirAll(dir, dirPerm)
}
func createFile(path string) error {
var f *os.File
dir, _ := filepath.Split(path)
err := createBasePath(dir)
if err != nil {
return err
}
f, err = os.Create(path)
if err == nil {
f.Close()
}
return err
}
func copyFile(src, dst string) error {
sBytes, err := ioutil.ReadFile(src)
if err != nil {
return err
}
return ioutil.WriteFile(dst, sBytes, filePerm)
}
|