a6a822268c
The plugin binary actually functions in two modes. The first mode is a regular CNI plugin. The second mode (when stared with "daemon" arg) runs a DHCP client daemon. When executed as a CNI plugin, it issues an RPC request to the daemon for actual processing. The daemon is required since a DHCP lease needs to be maintained by periodically renewing it. One instance of the daemon can server arbitrary number of containers/leases.
93 lines
2.6 KiB
Go
93 lines
2.6 KiB
Go
// Copyright 2015 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ns
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import (
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"fmt"
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"os"
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"runtime"
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"syscall"
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)
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var setNsMap = map[string]uintptr{
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"386": 346,
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"amd64": 308,
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"arm": 374,
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}
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// SetNS sets the network namespace on a target file.
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func SetNS(f *os.File, flags uintptr) error {
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if runtime.GOOS != "linux" {
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return fmt.Errorf("unsupported OS: %s", runtime.GOOS)
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}
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trap, ok := setNsMap[runtime.GOARCH]
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if !ok {
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return fmt.Errorf("unsupported arch: %s", runtime.GOARCH)
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}
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_, _, err := syscall.RawSyscall(trap, f.Fd(), flags, 0)
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if err != 0 {
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return err
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}
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return nil
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}
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// WithNetNSPath executes the passed closure under the given network
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// namespace, restoring the original namespace afterwards.
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// Changing namespaces must be done on a goroutine that has been
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// locked to an OS thread. If lockThread arg is true, this function
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// locks the goroutine prior to change namespace and unlocks before
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// returning
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func WithNetNSPath(nspath string, lockThread bool, f func(*os.File) error) error {
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ns, err := os.Open(nspath)
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if err != nil {
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return fmt.Errorf("Failed to open %v: %v", nspath, err)
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}
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defer ns.Close()
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return WithNetNS(ns, lockThread, f)
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}
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// WithNetNS executes the passed closure under the given network
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// namespace, restoring the original namespace afterwards.
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// Changing namespaces must be done on a goroutine that has been
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// locked to an OS thread. If lockThread arg is true, this function
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// locks the goroutine prior to change namespace and unlocks before
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// returning
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func WithNetNS(ns *os.File, lockThread bool, f func(*os.File) error) error {
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if lockThread {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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}
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// save a handle to current (host) network namespace
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thisNS, err := os.Open("/proc/self/ns/net")
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if err != nil {
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return fmt.Errorf("Failed to open /proc/self/ns/net: %v", err)
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}
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defer thisNS.Close()
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if err = SetNS(ns, syscall.CLONE_NEWNET); err != nil {
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return fmt.Errorf("Error switching to ns %v: %v", ns.Name(), err)
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}
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if err = f(thisNS); err != nil {
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return err
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}
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// switch back
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return SetNS(thisNS, syscall.CLONE_NEWNET)
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}
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