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tools.go
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tools.go
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// Copyright (c) 2018 Cisco and/or its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tools
import (
"context"
"fmt"
"net"
"os"
"time"
"regexp"
"syscall"
"google.golang.org/grpc"
)
const (
// location of network namespace for a process
netnsfile = "/proc/self/ns/net"
// MaxSymLink is maximum length of Symbolic Link
MaxSymLink = 8192
)
// GetCurrentNS discoveres the namespace of a running process and returns in a string.
func GetCurrentNS() (string, error) {
buf := make([]byte, MaxSymLink)
numBytes, err := syscall.Readlink(netnsfile, buf)
if err != nil {
return "", err
}
link := string(buf[0:numBytes])
nsRegExp := regexp.MustCompile("net:\\[(.*)\\]")
submatches := nsRegExp.FindStringSubmatch(link)
if len(submatches) >= 1 {
return submatches[1], nil
}
return "", fmt.Errorf("namespace is not found")
}
// SocketCleanup check for the presense of a stale socket and if it finds it, removes it.
func SocketCleanup(listenEndpoint string) error {
fi, err := os.Stat(listenEndpoint)
if err == nil && (fi.Mode()&os.ModeSocket) != 0 {
if err := os.Remove(listenEndpoint); err != nil {
return fmt.Errorf("cannot remove listen endpoint %s with error: %+v", listenEndpoint, err)
}
}
if err != nil && !os.IsNotExist(err) {
return fmt.Errorf("failure stat of socket file %s with error: %+v", listenEndpoint, err)
}
return nil
}
// SocketOperationCheck checks for liveness of a gRPC server socket.
func SocketOperationCheck(listenEndpoint string) (*grpc.ClientConn, error) {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
conn, err := dial(ctx, listenEndpoint)
if err != nil {
return nil, err
}
return conn, nil
}
func dial(ctx context.Context, unixSocketPath string) (*grpc.ClientConn, error) {
c, err := grpc.DialContext(ctx, unixSocketPath, grpc.WithInsecure(), grpc.WithBlock(),
grpc.WithDialer(func(addr string, timeout time.Duration) (net.Conn, error) {
return net.DialTimeout("unix", addr, timeout)
}),
)
return c, err
}