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// Copyright 2019 The gVisor Authors.
//
// 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 uds contains helpers for testing external UDS functionality.
package uds
import (
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/unet"
)
// createEchoSocket creates a socket that echoes back anything received.
//
// Only works for stream, seqpacket sockets.
func createEchoSocket(path string, protocol int) (cleanup func(), err error) {
fd, err := unix.Socket(unix.AF_UNIX, protocol, 0)
if err != nil {
return nil, fmt.Errorf("error creating echo(%d) socket: %v", protocol, err)
}
if err := unix.Bind(fd, &unix.SockaddrUnix{Name: path}); err != nil {
return nil, fmt.Errorf("error binding echo(%d) socket: %v", protocol, err)
}
if err := unix.Listen(fd, 0); err != nil {
return nil, fmt.Errorf("error listening echo(%d) socket: %v", protocol, err)
}
server, err := unet.NewServerSocket(fd)
if err != nil {
return nil, fmt.Errorf("error creating echo(%d) unet socket: %v", protocol, err)
}
acceptAndEchoOne := func() error {
s, err := server.Accept()
if err != nil {
return fmt.Errorf("failed to accept: %v", err)
}
defer s.Close()
for {
buf := make([]byte, 512)
for {
n, err := s.Read(buf)
if err == io.EOF {
return nil
}
if err != nil {
return fmt.Errorf("failed to read: %d, %v", n, err)
}
n, err = s.Write(buf[:n])
if err != nil {
return fmt.Errorf("failed to write: %d, %v", n, err)
}
}
}
}
go func() {
for {
if err := acceptAndEchoOne(); err != nil {
log.Warningf("Failed to handle echo(%d) socket: %v", protocol, err)
return
}
}
}()
cleanup = func() {
if err := server.Close(); err != nil {
log.Warningf("Failed to close echo(%d) socket: %v", protocol, err)
}
}
return cleanup, nil
}
// createNonListeningSocket creates a socket that is bound but not listening.
//
// Only relevant for stream, seqpacket sockets.
func createNonListeningSocket(path string, protocol int) (cleanup func(), err error) {
fd, err := unix.Socket(unix.AF_UNIX, protocol, 0)
if err != nil {
return nil, fmt.Errorf("error creating nonlistening(%d) socket: %v", protocol, err)
}
if err := unix.Bind(fd, &unix.SockaddrUnix{Name: path}); err != nil {
return nil, fmt.Errorf("error binding nonlistening(%d) socket: %v", protocol, err)
}
cleanup = func() {
if err := unix.Close(fd); err != nil {
log.Warningf("Failed to close nonlistening(%d) socket: %v", protocol, err)
}
}
return cleanup, nil
}
// createNullSocket creates a socket that reads anything received.
//
// Only works for dgram sockets.
func createNullSocket(path string, protocol int) (cleanup func(), err error) {
fd, err := unix.Socket(unix.AF_UNIX, protocol, 0)
if err != nil {
return nil, fmt.Errorf("error creating null(%d) socket: %v", protocol, err)
}
if err := unix.Bind(fd, &unix.SockaddrUnix{Name: path}); err != nil {
return nil, fmt.Errorf("error binding null(%d) socket: %v", protocol, err)
}
s, err := unet.NewSocket(fd)
if err != nil {
return nil, fmt.Errorf("error creating null(%d) unet socket: %v", protocol, err)
}
go func() {
buf := make([]byte, 512)
for {
n, err := s.Read(buf)
if err != nil {
log.Warningf("failed to read: %d, %v", n, err)
return
}
}
}()
cleanup = func() {
if err := s.Close(); err != nil {
log.Warningf("Failed to close null(%d) socket: %v", protocol, err)
}
}
return cleanup, nil
}
type socketCreator func(path string, proto int) (cleanup func(), err error)
// CreateSocketTree creates a local tree of unix domain sockets for use in
// testing:
// * /stream/echo
// * /stream/nonlistening
// * /seqpacket/echo
// * /seqpacket/nonlistening
// * /dgram/null
func CreateSocketTree(baseDir string) (dir string, cleanup func(), err error) {
dir, err = ioutil.TempDir(baseDir, "sockets")
if err != nil {
return "", nil, fmt.Errorf("error creating temp dir: %v", err)
}
var protocols = []struct {
protocol int
name string
sockets map[string]socketCreator
}{
{
protocol: unix.SOCK_STREAM,
name: "stream",
sockets: map[string]socketCreator{
"echo": createEchoSocket,
"nonlistening": createNonListeningSocket,
},
},
{
protocol: unix.SOCK_SEQPACKET,
name: "seqpacket",
sockets: map[string]socketCreator{
"echo": createEchoSocket,
"nonlistening": createNonListeningSocket,
},
},
{
protocol: unix.SOCK_DGRAM,
name: "dgram",
sockets: map[string]socketCreator{
"null": createNullSocket,
},
},
}
var cleanups []func()
for _, proto := range protocols {
protoDir := filepath.Join(dir, proto.name)
if err := os.Mkdir(protoDir, 0755); err != nil {
return "", nil, fmt.Errorf("error creating %s dir: %v", proto.name, err)
}
for name, fn := range proto.sockets {
path := filepath.Join(protoDir, name)
cleanup, err := fn(path, proto.protocol)
if err != nil {
return "", nil, fmt.Errorf("error creating %s %s socket: %v", proto.name, name, err)
}
cleanups = append(cleanups, cleanup)
}
}
cleanup = func() {
for _, c := range cleanups {
c()
}
os.RemoveAll(dir)
}
return dir, cleanup, nil
}
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