client

package
v0.0.0-...-3d5c393 Latest Latest
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 Go to latest Published: Dec 16, 2024 License: BSD-3-Clause Imports: 33 Imported by: 1

Documentation

Overview

Package client provides an exec.Command and ssh like interface for cpu sessions. It attempts to cleave as much as possible to the original. The choice between options and environment variables mirrors this effort. For example, the nonce for the mount protocol back is an environment variable. command name and arguments are passed in os.Args The only required parameter for Command() is a host name; if os.Args is empty, the remote server reads SHELL and starts a shell. Similarly, because the root for the client namespace is known only to the client. it is settable in the Cmd struct.

This is a bit of an odd experiment. For the union, we build a unionfs, and a cpiofs. But a cpiofs, most of the time, says "can't do that." Hence the cpiofs is the "default" case for file operations, and this system mounts "in front of" the cpio. Rather than having the cpio fail anything looking like a write, we embed a struct in the fs that performs those operations on the mounts. Still an experiment, and whether the simplification of having one, not two, file systems is worth the increased complexity is an open question.

Index

Constants

View Source 
const (

	// DefaultNameSpace is the default used if the user does not request
	// something else.
	DefaultNameSpace = "/lib:/lib64:/usr:/bin:/etc:/home"
)
View Source 
const (
	// DefaultPort is the default cpu port.
	DefaultPort = "17010"
)

Variables

View Source 
var (
	// DefaultKeyFile is the default key for cpu users.
	DefaultKeyFile = filepath.Join(os.Getenv("HOME"), ".ssh/cpu_rsa")
	// Debug9p enables 9p debugging.
	Debug9p bool
	// Dump9p enables dumping 9p packets.
	Dump9p bool
	// DumpWriter is an io.Writer to which dump packets are written.
	DumpWriter io.Writer = os.Stderr
)

Functions

func GetHostName 

func GetHostName(host string) string

GetHostName reads the host name from the ssh config file, if needed. If it is not found, the host name is returned.

func GetHostUser 

func GetHostUser(n string) (host, user string)

GetHostUser gets the user and host name. In ssh syntax, these can be in one string, or defined in .ssh/config, or (for user), as $USER. Given that just about anything can be valid, and errors will be caught in other places, it does not return an error. Also, experimentally, in the name@host form, name overrides any use name that might be in .ssh/config. Host, on the other hand, is always determined from .ssh/config. The host name is also pulled from .ssh/config; calls to GetHostName can be replaced as needed, but that's for the future.

func GetKeyFile 

func GetKeyFile(host, kf string) string

GetKeyFile picks a keyfile if none has been set. It will use ssh config, else use a default.

func GetPort 

func GetPort(host, port string) (string, error)

GetPort gets a port. It verifies that the port fits in 16-bit space. The rules here are messy, since config.Get will return "22" if there is no entry in .ssh/config.

func JoinFSTab 

func JoinFSTab(tables ...string) string

JoinFSTab joins an arbitrary number of fstab-style strings. The intent is to deal with strings that may not be well formatted as provided by users, e.g. too many newlines, not enough, and so on.

func NewNullAuthHandler 

func NewNullAuthHandler(l net.Listener, fs billy.Filesystem, nonce string) nfs.Handler

NewNullAuthHandler creates a handler for the provided filesystem TODO: see if the newer NFS can supply this.

func NewOSFS 

func NewOSFS(r string) billy.Filesystem

NewOSFS returns a billy.FileSystem for a path.

func NewfsCPIO 

func NewfsCPIO(c string, mounts ...MountPoint) (*fsCPIO, error)

NewfsCPIO returns a fsCPIO, properly initialized. c is a string, referencing a CPIO file. If it is non-zero length, the CPIO file becomes the "backing root" for the namespace. This allows the use of flattened docker containers, so that one does not always need to run docker to use a docker container.

func ParseBinds 

func ParseBinds(s string) (string, error)

ParseBinds parses a CPU_NAMESPACE-style string to a an fstab format string.

func SetVerbose 

func SetVerbose(f func(string, ...interface{}))

SetVerbose sets the verbose printing function. e.g., one might call SetVerbose(log.Printf)

func SrvNFS 

func SrvNFS(cl *Cmd, n string, dir string) (func() error, string, error)

SrvNFS sets up an nfs server. n, which can be empty, names a CPIO file for the "backing root". dir is used for a root, or possibly limited to $HOME. dir of more than 1 element is still not supported. This API will change if needs dictate. So far its simplicity has been sufficient.

Types

type COS 

type COS struct {
	billy.Filesystem
}

COS or OSFS + Change wraps a billy.FS to not fail the `Change` interface.

func (COS) Chmod 

func (fs COS) Chmod(name string, mode os.FileMode) error

Chmod changes mode

func (COS) Chown 

func (fs COS) Chown(name string, uid, gid int) error

Chown changes ownership

func (COS) Chtimes 

func (fs COS) Chtimes(name string, atime time.Time, mtime time.Time) error

Chtimes changes access time

func (COS) Lchown 

func (fs COS) Lchown(name string, uid, gid int) error

Lchown changes ownership. As in lchown(2), it does not follow a symlink.

type CPIO9P 

type CPIO9P struct {
	p9.DefaultWalkGetAttr
	// contains filtered or unexported fields
}

CPIO9P is a p9.Attacher.

func NewCPIO9P 

func NewCPIO9P(c string) (*CPIO9P, error)

NewCPIO9P returns a CPIO9P, properly initialized, from a path.

func NewCPIO9PReaderAt 

func NewCPIO9PReaderAt(r io.ReaderAt) (*CPIO9P, error)

NewCPIO9PReaderAt returns a CPIO9P, properly initialized, from an io.ReaderAt.

func (*CPIO9P) Attach 

func (s *CPIO9P) Attach() (p9.File, error)

Attach implements p9.Attacher.Attach. Only works for root.

type CPIO9PFID 

type CPIO9PFID struct {
	p9.DefaultWalkGetAttr
	templatefs.XattrUnimplemented
	templatefs.NilCloser
	templatefs.NilSyncer
	templatefs.NoopRenamed
	// contains filtered or unexported fields
}

CPIO9PFID defines a FID. It kind of sucks because it has a pointer for every FID. Luckily they go away when clunked.

func (*CPIO9PFID) Create 

func (l *CPIO9PFID) Create(name string, mode p9.OpenFlags, permissions p9.FileMode, _ p9.UID, _ p9.GID) (p9.File, p9.QID, uint32, error)

Create implements p9.File.Create.

func (*CPIO9PFID) Flush 

func (l *CPIO9PFID) Flush() error

Flush implements p9.File.Flush.

func (*CPIO9PFID) GetAttr 

func (l *CPIO9PFID) GetAttr(req p9.AttrMask) (p9.QID, p9.AttrMask, p9.Attr, error)

GetAttr implements p9.File.GetAttr.

Not fully implemented. 

func (l *CPIO9PFID) Link(target p9.File, newname string) error

Link implements p9.File.Link.

Not properly implemented.

func (*CPIO9PFID) Lock 

func (*CPIO9PFID) Lock(pid int, locktype p9.LockType, flags p9.LockFlags, start, length uint64, client string) (p9.LockStatus, error)

Lock implements lock by doing nothing.

func (*CPIO9PFID) Mkdir 

func (l *CPIO9PFID) Mkdir(name string, permissions p9.FileMode, _ p9.UID, _ p9.GID) (p9.QID, error)

Mkdir implements p9.File.Mkdir.

Not properly implemented.

func (*CPIO9PFID) Mknod 

func (*CPIO9PFID) Mknod(name string, mode p9.FileMode, major uint32, minor uint32, _ p9.UID, _ p9.GID) (p9.QID, error)

Mknod implements p9.File.Mknod.

func (*CPIO9PFID) Open 

func (l *CPIO9PFID) Open(mode p9.OpenFlags) (p9.QID, uint32, error)

Open implements p9.File.Open.

func (*CPIO9PFID) ReadAt 

func (l *CPIO9PFID) ReadAt(p []byte, offset int64) (int, error)

ReadAt implements p9.File.ReadAt.

func (*CPIO9PFID) Readdir 

func (l *CPIO9PFID) Readdir(offset uint64, count uint32) (p9.Dirents, error)

Readdir implements p9.File.Readdir. This is a bit of a mess in cpio, but the good news is that files will be in some sort of order ... 

func (l *CPIO9PFID) Readlink() (string, error)

Readlink implements p9.File.Readlink.

func (*CPIO9PFID) Rename 

func (*CPIO9PFID) Rename(directory p9.File, name string) error

Rename implements p9.File.Rename.

func (*CPIO9PFID) RenameAt 

func (l *CPIO9PFID) RenameAt(oldName string, newDir p9.File, newName string) error

RenameAt implements p9.File.RenameAt. There is no guarantee that there is not a zipslip issue.

func (*CPIO9PFID) SetAttr 

func (l *CPIO9PFID) SetAttr(mask p9.SetAttrMask, attr p9.SetAttr) error

SetAttr implements SetAttr.

func (*CPIO9PFID) StatFS 

func (*CPIO9PFID) StatFS() (p9.FSStat, error)

StatFS implements p9.File.StatFS.

Not implemented. 

func (l *CPIO9PFID) Symlink(oldname string, newname string, _ p9.UID, _ p9.GID) (p9.QID, error)

Symlink implements p9.File.Symlink.

Not properly implemented.

func (*CPIO9PFID) UnlinkAt 

func (l *CPIO9PFID) UnlinkAt(name string, flags uint32) error

UnlinkAt implements p9.File.UnlinkAt.

func (*CPIO9PFID) Walk 

func (l *CPIO9PFID) Walk(names []string) ([]p9.QID, p9.File, error)

Walk implements p9.File.Walk.

func (*CPIO9PFID) WriteAt 

func (l *CPIO9PFID) WriteAt(p []byte, offset int64) (int, error)

WriteAt implements p9.File.WriteAt.

type CPU9P 

type CPU9P struct {
	p9.DefaultWalkGetAttr
	// contains filtered or unexported fields
}

CPU9P is a p9.Attacher.

func NewCPU9P 

func NewCPU9P(root string) *CPU9P

NewCPU9P returns a CPU9P, properly initialized.

func (*CPU9P) Attach 

func (l *CPU9P) Attach() (p9.File, error)

Attach implements p9.Attacher.Attach.

func (*CPU9P) Close 

func (l *CPU9P) Close() error

Close implements p9.File.Close.

func (*CPU9P) Create 

func (l *CPU9P) Create(name string, mode p9.OpenFlags, permissions p9.FileMode, _ p9.UID, _ p9.GID) (p9.File, p9.QID, uint32, error)

Create implements p9.File.Create.

func (*CPU9P) FSync 

func (l *CPU9P) FSync() error

FSync implements p9.File.FSync.

func (*CPU9P) Flush 

func (l *CPU9P) Flush() error

Flush implements p9.File.Flush.

func (*CPU9P) GetAttr 

func (l *CPU9P) GetAttr(req p9.AttrMask) (p9.QID, p9.AttrMask, p9.Attr, error)

GetAttr implements p9.File.GetAttr.

Not fully implemented.

func (*CPU9P) GetXattr 

func (l *CPU9P) GetXattr(attr string) ([]byte, error)

GetXattr implements p9.File.GetXattr 

func (l *CPU9P) Link(target p9.File, newname string) error

Link implements p9.File.Link.

Not properly implemented.

func (*CPU9P) ListXattrs 

func (l *CPU9P) ListXattrs() ([]string, error)

ListXattrs implements p9.File.ListXattrs

func (*CPU9P) Lock 

func (l *CPU9P) Lock(pid int, locktype p9.LockType, flags p9.LockFlags, start, length uint64, client string) (p9.LockStatus, error)

Lock implements p9.File.Lock.

func (*CPU9P) Mkdir 

func (l *CPU9P) Mkdir(name string, permissions p9.FileMode, _ p9.UID, _ p9.GID) (p9.QID, error)

Mkdir implements p9.File.Mkdir.

Not properly implemented.

func (*CPU9P) Mknod 

func (*CPU9P) Mknod(name string, mode p9.FileMode, major uint32, minor uint32, _ p9.UID, _ p9.GID) (p9.QID, error)

Mknod implements p9.File.Mknod.

func (*CPU9P) Open 

func (l *CPU9P) Open(mode p9.OpenFlags) (p9.QID, uint32, error)

Open implements p9.File.Open.

func (*CPU9P) ReadAt 

func (l *CPU9P) ReadAt(p []byte, offset int64) (int, error)

ReadAt implements p9.File.ReadAt.

func (*CPU9P) Readdir 

func (l *CPU9P) Readdir(offset uint64, count uint32) (p9.Dirents, error)

Readdir implements p9.File.Readdir. 

func (l *CPU9P) Readlink() (string, error)

Readlink implements p9.File.Readlink.

func (*CPU9P) Remove 

func (l *CPU9P) Remove() error

Remove implements p9.File.Remove

func (*CPU9P) RemoveXattr 

func (l *CPU9P) RemoveXattr(attr string) error

RemoveXattr implements p9.File.RemoveXattr

func (*CPU9P) Rename 

func (*CPU9P) Rename(directory p9.File, name string) error

Rename implements p9.File.Rename.

func (*CPU9P) RenameAt 

func (l *CPU9P) RenameAt(oldName string, newDir p9.File, newName string) error

RenameAt implements p9.File.RenameAt. There is no guarantee that there is not a zipslip issue.

func (*CPU9P) Renamed 

func (l *CPU9P) Renamed(parent p9.File, newName string)

Renamed implements p9.File.Renamed.

func (*CPU9P) SetAttr 

func (l *CPU9P) SetAttr(mask p9.SetAttrMask, attr p9.SetAttr) error

SetAttr implements p9.File.SetAttr.

func (*CPU9P) SetXattr 

func (l *CPU9P) SetXattr(attr string, data []byte, flags p9.XattrFlags) error

SetXattr implements p9.File.SetXattr

func (*CPU9P) StatFS 

func (*CPU9P) StatFS() (p9.FSStat, error)

StatFS implements p9.File.StatFS.

Not implemented. 

func (l *CPU9P) Symlink(oldname string, newname string, _ p9.UID, _ p9.GID) (p9.QID, error)

Symlink implements p9.File.Symlink.

Not properly implemented.

func (*CPU9P) UnlinkAt 

func (l *CPU9P) UnlinkAt(name string, flags uint32) error

UnlinkAt implements p9.File.UnlinkAt. The flags docs are not very clear, but we always block on the unlink anyway.

func (*CPU9P) Walk 

func (l *CPU9P) Walk(names []string) ([]p9.QID, p9.File, error)

Walk implements p9.File.Walk.

func (*CPU9P) WriteAt 

func (l *CPU9P) WriteAt(p []byte, offset int64) (int, error)

WriteAt implements p9.File.WriteAt. There is a very rare case where O_APPEND files are written more than once, and we get an error. That error is generated by the Go runtime, after checking the open flag in the os.File struct. I.e. the error is not generated by a system call, so it is very cheap to try the WriteAt, check the error, and call Write if it is the rare case of a second write to an append-only file..

type Cmd 

type Cmd struct {

	// CPU-specific options.
	// As in exec.Command, these controls are exposed and can
	// be set directly.
	Host string
	// HostName as found in .ssh/config; set to Host if not found
	HostName          string
	Args              []string
	Root              string
	HostKeyFile       string
	PrivateKeyFile    string
	DisablePrivateKey bool
	Port              string
	Timeout           time.Duration
	Env               []string
	SessionIn         io.WriteCloser
	SessionOut        io.Reader
	SessionErr        io.Reader
	Stdin             io.Reader
	Stdout            io.Writer
	Stderr            io.Writer
	Row               int
	Col               int

	// NameSpace is a string as defined in the cpu documentation.
	NameSpace string
	// FSTab is an fstab(5)-format string
	FSTab string
	// Ninep determines if client will run a 9P server
	Ninep bool
	// contains filtered or unexported fields
}

Cmd is a cpu client. It implements as much of exec.Command as makes sense.

func Command 

func Command(host string, args ...string) *Cmd

Command implements exec.Command. The required parameter is a host. The args arg args to $SHELL. If there are no args, then starting $SHELL is assumed.

func (*Cmd) Close 

func (c *Cmd) Close() error

Close ends a cpu session, doing whatever is needed.

func (*Cmd) Dial 

func (c *Cmd) Dial() error

Dial implements ssh.Dial for cpu. Additionaly, if Cmd.Root is not "", it starts up a server for 9p requests. Note that any bind parsing is deferred until this point, to avoid callers getting ordering of setting variables in the Cmd wrong.

func (*Cmd) HostKeyConfig 

func (c *Cmd) HostKeyConfig(hostKeyFile string) error

HostKeyConfig sets the host key. It is optional.

func (*Cmd) Listen 

func (c *Cmd) Listen(n, addr string) (net.Listener, error)

Listen implements net.Listen on the ssh socket.

func (*Cmd) Outputs 

func (c *Cmd) Outputs() ([]bytes.Buffer, error)

Outputs returns a slice of bytes.Buffer for stdout and stderr, and an error if either had trouble being read.

func (*Cmd) Run 

func (c *Cmd) Run() error

Run runs a command with Start, and waits for it to finish with Wait.

func (*Cmd) SSHStdin 

func (c *Cmd) SSHStdin(w io.WriteCloser, r io.Reader)

SSHStdin implements an ssh-like reader, honoring ~ commands.

func (*Cmd) SetEnv 

func (c *Cmd) SetEnv(envs ...string) error

SetEnv sets zero or more environment variables for a Session. If envs is nil or a zero length slice, no variables are set.

func (*Cmd) SetOptions 

func (c *Cmd) SetOptions(opts ...Set) error

SetOptions sets various options into the Command.

func (*Cmd) SetupInteractive 

func (c *Cmd) SetupInteractive() error

SetupInteractive sets up a cpu client for interactive access. It adds a function to c.Closers to clean up the terminal.

func (*Cmd) Signal 

func (c *Cmd) Signal(s ssh.Signal) error

Signal implements ssh.Signal

func (*Cmd) Start 

func (c *Cmd) Start() error

Start implements exec.Start for CPU.

func (*Cmd) TTYIn 

func (c *Cmd) TTYIn(s *ssh.Session, w io.WriteCloser, r io.Reader)

TTYIn manages tty input for a cpu session. It exists mainly to deal with ~.

func (*Cmd) UserKeyConfig 

func (c *Cmd) UserKeyConfig() error

UserKeyConfig sets up authentication for a User Key. It is required in almost all cases.

func (*Cmd) Wait 

func (c *Cmd) Wait() error

Wait waits for a Cmd to finish.

type MountPoint 

type MountPoint struct {
	// contains filtered or unexported fields
}

MountPoint is a mountpoint in an fsCPIO

func WithMount 

func WithMount(n string, fs billy.Filesystem) MountPoint

WithMount allows the addition of mounts to an fsCPIO, as part of a NewfsCPIO call.

type NullAuthHandler 

type NullAuthHandler struct {
	// contains filtered or unexported fields
}

NullAuthHandler returns a NFS backing that exposes a given file system in response to all mount requests.

func (*NullAuthHandler) Change 

func (h *NullAuthHandler) Change(fs billy.Filesystem) billy.Change

Change provides an interface for updating file attributes.

func (*NullAuthHandler) FSStat 

func (h *NullAuthHandler) FSStat(ctx context.Context, f billy.Filesystem, s *nfs.FSStat) error

FSStat provides information about a filesystem.

func (*NullAuthHandler) FromHandle 

func (h *NullAuthHandler) FromHandle([]byte) (billy.Filesystem, []string, error)

FromHandle is handled by CachingHandler

func (*NullAuthHandler) HandleLimit 

func (h *NullAuthHandler) HandleLimit() int

HandleLimit is handled by cachingHandler

func (*NullAuthHandler) InvalidateHandle 

func (c *NullAuthHandler) InvalidateHandle(billy.Filesystem, []byte) error

InvalidateHandle is handled by cachingHandler

func (*NullAuthHandler) Mount 

func (h *NullAuthHandler) Mount(ctx context.Context, conn net.Conn, req nfs.MountRequest) (status nfs.MountStatus, hndl billy.Filesystem, auths []nfs.AuthFlavor)

Mount backs Mount RPC Requests, allowing for access control policies.

func (*NullAuthHandler) ToHandle 

func (h *NullAuthHandler) ToHandle(f billy.Filesystem, s []string) []byte

ToHandle is handled by CachingHandler

type Set 

type Set func(*Cmd) error

Set is the type of function used to set options in SetOptions.

func With9P 

func With9P(p9 bool) Set

With9P enables the 9P2000 server in cpu. The server is by default disabled.

func WithDisablePrivateKey 

func WithDisablePrivateKey(disable bool) Set

WithDisablePrivateKey disables using private keys to encrypt the SSH connection.

func WithFSTab 

func WithFSTab(fstab string) Set

WithFSTab reads a file for the FSTab member.

func WithHostKeyFile 

func WithHostKeyFile(key string) Set

WithHostKeyFile adds a host key to a Cmd

func WithNameSpace 

func WithNameSpace(ns string) Set

WithNameSpace sets the namespace to Cmd.There is no default: having some default violates the principle of least surprise for package users.

func WithNetwork 

func WithNetwork(network string) Set

WithNetwork sets the network. This almost never needs to be set, save for vsock.

func WithPort 

func WithPort(port string) Set

WithPort sets the port in the Cmd. It calls GetPort with the passed-in port before assigning it.

func WithPrivateKeyFile 

func WithPrivateKeyFile(key string) Set

WithPrivateKeyFile adds a private key file to a Cmd

func WithRoot 

func WithRoot(root string) Set

WithRoot adds a root to a Cmd

func WithServer 

func WithServer(a p9.Attacher) Set

WithServer allows setting custom 9P servers. One use: should users wish to serve from a flattened docker container saved as a cpio or tar.

func WithTimeout 

func WithTimeout(timeout string) Set

WithTimeout sets the 9p timeout.

type Union9P 

type Union9P struct {
	// contains filtered or unexported fields
}

Union9P is a p9.Attacher.

func NewUnion9P 

func NewUnion9P(mounts []UnionMount) (*Union9P, error)

NewUnion9P returns a Union9P, properly initialized, from a []UnionMount. Each UnionMount has a []string that defines a walk path. The []string argument is matched to each walk path in the []UnionMount in turn. As in Plan 9, the first match is used; if the walk to that server fails, the code returns the error; it does not go any further.

I.e., if /home and /home/rminnich are in the table, they need to be in the order /home/rminnich /home in the case that the second mount does not include /home/rminnich. (it could be from a different 9p server, for example). Having a UnionMount with an empty []string is allowed; this will match any walk []string and hence acts as a default.

For example, in Sidecore, the code looks like this: home, err := NewCPU9P(...) container, err := NewCPIO9(...) m1 := NewUnionMount([]string{"/home"}, home) m2 := NewUnionMount([]string{}, container) u := NewUnion9P([]UnionMount{home, container}) This ensures /home matches first, and the container CPIO matches the rest.

If a default is not desired, callers should only use Union Mount structs with non-empty []string. Only one Mount with an empty walk slice should be used, as the search will always stop there. It is allowed to have multiple Mounts for a single p9.File. E.g, give a p9.File, f, once can: m1 := NewUnionMount([]string{"/etc", f) m2 := NewUnionMount([]string{"/bin", f) u := NewUnion9P([]UnionMount{m1, m2}) and no matter what other directories exist in f, only /etc and /bin will match.

Again, to add a default case, using, e.g., another p9.File, one might have m1 := NewUnionMount([]string{"/etc}", f) m2 := NewUnionMount([]string{"/bin}", f) mdefault := NewUnionMount([]string{""}, fi2) u := NewUnion9P([]UnionMount{m1, m2, mdefault})

func (*Union9P) Attach 

func (u *Union9P) Attach() (p9.File, error)

Attach implements p9.Attacher.Attach.

type UnionMount 

type UnionMount struct {
	// contains filtered or unexported fields
}

Bind is a single bind For a given Twalk, the walk []string will be compared to the string slice in the Twalk. If there is match, the mount is called with the complete Twalk []string.

func NewUnionMount 

func NewUnionMount(w []string, m p9.File) UnionMount

NewUnionMount creates a new Union Mount from a []string and a p9.File.

Source Files

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