tools/mounttable/impl.go

package main

import (
	"errors"
	"fmt"
	"time"

	"v.io/lib/cmdline"
	"v.io/v23"
	"v.io/v23/context"
	"v.io/v23/ipc"
	"v.io/v23/naming"
	"v.io/v23/options"
	"v.io/v23/security"
	"v.io/v23/vlog"
)

var cmdGlob = &cmdline.Command{
	Run:      runGlob,
	Name:     "glob",
	Short:    "returns all matching entries in the mount table",
	Long:     "returns all matching entries in the mount table",
	ArgsName: "[<mount name>] <pattern>",
	ArgsLong: `
<mount name> is a mount name on a mount table.  Defaults to namespace root.
<pattern> is a glob pattern that is matched against all the entries below the
specified mount name.
`,
}

func runGlob(cmd *cmdline.Command, args []string) error {
	ctx, cancel := context.WithTimeout(gctx, time.Minute)
	defer cancel()

	if len(args) == 1 {
		roots := v23.GetNamespace(ctx).Roots()
		if len(roots) == 0 {
			return errors.New("no namespace root")
		}
		args = append([]string{roots[0]}, args...)
	}
	if expected, got := 2, len(args); expected != got {
		return cmd.UsageErrorf("glob: incorrect number of arguments, expected %d, got %d", expected, got)
	}

	name, pattern := args[0], args[1]
	client := v23.GetClient(ctx)
	call, err := client.StartCall(ctx, name, ipc.GlobMethod, []interface{}{pattern}, options.NoResolve{})
	if err != nil {
		return err
	}
	for {
		var gr naming.VDLGlobReply
		if err := call.Recv(&gr); err != nil {
			break
		}
		switch v := gr.(type) {
		case naming.VDLGlobReplyEntry:
			fmt.Fprint(cmd.Stdout(), v.Value.Name)
			for _, s := range v.Value.Servers {
				fmt.Fprintf(cmd.Stdout(), " %s (TTL %s)", s.Server, time.Duration(s.TTL)*time.Second)
			}
			fmt.Fprintln(cmd.Stdout())
		}
	}
	if err := call.Finish(); err != nil {
		return err
	}
	return nil
}

type blessingPatterns struct {
	list []security.BlessingPattern
}

func (bp *blessingPatterns) Set(s string) error {
	bp.list = append(bp.list, security.BlessingPattern(s))
	return nil
}

func (bp *blessingPatterns) String() string {
	return fmt.Sprintf("%v", bp.list)
}

func (bp *blessingPatterns) Get() interface{} { return bp.list }

var flagMountBlessingPatterns blessingPatterns

var cmdMount = &cmdline.Command{
	Run:      runMount,
	Name:     "mount",
	Short:    "Mounts a server <name> onto a mount table",
	Long:     "Mounts a server <name> onto a mount table",
	ArgsName: "<mount name> <name> <ttl> [M|R]",
	ArgsLong: `
<mount name> is a mount name on a mount table.

<name> is the rooted object name of the server.

<ttl> is the TTL of the new entry. It is a decimal number followed by a unit
suffix (s, m, h). A value of 0s represents an infinite duration.

[M|R] are mount options. M indicates that <name> is a mounttable. R indicates
that existing entries should be removed.
`,
}

func runMount(cmd *cmdline.Command, args []string) error {
	got := len(args)
	if got < 2 || got > 4 {
		return cmd.UsageErrorf("mount: incorrect number of arguments, expected 2, 3, or 4, got %d", got)
	}
	name := args[0]
	server := args[1]
	var flags naming.MountFlag
	var seconds uint32
	if got >= 3 {
		ttl, err := time.ParseDuration(args[2])
		if err != nil {
			return fmt.Errorf("TTL parse error: %v", err)
		}
		seconds = uint32(ttl.Seconds())
	}
	if got >= 4 {
		for _, c := range args[3] {
			switch c {
			case 'M':
				flags |= naming.MountFlag(naming.MT)
			case 'R':
				flags |= naming.MountFlag(naming.Replace)
			}
		}
	}
	ctx, cancel := context.WithTimeout(gctx, time.Minute)
	defer cancel()
	client := v23.GetClient(ctx)

	patterns := flagMountBlessingPatterns.list
	if len(patterns) == 0 {
		var err error
		if patterns, err = blessingPatternsFromServer(ctx, server); err != nil {
			return err
		}
		vlog.Infof("Server at %q has blessings %v", name, patterns)
	}
	call, err := client.StartCall(ctx, name, "MountX", []interface{}{server, patterns, seconds, flags}, options.NoResolve{})
	if err != nil {
		return err
	}
	if err := call.Finish(); err != nil {
		return err
	}
	fmt.Fprintln(cmd.Stdout(), "Name mounted successfully.")
	return nil
}

var cmdUnmount = &cmdline.Command{
	Run:      runUnmount,
	Name:     "unmount",
	Short:    "removes server <name> from the mount table",
	Long:     "removes server <name> from the mount table",
	ArgsName: "<mount name> <name>",
	ArgsLong: `
<mount name> is a mount name on a mount table.
<name> is the rooted object name of the server.
`,
}

func runUnmount(cmd *cmdline.Command, args []string) error {
	if expected, got := 2, len(args); expected != got {
		return cmd.UsageErrorf("unmount: incorrect number of arguments, expected %d, got %d", expected, got)
	}
	ctx, cancel := context.WithTimeout(gctx, time.Minute)
	defer cancel()
	client := v23.GetClient(ctx)
	call, err := client.StartCall(ctx, args[0], "Unmount", []interface{}{args[1]}, options.NoResolve{})
	if err != nil {
		return err
	}
	if err := call.Finish(); err != nil {
		return err
	}
	fmt.Fprintln(cmd.Stdout(), "Unmount successful or name not mounted.")
	return nil
}

var cmdResolveStep = &cmdline.Command{
	Run:      runResolveStep,
	Name:     "resolvestep",
	Short:    "takes the next step in resolving a name.",
	Long:     "takes the next step in resolving a name.",
	ArgsName: "<mount name>",
	ArgsLong: `
<mount name> is a mount name on a mount table.
`,
}

func runResolveStep(cmd *cmdline.Command, args []string) error {
	if expected, got := 1, len(args); expected != got {
		return cmd.UsageErrorf("mount: incorrect number of arguments, expected %d, got %d", expected, got)
	}
	ctx, cancel := context.WithTimeout(gctx, time.Minute)
	defer cancel()
	client := v23.GetClient(ctx)
	call, err := client.StartCall(ctx, args[0], "ResolveStep", []interface{}{}, options.NoResolve{})
	if err != nil {
		return err
	}
	var entry naming.VDLMountEntry
	if err := call.Finish(&entry); err != nil {
		return err
	}
	fmt.Fprintf(cmd.Stdout(), "Servers: %v Suffix: %q MT: %v\n", entry.Servers, entry.Name, entry.MT)
	return nil
}

func root() *cmdline.Command {
	cmdMount.Flags.Var(&flagMountBlessingPatterns, "blessing_pattern", "blessing pattern that matches the blessings of the server being mounted. Can be specified multiple times to add multiple patterns. If none is provided, the server will be contacted to determine this value.")
	return &cmdline.Command{
		Name:  "mounttable",
		Short: "Tool for interacting with a Veyron mount table",
		Long: `
The mounttable tool facilitates interaction with a Veyron mount table.
`,
		Children: []*cmdline.Command{cmdGlob, cmdMount, cmdUnmount, cmdResolveStep},
	}
}

func blessingPatternsFromServer(ctx *context.T, server string) ([]security.BlessingPattern, error) {
	vlog.Infof("Contacting %q to determine the blessings presented by it", server)
	ctx, cancel := context.WithTimeout(ctx, time.Minute)
	defer cancel()
	call, err := v23.GetClient(ctx).StartCall(ctx, server, ipc.ReservedSignature, nil)
	if err != nil {
		return nil, fmt.Errorf("Unable to extract blessings presented by %q: %v", server, err)
	}
	blessings, _ := call.RemoteBlessings()
	if len(blessings) == 0 {
		return nil, fmt.Errorf("No recognizable blessings presented by %q, it cannot be securely mounted", server)
	}
	// This translation between BlessingPattern and string is silly!
	// Kill the BlessingPatterns type and make methods on that type
	// functions instead!
	patterns := make([]security.BlessingPattern, len(blessings))
	for i := range blessings {
		patterns[i] = security.BlessingPattern(blessings[i])
	}
	return patterns, nil
}