clawbot
8bb3d949d9
check / check (push) Waiting to run
A SIGINT, SIGTERM or SIGHUP at the mnemonic prompt killed the tool with echo still off. The prompt now catches them from before echo goes off and reads the line in a goroutine. Once the line is read or a signal arrives, it puts the terminal settings back and stops catching; if a signal has arrived by then, it sends the tool the same signal again, so the tool is still ended by it (130 for SIGINT in a shell). A test sends SIGINT at the prompt on a pseudo-terminal. The signals package moves from internal/cli to internal/signals, since the mnemonic prompt now uses it as well. Untested: a signal that comes just as the line is read. Model: opus-5-5
118 lines
3.1 KiB
Go
118 lines
3.1 KiB
Go
package ssh
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import (
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"context"
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"errors"
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"fmt"
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"os"
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"os/exec"
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"slices"
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"syscall"
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"github.com/spf13/cobra"
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"sneak.berlin/go/keyfunc/internal/mnemonic"
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"sneak.berlin/go/keyfunc/internal/signals"
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)
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// StatusError says the tool should end with the status ssh ended with.
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// Only "ssh to" gives one back; every other error ends the tool with
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// status 1.
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type StatusError struct {
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Status int
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}
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// Error says which status ssh ended with.
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func (e StatusError) Error() string {
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return fmt.Sprintf("ssh exited with status %d", e.Status)
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}
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// to returns the command that runs ssh with the derived key held by an
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// agent of the tool's own.
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func to() *cobra.Command {
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cmd := &cobra.Command{
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Use: "to <host> [ssh arguments...]",
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Short: "run ssh with the derived key served from its own agent",
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Long: "Serves the derived key from an SSH agent that runs " +
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"inside the tool and points the system ssh at it. The host " +
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"and everything after it are given to ssh unchanged, the " +
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"tool ends with the status ssh ended with, and the key is " +
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"never written to disk.",
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Args: cobra.MinimumNArgs(1),
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RunE: func(cmd *cobra.Command, args []string) error {
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key, comment, err := derived(cmd)
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if err != nil {
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return err
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}
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// From here until the agent is taken down, a signal
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// cancels the context instead of ending the tool, so
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// ssh ends and the socket and its directory are still
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// removed.
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ctx, stop := signals.Context(cmd.Context())
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defer stop()
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served, err := key.Serve(ctx, comment)
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if err != nil {
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return err
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}
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defer served.Stop()
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// IdentitiesOnly yes in the user's ssh configuration
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// would keep the agent's key from being offered. The
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// agent holds only the derived key, so turning it off
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// adds no other key.
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argv := slices.Concat([]string{
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"-o", "IdentityAgent=" + served.Socket(),
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"-o", "IdentitiesOnly=no",
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}, args)
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return connect(ctx, argv)
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},
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}
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// Everything from the host onwards belongs to ssh, so flag
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// reading stops at the first argument that is not a flag.
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cmd.Flags().SetInterspersed(false)
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addComment(cmd)
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return cmd
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}
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// connect runs ssh on the terminal the tool was given and turns the
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// status it ended with into the status the tool ends with.
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func connect(ctx context.Context, argv []string) error {
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//nolint:gosec // the arguments are the user's own, meant for ssh
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command := exec.CommandContext(ctx, "ssh", argv...)
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command.Env = mnemonic.ChildEnv()
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command.Stdin = os.Stdin
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command.Stdout = os.Stdout
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command.Stderr = os.Stderr
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// A cancelled context means a signal arrived. Send ssh a
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// SIGTERM rather than the default kill, so it puts the terminal
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// back the way it found it before it goes.
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command.Cancel = func() error {
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return command.Process.Signal(syscall.SIGTERM)
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}
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err := command.Run()
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if err == nil {
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return nil
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}
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if ended, ok := errors.AsType[*exec.ExitError](err); ok {
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status := ended.ExitCode()
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if status < 0 {
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// A signal ended ssh, and a signal has no status of its
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// own to pass on.
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status = 1
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}
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return StatusError{Status: status}
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}
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return fmt.Errorf("running ssh: %w", err)
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}
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