Revert "remove podman system connection"

This reverts commit 66e1626282fab661ac12a354f70b3b2221c69d7c. We
are reenabling podman-system-connection.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

3 files changed, 246 insertions, 0 deletions

diff --git a/cmd/podman/system/connection.go b/cmd/podman/system/connection.go
new file mode 100644
index 000000000..bdb113ea3
--- /dev/null
+++ b/cmd/podman/system/connection.go
@@ -0,0 +1,208 @@
+package system
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"os/user"
+	"regexp"
+
+	"github.com/containers/common/pkg/config"
+	"github.com/containers/libpod/v2/cmd/podman/registry"
+	"github.com/containers/libpod/v2/libpod/define"
+	"github.com/containers/libpod/v2/pkg/domain/entities"
+	"github.com/containers/libpod/v2/pkg/terminal"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+)
+
+const schemaPattern = "^[A-Za-z][A-Za-z0-9+.-]*:"
+
+var (
+	// Skip creating engines since this command will obtain connection information to engine
+	noOp = func(cmd *cobra.Command, args []string) error {
+		return nil
+	}
+	connectionCmd = &cobra.Command{
+		Use:  "connection [flags] destination",
+		Args: cobra.ExactArgs(1),
+		Long: `Store ssh destination information in podman configuration.
+  "destination" is of the form [user@]hostname or
+  an URI of the form ssh://[user@]hostname[:port]
+`,
+		Short:              "Record remote ssh destination",
+		PersistentPreRunE:  noOp,
+		PersistentPostRunE: noOp,
+		TraverseChildren:   false,
+		RunE:               connection,
+		Example: `podman system connection server.fubar.com
+  podman system connection --identity ~/.ssh/dev_rsa ssh://root@server.fubar.com:2222
+  podman system connection --identity ~/.ssh/dev_rsa --port 22 root@server.fubar.com`,
+	}
+
+	cOpts = struct {
+		Identity string
+		Port     int
+		UDSPath  string
+	}{}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: connectionCmd,
+		Parent:  systemCmd,
+	})
+
+	flags := connectionCmd.Flags()
+	flags.IntVarP(&cOpts.Port, "port", "p", 22, "port number for destination")
+	flags.StringVar(&cOpts.UDSPath, "socket-path", "", "path to podman socket on remote host. (default '/run/podman/podman.sock' or '/run/user/{uid}/podman/podman.sock)")
+}
+
+func connection(cmd *cobra.Command, args []string) error {
+	// Default to ssh: schema if none given
+	dest := []byte(args[0])
+	if match, err := regexp.Match(schemaPattern, dest); err != nil {
+		return errors.Wrapf(err, "internal regex error %q", schemaPattern)
+	} else if !match {
+		dest = append([]byte("ssh://"), dest...)
+	}
+
+	uri, err := url.Parse(string(dest))
+	if err != nil {
+		return errors.Wrapf(err, "failed to parse %q", string(dest))
+	}
+
+	if uri.User.Username() == "" {
+		if uri.User, err = getUserInfo(uri); err != nil {
+			return err
+		}
+	}
+
+	if cmd.Flag("socket-path").Changed {
+		uri.Path = cmd.Flag("socket-path").Value.String()
+	}
+
+	if cmd.Flag("port").Changed {
+		uri.Host = net.JoinHostPort(uri.Hostname(), cmd.Flag("port").Value.String())
+	}
+
+	if uri.Port() == "" {
+		uri.Host = net.JoinHostPort(uri.Hostname(), cmd.Flag("port").DefValue)
+	}
+
+	if uri.Path == "" {
+		if uri.Path, err = getUDS(cmd, uri); err != nil {
+			return errors.Wrapf(err, "failed to connect to  %q", uri.String())
+		}
+	}
+
+	custom, err := config.ReadCustomConfig()
+	if err != nil {
+		return err
+	}
+
+	if cmd.Flag("identity").Changed {
+		custom.Engine.RemoteIdentity = cOpts.Identity
+	}
+
+	custom.Engine.RemoteURI = uri.String()
+	return custom.Write()
+}
+
+func getUserInfo(uri *url.URL) (*url.Userinfo, error) {
+	var (
+		usr *user.User
+		err error
+	)
+	if u, found := os.LookupEnv("_CONTAINERS_ROOTLESS_UID"); found {
+		usr, err = user.LookupId(u)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to find user %q", u)
+		}
+	} else {
+		usr, err = user.Current()
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to obtain current user")
+		}
+	}
+
+	pw, set := uri.User.Password()
+	if set {
+		return url.UserPassword(usr.Username, pw), nil
+	}
+	return url.User(usr.Username), nil
+}
+
+func getUDS(cmd *cobra.Command, uri *url.URL) (string, error) {
+	var authMethods []ssh.AuthMethod
+	passwd, set := uri.User.Password()
+	if set {
+		authMethods = append(authMethods, ssh.Password(passwd))
+	}
+
+	ident := cmd.Flag("identity")
+	if ident.Changed {
+		auth, err := terminal.PublicKey(ident.Value.String(), []byte(passwd))
+		if err != nil {
+			return "", errors.Wrapf(err, "Failed to read identity %q", ident.Value.String())
+		}
+		authMethods = append(authMethods, auth)
+	}
+
+	if sock, found := os.LookupEnv("SSH_AUTH_SOCK"); found {
+		logrus.Debugf("Found SSH_AUTH_SOCK %q, ssh-agent signer enabled", sock)
+
+		c, err := net.Dial("unix", sock)
+		if err != nil {
+			return "", err
+		}
+		a := agent.NewClient(c)
+		authMethods = append(authMethods, ssh.PublicKeysCallback(a.Signers))
+	}
+
+	config := &ssh.ClientConfig{
+		User:            uri.User.Username(),
+		Auth:            authMethods,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+	dial, err := ssh.Dial("tcp", uri.Host, config)
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to connect to %q", uri.Host)
+	}
+	defer dial.Close()
+
+	session, err := dial.NewSession()
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to create new ssh session on %q", uri.Host)
+	}
+	defer session.Close()
+
+	// Override podman binary for testing etc
+	podman := "podman"
+	if v, found := os.LookupEnv("PODMAN_BINARY"); found {
+		podman = v
+	}
+	run := podman + " info --format=json"
+
+	var buffer bytes.Buffer
+	session.Stdout = &buffer
+	if err := session.Run(run); err != nil {
+		return "", errors.Wrapf(err, "failed to run %q", run)
+	}
+
+	var info define.Info
+	if err := json.Unmarshal(buffer.Bytes(), &info); err != nil {
+		return "", errors.Wrapf(err, "failed to parse 'podman info' results")
+	}
+
+	if info.Host.RemoteSocket == nil || len(info.Host.RemoteSocket.Path) == 0 {
+		return "", fmt.Errorf("remote podman %q failed to report its UDS socket", uri.Host)
+	}
+	return info.Host.RemoteSocket.Path, nil
+}
diff --git a/docs/source/markdown/podman-system-connection.1.md b/docs/source/markdown/podman-system-connection.1.md
new file mode 100644
index 000000000..ed73980d6
--- /dev/null
+++ b/docs/source/markdown/podman-system-connection.1.md
@@ -0,0 +1,37 @@
+% podman-system-connection(1)
+
+## NAME
+podman\-system\-connection - Record ssh destination for remote podman service
+
+## SYNOPSIS
+**podman system connection** [*options*] [*ssh destination*]
+
+## DESCRIPTION
+Record ssh destination for remote podman service(s). The ssh destination is given as one of:
+ - [user@]hostname[:port]
+ - ssh://[user@]hostname[:port]
+
+The user will be prompted for the remote ssh login password or key file pass phrase as required. `ssh-agent` is supported if it is running.
+
+## OPTIONS
+
+**-p**, **--port**=*port*
+
+Port for ssh destination. The default value is `22`.
+
+**--socket-path**=*path*
+
+Path to podman service unix domain socket on the ssh destination host
+
+## EXAMPLE
+```
+$ podman system connection podman.fubar.com
+
+$ podman system connection --identity ~/.ssh/dev_rsa ssh://root@server.fubar.com:2222
+
+```
+## SEE ALSO
+podman-system(1) , containers.conf(5) , connections.conf(5)
+
+## HISTORY
+June 2020, Originally compiled by Jhon Honce (jhonce at redhat dot com)
diff --git a/docs/source/markdown/podman-system.1.md b/docs/source/markdown/podman-system.1.md
index 814462ed6..1f19fd0b6 100644
--- a/docs/source/markdown/podman-system.1.md
+++ b/docs/source/markdown/podman-system.1.md
@@ -14,6 +14,7 @@ The system command allows you to manage the podman systems
 | Command    | Man Page                                                     | Description                                                                  |
 | -------    | ---------------------------------------------------          | ---------------------------------------------------------------------------- |
 | df         | [podman-system-df(1)](podman-system-df.1.md)                 | Show podman disk usage.                                                      |
+| connection | [podman-system-connection(1)](podman-system-connection.1.md) | Record ssh destination for remote podman service.                            |
 | info       | [podman-system-info(1)](podman-info.1.md)                    | Displays Podman related system information.                                  |
 | migrate    | [podman-system-migrate(1)](podman-system-migrate.1.md)       | Migrate existing containers to a new podman version.                         |
 | prune      | [podman-system-prune(1)](podman-system-prune.1.md)           | Remove all unused container, image and volume data.                          |