Re: [Qemu-devel] [PATCH 2/4] block/ssh: Add InetSocketAddress and accept it

[Kevin Wolf <kwolf@redhat.com>]

Am 11.10.2016 um 09:37 hat Ashijeet Acharya geschrieben:
> Add InetSocketAddress compatibility to SSH driver.
> 
> Add a new option "server" to the SSH block driver which then accepts
> a InetSocketAddress.
> 
> "host" and "port" are supported as legacy options and are mapped to
> their InetSocketAddress representation.
> 
> Signed-off-by: Ashijeet Acharya <ashijeetacharya@gmail.com>
> ---
>  block/ssh.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 78 insertions(+), 9 deletions(-)
> 
> diff --git a/block/ssh.c b/block/ssh.c
> index 75cb7bc..702871a 100644
> --- a/block/ssh.c
> +++ b/block/ssh.c
> @@ -32,8 +32,11 @@
>  #include "qemu/error-report.h"
>  #include "qemu/sockets.h"
>  #include "qemu/uri.h"
> +#include "qapi-visit.h"
>  #include "qapi/qmp/qint.h"
>  #include "qapi/qmp/qstring.h"
> +#include "qapi/qmp-input-visitor.h"
> +#include "qapi/qmp-output-visitor.h"
>  
>  /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
>   * this block driver code.
> @@ -74,6 +77,8 @@ typedef struct BDRVSSHState {
>       */
>      LIBSSH2_SFTP_ATTRIBUTES attrs;
>  
> +    InetSocketAddress *inet;
> +
>      /* Used to warn if 'flush' is not supported. */
>      char *hostport;
>      bool unsafe_flush_warning;
> @@ -263,7 +268,9 @@ static bool ssh_has_filename_options_conflict(QDict *options, Error **errp)
>              !strcmp(qe->key, "port") ||
>              !strcmp(qe->key, "path") ||
>              !strcmp(qe->key, "user") ||
> -            !strcmp(qe->key, "host_key_check"))
> +            !strcmp(qe->key, "host_key_check") ||
> +            !strcmp(qe->key, "server") ||
> +            !strncmp(qe->key, "server.", 7))

There is strstart() from cutils.c which looks a bit nicer (you don't
have to specify the string length then).

>          {
>              error_setg(errp, "Option '%s' cannot be used with a file name",
>                         qe->key);
> @@ -555,13 +562,71 @@ static QemuOptsList ssh_runtime_opts = {
>      },
>  };
>  
> +static bool ssh_process_legacy_socket_options(QDict *output_opts,
> +                                              QemuOpts *legacy_opts,
> +                                              Error **errp)
> +{
> +    const char *host = qemu_opt_get(legacy_opts, "host");
> +    const char *port = qemu_opt_get(legacy_opts, "port");
> +
> +    if (!host && port) {
> +        error_setg(errp, "port may not be used without host");
> +        return false;
> +    }

This check is rather pointless if !host causes an error anyway.

> +    if (!host) {
> +        error_setg(errp, "No hostname was specified");
> +        return false;
> +    } else {
> +        qdict_put(output_opts, "server.host", qstring_from_str(host));
> +        qdict_put(output_opts, "server.port",
> +                  qstring_from_str(port ?: stringify(22)));
> +    }
> +
> +    return true;
> +}
> +
> +static InetSocketAddress *ssh_config(BDRVSSHState *s, QDict *options,
> +                                     Error **errp)
> +{
> +    InetSocketAddress *inet = NULL;
> +    QDict *addr = NULL;
> +    QObject *crumpled_addr = NULL;
> +    Visitor *iv = NULL;
> +    Error *local_error = NULL;
> +
> +    qdict_extract_subqdict(options, &addr, "server.");
> +    if (!qdict_size(addr)) {
> +        error_setg(errp, "SSH server address missing");
> +        goto out;
> +    }
> +
> +    crumpled_addr = qdict_crumple(addr, true, errp);
> +    if (!crumpled_addr) {
> +        goto out;
> +    }
> +
> +    iv = qmp_input_visitor_new(crumpled_addr, true);

I believe you need qobject_input_visitor_new_autocast() here.

Do integer properties like port work for you without it?

> +    visit_type_InetSocketAddress(iv, NULL, &inet, &local_error);
> +    if (local_error) {
> +        error_propagate(errp, local_error);
> +        goto out;
> +    }
> +
> +out:
> +    QDECREF(addr);
> +    qobject_decref(crumpled_addr);
> +    visit_free(iv);
> +    return inet;
> +}
> +
>  static int connect_to_ssh(BDRVSSHState *s, QDict *options,
>                            int ssh_flags, int creat_mode, Error **errp)
>  {
>      int r, ret;
>      QemuOpts *opts = NULL;
>      Error *local_err = NULL;
> -    const char *host, *user, *path, *host_key_check;
> +    const char *user, *path, *host_key_check;
>      int port;
>  
>      opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort);
> @@ -572,15 +637,11 @@ static int connect_to_ssh(BDRVSSHState *s, QDict *options,
>          goto err;
>      }
>  
> -    host = qemu_opt_get(opts, "host");
> -    if (!host) {
> +    if (!ssh_process_legacy_socket_options(options, opts, errp)) {
>          ret = -EINVAL;
> -        error_setg(errp, "No hostname was specified");
>          goto err;
>      }
>  
> -    port = qemu_opt_get_number(opts, "port", 22);
> -
>      path = qemu_opt_get(opts, "path");
>      if (!path) {
>          ret = -EINVAL;
> @@ -603,9 +664,16 @@ static int connect_to_ssh(BDRVSSHState *s, QDict *options,
>          host_key_check = "yes";
>      }
>  
> +    /* Pop the config into our state object, Exit if invalid */
> +    s->inet = ssh_config(s, options, errp);
> +    if (!s->inet) {
> +        goto err;
> +    }
> +
>      /* Construct the host:port name for inet_connect. */
>      g_free(s->hostport);
> -    s->hostport = g_strdup_printf("%s:%d", host, port);
> +    port = atoi(s->inet->port);
> +    s->hostport = g_strdup_printf("%s:%d", s->inet->host, port);

Oh, it isn't even an integer. I never realised that we support things
like 'port=ssh', but apparently we do!

That explains why your testing didn't show the need for the other
visitor type. You'd still see it for 'to', 'ipv4' and 'ipv6'.

Anyway, I believe that constructing a string here is backwards (and
doing atoi() first before converting it back to a string would actually
break port=<service-name>).

The choices that I see is making inet_connect_saddr() public, which
directly takes the InetSocketAddress, or using QIOChannelSocket like NBD
(though that looks like a larger change).

>      /* Open the socket and connect. */
>      s->sock = inet_connect(s->hostport, errp);
> @@ -634,7 +702,8 @@ static int connect_to_ssh(BDRVSSHState *s, QDict *options,
>      }
>  
>      /* Check the remote host's key against known_hosts. */
> -    ret = check_host_key(s, host, port, host_key_check, errp);
> +    ret = check_host_key(s, s->inet->host, port, host_key_check,
> +                         errp);
>      if (ret < 0) {
>          goto err;
>      }

The rest of the patch looks good to me.

Kevin