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

[Ashijeet Acharya <ashijeetacharya@gmail.com>]

On Wed, Oct 12, 2016 at 9:21 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> 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).

Okay, I will use that.

>
>>          {
>>              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.

Hmm... I will remove it.

>
>> +    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?

In InetSocketAddress 'port' is of the type 'char*' but now I think
using qobject_input_visitor_new_autocast() will be right since there
are other fields as well.

>
>> +    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'.

Yes, this is what I mentioned above.

>
> 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).

Okay, I will convert the driver to use one of the options you suggested above.

>
>>      /* 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.
Nice! I will try to post v2 soon.

Ashijeet
>
> Kevin