Re: [PATCH for-9.1 6/9] block/nbd: Use URI parsing code from glib

From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Eric Blake <eblake@redhat.com>
Cc: "Thomas Huth" <thuth@redhat.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Vladimir Sementsov-Ogievskiy" <vsementsov@yandex-team.ru>,
	"Peter Lieven" <pl@kamp.de>,
	"Richard W.M. Jones" <rjones@redhat.com>,
	qemu-devel@nongnu.org, "Kevin Wolf" <kwolf@redhat.com>,
	"Hanna Reitz" <hreitz@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Konstantin Kostiuk" <kkostiuk@redhat.com>,
	qemu-block@nongnu.org
Subject: Re: [PATCH for-9.1 6/9] block/nbd: Use URI parsing code from glib
Date: Thu, 28 Mar 2024 14:59:56 +0000	[thread overview]
Message-ID: <ZgWF7MGNAlMb_WvY@redhat.com> (raw)
In-Reply-To: <sv4rp7w2cnjy5xykp4t3w5gf3zwnohe5eso422whl2ux2ofixa@xwjphousol77>

On Thu, Mar 28, 2024 at 09:54:49AM -0500, Eric Blake wrote:
> On Thu, Mar 28, 2024 at 03:06:03PM +0100, Thomas Huth wrote:
> > Since version 2.66, glib has useful URI parsing functions, too.
> > Use those instead of the QEMU-internal ones to be finally able
> > to get rid of the latter. The g_uri_get_host() also takes care
> > of removing the square brackets from IPv6 addresses, so we can
> > drop that part of the QEMU code now, too.
> > 
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  block/nbd.c | 66 ++++++++++++++++++++++++++++++-----------------------
> >  1 file changed, 38 insertions(+), 28 deletions(-)
> > 
> > diff --git a/block/nbd.c b/block/nbd.c
> > index ef05f7cdfd..95b507f872 100644
> > --- a/block/nbd.c
> > +++ b/block/nbd.c
> > @@ -31,7 +31,6 @@
> >  #include "qemu/osdep.h"
> >  
> >  #include "trace.h"
> > -#include "qemu/uri.h"
> >  #include "qemu/option.h"
> >  #include "qemu/cutils.h"
> >  #include "qemu/main-loop.h"
> > @@ -1514,30 +1513,34 @@ static void nbd_client_close(BlockDriverState *bs)
> >  
> >  static int nbd_parse_uri(const char *filename, QDict *options)
> >  {
> > -    URI *uri;
> > +    GUri *uri;
> 
> Is it worth using 'g_autoptr(GUri) uri = NULL;' here, to simplify cleanup later?
> 
> >      const char *p;
> > -    QueryParams *qp = NULL;
> > +    GHashTable *qp = NULL;
> 
> Presumably would be easier if qp is also auto-free.
> 
> > +    int qp_n;
> >      int ret = 0;
> >      bool is_unix;
> > +    const char *uri_scheme, *uri_query, *uri_server;
> > +    int uri_port;
> >  
> > -    uri = uri_parse(filename);
> > +    uri = g_uri_parse(filename, G_URI_FLAGS_NONE, NULL);
> 
> The glib API is fairly close to what we have in qemu, making this a
> nice switchover.
> 
> >          /* nbd[+tcp]://host[:port]/export */
> > -        if (!uri->server) {
> > +        if (!uri_server) {
> >              ret = -EINVAL;
> >              goto out;
> >          }
> >  
> > -        /* strip braces from literal IPv6 address */
> > -        if (uri->server[0] == '[') {
> > -            host = qstring_from_substr(uri->server, 1,
> > -                                       strlen(uri->server) - 1);
> > -        } else {
> > -            host = qstring_from_str(uri->server);
> > -        }
> > -
> >          qdict_put_str(options, "server.type", "inet");
> > -        qdict_put(options, "server.host", host);
> > +        qdict_put_str(options, "server.host", uri_server);
> >  
> > -        port_str = g_strdup_printf("%d", uri->port ?: NBD_DEFAULT_PORT);
> > +        port_str = g_strdup_printf("%d", uri_port != -1 ? uri_port
> > +                                                        : NBD_DEFAULT_PORT);
> >          qdict_put_str(options, "server.port", port_str);
> 
> If a user requests nbd://hostname:0/export, this now sets server.port
> to "0" instead of "10809".  Is that an intentional change?  No one
> actually passes an explicit ":0" port on purpose, but we do have to
> worry about malicious URIs.

Passing '0' will cause the kernel to allocate a random free
port, so that is potentially introducing new semantics ?

With regards,
Daniel
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