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

[Thomas Huth <thuth@redhat.com>]

On 28/03/2024 15.59, Daniel P. Berrangé wrote:
> 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?

Sounds like a good idea, I'll give it a try!

>>>       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 ?

Ok, so passing a 0 does not really make sense, since QEMU needs to know the 
exact port. I'll change the check from "uri_port != -1" to "uri_port > 0" in 
the next version.

  Thomas