Re: [Qemu-devel] [PATCH 3/4] qemu-char: Convert udp char backend to parse/kind

[Markus Armbruster]

Peter Maydell <address@hidden> writes:

> Convert the udp char backend to the new style QAPI framework.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  qemu-char.c | 69 
> +++++++++++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 54 insertions(+), 15 deletions(-)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index cac7edb..a01ccdc 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2383,20 +2383,6 @@ static CharDriverState *qemu_chr_open_udp_fd(int fd)
>      return chr;
>  }
>  
> -static CharDriverState *qemu_chr_open_udp(QemuOpts *opts)
> -{
> -    Error *local_err = NULL;
> -    int fd = -1;
> -
> -    fd = inet_dgram_opts(opts, &local_err);
> -    if (fd < 0) {
> -        qerror_report_err(local_err);
> -        error_free(local_err);
> -        return NULL;
> -    }
> -    return qemu_chr_open_udp_fd(fd);
> -}
> -
>  /***********************************************************/
>  /* TCP Net console */
>  
> @@ -3449,6 +3435,58 @@ static void qemu_chr_parse_socket(QemuOpts *opts, 
> ChardevBackend *backend,
>      backend->socket->addr = addr;
>  }
>  
> +static void qemu_chr_parse_udp(QemuOpts *opts, ChardevBackend *backend,
> +                               Error **errp)
> +{
> +    const char *host = qemu_opt_get(opts, "host");
> +    const char *port = qemu_opt_get(opts, "port");
> +    bool ipv4 = qemu_opt_get_bool(opts, "ipv4", 0);
> +    bool ipv6 = qemu_opt_get_bool(opts, "ipv6", 0);
> +    const char *localaddr = qemu_opt_get(opts, "localaddr");
> +    const char *localport = qemu_opt_get(opts, "localport");
> +    bool has_local = false;
> +    SocketAddress *addr;
> +
> +    if (host == NULL || strlen(host) == 0) {
> +        host = "localhost";
> +    }

We have to make up *some* value, because the host is mandatory for
InetSocketAddress in the schema.

The value We make up matches inet_dgram_opts().  Duplicating its choice
here isn't so hot.  At least it's an obvious choice.

Perhaps host = "" would do.  Your choice.

> +    if (port == NULL || strlen(port) == 0) {
> +        error_setg(errp, "chardev: udp: remote port not specified");
> +        return;
> +    }
> +    if (localport == NULL || strlen(localport) == 0) {
> +        localport = "0";
> +    } else {
> +        has_local = true;
> +    }
> +    if (localaddr == NULL || strlen(localaddr) == 0) {
> +        localaddr = "";
> +    } else {
> +        has_local = true;
> +    }

I neither localaddr not localport are specified, has_local remains
false.  Good.

If one of them is specified, we need to make up a value for the other,
because they're mandatory for InetSocketAddress in the schema.  We make
up values the eventual consumer inet_dgram_opts() treates the same as
"not specified".  Not nice, but it works.

> +
> +    backend->udp = g_new0(ChardevUdp, 1);
> +
> +    addr = g_new0(SocketAddress, 1);
> +    addr->kind = SOCKET_ADDRESS_KIND_INET;
> +    addr->inet = g_new0(InetSocketAddress, 1);
> +    addr->inet->host = g_strdup(host);
> +    addr->inet->port = g_strdup(port);
> +    addr->inet->has_ipv4 = addr->inet->ipv4 = ipv4;

This turns "ipv4=off" into "ipv4 not specified".  Works because the
eventual consumer inet_dgram_opts() treats them the same.  Still,
setting ->has_to = qemu_opt_get(opts, "ipv4") would be more obviously
correct.

> +    addr->inet->has_ipv6 = addr->inet->ipv6 = ipv6;

Likewise.

> +    backend->udp->remote = addr;
> +
> +    if (has_local) {
> +        backend->udp->has_local = true;
> +        addr = g_new0(SocketAddress, 1);
> +        addr->kind = SOCKET_ADDRESS_KIND_INET;
> +        addr->inet = g_new0(InetSocketAddress, 1);
> +        addr->inet->host = g_strdup(localaddr);
> +        addr->inet->port = g_strdup(localport);
> +        backend->udp->local = addr;
> +    }
> +}
> +

Like for backend=socket [PATCH 1], we're converting from QemuOpts to
QAPI-generated data structures, only to convert it right back, because
the internal interfaces haven't been qapified.  Ugly, but out of scope
for this series.

>  typedef struct CharDriver {
>      const char *name;
>      /* old, pre qapi */
> @@ -4139,7 +4177,8 @@ static void register_types(void)
>      register_char_driver_qapi("null", CHARDEV_BACKEND_KIND_NULL, NULL);
>      register_char_driver_qapi("socket", CHARDEV_BACKEND_KIND_SOCKET,
>                                qemu_chr_parse_socket);
> -    register_char_driver("udp", qemu_chr_open_udp);
> +    register_char_driver_qapi("udp", CHARDEV_BACKEND_KIND_UDP,
> +                              qemu_chr_parse_udp);
>      register_char_driver_qapi("ringbuf", CHARDEV_BACKEND_KIND_RINGBUF,
>                                qemu_chr_parse_ringbuf);
>      register_char_driver_qapi("file", CHARDEV_BACKEND_KIND_FILE,