Re: [Qemu-devel] [PATCH] slirp: add 'cmd:' target for guestfwd

[Alexander Graf]

On 04.06.2011, at 08:12, Alexander Graf wrote:

> When using guestfwd=, Qemu only connects the virtual server's TCP port
> to a single chardev. This is useless in most cases, as we usually want
> to have more than a single connection from the guest to the outside world.
> 
> This patch adds a new cmd: target to guestfwd= that allows for execution
> of a command on every TCP connection. This leverages the same code as
> the -smb parameter, just that here the command is user defined.
> 
> Reported-by: Sascha Wilde <address@hidden>
> Signed-off-by: Alexander Graf <address@hidden>


Ping?


Alex

> ---
> net/slirp.c     |   44 ++++++++++++++++++++++++++++----------------
> qemu-options.hx |   20 +++++++++++++++++++-
> 2 files changed, 47 insertions(+), 17 deletions(-)
> 
> diff --git a/net/slirp.c b/net/slirp.c
> index e057a14..4e4e3c3 100644
> --- a/net/slirp.c
> +++ b/net/slirp.c
> @@ -615,25 +615,37 @@ static int slirp_guestfwd(SlirpState *s, const char 
> *config_str,
> 
>     fwd = qemu_malloc(sizeof(struct GuestFwd));
>     snprintf(buf, sizeof(buf), "guestfwd.tcp.%d", port);
> -    fwd->hd = qemu_chr_open(buf, p, NULL);
> -    if (!fwd->hd) {
> -        error_report("could not open guest forwarding device '%s'", buf);
> -        qemu_free(fwd);
> -        return -1;
> -    }
> 
> -    if (slirp_add_exec(s->slirp, 3, fwd->hd, &server, port) < 0) {
> -        error_report("conflicting/invalid host:port in guest forwarding "
> -                     "rule '%s'", config_str);
> -        qemu_free(fwd);
> -        return -1;
> +    if ((strlen(p) > 4) && !strncmp(p, "cmd:", 4)) {
> +        if (slirp_add_exec(s->slirp, 0, &p[4], &server, port) < 0) {
> +            error_report("conflicting/invalid host:port in guest forwarding "
> +                         "rule '%s'", config_str);
> +            qemu_free(fwd);
> +            return -1;
> +        }
> +    } else {
> +        fwd->hd = qemu_chr_open(buf, p, NULL);
> +        if (!fwd->hd) {
> +            error_report("could not open guest forwarding device '%s'", buf);
> +            qemu_free(fwd);
> +            return -1;
> +        }
> +
> +        if (slirp_add_exec(s->slirp, 3, fwd->hd, &server, port) < 0) {
> +            error_report("conflicting/invalid host:port in guest forwarding "
> +                         "rule '%s'", config_str);
> +            qemu_free(fwd);
> +            return -1;
> +        }
> +
> +        fwd->server = server;
> +        fwd->port = port;
> +        fwd->slirp = s->slirp;
> +
> +        qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
> +                              NULL, fwd);
>     }
> -    fwd->server = server;
> -    fwd->port = port;
> -    fwd->slirp = s->slirp;
> 
> -    qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
> -                          NULL, fwd);
>     return 0;
> 
>  fail_syntax:
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 82e085a..cc62d20 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1242,10 +1242,28 @@ telnet localhost 5555
> Then when you use on the host @code{telnet localhost 5555}, you
> connect to the guest telnet server.
> 
> address@hidden guestfwd=[tcp]:@var{server}:@address@hidden
> address@hidden guestfwd=[tcp]:@var{server}:@address@hidden|@var{cmd:command}]
> Forward guest TCP connections to the IP address @var{server} on port 
> @var{port}
> to the character device @var{dev}. This option can be given multiple times.
> 
> +You can either use a chardev directly and have that one used throughout 
> Qemu's
> +lifetime, like in the following example:
> +
> address@hidden
> +# open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
> +# the guest accesses it
> +qemu -net user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 [...]
> address@hidden example
> +
> +Or you can execute a command on every TCP connection established by the 
> guest,
> +so that Qemu behaves similar to an inetd process for that virtual server:
> +
> address@hidden
> +# call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
> +# and connect the TCP stream to its stdin/stdout
> +qemu -net user,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321
> address@hidden example
> +
> @end table
> 
> Note: Legacy stand-alone options -tftp, -bootp, -smb and -redir are still
> -- 
> 1.6.0.2
> 
>