Commit b412eb61 authored by Alexander Graf's avatar Alexander Graf Committed by Jan Kiszka
Browse files

slirp: add 'cmd:' target for guestfwd 



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: default avatarSascha Wilde <wilde@intevation.de>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
parent 1cb1c5d1

net/slirp.c

+27 −17
Original line number Diff line number Diff line
@@ -626,6 +626,15 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, 


    fwd = g_malloc(sizeof(struct GuestFwd));

    snprintf(buf, sizeof(buf), "guestfwd.tcp.%d", port);



    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);

            g_free(fwd);

            return -1;

        }

    } else {

        fwd->hd = qemu_chr_new(buf, p, NULL);

        if (!fwd->hd) {

            error_report("could not open guest forwarding device '%s'", buf);
@@ -645,6 +654,7 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, 


        qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,

                              NULL, fwd);

    }

    return 0;



 fail_syntax:

qemu-options.hx

+21 −1
Original line number Diff line number Diff line
@@ -1421,8 +1421,28 @@ Then when you use on the host @code{telnet localhost 5555}, you 
connect to the guest telnet server.



@item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}

@item guestfwd=[tcp]:@var{server}:@var{port}-@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.

to the character device @var{dev} or to a program executed by @var{cmd:command}

which gets spawned for each connection. 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:



@example

# 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 [...]

@end 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:



@example

# 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'

@end example



@end table