Maybe I'm missing something, but it looks like hostfwd_add doesn't fully
work with -netdev.
Command definition from hmp-commands.hx:
{
.name = "hostfwd_add",
.args_type = "arg1:s,arg2:s?,arg3:s?",
.params = "[vlan_id name]
[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport",
.help = "redirect TCP or UDP connections from host to guest
(requires -net user)",
.mhandler.cmd = net_slirp_hostfwd_add,
},
Note: params says command takes either 1 or 3 arguments. args_type
can't express that, so it asks for 1-3.
Command handler:
void net_slirp_hostfwd_add(Monitor *mon, const QDict *qdict)
{
const char *redir_str;
SlirpState *s;
const char *arg1 = qdict_get_str(qdict, "arg1");
const char *arg2 = qdict_get_try_str(qdict, "arg2");
const char *arg3 = qdict_get_try_str(qdict, "arg3");
if (arg2) {
s = slirp_lookup(mon, arg1, arg2);
redir_str = arg3;
} else {
s = slirp_lookup(mon, NULL, NULL);
redir_str = arg1;
}
if (s) {
slirp_hostfwd(s, redir_str, 0);
}
}
If I understand the code correctly, the command has the following forms:
* hostfwd_add REDIR
This form uses the default stack (first member of slirp_stacks).
Seems to work okay with -netdev:
$ qemu-system-x86_64 --nodefaults --enable-kvm -vnc :0 -S -m 384 -monitor
stdio -netdev user,id=net.0 -device virtio-net-pci,netdev=net.0,id=nic.0
QEMU 0.15.92 monitor - type 'help' for more information
(qemu) hostfwd_add tcp::12345-:22
(qemu) info usernet
VLAN -1 (net.0):
Protocol[State] FD Source Address Port Dest. Address Port RecvQ
SendQ
TCP[HOST_FORWARD] 12 * 12345 10.0.2.15 22 0
0
* hostfwd_add VLAN STACK REDIR
This form was added in commit f13b572c "slirp: Make hostfwd_add/remove
multi-instance-aware".
I don't like how it overloads the command; adding the optional
arguments at the end would have been cleaner. Water under the bridge.
Note that slirp_lookup() converts VLAN to an int (without error
checking, i.e. non-integers are silently interpreted as zero, integers
out of bounds are silently truncated).
Anyway, I can't make it work with -netdev:
(qemu) hostfwd_add -1 net.0 tcp::12345-:22
unknown VLAN -1
* Just for giggles: what if I give two arguments?
$ qemu-system-x86_64--nodefaults --enable-kvm -vnc :0 -S -m 384 -monitor
stdio -net user -device virtio-net-pci,id=nic.0,vlan=0QEMU 0.15.92 monitor -
type 'help' for more information
(qemu) hostfwd_add 0 user.0
invalid host forwarding rule '(null)'
The (null) is from a printf-like function printing a null pointer with
conversion %s. Crash bug on some systems.
