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: Sascha Wilde <wilde@intevation.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 8b66264..ecf7ca1 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1421,8 +1421,28 @@
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
