[Qemu-devel] CharUDP - Connection refused

[poma <pomidorabelisima@gmail.com>]

Hi Fi

With or without the patch[1] the same result - "Connection refused".

UDP network console,
the character device acts as a UDP netconsole service, sending and receiving packets.
This is a lossy service.


= HOST:

virt-manager:

Add New Virtual Serial Device
Device Type: UDP net cosnole (udp)
Host: 127.0.0.1 Port: 4555
Bind Host: Server mode (bind)


Serial Device 1 (Primary Console)
Device Type: udp
Source host: 127.0.0.1:4555
  Bind host: 127.0.0.1:4556


/etc/libvirt/qemu/domain.xml
...
    <serial type='udp'>
      <source mode='bind' host='127.0.0.1' service='4556'/>
      <source mode='connect' host='127.0.0.1' service='4555'/>
      <target port='0'/>
    </serial>
    <console type='udp'>
      <source mode='bind' host='127.0.0.1' service='4556'/>
      <source mode='connect' host='127.0.0.1' service='4555'/>
      <target type='serial' port='0'/>
    </console>


qemu-system-x86_64 ... \
-chardev udp,id=charserial0,host=127.0.0.1,port=4555,localaddr=127.0.0.1,localport=4556 \
-device isa-serial,chardev=charserial0,id=serial0


# netstat -an | grep 4555
udp        0      0 127.0.0.1:4556          127.0.0.1:4555          ESTABLISHED


# nc -vv -u 127.0.0.1 4555
Ncat: Version 6.47 ( http://nmap.org/ncat )
libnsock nsi_new2(): nsi_new (IOD #1)
libnsock nsock_connect_udp(): UDP connection requested to 127.0.0.1:4555 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [127.0.0.1:4555]
Ncat: Connected to 127.0.0.1:4555.
libnsock nsi_new2(): nsi_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [127.0.0.1:4555] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26

libnsock nsock_trace_handler_callback(): Callback: READ SUCCESS for EID 26 [peer unspecified] (1 bytes): .
libnsock nsock_trace_handler_callback(): Callback: WRITE SUCCESS for EID 35 [127.0.0.1:4555]
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 42
libnsock nsock_trace_handler_callback(): Callback: READ ERROR [Connection refused (111)] for EID 18 [127.0.0.1:4555]
Ncat: Connection refused.

# nc -vv -u 127.0.0.1 4556
Ncat: Version 6.47 ( http://nmap.org/ncat )
libnsock nsi_new2(): nsi_new (IOD #1)
libnsock nsock_connect_udp(): UDP connection requested to 127.0.0.1:4556 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [127.0.0.1:4556]
Ncat: Connected to 127.0.0.1:4556.
libnsock nsi_new2(): nsi_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [127.0.0.1:4556] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26

libnsock nsock_trace_handler_callback(): Callback: READ SUCCESS for EID 26 [peer unspecified] (1 bytes): .
libnsock nsock_trace_handler_callback(): Callback: WRITE SUCCESS for EID 35 [127.0.0.1:4556]
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 42
libnsock nsock_trace_handler_callback(): Callback: READ ERROR [Connection refused (111)] for EID 18 [127.0.0.1:4556]
Ncat: Connection refused.


# socat -d -d UDP:127.0.0.1:4555 -
2015/10/04 13:18:29 socat[5655] N opening connection to AF=2 127.0.0.1:4555
2015/10/04 13:18:29 socat[5655] N successfully connected from local address AF=2 127.0.0.1:40785
2015/10/04 13:18:29 socat[5655] N reading from and writing to stdio
2015/10/04 13:18:29 socat[5655] N starting data transfer loop with FDs [3,3] and [0,1]

2015/10/04 13:18:34 socat[5655] E read(3, 0x557184904210, 8192): Connection refused
2015/10/04 13:18:34 socat[5655] N exit(1)

# socat -d -d UDP:127.0.0.1:4556 -
2015/10/04 13:18:47 socat[5658] N opening connection to AF=2 127.0.0.1:4556
2015/10/04 13:18:47 socat[5658] N successfully connected from local address AF=2 127.0.0.1:49650
2015/10/04 13:18:47 socat[5658] N reading from and writing to stdio
2015/10/04 13:18:47 socat[5658] N starting data transfer loop with FDs [3,3] and [0,1]

2015/10/04 13:18:51 socat[5658] E read(3, 0x561b414be210, 8192): Connection refused
2015/10/04 13:18:51 socat[5658] N exit(1)


How is it supposed to work?


= DOMAIN:

$ hostnamectl status | egrep Chassis\|Virtualization
           Chassis: vm
    Virtualization: kvm

$ cat /proc/cmdline 
BOOT_IMAGE=vmlinuz0 initrd=initrd0.img root=live:CDLABEL=Rawhide-Xfce-Live-1003 rootfstype=auto ro rd.live.image console=tty0 console=ttyS0

$ systemctl status serial-getty@ttyS0.service 
● serial-getty@ttyS0.service - Serial Getty on ttyS0
   Loaded: loaded (/usr/lib/systemd/system/serial-getty@.service; disabled; vendor preset: disabled)
   Active: active (running) since Sun 2015-10-04 09:02:06 EDT; 48s ago
     Docs: man:agetty(8)
           man:systemd-getty-generator(8)
           http://0pointer.de/blog/projects/serial-console.html
 Main PID: 1109 (agetty)
   CGroup: /system.slice/system-serial\x2dgetty.slice/serial-getty@ttyS0.service
           └─1109 /sbin/agetty --keep-baud 115200 38400 9600 ttyS0 vt220

Oct 04 09:02:06 localhost systemd[1]: Started Serial Getty on ttyS0.


= SW VERSIONS:

$ qemu-system-x86_64 -version
QEMU emulator version 2.4.0.1 (qemu-2.4.0.1-2.fc24), Copyright (c) 2003-2008 Fabrice Bellard
$ libvirtd --version
libvirtd (libvirt) 1.2.20
$ virt-manager --version
1.2.1

$ rpm -q qemu libvirt virt-manager
qemu-2.4.0.1-2.fc24.x86_64
libvirt-1.2.20-1.fc24.x86_64
virt-manager-1.2.1-3.fc24.noarch


[1]
char: udp chardev shouldn't require an explicit open.
http://patchwork.ozlabs.org/patch/311730