On Mon, 2011-02-28 at 17:03 +0800, Jason Wang wrote:
> This patch adds the following helpers to help autotest to control the
> tap/bridge by itself instead of depending qemu-ifup script:
> - Helper to create tap and probe the vnet header.
> - Helper to convert the interface name to index.
> - Helper to add a interface to a bridge.
I see why you've chose to not raise exceptions on the helpers themselves
(historically we don't put exception raising functions on kvm_utils),
but we've changed things (see the LoginError functions).
So I propose the NetError exceptions to come here, and make the helpers
throw the exceptions directly, so we have code slightly more concise.
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
> client/tests/kvm/kvm_utils.py | 109
> +++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 109 insertions(+), 0 deletions(-)
>
> diff --git a/client/tests/kvm/kvm_utils.py b/client/tests/kvm/kvm_utils.py
> index de52b65..68f27dd 100644
> --- a/client/tests/kvm/kvm_utils.py
> +++ b/client/tests/kvm/kvm_utils.py
> @@ -6,6 +6,7 @@ KVM test utility functions.
>
> import time, string, random, socket, os, signal, re, logging, commands,
> cPickle
> import fcntl, shelve, ConfigParser, rss_file_transfer, threading, sys,
> UserDict
> +import struct
> from autotest_lib.client.bin import utils, os_dep
> from autotest_lib.client.common_lib import error, logging_config
> import kvm_subprocess
> @@ -15,6 +16,18 @@ try:
> except ImportError:
> KOJI_INSTALLED = False
>
> +# From include/linux/sockios.h
> +SIOCSIFFLAGS = 0x8914
> +SIOCGIFINDEX = 0x8933
> +SIOCBRADDIF = 0x89a2
> +# From linux/include/linux/if_tun.h
> +TUNSETIFF = 0x400454ca
> +TUNGETIFF = 0x800454d2
> +TUNGETFEATURES = 0x800454cf
> +IFF_UP = 0x1
> +IFF_TAP = 0x0002
> +IFF_NO_PI = 0x1000
> +IFF_VNET_HDR = 0x4000
>
> def _lock_file(filename):
> f = open(filename, "w")
> @@ -1726,3 +1739,99 @@ def mount(src, mount_point, type, perm="rw"):
> logging.error("Can't find mounted NFS share - /etc/mtab contents
> \n%s",
> file("/etc/mtab").read())
> return False
> +
> +
> +def if_nametoindex(ifname):
> + """
> + Map an interface name into its corresponding index.
> + Returns 0 on error, as 0 is not a valid index
> +
> + @param ifname: interface name
> + """
> + index = 0
> + ctrl_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
> + ifr = struct.pack("16si", ifname, 0)
> + r = fcntl.ioctl(ctrl_sock, SIOCGIFINDEX, ifr)
> + index = struct.unpack("16si", r)[1]
> + ctrl_sock.close()
> + return index
> +
> +
> +def vnet_hdr_probe(tapfd):
> + """
> + Check if the IFF_VNET_HDR is support by tun.
> +
> + @param tapfd: the file descriptor of /dev/net/tun
> + """
> + u = struct.pack("I", 0)
> + r = fcntl.ioctl(tapfd, TUNGETFEATURES, u)
> + flags = struct.unpack("I", r)[0]
> + if flags & IFF_VNET_HDR:
> + return True
> + else:
> + return False
> +
> +
> +def open_tap(ifname, vnet_hdr=True):
> + """
> + Open a tap device and returns its file descriptor which is used by
> + fd=<fd> parameter of qemu-kvm.
> +
> + @param ifname: TAP interface name
> + @param vnet_hdr: Whether enable the vnet header
> + """
> + try:
> + tapfd = os.open("/dev/net/tun", os.O_RDWR)
> + except OSError:
> + logging.error("Can't not open /dev/net/tun")
> + return -1
> + flags = IFF_TAP | IFF_NO_PI
> + if vnet_hdr and vnet_hdr_probe(tapfd):
> + flags |= IFF_VNET_HDR
> +
> + ifr = struct.pack("16sh", ifname, flags)
> + try:
> + r = fcntl.ioctl(tapfd, TUNSETIFF, ifr)
> + except EnvironmentError:
> + logging.error("Could not create tap device")
> + return -1
> + ifname = struct.unpack("16sh", r)[0].strip("\x00")
> + return tapfd
> +
> +
> +def add_to_bridge(ifname, brname):
> + """
> + Add a TAP device to bridge
> +
> + @param ifname: Name of TAP device
> + @param brname: Name of the bridge
> + """
> + ctrl_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
> + index = if_nametoindex(ifname)
> + if index == 0:
> + logging.error("Interface %s does not exist" % ifname)
> + return -1
> + ifr = struct.pack("16si", brname, index)
> + try:
> + r = fcntl.ioctl(ctrl_sock, SIOCBRADDIF, ifr)
> + except EnvironmentError:
> + logging.error("Fail to add %s to bridge %s" % (ifname, brname))
> + return -1
> + ctrl_sock.close()
> + return 0
> +
> +def bring_up_ifname(ifname):
> + """
> + Bring up an interface
> +
> + @param ifname: Name of the interface
> + """
> + ctrl_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
> + ifr = struct.pack("16si", ifname, IFF_UP)
> + try:
> + fcntl.ioctl(ctrl_sock, SIOCSIFFLAGS, ifr)
> + except EnvironmentError:
> + logging.error("Fail to bring up interface %s" % ifname)
> + return -1
> + ctrl_sock.close()
> + return 0
>
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