# Copyright (C) 2013-2014 Canonical Ltd.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Blake Rouse <blake.rouse@canonical.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import errno
import logging
import os
import re

from cloudinit import util

LOG = logging.getLogger(__name__)
SYS_CLASS_NET = "/sys/class/net/"
DEFAULT_PRIMARY_INTERFACE = 'eth0'


def sys_dev_path(devname, path=""):
    return SYS_CLASS_NET + devname + "/" + path


def read_sys_net(devname, path, translate=None,
                 on_enoent=None, on_keyerror=None,
                 on_einval=None):
    dev_path = sys_dev_path(devname, path)
    try:
        contents = util.load_file(dev_path)
    except (OSError, IOError) as e:
        e_errno = getattr(e, 'errno', None)
        if e_errno in (errno.ENOENT, errno.ENOTDIR):
            if on_enoent is not None:
                return on_enoent(e)
        if e_errno in (errno.EINVAL,):
            if on_einval is not None:
                return on_einval(e)
        raise
    contents = contents.strip()
    if translate is None:
        return contents
    try:
        return translate[contents]
    except KeyError as e:
        if on_keyerror is not None:
            return on_keyerror(e)
        else:
            LOG.debug("Found unexpected (not translatable) value"
                      " '%s' in '%s", contents, dev_path)
            raise


def read_sys_net_safe(iface, field, translate=None):
    def on_excp_false(e):
        return False
    return read_sys_net(iface, field,
                        on_keyerror=on_excp_false,
                        on_enoent=on_excp_false,
                        on_einval=on_excp_false,
                        translate=translate)


def read_sys_net_int(iface, field):
    val = read_sys_net_safe(iface, field)
    if val is False:
        return None
    try:
        return int(val)
    except TypeError:
        return None


def is_up(devname):
    # The linux kernel says to consider devices in 'unknown'
    # operstate as up for the purposes of network configuration. See
    # Documentation/networking/operstates.txt in the kernel source.
    translate = {'up': True, 'unknown': True, 'down': False}
    return read_sys_net_safe(devname, "operstate", translate=translate)


def is_wireless(devname):
    return os.path.exists(sys_dev_path(devname, "wireless"))


def is_bridge(devname):
    return os.path.exists(sys_dev_path(devname, "bridge"))


def is_connected(devname):
    # is_connected isn't really as simple as that.  2 is
    # 'physically connected'. 3 is 'not connected'. but a wlan interface will
    # always show 3.
    iflink = read_sys_net_safe(devname, "iflink")
    if iflink == "2":
        return True
    if not is_wireless(devname):
        return False
    LOG.debug("'%s' is wireless, basing 'connected' on carrier", devname)
    return read_sys_net_safe(devname, "carrier",
                             translate={'0': False, '1': True})


def is_physical(devname):
    return os.path.exists(sys_dev_path(devname, "device"))


def is_present(devname):
    return os.path.exists(sys_dev_path(devname))


def get_devicelist():
    return os.listdir(SYS_CLASS_NET)


class ParserError(Exception):
    """Raised when a parser has issue parsing a file/content."""


def is_disabled_cfg(cfg):
    if not cfg or not isinstance(cfg, dict):
        return False
    return cfg.get('config') == "disabled"


def generate_fallback_config():
    """Determine which attached net dev is most likely to have a connection and
       generate network state to run dhcp on that interface"""
    # get list of interfaces that could have connections
    invalid_interfaces = set(['lo'])
    potential_interfaces = set(get_devicelist())
    potential_interfaces = potential_interfaces.difference(invalid_interfaces)
    # sort into interfaces with carrier, interfaces which could have carrier,
    # and ignore interfaces that are definitely disconnected
    connected = []
    possibly_connected = []
    for interface in potential_interfaces:
        if interface.startswith("veth"):
            continue
        if is_bridge(interface):
            # skip any bridges
            continue
        carrier = read_sys_net_int(interface, 'carrier')
        if carrier:
            connected.append(interface)
            continue
        # check if nic is dormant or down, as this may make a nick appear to
        # not have a carrier even though it could acquire one when brought
        # online by dhclient
        dormant = read_sys_net_int(interface, 'dormant')
        if dormant:
            possibly_connected.append(interface)
            continue
        operstate = read_sys_net_safe(interface, 'operstate')
        if operstate in ['dormant', 'down', 'lowerlayerdown', 'unknown']:
            possibly_connected.append(interface)
            continue

    # don't bother with interfaces that might not be connected if there are
    # some that definitely are
    if connected:
        potential_interfaces = connected
    else:
        potential_interfaces = possibly_connected

    # if eth0 exists use it above anything else, otherwise get the interface
    # that we can read 'first' (using the sorted defintion of first).
    names = list(sorted(potential_interfaces))
    if DEFAULT_PRIMARY_INTERFACE in names:
        names.remove(DEFAULT_PRIMARY_INTERFACE)
        names.insert(0, DEFAULT_PRIMARY_INTERFACE)
    target_name = None
    target_mac = None
    for name in names:
        mac = read_sys_net_safe(name, 'address')
        if mac:
            target_name = name
            target_mac = mac
            break
    if target_mac and target_name:
        nconf = {'config': [], 'version': 1}
        nconf['config'].append(
            {'type': 'physical', 'name': target_name,
             'mac_address': target_mac, 'subnets': [{'type': 'dhcp'}]})
        return nconf
    else:
        # can't read any interfaces addresses (or there are none); give up
        return None


def apply_network_config_names(netcfg, strict_present=True, strict_busy=True):
    """read the network config and rename devices accordingly.
    if strict_present is false, then do not raise exception if no devices
    match.  if strict_busy is false, then do not raise exception if the
    device cannot be renamed because it is currently configured.

    renames are only attempted for interfaces of type 'physical'.  It is
    expected that the network system will create other devices with the
    correct name in place."""
    renames = []
    for ent in netcfg.get('config', {}):
        if ent.get('type') != 'physical':
            continue
        mac = ent.get('mac_address')
        name = ent.get('name')
        if not mac:
            continue
        renames.append([mac, name])

    return _rename_interfaces(renames)


def interface_has_own_mac(ifname, strict=False):
    """return True if the provided interface has its own address.

    Based on addr_assign_type in /sys.  Return true for any interface
    that does not have a 'stolen' address. Examples of such devices
    are bonds or vlans that inherit their mac from another device.
    Possible values are:
      0: permanent address    2: stolen from another device
      1: randomly generated   3: set using dev_set_mac_address"""

    assign_type = read_sys_net_int(ifname, "addr_assign_type")
    if strict and assign_type is None:
        raise ValueError("%s had no addr_assign_type.")
    return assign_type in (0, 1, 3)


def _get_current_rename_info(check_downable=True):
    """Collect information necessary for rename_interfaces.

    returns a dictionary by mac address like:
       {mac:
         {'name': name
          'up': boolean: is_up(name),
          'downable': None or boolean indicating that the
                      device has only automatically assigned ip addrs.}}
    """
    bymac = {}
    for mac, name in get_interfaces_by_mac().items():
        bymac[mac] = {'name': name, 'up': is_up(name), 'downable': None}

    if check_downable:
        nmatch = re.compile(r"[0-9]+:\s+(\w+)[@:]")
        ipv6, _err = util.subp(['ip', '-6', 'addr', 'show', 'permanent',
                                'scope', 'global'], capture=True)
        ipv4, _err = util.subp(['ip', '-4', 'addr', 'show'], capture=True)

        nics_with_addresses = set()
        for bytes_out in (ipv6, ipv4):
            nics_with_addresses.update(nmatch.findall(bytes_out))

        for d in bymac.values():
            d['downable'] = (d['up'] is False or
                             d['name'] not in nics_with_addresses)

    return bymac


def _rename_interfaces(renames, strict_present=True, strict_busy=True,
                       current_info=None):

    if not len(renames):
        LOG.debug("no interfaces to rename")
        return

    if current_info is None:
        current_info = _get_current_rename_info()

    cur_bymac = {}
    for mac, data in current_info.items():
        cur = data.copy()
        cur['mac'] = mac
        cur_bymac[mac] = cur

    def update_byname(bymac):
        return dict((data['name'], data)
                    for data in bymac.values())

    def rename(cur, new):
        util.subp(["ip", "link", "set", cur, "name", new], capture=True)

    def down(name):
        util.subp(["ip", "link", "set", name, "down"], capture=True)

    def up(name):
        util.subp(["ip", "link", "set", name, "up"], capture=True)

    ops = []
    errors = []
    ups = []
    cur_byname = update_byname(cur_bymac)
    tmpname_fmt = "cirename%d"
    tmpi = -1

    for mac, new_name in renames:
        cur = cur_bymac.get(mac, {})
        cur_name = cur.get('name')
        cur_ops = []
        if cur_name == new_name:
            # nothing to do
            continue

        if not cur_name:
            if strict_present:
                errors.append(
                    "[nic not present] Cannot rename mac=%s to %s"
                    ", not available." % (mac, new_name))
            continue

        if cur['up']:
            msg = "[busy] Error renaming mac=%s from %s to %s"
            if not cur['downable']:
                if strict_busy:
                    errors.append(msg % (mac, cur_name, new_name))
                continue
            cur['up'] = False
            cur_ops.append(("down", mac, new_name, (cur_name,)))
            ups.append(("up", mac, new_name, (new_name,)))

        if new_name in cur_byname:
            target = cur_byname[new_name]
            if target['up']:
                msg = "[busy-target] Error renaming mac=%s from %s to %s."
                if not target['downable']:
                    if strict_busy:
                        errors.append(msg % (mac, cur_name, new_name))
                    continue
                else:
                    cur_ops.append(("down", mac, new_name, (new_name,)))

            tmp_name = None
            while tmp_name is None or tmp_name in cur_byname:
                tmpi += 1
                tmp_name = tmpname_fmt % tmpi

            cur_ops.append(("rename", mac, new_name, (new_name, tmp_name)))
            target['name'] = tmp_name
            cur_byname = update_byname(cur_bymac)
            if target['up']:
                ups.append(("up", mac, new_name, (tmp_name,)))

        cur_ops.append(("rename", mac, new_name, (cur['name'], new_name)))
        cur['name'] = new_name
        cur_byname = update_byname(cur_bymac)
        ops += cur_ops

    opmap = {'rename': rename, 'down': down, 'up': up}

    if len(ops) + len(ups) == 0:
        if len(errors):
            LOG.debug("unable to do any work for renaming of %s", renames)
        else:
            LOG.debug("no work necessary for renaming of %s", renames)
    else:
        LOG.debug("achieving renaming of %s with ops %s", renames, ops + ups)

        for op, mac, new_name, params in ops + ups:
            try:
                opmap.get(op)(*params)
            except Exception as e:
                errors.append(
                    "[unknown] Error performing %s%s for %s, %s: %s" %
                    (op, params, mac, new_name, e))

    if len(errors):
        raise Exception('\n'.join(errors))


def get_interface_mac(ifname):
    """Returns the string value of an interface's MAC Address"""
    path = "address"
    if os.path.isdir(sys_dev_path(ifname, "bonding_slave")):
        # for a bond slave, get the nic's hwaddress, not the address it
        # is using because its part of a bond.
        path = "bonding_slave/perm_hwaddr"
    return read_sys_net_safe(ifname, path)


def get_interfaces_by_mac():
    """Build a dictionary of tuples {mac: name}.

    Bridges and any devices that have a 'stolen' mac are excluded."""
    try:
        devs = get_devicelist()
    except OSError as e:
        if e.errno == errno.ENOENT:
            devs = []
        else:
            raise
    ret = {}
    for name in devs:
        if not interface_has_own_mac(name):
            continue
        if is_bridge(name):
            continue
        mac = get_interface_mac(name)
        # some devices may not have a mac (tun0)
        if not mac:
            continue
        if mac in ret:
            raise RuntimeError(
                "duplicate mac found! both '%s' and '%s' have mac '%s'" %
                (name, ret[mac], mac))
        ret[mac] = name
    return ret


class RendererNotFoundError(RuntimeError):
    pass


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