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#  Functions

# ######################################

log () {

  case "$1" in

    INFO | WARNING | ERROR )

      echo "$1: ${@:2}"

      ;;

    DEBUG)

      echo "$1: ${@:2}"

      ;;

    *)

      echo "-- $@"

      ;;

  esac

}

# ContainsElement: checks if first parameter is among the array given as second parameter

# returns 0 if the element is found in the list and 1 if not

# usage: containsElement $item $list

containsElement () {

  local e

  for e in "${@:2}"; do [[ "$e" == "$1" ]] && return 0; done

  return 1

}

# Generate random MAC address

genMAC () {

  hexchars="0123456789ABCDEF"

  end=$( for i in {1..8} ; do echo -n ${hexchars:$(( $RANDOM % 16 )):1} ; done | sed -e 's/\(..\)/:\1/g' )

  echo "FE:05$end"

}

# atoi: Returns the integer representation of an IP arg, passed in ascii

# dotted-decimal notation (x.x.x.x)

atoi() {

  IP=$1

  IPnum=0

  for (( i=0 ; i<4 ; ++i ))

  do

    ((IPnum+=${IP%%.*}*$((256**$((3-${i}))))))

    IP=${IP#*.}

  done

  echo $IPnum

}

# itoa: returns the dotted-decimal ascii form of an IP arg passed in integer

# format

itoa() {

  echo -n $(($(($(($((${1}/256))/256))/256))%256)).

  echo -n $(($(($((${1}/256))/256))%256)).

  echo -n $(($((${1}/256))%256)).

  echo $((${1}%256))

}

cidr2mask() {

  local i mask=""

  local full_octets=$(($1/8))

  local partial_octet=$(($1%8))

  for ((i=0;i<4;i+=1)); do

    if [ $i -lt $full_octets ]; then

      mask+=255

    elif [ $i -eq $full_octets ]; then

      mask+=$((256 - 2**(8-$partial_octet)))

    else

      mask+=0

    fi

    test $i -lt 3 && mask+=.

  done

  echo $mask

}

# Generates and returns a new IP and MASK in a superset (inmediate wider range)

# of the given IP/MASK

# usage: getNonConflictingIP IP MASK

# returns NEWIP MASK

getNonConflictingIP () {

    local IP="$1"

    local CIDR="$2"

    let "newCIDR=$CIDR-1"

    local i=$(atoi $IP)

    let "j=$i^(1<<(32-$CIDR))"

    local newIP=$(itoa j)

    echo $newIP $newCIDR

}

# generates unused, random names for macvlan or bridge devices

# usage: generateNetDevNames DEVICETYPE

#   DEVICETYPE must be either 'macvlan' or 'bridge'

# returns:

#   - bridgeXXXXXX if DEVICETYPE is 'bridge'

#   - macvlanXXXXXX, macvtapXXXXXX if DEVICETYPE is 'macvlan'

generateNetdevNames () {

  devicetype=$1

  local netdevinterfaces=($(ip link show | awk "/$devicetype/ { print \$2 }" | cut -d '@' -f 1 | tr -d :))

  local randomID=$(cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 6 | head -n 1)

  # check if the device already exists and regenerate the name if so

  while containsElement "$devicetype$randomID" "${netdevinterfaces[@]}"; do randomID=$(cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 6 | head -n 1); done

  echo "$randomID"

}

setupBridge () {

  set -x

  local iface="$1"

  local mode="$2"

  local deviceID=$(generateNetdevNames $mode)

  local bridgeName="$mode$deviceID"

  if [[ $mode == "bridge" ]]; then

    brctl addbr "$bridgeName"

    brctl addif "$bridgeName" "$iface"

  else # use macvlan devices by default

    vtapdev="macvtap${deviceID}"

    until $(ip link add link $iface name $vtapdev type macvtap mode bridge); do

      sleep 1

    done

    ip link set $vtapdev address "$MAC"

    ip link set $vtapdev up

    # create a macvlan device for the host

    ip link add link $iface name $bridgeName type macvlan mode bridge

    ip link set $bridgeName up

    # create dev file (there is no udev in container: need to be done manually)

    IFS=: read major minor < <(cat /sys/devices/virtual/net/$vtapdev/tap*/dev)

    mknod "/dev/$vtapdev" c $major $minor

  fi

  set +x

  # get a new IP for the guest machine in a broader network broadcast domain

  if ! [[ -z $IP ]]; then

    newIP=($(getNonConflictingIP $IP $CIDR))

    ip address del "$IP/$CIDR" dev "$iface"

    ip address add "${newIP[0]}/${newIP[1]}" dev "$bridgeName"

  fi

  ip link set dev "$bridgeName" up

  echo $deviceID

}

# Setup macvtap device to connect later the VM and setup a new macvlan devide

# to connect the host machine to the network

configureNetworks () {

  local IP

  local i=0

  local GATEWAY=$(ip r | grep default | awk '{print $3}')

  for iface in "${local_ifaces[@]}"; do

    IPs=$(ip address show dev $iface | grep inet | awk '/inet / { print $2 }' | cut -f1 -d/)

    IPs=($IPs)

    MAC=$(ip link show $iface | awk '/ether/ { print $2 }')

    log "DEBUG" "Container original MAC address: $MAC"

    # If the container has more than one IP configured in a given interface,

    # the user can select which one to use.

    # The SELECTED_NETWORK environment variable is used to select that IP.

    # This env variable must be in the form IP/MASK (e.g. 1.2.3.4/24).

    #

    # If this env variable is not set, the IP to be given to the VM is

    # the first in the list for that interface (default behaviour).

    if ! [[ -z "$SELECTED_NETWORK" ]]; then

      local given_ip given_mask

      IFS=/ read given_ip given_mask <<< $SELECTED_NETWORK

      local given_addr=$(atoi $given_ip)

      local given_mask=$((0xffffffff << (32 - $given_mask) & 0xffffffff))

      local given_broadcast=$((given_addr | ~given_mask & 0xffffffff))

      local given_network=$((given_addr & given_mask))

      for configured_ip in "${IPs[@]}"; do

        local configured_ip=$(atoi $configured_ip)

        if [[ $configured_ip -gt $given_network && $configured_ip -lt $given_broadcast ]]; then

          IP=$(itoa $configured_ip)

          log "INFO" "SELECTED_NETWORK ($SELECTED_NETWORK) found with ip $IP in $iface interface."

        fi

      done

      [[ -z "$IP" ]] && log "WARNING" "SELECTED_NETWORK ($SELECTED_NETWORK) not found in $iface interface."

    else

      IP=${IPs[0]}

    fi

    local CIDR=$(ip address show dev $iface | awk "/inet $IP/ { print \$2 }" | cut -f2 -d/)

    # use container MAC address ($MAC) for tap device

    # and generate a new one for the local interface

    ip link set $iface down

    ip link set $iface address $(genMAC)

    ip link set $iface up

    # setup the macvtap devices for bridging the VM

    deviceID=($(setupBridge $iface "macvlan"))

    bridgeName="macvlan$deviceID"

    # kvm configuration:

    let fd=$i+3

    NET_OPTS="$KVM_NET_OPTS -netdev tap,id=net$i,vhost=on,fd=$fd ${fd}<>/dev/macvtap$deviceID"

    setupDhcp

    log "DEBUG" "bridgeName: $bridgeName"

    NET_OPTS=" -device virtio-net-pci,netdev=net$i,mac=$MAC $NET_OPTS"

    let i++

  done

}

configureDHCP() {

  VM_NET_TAP="_VmMacvtap"

if [[ "$GATEWAY" == "172."* ]]; then

  # Configuration for static IP

  configureNAT

  #configureNAT

else

  # Configuration for DHCP IP

  configureDHCP

  #configureDHCP

fi

# Get all interfaces:

  local_ifaces=($(ip link show | grep -v noop | grep state | grep -v LOOPBACK | awk '{print $2}' | tr -d : | sed 's/@.*$//'))

  local_bridges=($(brctl show | tail -n +2 | awk '{print $1}'))

  # Get non-bridge interfaces:

  for i in "${local_bridges[@]}"

  do

    local_ifaces=(${local_ifaces[@]//*$i*})

  done

DEFAULT_ROUTE=$(ip route | grep default | awk '{print $3}')

configureNetworks

  # Hack for guest VMs complaining about "bad udp checksums in 5 packets"

  /usr/sbin/iptables -A POSTROUTING -t mangle -p udp --dport bootpc -j CHECKSUM --checksum-fill

  # Build DNS options from container /etc/resolv.conf

  nameservers=($(grep nameserver /etc/resolv.conf | sed 's/nameserver //'))

  searchdomains=$(grep search /etc/resolv.conf | sed 's/search //' | sed 's/ /,/g')

  domainname=$(echo $searchdomains | awk -F"," '{print $1}')

  for nameserver in "${nameservers[@]}"; do

    [[ -z $DNS_SERVERS ]] && DNS_SERVERS=$nameserver || DNS_SERVERS="$DNS_SERVERS,$nameserver"

  done

  DNSMASQ_OPTS="$DNSMASQ_OPTS                         \

    --dhcp-option=option:dns-server,$DNS_SERVERS      \

    --dhcp-option=option:router,$DEFAULT_ROUTE        \

    --dhcp-option=option:domain-search,$searchdomains \

    --dhcp-option=option:domain-name,$domainname      \

    "

  [[ -z $(hostname -d) ]] || DNSMASQ_OPTS="$DNSMASQ_OPTS --dhcp-option=option:domain-name,$(hostname -d)"

  log "INFO" "Lauching dnsmasq"

  log "DEBUG" "dnsmasq options: $DNSMASQ_OPTS"

  $DNSMASQ $DNSMASQ_OPTS

NET_OPTS="${NET_OPTS} -device virtio-net-pci,romfile=,netdev=hostnet0,mac=${VM_NET_MAC},id=net0"

# Hack for guest VMs complaining about "bad udp checksums in 5 packets"

iptables -A POSTROUTING -t mangle -p udp --dport bootpc -j CHECKSUM --checksum-fill

# iptables -A POSTROUTING -t mangle -p udp --dport bootpc -j CHECKSUM --checksum-fill