#!/usr/bin/env bash
# author: joe.zheng
# version: 23.12.08

set -e

BASE=0
COUNT=1
ISO="none"
CPU=2
MEM="4G"
SHARE="share"

DRY_RUN="n"
HOST_NAME="$(cat /proc/sys/kernel/hostname)"
HOST_ADDR="$(ip route get 1 | head -1 | awk '{print $7}')"
HOST_ID="$([ -e /etc/machine-id ] && cat /etc/machine-id || hostid)"
QEMU_EXEC="qemu-system-x86_64"
VM_PREFIX="vm-"
TAP_PREFIX="tap"
DNS_SEARCH="dnssearch=sh.intel.com,dnssearch=intel.com"

NO_DEF_NET="${NO_DEFAULT_NETWORK:-n}"
NO_BRG_NET="${NO_BRIDGE_NETWORK:-y}"

function usage() {
  local self=`basename $0`
  local version="$(sed -n '1,4s/# version: \(.*\)/\1/p' $0)"

  cat <<EOF
Usage: $self [-b <base>][-c <cpu>][-i <iso>][-m <mem>][-s <share>][-h][-n] [<count>]
  Start QEMU VMs each with two network interfaces, vnc display, ssh port forwarding,
  monitor through telnet, and shared folder with the host

  -b <base>:  base index of the VM, default: $BASE
  -c <cpu>:   logical cpu cores, default: $CPU
  -h:         print the usage message
  -i <iso>:   ISO image file for the OS installation, default: $ISO
  -m <mem>:   memory, default: $MEM
  -n:         dry run, print out information only, default: $DRY_RUN
  -s <share>: shared folder between host and VMs, "none" to disable, default: $SHARE

  <count>:    number of the VMs, default: $COUNT

  We assume the index of the VM is consecutive, e.g.:
  if the base index is 0, the 2 VMs will be named ${VM_PREFIX}0 and ${VM_PREFIX}1

  The file name of the disk image matches the VM index, e.g. ${VM_PREFIX}0 will use ${VM_PREFIX}0.img

  The tap device name matches the VM index too, e.g. ${VM_PREFIX}0 will use ${TAP_PREFIX}0.
  The tap devices should be created and configured in advance

  The MAC address of the network interface is derived from VM name, it is deterministic

  The share folder need to be mounted in the VM, e.g.:

    mkdir -p /mnt/share && \\
    mount -t 9p -o trans=virtio,version=9p2000.L,msize=512000 share /mnt/share

Environment variables:
  NO_DEFAULT_NETWORK:   "y" to disable the default network interface, default: $NO_DEF_NET
  NO_BRIDGE_NETWORK:    "y" to disable the bridge network interface, default: $NO_BRG_NET

Examples:
  # Check information before actual execution
  $self -n

  # Start a VM to install OS from an ISO image
  $self -i ubuntu-16.04.6-server-amd64.iso

  # Start a VM named ${VM_PREFIX}$BASE
  $self

  # Start a VM named ${VM_PREFIX}$BASE with bridged network interface
  sudo env NO_BRIDGE_NETWORK=n $self

  # Start 2 VMs named ${VM_PREFIX}1 and ${VM_PREFIX}2, each has 2 cores and 1G memory
  # the "host" folder will be used to share data between host and VMs
  $self -c 2 -m 1G -b 1 -s host 2

Version: $version
EOF

}

function gen_mac() {
  crc32 <(echo -n "$*") | sed 's/../& /g' | xargs printf "52:54:%s:%s:%s:%s"
}

while getopts ":b:c:hi:nm:s:" opt; do
  case $opt in
    b ) BASE=$OPTARG;;
    c ) CPU=$OPTARG;;
    h ) usage && exit;;
    i ) ISO=$OPTARG;;
    m ) MEM=$OPTARG;;
    n ) DRY_RUN=y;;
    s ) SHARE=$OPTARG;;
    * ) usage && exit 1;;
  esac
done

shift $((OPTIND-1))

# ensure we can find qemu as root user
local_bin="/usr/local/bin"
if [[ $PATH != *"$local_bin"* ]]; then
  PATH="$local_bin:$PATH"
fi

[[ $DRY_RUN == "y" ]] && QEMU_EXEC="echo $QEMU_EXEC"

if [[ -n $1 && $1 > 0 ]]; then
  COUNT=$1
fi

CDROM=""
if [[ $ISO != "none" ]]; then
    CDROM="-cdrom $ISO"
fi

for ((i=BASE; i<BASE+COUNT; i++)); do
  name=${VM_PREFIX}$i
  tap=${TAP_PREFIX}$i
  vnc=$((i + 10))     # vnc to 5900 + 10 + $i
  ssh=$((i + 2200))   # ssh to 2200 + $i
  con=$((i + 3300))   # access console by telnet to 3300 + $i
  mon=$((i + 4400))   # access monitor by telnet to 4400 + $i

  # to ensure there is no mac address conflict
  mac1=$(gen_mac $HOST_ID.${name}.1)
  mac2=$(gen_mac $HOST_ID.${name}.2)

  # generate a stable uuid
  uuid=$(uuidgen -s -n @dns -N $HOST_ID.$name)

  extra=""

  # default network
  if [[ $NO_DEF_NET != y ]]; then
    hostfwd="hostfwd=tcp::$ssh-:22"
    extra="$extra -netdev user,id=netdef,hostname="$HOST_NAME-$name",$DNS_SEARCH,$hostfwd \
          -device virtio-net,disable-modern=off,netdev=netdef,mac=$mac1"
  fi
  # bridge network
  if [[ $NO_BRG_NET != y ]]; then
    extra="$extra -netdev tap,id=neths,ifname=$tap,vhost=on,script=no,downscript=no \
          -device virtio-net,disable-modern=off,netdev=neths,mac=$mac2"
  fi

  # shared folder
  if [[ -n $SHARE && $SHARE != "none" ]]; then
    if [[ -d $SHARE ]]; then
      SHARE="$(cd $SHARE && pwd -P)"
    else
      mkdir -p $SHARE
    fi
    extra="$extra -fsdev local,security_model=mapped,id=fsshare,path=$SHARE \
          -device virtio-9p-pci,fsdev=fsshare,mount_tag=share"
  fi

  # vfio device assignment
  if [[ -x "get-vfio-dev" ]]; then
    extra="$extra $(./get-vfio-dev $i)"
  fi

  $QEMU_EXEC \
    -enable-kvm \
    -machine kernel_irqchip=on \
    -cpu host \
    -vga std \
    -display vnc=:$vnc \
    -monitor telnet::$mon,server,nowait \
    -serial telnet::$con,server,nowait \
    -daemonize \
    -smp $CPU \
    -m $MEM \
    -name $name \
    -uuid $uuid \
    -boot order=cd,once=d $CDROM \
    -drive file=${VM_PREFIX}$i.img,if=virtio \
    -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 \
    $extra

  if [[ $NO_DEF_NET != y ]]; then
    forward_disabled=""
  else
    forward_disabled=" (disabled)"
  fi

  cat <<EOF
  name:     $name
  uuid:     $uuid
  host-ip:  $HOST_ADDR
  vnc-port: $((vnc + 5900))
  ssh-port: $ssh$forward_disabled
  con-port: $con
  mon-port: $mon

EOF
done