#!/bin/sh

# Client script for LXC container images.
#
# Copyright © 2014 Stéphane Graber <stgraber@ubuntu.com>
#
#  This library is free software; you can redistribute it and/or
#  modify it under the terms of the GNU Lesser General Public
#  License as published by the Free Software Foundation; either
#  version 2.1 of the License, or (at your option) any later version.

#  This library is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#  Lesser General Public License for more details.

#  You should have received a copy of the GNU Lesser General Public
#  License along with this library; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
#  USA

set -eu

LOCALSTATEDIR="@LOCALSTATEDIR@"
LXC_HOOK_DIR="@LXCHOOKDIR@"
LXC_TEMPLATE_CONFIG="@LXCTEMPLATECONFIG@"

# Defaults
DOWNLOAD_ARCH=
DOWNLOAD_BUILD=
DOWNLOAD_COMPAT_LEVEL=4
DOWNLOAD_DIST=
DOWNLOAD_FLUSH_CACHE="false"
DOWNLOAD_FORCE_CACHE="false"
DOWNLOAD_INTERACTIVE="false"
DOWNLOAD_KEYID="0xE7FB0CAEC8173D669066514CBAEFF88C22F6E216"
DOWNLOAD_LIST_IMAGES="false"
DOWNLOAD_MODE="system"
DOWNLOAD_READY_GPG="false"
DOWNLOAD_RELEASE=
DOWNLOAD_SERVER="images.linuxcontainers.org"
DOWNLOAD_SHOW_GPG_WARNING="true"
DOWNLOAD_SHOW_HTTP_WARNING="true"
DOWNLOAD_TARGET="system"
DOWNLOAD_URL=
DOWNLOAD_USE_CACHE="false"
DOWNLOAD_VALIDATE="true"
DOWNLOAD_VARIANT="default"

LXC_MAPPED_GID=
LXC_MAPPED_UID=
LXC_NAME=
LXC_PATH=
LXC_ROOTFS=

if [ -z "${DOWNLOAD_KEYSERVER+x}" ]; then
	DOWNLOAD_KEYSERVER="hkp://pool.sks-keyservers.net"

	# Deal with GPG over http proxy
	if [ -n "${http_proxy:-}" ]; then
	    DOWNLOAD_KEYSERVER="hkp://p80.pool.sks-keyservers.net:80"
	fi
fi

# Make sure the usual locations are in PATH
export PATH=$PATH:/usr/sbin:/usr/bin:/sbin:/bin

# Some useful functions
cleanup() {
    if [ -d "$DOWNLOAD_TEMP" ]; then
        rm -Rf $DOWNLOAD_TEMP
    fi
}

wget_wrapper() {
    for i in $(seq 3); do
        if wget $@; then
            return 0
        fi
    done

    return 1
}

download_file() {
    if ! wget_wrapper -T 30 -q https://${DOWNLOAD_SERVER}/$1 -O $2 >/dev/null 2>&1; then
        if ! wget_wrapper -T 30 -q http://${DOWNLOAD_SERVER}/$1 -O $2 >/dev/null 2>&1; then
            if [ "$3" = "noexit" ]; then
                return 1
            else
                echo "ERROR: Failed to download http://${DOWNLOAD_SERVER}/$1" 1>&2
                exit 1
            fi
        elif [ "$DOWNLOAD_SHOW_HTTP_WARNING" = "true" ]; then
            DOWNLOAD_SHOW_HTTP_WARNING="false"
            echo "WARNING: Failed to download the file over HTTPs." 1>&2
            echo -n "         The file was instead download over HTTP. " 1>&2
            echo "A server replay attack may be possible!" 1>&2
        fi
    fi
}

download_sig() {
    if ! download_file $1 $2 noexit; then
        if [ "$DOWNLOAD_VALIDATE" = "true" ]; then
            if [ "$3" = "normal" ]; then
                echo "ERROR: Failed to download http://${DOWNLOAD_SERVER}/$1" 1>&2
                exit 1
            else
                return 1
            fi
        else
            return 0
        fi
    fi
}

gpg_setup() {
    if [ "$DOWNLOAD_VALIDATE" = "false" ]; then
        return
    fi

    if [ "$DOWNLOAD_READY_GPG" = "true" ]; then
        return
    fi

    echo "Setting up the GPG keyring"

    mkdir -p "$DOWNLOAD_TEMP/gpg"
    chmod 700 "$DOWNLOAD_TEMP/gpg"
    export GNUPGHOME="$DOWNLOAD_TEMP/gpg"

    success=
    for i in $(seq 3); do
        if gpg --keyserver $DOWNLOAD_KEYSERVER \
            --recv-keys ${DOWNLOAD_KEYID} >/dev/null 2>&1; then
            success=1
            break
        fi
    done

    if [ -z "$success" ]; then
        echo "ERROR: Unable to fetch GPG key from keyserver."
        exit 1
    fi

    DOWNLOAD_READY_GPG="true"
}

gpg_validate() {
    if [ "$DOWNLOAD_VALIDATE" = "false" ]; then
        if [ "$DOWNLOAD_SHOW_GPG_WARNING" = "true" ]; then
            echo "WARNING: Running without gpg validation!" 1>&2
        fi
        DOWNLOAD_SHOW_GPG_WARNING="false"
        return 0
    fi

    if ! gpg --verify $1 >/dev/zero 2>&1; then
        echo "ERROR: Invalid signature for $1" 1>&2
        exit 1
    fi
}

in_userns() {
    [ -e /proc/self/uid_map ] || { echo no; return; }
    while read line; do
        fields=$(echo $line | awk '{ print $1 " " $2 " " $3 }')
        [ "$fields" = "0 0 4294967295" ] && { echo no; return; } || true
        echo $fields | grep -q " 0 1$" && { echo userns-root; return; } || true
    done < /proc/self/uid_map

    [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ] && \
        { echo userns-root; return; }
    echo yes
}

relevant_file() {
    FILE_PATH="${LXC_CACHE_PATH}/$1"
    if [ -e "${FILE_PATH}-${DOWNLOAD_MODE}" ]; then
        FILE_PATH="${FILE_PATH}-${DOWNLOAD_MODE}"
    fi
    if [ -e "$FILE_PATH.${DOWNLOAD_COMPAT_LEVEL}" ]; then
        FILE_PATH="${FILE_PATH}.${DOWNLOAD_COMPAT_LEVEL}"
    fi

    echo $FILE_PATH
}

usage() {
    cat <<EOF
LXC container image downloader

Special arguments:
[ -h | --help ]: Print this help message and exit.
[ -l | --list ]: List all available images and exit.

Required arguments:
[ -d | --dist <distribution> ]: The name of the distribution
[ -r | --release <release> ]: Release name/version
[ -a | --arch <architecture> ]: Architecture of the container

Optional arguments:
[ --variant <variant> ]: Variant of the image (default: "default")
[ --server <server> ]: Image server (default: "images.linuxcontainers.org")
[ --keyid <keyid> ]: GPG keyid (default: 0x...)
[ --keyserver <keyserver> ]: GPG keyserver to use. Environment variable: DOWNLOAD_KEYSERVER
[ --no-validate ]: Disable GPG validation (not recommended)
[ --flush-cache ]: Flush the local copy (if present)
[ --force-cache ]: Force the use of the local copy even if expired

LXC internal arguments (do not pass manually!):
[ --name <name> ]: The container name
[ --path <path> ]: The path to the container
[ --rootfs <rootfs> ]: The path to the container's rootfs
[ --mapped-uid <map> ]: A uid map (user namespaces)
[ --mapped-gid <map> ]: A gid map (user namespaces)

Environment Variables:
DOWNLOAD_KEYSERVER : The URL of the key server to use, instead of the default.
                     Can be further overridden by using optional argument --keyserver

EOF
    return 0
}

options=$(getopt -o d:r:a:hl -l dist:,release:,arch:,help,list,variant:,\
server:,keyid:,keyserver:,no-validate,flush-cache,force-cache,name:,path:,\
rootfs:,mapped-uid:,mapped-gid: -- "$@")

if [ $? -ne 0 ]; then
    usage
    exit 1
fi
eval set -- "$options"

while :; do
    case "$1" in
        -h|--help)          usage && exit 1;;
        -l|--list)          DOWNLOAD_LIST_IMAGES="true"; shift 1;;
        -d|--dist)          DOWNLOAD_DIST=$2; shift 2;;
        -r|--release)       DOWNLOAD_RELEASE=$2; shift 2;;
        -a|--arch)          DOWNLOAD_ARCH=$2; shift 2;;
        --variant)          DOWNLOAD_VARIANT=$2; shift 2;;
        --server)           DOWNLOAD_SERVER=$2; shift 2;;
        --keyid)            DOWNLOAD_KEYID=$2; shift 2;;
        --keyserver)        DOWNLOAD_KEYSERVER=$2; shift 2;;
        --no-validate)      DOWNLOAD_VALIDATE="false"; shift 1;;
        --flush-cache)      DOWNLOAD_FLUSH_CACHE="true"; shift 1;;
        --force-cache)      DOWNLOAD_FORCE_CACHE="true"; shift 1;;
        --name)             LXC_NAME=$2; shift 2;;
        --path)             LXC_PATH=$2; shift 2;;
        --rootfs)           LXC_ROOTFS=$2; shift 2;;
        --mapped-uid)       LXC_MAPPED_UID=$2; shift 2;;
        --mapped-gid)       LXC_MAPPED_GID=$2; shift 2;;
        *)                  break;;
    esac
done

# Check for required binaries
for bin in tar xz wget; do
    if ! type $bin >/dev/null 2>&1; then
        echo "ERROR: Missing required tool: $bin" 1>&2
        exit 1
    fi
done

# Check for GPG
if [ "$DOWNLOAD_VALIDATE" = "true" ]; then
    if ! type gpg >/dev/null 2>&1; then
        echo "ERROR: Missing recommended tool: gpg" 1>&2
        echo "You can workaround this by using --no-validate." 1>&2
        exit 1
    fi
fi

# Check that we have all variables we need
if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
    if [ "$DOWNLOAD_LIST_IMAGES" != "true" ]; then
        echo "ERROR: Not running through LXC." 1>&2
        exit 1
    fi
fi

USERNS=$(in_userns)

if [ "$USERNS" != "no" ]; then
    if [ "$USERNS" = "yes" ]; then
        if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
            echo "ERROR: In a user namespace without a map." 1>&2
            exit 1
        fi
        DOWNLOAD_MODE="user"
        DOWNLOAD_TARGET="user"
    else
        DOWNLOAD_MODE="user"
        DOWNLOAD_TARGET="system"
    fi
fi

if [ -z "$DOWNLOAD_DIST" ] || [ -z "$DOWNLOAD_RELEASE" ] || \
   [ -z "$DOWNLOAD_ARCH" ]; then
    DOWNLOAD_INTERACTIVE="true"
fi

# Trap all exit signals
trap cleanup EXIT HUP INT TERM

if ! type mktemp >/dev/null 2>&1; then
    DOWNLOAD_TEMP=/tmp/lxc-download.$$
    mkdir -p $DOWNLOAD_TEMP
else
    DOWNLOAD_TEMP=$(mktemp -d)
fi

# Simply list images
if [ "$DOWNLOAD_LIST_IMAGES" = "true" ] || \
   [ "$DOWNLOAD_INTERACTIVE" = "true" ]; then
    # Initialize GPG
    gpg_setup

    # Grab the index
    DOWNLOAD_INDEX_PATH=/meta/1.0/index-${DOWNLOAD_MODE}

    echo "Downloading the image index"
    if ! download_file ${DOWNLOAD_INDEX_PATH}.${DOWNLOAD_COMPAT_LEVEL} \
         ${DOWNLOAD_TEMP}/index noexit ||
       ! download_sig ${DOWNLOAD_INDEX_PATH}.${DOWNLOAD_COMPAT_LEVEL}.asc \
            ${DOWNLOAD_TEMP}/index.asc noexit; then
        download_file ${DOWNLOAD_INDEX_PATH} ${DOWNLOAD_TEMP}/index normal
        download_sig  ${DOWNLOAD_INDEX_PATH}.asc \
            ${DOWNLOAD_TEMP}/index.asc normal
    fi

    gpg_validate ${DOWNLOAD_TEMP}/index.asc

    # Parse it
    echo ""
    echo "---"
    printf "DIST\tRELEASE\tARCH\tVARIANT\tBUILD\n"
    echo "---"
    while read line; do
        # Basic CSV parser
        OLD_IFS=$IFS
        IFS=";"
        set -- $line
        IFS=$OLD_IFS

        [ -n "$DOWNLOAD_DIST" ] && [ "$1" != "$DOWNLOAD_DIST" ] && continue
        [ -n "$DOWNLOAD_RELEASE" ] && [ "$2" != "$DOWNLOAD_RELEASE" ] && continue
        [ -n "$DOWNLOAD_ARCH" ] && [ "$3" != "$DOWNLOAD_ARCH" ] && continue
        [ -n "$DOWNLOAD_VARIANT" ] && [ "$4" != "$DOWNLOAD_VARIANT" ] && continue
        [ -z "$5" ] || [ -z "$6" ] && continue

        printf "$1\t$2\t$3\t$4\t$5\n"
    done < ${DOWNLOAD_TEMP}/index
    echo "---"

    if [ "$DOWNLOAD_LIST_IMAGES" = "true" ]; then
        exit 1
    fi

    # Interactive mode
    echo ""

    if [ -z "$DOWNLOAD_DIST" ]; then
        echo -n "Distribution: "
        read DOWNLOAD_DIST
    fi

    if [ -z "$DOWNLOAD_RELEASE" ]; then
        echo -n "Release: "
        read DOWNLOAD_RELEASE
    fi

    if [ -z "$DOWNLOAD_ARCH" ]; then
        echo -n "Architecture: "
        read DOWNLOAD_ARCH
    fi

    echo ""
fi

# Setup the cache
if [ "$DOWNLOAD_TARGET" = "system" ]; then
    LXC_CACHE_BASE="$LOCALSTATEDIR/cache/lxc/"
else
    LXC_CACHE_BASE="$HOME/.cache/lxc/"
fi

# Allow the setting of the LXC_CACHE_PATH with the usage of environment variables.
LXC_CACHE_PATH=${LXC_CACHE_PATH:-"$LXC_CACHE_BASE"}
LXC_CACHE_PATH=$LXC_CACHE_PATH/download/$DOWNLOAD_DIST
LXC_CACHE_PATH="$LXC_CACHE_PATH/$DOWNLOAD_RELEASE/$DOWNLOAD_ARCH/"
LXC_CACHE_PATH="$LXC_CACHE_PATH/$DOWNLOAD_VARIANT"

if [ -d "$LXC_CACHE_PATH" ]; then
    if [ "$DOWNLOAD_FLUSH_CACHE" = "true" ]; then
        echo "Flushing the cache..."
        rm -Rf $LXC_CACHE_PATH
    elif [ "$DOWNLOAD_FORCE_CACHE" = "true" ]; then
        DOWNLOAD_USE_CACHE="true"
    else
        DOWNLOAD_USE_CACHE="true"
        if [ -e "$(relevant_file expiry)" ]; then
            if [ "$(cat $(relevant_file expiry))" -lt $(date +%s) ]; then
                echo "The cached copy has expired, re-downloading..."
                DOWNLOAD_USE_CACHE="false"
            fi
        fi
    fi
fi

# Download what's needed
if [ "$DOWNLOAD_USE_CACHE" = "false" ]; then
    # Initialize GPG
    gpg_setup

    # Grab the index
    DOWNLOAD_INDEX_PATH=/meta/1.0/index-${DOWNLOAD_MODE}

    echo "Downloading the image index"
    if ! download_file ${DOWNLOAD_INDEX_PATH}.${DOWNLOAD_COMPAT_LEVEL} \
         ${DOWNLOAD_TEMP}/index noexit ||
       ! download_sig ${DOWNLOAD_INDEX_PATH}.${DOWNLOAD_COMPAT_LEVEL}.asc \
            ${DOWNLOAD_TEMP}/index.asc noexit; then
        download_file ${DOWNLOAD_INDEX_PATH} ${DOWNLOAD_TEMP}/index normal
        download_sig  ${DOWNLOAD_INDEX_PATH}.asc \
            ${DOWNLOAD_TEMP}/index.asc normal
    fi

    gpg_validate ${DOWNLOAD_TEMP}/index.asc

    # Parse it
    while read line; do
        # Basic CSV parser
        OLD_IFS=$IFS
        IFS=";"
        set -- $line
        IFS=$OLD_IFS

        if [ "$1" != "$DOWNLOAD_DIST" ] || \
           [ "$2" != "$DOWNLOAD_RELEASE" ] || \
           [ "$3" != "$DOWNLOAD_ARCH" ] || \
           [ "$4" != "$DOWNLOAD_VARIANT" ] || \
           [ -z "$6" ]; then
            continue
        fi

        DOWNLOAD_BUILD=$5
        DOWNLOAD_URL=$6
        break
    done < ${DOWNLOAD_TEMP}/index

    if [ -z "$DOWNLOAD_URL" ]; then
        echo "ERROR: Couldn't find a matching image." 1>&1
        exit 1
    fi

    if [ -d "$LXC_CACHE_PATH" ] && [ -f "$LXC_CACHE_PATH/build_id" ] && \
       [ "$(cat $LXC_CACHE_PATH/build_id)" = "$DOWNLOAD_BUILD" ]; then
        echo "The cache is already up to date."
        echo "Using image from local cache"
    else
        # Download the actual files
        echo "Downloading the rootfs"
        download_file $DOWNLOAD_URL/rootfs.tar.xz \
            ${DOWNLOAD_TEMP}/rootfs.tar.xz normal
        download_sig  $DOWNLOAD_URL/rootfs.tar.xz.asc \
             ${DOWNLOAD_TEMP}/rootfs.tar.xz.asc normal
        gpg_validate ${DOWNLOAD_TEMP}/rootfs.tar.xz.asc

        echo "Downloading the metadata"
        download_file $DOWNLOAD_URL/meta.tar.xz \
            ${DOWNLOAD_TEMP}/meta.tar.xz normal
        download_sig  $DOWNLOAD_URL/meta.tar.xz.asc \
            ${DOWNLOAD_TEMP}/meta.tar.xz.asc normal
        gpg_validate ${DOWNLOAD_TEMP}/meta.tar.xz.asc

        if [ -d $LXC_CACHE_PATH ]; then
            rm -Rf $LXC_CACHE_PATH
        fi
        mkdir -p $LXC_CACHE_PATH
        mv ${DOWNLOAD_TEMP}/rootfs.tar.xz $LXC_CACHE_PATH
        if ! tar Jxf ${DOWNLOAD_TEMP}/meta.tar.xz -C $LXC_CACHE_PATH; then
            echo "ERROR: Invalid rootfs tarball." 2>&1
            exit 1
        fi

        echo $DOWNLOAD_BUILD > $LXC_CACHE_PATH/build_id

        if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
            chown -R $LXC_MAPPED_UID $LXC_CACHE_BASE >/dev/null 2>&1 || true
        fi
        if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
            chgrp -R $LXC_MAPPED_GID $LXC_CACHE_BASE >/dev/null 2>&1 || true
        fi
        echo "The image cache is now ready"
    fi
else
    echo "Using image from local cache"
fi

# Unpack the rootfs
echo "Unpacking the rootfs"

EXCLUDES=""
excludelist=$(relevant_file excludes)
if [ -f "${excludelist}" ]; then
    while read line; do
        EXCLUDES="$EXCLUDES --exclude=$line"
    done < $excludelist
fi

tar  --anchored ${EXCLUDES} --numeric-owner -xpJf \
    ${LXC_CACHE_PATH}/rootfs.tar.xz -C ${LXC_ROOTFS}

mkdir -p ${LXC_ROOTFS}/dev/pts/

# Setup the configuration
configfile=$(relevant_file config)
fstab=$(relevant_file fstab)
if [ ! -e $configfile ]; then
    echo "ERROR: meta tarball is missing the configuration file" 1>&2
    exit 1
fi

## Extract all the network config entries
sed -i -e "/lxc.network/{w ${LXC_PATH}/config-network" -e "d}" \
    ${LXC_PATH}/config

## Extract any other config entry
sed -i -e "/lxc./{w ${LXC_PATH}/config-auto" -e "d}" ${LXC_PATH}/config

## Append the defaults
echo "" >> ${LXC_PATH}/config
echo "# Distribution configuration" >> ${LXC_PATH}/config
cat $configfile >> ${LXC_PATH}/config

## Add the container-specific config
echo "" >> ${LXC_PATH}/config
echo "# Container specific configuration" >> ${LXC_PATH}/config
if [ -e "${LXC_PATH}/config-auto" ]; then
    cat ${LXC_PATH}/config-auto >> ${LXC_PATH}/config
    rm ${LXC_PATH}/config-auto
fi
if [ -e "$fstab" ]; then
    echo "lxc.mount = ${LXC_PATH}/fstab" >> ${LXC_PATH}/config
fi
echo "lxc.utsname = ${LXC_NAME}" >> ${LXC_PATH}/config

## Re-add the previously removed network config
if [ -e "${LXC_PATH}/config-network" ]; then
    echo "" >> ${LXC_PATH}/config
    echo "# Network configuration" >> ${LXC_PATH}/config
    cat ${LXC_PATH}/config-network >> ${LXC_PATH}/config
    rm ${LXC_PATH}/config-network
fi

TEMPLATE_FILES="${LXC_PATH}/config"

# Setup the fstab
if [ -e $fstab ]; then
    cp ${fstab} ${LXC_PATH}/fstab
    TEMPLATE_FILES="$TEMPLATE_FILES ${LXC_PATH}/fstab"
fi

# Look for extra templates
if [ -e "$(relevant_file templates)" ]; then
    while read line; do
        fullpath=${LXC_ROOTFS}/$line
        [ ! -e "$fullpath" ] && continue
        TEMPLATE_FILES="$TEMPLATE_FILES $fullpath"
    done < $(relevant_file templates)
fi

# Replace variables in all templates
for file in $TEMPLATE_FILES; do
    [ ! -f "$file" ] && continue

    sed -i "s#LXC_NAME#$LXC_NAME#g" $file
    sed -i "s#LXC_PATH#$LXC_PATH#g" $file
    sed -i "s#LXC_ROOTFS#$LXC_ROOTFS#g" $file
    sed -i "s#LXC_TEMPLATE_CONFIG#$LXC_TEMPLATE_CONFIG#g" $file
    sed -i "s#LXC_HOOK_DIR#$LXC_HOOK_DIR#g" $file
done

# prevent mingetty from calling vhangup(2) since it fails with userns on CentOS / Oracle
if [ -f ${LXC_ROOTFS}/etc/init/tty.conf ]; then
    sed -i 's|mingetty|mingetty --nohangup|' ${LXC_ROOTFS}/etc/init/tty.conf
fi

if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
    chown $LXC_MAPPED_UID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
fi
if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
    chgrp $LXC_MAPPED_GID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
fi

if [ -e "$(relevant_file create-message)" ]; then
    echo ""
    echo "---"
    cat "$(relevant_file create-message)"
fi

exit 0