#!/bin/sh

# Run gpg once to create default options
GNUPGHOME=/root
export GNUPGHOME
/usr/bin/gpg --yes 2>/dev/null </dev/null

# if this file is present, cancel the boot (exit this script)
CANCEL_BOOT_FLAG=/tmp/CANCEL_BOOT

# how many times to fail in attempting to contact primary server
# before falling back to original. if the backup fails this many times
# too, then the process is repeated started with the primary server
ATTEMPTS_BEFORE_BACKUP=3

# where all the configuration files for contacting
# the boot server are stored
BOOT_DIR=/usr/boot/

# get the server we are going to be contacting
BOOT_SERVER=`cat $BOOT_DIR/boot_server`
BOOT_SERVER_PORT=`cat $BOOT_DIR/boot_server_port`

# the file to request from the boot server
BOOT_SERVER_PATH=`cat $BOOT_DIR/boot_server_path`

# location of the cacert for this boot server
BOOT_SERVER_CACERT=$BOOT_DIR/cacert.pem

# location of the gpg key ring to verify scripts
BOOT_SERVER_GPG_KEYRING=$BOOT_DIR/pubring.gpg

# get the backup server we are going to be contacting
BACKUP_BOOT_SERVER=`cat $BOOT_DIR/backup/boot_server`
BACKUP_BOOT_SERVER_PORT=`cat $BOOT_DIR/backup/boot_server_port`

# the file to request from the backup boot server
BACKUP_BOOT_SERVER_PATH=`cat $BOOT_DIR/backup/boot_server_path`

# location of the cacert for the backup boot server
BACKUP_BOOT_SERVER_CACERT=$BOOT_DIR/backup/cacert.pem

# location of the gpg key ring for backup server to verify scripts
BACKUP_BOOT_SERVER_GPG_KEYRING=$BOOT_DIR/backup/pubring.gpg

# location of a file containing this boot cd version
BOOT_VERSION_FILE=/pl_version

# the locations of the downloaded scripts
UNVERIFIED_SCRIPT=/tmp/bootscript.gpg
VERIFIED_SCRIPT=/tmp/bootscript


# --------------------------


# now, contact the boot server, run the script, and do it over again.
contact_count=0

# set to one when we are trying to contact backup server
on_backup_server=0

# start out contacting the primary servers
CONNECT_BOOT_SERVER=$BOOT_SERVER
CONNECT_BOOT_SERVER_PORT=$BOOT_SERVER_PORT
CONNECT_BOOT_SERVER_PATH=$BOOT_SERVER_PATH
CONNECT_BOOT_SERVER_GPG_KEYRING=$BOOT_SERVER_GPG_KEYRING
CONNECT_BOOT_SERVER_CACERT=$BOOT_SERVER_CACERT

while : ; do

    if [[ -f $CANCEL_BOOT_FLAG ]]; then
	echo "pl_boot: got request to cancel boot, exiting"
	exit 0
    fi
    
    if [[ $contact_count -ge $ATTEMPTS_BEFORE_BACKUP ]]; then

	contact_count=0

	if [[ $on_backup_server == 1 ]]; then
	    echo "pl_boot: failed to contact backup server, trying primary."

	    on_backup_server=0

	    CONNECT_BOOT_SERVER=$BOOT_SERVER
	    CONNECT_BOOT_SERVER_PORT=$BOOT_SERVER_PORT
	    CONNECT_BOOT_SERVER_PATH=$BOOT_SERVER_PATH
	    CONNECT_BOOT_SERVER_GPG_KEYRING=$BOOT_SERVER_GPG_KEYRING
	    CONNECT_BOOT_SERVER_CACERT=$BOOT_SERVER_CACERT
	else
	    echo "pl_boot: failed to contact primary server, trying backup."

	    on_backup_server=1

	    CONNECT_BOOT_SERVER=$BACKUP_BOOT_SERVER
	    CONNECT_BOOT_SERVER_PORT=$BACKUP_BOOT_SERVER_PORT
	    CONNECT_BOOT_SERVER_PATH=$BACKUP_BOOT_SERVER_PATH
	    CONNECT_BOOT_SERVER_GPG_KEYRING=$BACKUP_BOOT_SERVER_GPG_KEYRING
	    CONNECT_BOOT_SERVER_CACERT=$BACKUP_BOOT_SERVER_CACERT
	fi
    fi

    if [[ $contact_count != 0 ]]; then

	if [[ $on_backup_server == 1 ]]; then
	    echo "pl_boot: attempting to fetch script from backup server in 30s"
	else
	    echo "pl_boot: attempting to fetch script from primary server in 30s"
	fi
	/bin/sleep 30
    fi

    # assemble the curl transaction
    CURL_CMD="/usr/bin/curl \
        --connect-timeout 60 \
        --max-time 600 \
        --form version=<$BOOT_VERSION_FILE \
        --form cmdline=</proc/cmdline \
        --form uptime=</proc/uptime \
        --form ifconfig=</tmp/ifconfig \
        --form nonce=</tmp/nonce \
        --location \
        --output $UNVERIFIED_SCRIPT \
        --sslv3  \
        --silent \
        --show-error \
        --fail \
        --stderr /tmp/curl_errors \
        --cacert $CONNECT_BOOT_SERVER_CACERT \
   https://$CONNECT_BOOT_SERVER:$CONNECT_BOOT_SERVER_PORT/$CONNECT_BOOT_SERVER_PATH"

    # assemble the gpg command line
    GPG_CMD="/usr/bin/gpg \
        --no-default-keyring \
        --keyring $CONNECT_BOOT_SERVER_GPG_KEYRING \
        --output $VERIFIED_SCRIPT \
        --always-trust \
        --decrypt $UNVERIFIED_SCRIPT"

    echo "pl_boot: generating new nonce"
    /usr/bin/head --bytes=32 /dev/urandom | \
	/usr/bin/od -tx1 -An --width=32 | \
	/bin/sed 's/ //g' > /tmp/nonce

    echo "pl_boot: fetching script from boot server $CONNECT_BOOT_SERVER"
    ((contact_count++))
    rm -f $UNVERIFIED_SCRIPT
    $CURL_CMD
    curl_err=$?
    if [ $curl_err -ne 0 ]; then
	echo "pl_boot: curl request failed with error $curl_err:"
	cat /tmp/curl_errors
	echo
	continue
    fi 

    echo "pl_boot: verifying downloaded script"
    rm -f $VERIFIED_SCRIPT
    $GPG_CMD 2> /tmp/gpg_errors
    if [ $? -ne 0 ]; then
	echo "pl_boot: failed to verify file:"
	cat /tmp/gpg_errors
	echo
	continue
    fi
    echo "pl_boot: decrypted and verified script succesfully"

    echo "pl_boot: handing control to download script"
    rm -f $UNVERIFIED_SCRIPT
    chmod +x $VERIFIED_SCRIPT
    $VERIFIED_SCRIPT
    
    echo "pl_boot: downloaded script has returned"
done

echo "pl_boot: automatic boot process canceled by user"