#!/bin/bash
#  $HeadURL$ $LastChangedRevision$

#  Properties
MY_ID=system_boot_net_dhcp
PARENT_ID=system_boot_net
MY_PRIVATE_ATTRIBUTES="uname status"
MY_PUBLIC_ATTRIBUTES=
MY_ATTRIBUTES="$MY_PRIVATE_ATTRIBUTES $MY_PUBLIC_ATTRIBUTES"
MY_HELPER_IDS=
for MY_ATTRIBUTE in ${MY_ATTRIBUTES^^}; do eval "$MY_ATTRIBUTE="; done

#  Defaults for the questions we ask (should only used here)

#  Other globals
PXESERVER_IPADDR=$(host $(uname -n) 2> /dev/null | sed 's/.*has address //')
DHCP_CLIENT_IPADDRS=$(echo 192.168.1.{60..69})
GATEWAY_IPADDR=192.168.1.1

#  Hooks
init_prologue()
{
    inherit DB_FILE SQLITE_CMD DHCP_CLIENT_IPADDRS
    local DHCP_CLIENT_IPADDR CMDLINE

    #  Create other tables
    debug 10 "init_prologue: creating other tables ..."
    $SQLITE_CMD $DB_FILE "drop table if exists dhcp_reservations;"
    $SQLITE_CMD $DB_FILE "create table dhcp_reservations (
                              ipaddr            text,
                              status            text,
                              macaddr           text unique,
                              uname             text unique,
                              primary key (ipaddr),
                              check (status == 'available' or uname not null),
                              check (status == 'available' or status == 'reserved'),
                              check (status == 'available' or macaddr not null)
                          );"

    debug 10 "init_prologue: preparing and running sql script to create empty DHCP reservation slots ..."
    {
        for DHCP_CLIENT_IPADDR in $DHCP_CLIENT_IPADDRS; do
            echo "INSERT INTO dhcp_reservations (ipaddr,status,macaddr,uname) VALUES ('$DHCP_CLIENT_IPADDR','available',NULL,NULL);"
        done
    } > /tmp/$PROGNAME.$$.init.sql
    $SQLITE_CMD $DB_FILE < /tmp/$PROGNAME.$$.init.sql ||{ 
        error "failed to initialse DHCP status table"
        return 1
    }
    rm -f /tmp/$PROGNAME.$$.init.sql

    #  Thu Jun 20 11:27:20 CEST 2013 - This function used to use a duplicate variable for DNS,
    #  DNS_DOMAIN instead of DNSCLIENT_DOMAIN. Now that it uses DNSCLIENT_DOMAIN, which is an 
    #  attribute stored in the database, which is *right now* being created, then this *init*
    #  function cannot use that variable. Instead of reverting to the old (and confusing way)
    #  we simply do not initialise the DHCP server here; this way it does not need to know
    #  the DNS domain in this function.
    #debug 10 "init_prologue: generating (empty) dhcpd.conf ..."
    #compile_dhcpd_conf || return $?
}

create_prologue()
{
    inherit ${MY_ATTRIBUTES^^}
    inherit MY_INHERITED_ATTRIBUTES ${MY_INHERITED_ATTRIBUTES^^}
    debug 10 "create_prologue: MY_INHERITED_ATTRIBUTES=\"$MY_INHERITED_ATTRIBUTES\", MACADDR=$MACADDR"

    info "creating DHCP reservations ..."
    reserve_dhcp_ipaddr_sql $MACADDR $UNAME || return $?

    #  If another DHCP server answers then this won't work.
    warning "be sure to disable any other DHCP server!!!"

    return 0
}

delete_epilogue()
{
    inherit ${MY_ATTRIBUTES^^}

    info "deleting DHCP reservations ..."
    release_dhcp_ipaddr_sql $MACADDR $UNAME || return $?

    return 0
}

list_prologue()
{
    UNAMES=$($SQLITE_CMD $DB_FILE "select group_concat(uname,' ') from attribute_values where helper == '$MY_ID' and attribute == 'status' and value == 'installing';")
    debug 10 "list_prologue: the following hosts are marked installing: $UNAMES"

    echo "DHCP reservations"
    echo "================="
    echo
    $SQLITE_CMD -column -header $DB_FILE "select ipaddr,uname,macaddr from dhcp_reservations where (status!='available');"
    echo
}

#  Support functions
compile_dhcpd_conf()
{
    local DHCPSERVER_RELEASE DHCPDCONF_FILE DHCPD_OUTPUT
    inherit DNSCLIENT_FLAG DNSCLIENT_DOMAIN DNSCLIENT_SERVERS GATEWAY_IPADDR PXESERVER_IPADDR

    debug 10 "compile_dhcpd_conf: restarting DHCP server ..."
    get_release_by_inspection DHCPSERVER_RELEASE || return $?

    case $DHCPSERVER_RELEASE in 
        lenny)   DHCPDCONF_FILE=/etc/dhcp3/dhcpd.conf ;;
        squeeze) DHCPDCONF_FILE=/etc/dhcp/dhcpd.conf ;;
        wheezy)  DHCPDCONF_FILE=/etc/dhcp/dhcpd.conf ;;
        *)       internal "$DHCPSERVER_RELEASE: unhandled" ;;
    esac
    debug 10 "compile_dhcpd_conf: recreating $DHCPDCONF_FILE ..."
    {
        echo "#  This file written by $PROGNAME at $(date)"
        if $DNSCLIENT_FLAG; then
             echo "option domain-name \"$DNSCLIENT_DOMAIN\";"
             echo "option domain-name-servers ${DNSCLIENT_SERVERS// /, };"
        fi
        echo "not authoritative;"
        echo "ddns-update-style none;"
        echo "update-static-leases on;"
        echo "deny unknown-clients;"
        echo "subnet 192.168.1.0 netmask 255.255.255.0 {"
        echo "    group {"
        echo "        option routers $GATEWAY_IPADDR;"
        echo "        next-server $PXESERVER_IPADDR;"
        echo "        filename \"pxelinux.0\";"
        $SQLITE_CMD -column $DB_FILE "select '        host ' || uname || ' { hardware ethernet ' || macaddr || '; fixed-address ' || ipaddr || '; } # ' || uname from dhcp_reservations WHERE (status == 'reserved');"
        echo "    }"
        echo "}"
    } > $DHCPDCONF_FILE

    case $DHCPSERVER_RELEASE in 
        lenny)   CMDLINE="/etc/init.d/dhcp3-server restart" ;;
        squeeze) CMDLINE="service isc-dhcp-server restart" ;;
        wheezy)  CMDLINE="service isc-dhcp-server restart" ;;
        *)       internal "$DHCPSERVER_RELEASE: unhandled" ;;
    esac
    DHCPD_OUTPUT=$(eval "$CMDLINE" 2>&1) || { error "dhcpd: failed (output was: $DHCPD_OUTPUT)"; return 1; }

    return 0
}

reserve_dhcp_ipaddr_sql()
{
    local MACADDR UNAME CMDLINE UPDATE_COUNT

    MACADDR=$1
    UNAME=$2

    CMDLINE="$SQLITE_CMD $DB_FILE \"UPDATE dhcp_reservations SET status='reserved',macaddr='$MACADDR',uname='$UNAME' WHERE (rowid IN (SELECT rowid FROM dhcp_reservations where (status=='available') limit 1)); SELECT CHANGES();\""
    debug 10 "reserve_dhcp_ipaddr_sql: running [$CMDLINE] ..."
    UPDATE_COUNT=$(eval "$CMDLINE") || internal "reserve_dhcp_ipaddr_sql: $SQLITE_CMD failed"
    debug 10 "reserve_dhcp_ipaddr_sql: UPDATE_COUNT=$UPDATE_COUNT"
    [ $UPDATE_COUNT = 1 ] || { error "failed to make DHCP reservation (is the SQL table of DHCP allocations full?)"; return 1; }

    compile_dhcpd_conf || return $?

    return 0
}

release_dhcp_ipaddr_sql()
{
    local MACADDR UNAME
    local CMDLINE 

    MACADDR=$1
    UNAME=$2

    CMDLINE="$SQLITE_CMD $DB_FILE \"UPDATE dhcp_reservations SET status='available',macaddr=NULL,uname=NULL WHERE (uname == '$UNAME');\""
    debug 10 "reserve_dhcp_ipaddr_sql: running [$CMDLINE] ..."
    eval "$CMDLINE" || internal "release_dhcp_ipaddr_sql: $SQLITE_CMD failed"
    
    compile_dhcpd_conf || return $?

    return 0
}