#!/usr/bin/env bash

# monkeysphere-host: Monkeysphere host admin tool
#
# The monkeysphere scripts are written by:
# Jameson Rollins <jrollins@finestructure.net>
# Jamie McClelland <jm@mayfirst.org>
# Daniel Kahn Gillmor <dkg@fifthhorseman.net>
# Micah Anderson <micah@riseup.net>
#
# They are Copyright 2008-2009, and are all released under the GPL,
# version 3 or later.

########################################################################
set -e

PGRM=$(basename $0)

SYSSHAREDIR=${MONKEYSPHERE_SYSSHAREDIR:-"/usr/share/monkeysphere"}
export SYSSHAREDIR
. "${SYSSHAREDIR}/common" || exit 1

SYSDATADIR=${MONKEYSPHERE_SYSDATADIR:-"/var/lib/monkeysphere"}
export SYSDATADIR

# sharedir for host functions
MHSHAREDIR="${SYSSHAREDIR}/mh"

# datadir for host functions
MHDATADIR="${SYSDATADIR}/host"

# UTC date in ISO 8601 format if needed
DATE=$(date -u '+%FT%T')

# unset some environment variables that could screw things up
unset GREP_OPTIONS

# default return code
RETURN=0

########################################################################
# FUNCTIONS
########################################################################

usage() {
    cat <<EOF >&2
usage: $PGRM <subcommand> [options] [args]
Monkeysphere host admin tool.

subcommands:
 show-key (s)                        output all host key information
 set-expire (e) EXPIRE               set host key expiration
 add-hostname (n+) NAME[:PORT]       add hostname user ID to host key
 revoke-hostname (n-) NAME[:PORT]    revoke hostname user ID
 add-revoker (o) FINGERPRINT         add a revoker to the host key
 revoke-key (r)                      revoke host key
 publish-key (p)                     publish host key to keyserver

 expert <expert-subcommand>          run expert command
 expert help                         expert command help

 version (v)                         show version number
 help (h,?)                          this help

EOF
}

# function to run command as monkeysphere user
su_monkeysphere_user() {
    # if the current user is the monkeysphere user, then just eval
    # command
    if [ $(id -un) = "$MONKEYSPHERE_USER" ] ; then
	eval "$@"

    # otherwise su command as monkeysphere user
    else
	su "$MONKEYSPHERE_USER" -c "$@"
    fi
}

# function to interact with the gpg keyring
gpg_host() {
    GNUPGHOME="$GNUPGHOME_HOST" gpg "$@"
}

# command to list the info about the host key, in colon format
gpg_host_list() {
    gpg_host --list-keys --with-colons --fixed-list-mode \
	--with-fingerprint --with-fingerprint \
	"0x${HOST_FINGERPRINT}!"

}

# command for edit key scripts, takes scripts on stdin
gpg_host_edit() {
    gpg_host --quiet --command-fd 0 --edit-key \
	"0x${HOST_FINGERPRINT}!" "$@"
}

# output just key fingerprint
fingerprint_host_key() {
    # set the pipefail option so functions fails if can't read sec key
    set -o pipefail

    gpg_host --list-secret-keys --fingerprint \
	--with-colons --fixed-list-mode 2> /dev/null | \
	grep '^fpr:' | head -1 | cut -d: -f10 2>/dev/null
}

# output the index of a user ID on the host key
# return 1 if user ID not found
find_host_userid() {
    local userID="$1"
    local tmpuidMatch
    local line

    # match to only ultimately trusted user IDs
    tmpuidMatch="u:$(echo $userID | gpg_escape)"

    # find the index of the requsted user ID
    # NOTE: this is based on circumstantial evidence that the order of
    # this output is the appropriate index
    line=$(gpg_host_list | egrep '^(uid|uat):' | cut -f2,10 -d: | \
	grep -n -x -F "$tmpuidMatch" 2>/dev/null)

    if [ "$line" ] ; then
	echo ${line%%:*}
	return 0
    else
	return 1
    fi
}

# function to check for host secret key
check_host_fail() {
    [ "$HOST_FINGERPRINT" ] || \
	failure "You don't appear to have a Monkeysphere host key on this server.  Please run 'monkeysphere-host expert import-key' first."
}

# show info about the host key
show_key() {
    local fingerprintSSH

    # FIXME: should not have to be priviledged user to see this info.
    # should be taken from publicly accessible key files, instead of
    # the keyring.

    gpg_host --fingerprint --list-key --list-options show-unusable-uids \
	"0x${HOST_FINGERPRINT}!" 2>/dev/null

    echo "OpenPGP fingerprint: $HOST_FINGERPRINT"

    if [ -f "${MHDATADIR}/ssh_host_rsa_key.pub" ] ; then
	fingerprintSSH=$(ssh-keygen -l -f "${MHDATADIR}/ssh_host_rsa_key.pub" | \
	    awk '{ print $1, $2, $4 }')
	echo "ssh fingerprint: $fingerprintSSH"
    else
	log info "SSH host key not found."
    fi

    # FIXME: show expiration date
    # FIXME: other relevant key parameters?
}

########################################################################
# MAIN
########################################################################

# unset variables that should be defined only in config file
unset KEYSERVER
unset MONKEYSPHERE_USER

# load configuration file
[ -e ${MONKEYSPHERE_HOST_CONFIG:="${SYSCONFIGDIR}/monkeysphere-host.conf"} ] && . "$MONKEYSPHERE_HOST_CONFIG"

# set empty config variable with ones from the environment, or with
# defaults
LOG_LEVEL=${MONKEYSPHERE_LOG_LEVEL:=${LOG_LEVEL:="INFO"}}
KEYSERVER=${MONKEYSPHERE_KEYSERVER:=${KEYSERVER:="pool.sks-keyservers.net"}}
AUTHORIZED_USER_IDS=${MONKEYSPHERE_AUTHORIZED_USER_IDS:=${AUTHORIZED_USER_IDS:="%h/.monkeysphere/authorized_user_ids"}}
RAW_AUTHORIZED_KEYS=${MONKEYSPHERE_RAW_AUTHORIZED_KEYS:=${RAW_AUTHORIZED_KEYS:="%h/.ssh/authorized_keys"}}
MONKEYSPHERE_USER=${MONKEYSPHERE_MONKEYSPHERE_USER:=${MONKEYSPHERE_USER:="monkeysphere"}}

# other variables
CHECK_KEYSERVER=${MONKEYSPHERE_CHECK_KEYSERVER:="true"}
GNUPGHOME_HOST=${MONKEYSPHERE_GNUPGHOME_HOST:="${MHDATADIR}"}

# host key fingerprint
HOST_FINGERPRINT=$(fingerprint_host_key)

# export variables needed in su invocation
export DATE
export MODE
export LOG_LEVEL
export MONKEYSPHERE_USER
export KEYSERVER
export GNUPGHOME_HOST
export GNUPGHOME
export HOST_FINGERPRINT

# get subcommand
COMMAND="$1"
[ "$COMMAND" ] || failure "Type '$PGRM help' for usage."
shift


case $COMMAND in
    'show-key'|'show'|'s')
	check_host_keyring
	show_key
	;;

    'set-expire'|'extend-key'|'e')
	check_host_keyring
	source "${MHSHAREDIR}/set_expire"
	set_expire "$@"
	;;

    'add-hostname'|'add-name'|'n+')
	check_host_keyring
	source "${MHSHAREDIR}/add_hostname"
	add_hostname "$@"
	;;

    'revoke-hostname'|'revoke-name'|'n-')
	check_host_keyring
	source "${MHSHAREDIR}/revoke_hostname"
	revoke_hostname "$@"
	;;

    'add-revoker'|'o')
	check_host_keyring
	source "${MHSHAREDIR}/add_revoker"
	add_revoker "$@"
	;;

    'revoke-key'|'r')
	check_host_keyring
	source "${MHSHAREDIR}/revoke_key"
	revoke_key "$@"
	;;

    'publish-key'|'publish'|'p')
	check_host_keyring
	source "${MHSHAREDIR}/publish_key"
	publish_key
	;;

    'expert')
	SUBCOMMAND="$1"
	shift
	case "$SUBCOMMAND" in
	    'help'|'h'|'?')
		cat <<EOF
usage: $PGRM expert <subcommand> [options] [args]

expert subcommands:
 import-key (i) [NAME[:PORT]]        import existing ssh key to gpg
 gen-key (g) [NAME[:PORT]]           generate gpg key for the host
   --length (-l) BITS                  key length in bits (2048)
 diagnostics (d)                     monkeysphere host status

EOF
		;;

	    'import-key'|'i')
		source "${MHSHAREDIR}/import_key"
		import_key "$@"
		;;

	    'gen-key'|'g')
		source "${MHSHAREDIR}/gen_key"
		gen_key "$@"
		;;

	    'diagnostics'|'d')
		source "${MHSHAREDIR}/diagnostics"
		diagnostics
		;;

	    *)
		failure "Unknown expert subcommand: '$COMMAND'
Type '$PGRM help' for usage."
		;;
	esac
	;;

    'version'|'v')
	echo "$VERSION"
	;;

    '--help'|'help'|'-h'|'h'|'?')
        usage
        ;;

    *)
        failure "Unknown command: '$COMMAND'
Type '$PGRM help' for usage."
        ;;
esac

exit "$RETURN"