#!/usr/bin/env bash

# monkeysphere: Monkeysphere client tool
#
# The monkeysphere scripts are written by:
# Jameson Rollins <jrollins@fifthhorseman.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.

########################################################################
PGRM=$(basename $0)

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

# sharedir for host functions
MSHAREDIR="${SYSSHAREDIR}/m"

# 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

# set the file creation mask to be only owner rw
umask 077

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

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

subcommands:
 update-known_hosts (k) [HOST]...    update known_hosts file
 update-authorized_keys (a)          update authorized_keys file
 import-subkey (i)                   import existing ssh key as gpg subkey
   --keyfile (-f) FILE                 key file to import
   --expire (-e) EXPIRE                date to expire
 gen-subkey (g) [KEYID]              generate an authentication subkey
   --length (-l) BITS                  key length in bits (2048)
   --expire (-e) EXPIRE                date to expire
 ssh-proxycommand                    monkeysphere ssh ProxyCommand
 subkey-to-ssh-agent (s)             store authentication subkey in ssh-agent
 version (v)                         show version number
 help (h,?)                          this help

EOF
}

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

# unset variables that should be defined only in config file
unset KEYSERVER
unset CHECK_KEYSERVER
unset KNOWN_HOSTS
unset HASH_KNOWN_HOSTS
unset AUTHORIZED_KEYS

# load global config
[ -r "${SYSCONFIGDIR}/monkeysphere.conf" ] && . "${SYSCONFIGDIR}/monkeysphere.conf"

# set monkeysphere home directory
MONKEYSPHERE_HOME=${MONKEYSPHERE_HOME:="${HOME}/.monkeysphere"}
mkdir -p -m 0700 "$MONKEYSPHERE_HOME"

# load local config
[ -e ${MONKEYSPHERE_CONFIG:="${MONKEYSPHERE_HOME}/monkeysphere.conf"} ] && . "$MONKEYSPHERE_CONFIG"

# set empty config variables with ones from the environment, or from
# config file, or with defaults
LOG_LEVEL=${MONKEYSPHERE_LOG_LEVEL:=${LOG_LEVEL:="INFO"}}
GNUPGHOME=${MONKEYSPHERE_GNUPGHOME:=${GNUPGHOME:="${HOME}/.gnupg"}}
KEYSERVER=${MONKEYSPHERE_KEYSERVER:="$KEYSERVER"}
# if keyserver not specified in env or monkeysphere.conf,
# look in gpg.conf
if [ -z "$KEYSERVER" ] ; then
    if [ -f "${GNUPGHOME}/gpg.conf" ] ; then
	KEYSERVER=$(grep -e "^[[:space:]]*keyserver " "${GNUPGHOME}/gpg.conf" | tail -1 | awk '{ print $2 }')
    fi
fi
# if it's still not specified, use the default
KEYSERVER=${KEYSERVER:="subkeys.pgp.net"}
CHECK_KEYSERVER=${MONKEYSPHERE_CHECK_KEYSERVER:=${CHECK_KEYSERVER:="true"}}
KNOWN_HOSTS=${MONKEYSPHERE_KNOWN_HOSTS:=${KNOWN_HOSTS:="${HOME}/.ssh/known_hosts"}}
HASH_KNOWN_HOSTS=${MONKEYSPHERE_HASH_KNOWN_HOSTS:=${HASH_KNOWN_HOSTS:="true"}}
AUTHORIZED_KEYS=${MONKEYSPHERE_AUTHORIZED_KEYS:=${AUTHORIZED_KEYS:="${HOME}/.ssh/authorized_keys"}}

# other variables not in config file
AUTHORIZED_USER_IDS=${MONKEYSPHERE_AUTHORIZED_USER_IDS:="${MONKEYSPHERE_HOME}/authorized_user_ids"}
REQUIRED_HOST_KEY_CAPABILITY=${MONKEYSPHERE_REQUIRED_HOST_KEY_CAPABILITY:="a"}
REQUIRED_USER_KEY_CAPABILITY=${MONKEYSPHERE_REQUIRED_USER_KEY_CAPABILITY:="a"}

# export GNUPGHOME and make sure gpg home exists with proper
# permissions
export GNUPGHOME
mkdir -p -m 0700 "$GNUPGHOME"
export LOG_LEVEL

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

case $COMMAND in
    'update-known_hosts'|'update-known-hosts'|'k')
	MODE='known_hosts'

	# touch the known_hosts file so that the file permission check
	# below won't fail upon not finding the file
	(umask 0022 && touch "$KNOWN_HOSTS")

	# check permissions on the known_hosts file path
	check_key_file_permissions "$USER" "$KNOWN_HOSTS" || failure

        # if hosts are specified on the command line, process just
        # those hosts
	if [ "$1" ] ; then
	    update_known_hosts "$@"
	    RETURN="$?"

        # otherwise, if no hosts are specified, process every host
        # in the user's known_hosts file
	else
	    # exit if the known_hosts file does not exist
	    if [ ! -e "$KNOWN_HOSTS" ] ; then
		log error "known_hosts file '$KNOWN_HOSTS' does not exist."
		exit
	    fi

	    process_known_hosts
	    RETURN="$?"
	fi
	;;

    'update-authorized_keys'|'update-authorized-keys'|'a')
	MODE='authorized_keys'

	# check permissions on the authorized_user_ids file path
	check_key_file_permissions "$USER" "$AUTHORIZED_USER_IDS" || failure

	# check permissions on the authorized_keys file path
	check_key_file_permissions "$USER" "$AUTHORIZED_KEYS" || failure

        # exit if the authorized_user_ids file is empty
	if [ ! -e "$AUTHORIZED_USER_IDS" ] ; then
	    log error "authorized_user_ids file '$AUTHORIZED_USER_IDS' does not exist."
	    exit
	fi

	# process authorized_user_ids file
	process_authorized_user_ids "$AUTHORIZED_USER_IDS"
	RETURN="$?"
	;;

    'import-subkey'|'i')
	source "${MSHAREDIR}/import_subkey"
	import_subkey "$@"
	;;

    'gen-subkey'|'g')
	source "${MSHAREDIR}/gen_subkey"
	gen_subkey "$@"
	;;

    'ssh-proxycommand'|'p')
	source "${MSHAREDIR}/ssh_proxycommand"
	ssh_proxycommand "$@"
	;;

    'subkey-to-ssh-agent'|'s')
	source "${MSHAREDIR}/subkey_to_ssh_agent"
	subkey_to_ssh_agent "$@"
	;;

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

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

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

exit "$RETURN"