#!/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.

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

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

# 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
 gen-subkey (g) [KEYID]              generate an authentication subkey
   --length (-l) BITS                  key length in bits (2048)
 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
}

# user gpg command to define common options
gpg_user() {
    gpg --no-greeting --quiet --no-tty "$@"
}

# take a secret key ID and check that only zero or one ID is provided,
# and that it corresponds to only a single secret key ID
check_gpg_sec_key_id() {
    local gpgSecOut

    case "$#" in
	0)
	    gpgSecOut=$(gpg_user --fixed-list-mode --list-secret-keys --with-colons 2>/dev/null | egrep '^sec:')
	    ;;
	1)
	    gpgSecOut=$(gpg_user --fixed-list-mode --list-secret-keys --with-colons "$keyID" | egrep '^sec:') || failure
	    ;;
	*)
	    failure "You must specify only a single primary key ID."
	    ;;
    esac

    # check that only a single secret key was found
    case $(echo "$gpgSecOut" | grep -c '^sec:') in
	0)
	    failure "No secret keys found.  Create an OpenPGP key with the following command:
 gpg --gen-key"
	    ;;
	1)
	    echo "$gpgSecOut" | cut -d: -f5
	    ;;
	*)
	    echo "Multiple primary secret keys found:"
	    echo "$gpgSecOut" | cut -d: -f5
	    echo "Please specify which primary key to use."
	    failure
	    ;;
    esac
}

# check that a valid authentication subkey does not already exist
check_gpg_authentication_subkey() {
    local keyID
    local IFS
    local line
    local type
    local validity
    local usage

    keyID="$1"

    # check that a valid authentication key does not already exist
    IFS=$'\n'
    for line in $(gpg_user --fixed-list-mode --list-keys --with-colons "$keyID") ; do
	type=$(echo "$line" | cut -d: -f1)
	validity=$(echo "$line" | cut -d: -f2)
	usage=$(echo "$line" | cut -d: -f12)

	# look at keys only
	if [ "$type" != 'pub' -a "$type" != 'sub' ] ; then
	    continue
	fi
	# check for authentication capability
	if ! check_capability "$usage" 'a' ; then
	    continue
	fi
	# if authentication key is valid, prompt to continue
	if [ "$validity" = 'u' ] ; then
	    echo "A valid authentication key already exists for primary key '$keyID'." 1>&2
	    if [ "$PROMPT" = "true" ] ; then
		read -p "Are you sure you would like to generate another one? (y/N) " OK; OK=${OK:N}
		if [ "${OK/y/Y}" != 'Y' ] ; then
		    failure "aborting."
		fi
		break
	    else
		failure "aborting."
	    fi
	fi
    done
}

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

# set unset default variables
GNUPGHOME=${GNUPGHOME:="${HOME}/.gnupg"}
KNOWN_HOSTS="${HOME}/.ssh/known_hosts"
HASH_KNOWN_HOSTS="true"
AUTHORIZED_KEYS="${HOME}/.ssh/authorized_keys"

# unset the check keyserver variable, since that needs to have
# different defaults for the different functions
unset CHECK_KEYSERVER

# 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
GNUPGHOME=${MONKEYSPHERE_GNUPGHOME:=$GNUPGHOME}
LOG_LEVEL=${MONKEYSPHERE_LOG_LEVEL:=$LOG_LEVEL}
KEYSERVER=${MONKEYSPHERE_KEYSERVER:=$KEYSERVER}
# if keyserver not specified in env or conf, then 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 $2 }')
    fi
fi
PROMPT=${MONKEYSPHERE_PROMPT:=$PROMPT}
KNOWN_HOSTS=${MONKEYSPHERE_KNOWN_HOSTS:=$KNOWN_HOSTS}
HASH_KNOWN_HOSTS=${MONKEYSPHERE_HASH_KNOWN_HOSTS:=$HASH_KNOWN_HOSTS}
AUTHORIZED_KEYS=${MONKEYSPHERE_AUTHORIZED_KEYS:=$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 $COMMAND in
    'update-known_hosts'|'update-known-hosts'|'k')
	# whether or not to check keyservers
	CHECK_KEYSERVER=${MONKEYSPHERE_CHECK_KEYSERVER:=${CHECK_KEYSERVER:="true"}}

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

	# otherwise, if no hosts are specified, process every host
	# in the user's known_hosts file
	else
	    process_known_hosts
	fi
	;;

    'update-authorized_keys'|'update-authorized-keys'|'a')
	# whether or not to check keyservers
	CHECK_KEYSERVER=${MONKEYSPHERE_CHECK_KEYSERVER:=${CHECK_KEYSERVER:="true"}}

	# process authorized_user_ids file
	process_authorized_user_ids "$AUTHORIZED_USER_IDS"
	;;

    '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