#!/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 2008-2010, and are all released under the GPL,
# version 3 or later.

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

# set the pipefail option so pipelines fail on first command failure
set -o pipefail

PGRM=$(basename $0)

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

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

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

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

# host pub key files
HOST_KEY_FILE="${SYSDATADIR}/host_keys.pub.pgp"

# 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

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

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

subcommands:
 import-key (i) FILE SERVICENAME       import PEM-encoded key from file
 show-keys (s) [KEYID ...]             output host key information
 publish-keys (p) [KEYID ...]          publish key(s) to keyserver
 set-expire (e) EXPIRE [KEYID]         set key expiration
 add-servicename (n+) SERVICENAME [KEYID]
                                       add a service name to key
 revoke-servicename (n-) SERVICENAME [KEYID]
                                       revoke a service name from key
 add-revoker (r+) REVOKER_KEYID|FILE [KEYID]
                                       add a revoker to key
 revoke-key [KEYID]                    generate and/or publish revocation
                                       certificate for key

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

See ${PGRM}(8) for more info.
EOF
}

# function to interact with the gpg keyring
gpg_host() {
    GNUPGHOME="$GNUPGHOME_HOST" gpg --no-greeting --quiet --no-tty "$@"
}

# list the info about the a key, in colon format, to stdout
gpg_host_list_keys() {
    if [ "$1" ] ; then
	gpg_host --list-keys --with-colons --fixed-list-mode \
	    --with-fingerprint --with-fingerprint \
	    "$1"
    else
	gpg_host --list-keys --with-colons --fixed-list-mode \
	    --with-fingerprint --with-fingerprint
    fi
}

# edit key scripts, takes scripts on stdin, and keyID as first input
gpg_host_edit() {
    gpg_host --command-fd 0 --edit-key "$@"
}

# export the monkeysphere OpenPGP pub key file
update_pgp_pub_file() {
    log debug "updating openpgp public key file '$HOST_KEY_FILE'..."
    gpg_host --export --armor --export-options export-minimal \
        $(gpg_host --list-secret-keys --with-colons --fingerprint | grep ^fpr | cut -f10 -d:) \
        > "$HOST_KEY_FILE"
}

# check that the service name is well formed. we assume that the
# service name refers to a host; DNS labels for host names are limited
# to a very small range of characters (see RFC 1912, section 2.1).

# FIXME: i'm failing to check here for label components that are
# all-number (e.g. ssh://666.666), which are technically not allowed
# (though some exist on the 'net, apparently)

# FIXME: this will probably misbehave if raw IP addresses are provided,
# either IPv4 or IPv6 using the bracket notation.

# FIXME: this doesn't address the use of hashed User IDs.

check_service_name() {
    local name="$1"
    local errs=""
    local scheme
    local port
    local assigned_ports

    [ -n "$name" ] || \
        failure "You must supply a service name to check"

    printf '%s' "$name" | perl -n -e '($str = $_) =~ s/\s//g ; exit !(lc($str) eq $_);' || \
        failure "Not a valid service name: '$name'

Service names should be canonicalized to all lower-case,
with no whitespace"

    [[ "$name" =~ ^[a-z0-9./:-]+$ ]] || \
        failure "Not a valid service name: '$name'

Service names should contain only lower-case ASCII letters
numbers, dots (.), hyphens (-), slashes (/), and a colon (:).
If you are using non-ASCII characters (e.g. IDN), you should
use the canonicalized ASCII (NAMEPREP -> Punycode) representation
(see RFC 3490)."

    [[ "$name" =~ \. ]] || \
        failure "Not a valid service name: '$name'

Service names should use fully-qualified domain names (FQDN), but the
domain name you chose appears to only have the local part.  For
example: don't use 'ssh://foo' ; use 'ssh://foo.example.com' instead."

    [[ "$name" =~ ^[a-z]([a-z0-9-]*[a-z0-9])?://[a-z0-9]([a-z0-9-]*[a-z0-9])?(\.|((\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)+))(:[1-9][0-9]{0,4})?$ ]] || \
        failure "Not a valid service name: '$name'

Service names look like <scheme>://full.example.com[:<portnumber>],
where <scheme> is something like ssh or https, and <portnumber> is
a decimal number (supplied only if the service is on a non-standard
port)."
    
    scheme=$(cut -f1 -d: <<<"$name")
    port=$(cut -f3 -d: <<<"$name")
    
    # check that the scheme name is found in the system services
    # database
    available_=$(get_port_for_service "$scheme") || \
        log error "Error looking up service scheme named '%s'" "$scheme"

    # FIXME: if the service isn't found, or does not have a port, what
    # should we do? at the moment, we're just warning.
    
    if [ -n "$port" ]; then
    # check that the port number is a legitimate port number (> 0, < 65536)
        [ "$port" -gt 0 ] && [ "$port" -lt 65536 ] || \
            failure "The given port number should be greater than 0 and
less than 65536.  '$port' is not OK"

    # if the port number is given, and the scheme is in the services
    # database, check that the port number does *not* match the
    # default port.
        if (printf '%s' "$assigned_ports" | grep -q -F -x "$port" ) ; then
            failure $(printf "The scheme %s uses port number %d by default.
You should leave off the port number if it is the default" "$scheme" "$port")
        fi
    fi

}

# fail if host key not present
check_no_keys() {
    [ -s "$HOST_KEY_FILE" ] \
	|| failure "You don't appear to have a Monkeysphere host key on this server.
Please run 'monkeysphere-host import-key' import a key."
}

# key input to functions, outputs full fingerprint of specified key if
# found
check_key_input() {
    local keyID="$1"
    # array of fingerprints
    local fprs=($(list_primary_fingerprints <"$HOST_KEY_FILE"))

    case ${#fprs[@]} in
	0)
	    failure "You don't appear to have any Monkeysphere host keys.
Please run 'monkeysphere-host import-key' to import a key."
	    ;;
	1)
	    :
	    ;;
	*)
	    if [ -z "$keyID" ] ; then
		failure "Your host keyring contains multiple keys.
Please specify one to act on (see 'monkeysphere-host show-keys')."
	    fi
	    ;;
    esac
    printf '%s\n' "${fprs[@]}" | grep "${keyID}$" \
	|| failure "Host key '$keyID' not found."
}

# return 0 if user ID was found.
# return 1 if user ID not found.
check_key_userid() {
    local keyID="$1"
    local userID="$2"
    local tmpuidMatch

    # match to only "unknown" user IDs (host has no need for ultimate trust)
    tmpuidMatch="uid:-:$(echo $userID | gpg_escape)"

    # See whether the requsted user ID is present
    gpg_host_list_keys "$keyID" | cut -f1,2,10 -d: | \
	grep -q -x -F "$tmpuidMatch" 2>/dev/null
}

prompt_userid_exists() {
    local userID="$1"
    local gpgOut
    local fingerprint

    if gpgOut=$(gpg_host_list_keys "=${userID}" 2>/dev/null) ; then
	fingerprint=$(echo "$gpgOut" | grep '^fpr:' | cut -d: -f10)
	if [ "$PROMPT" != "false" ] ; then
	    printf "Service name '%s' is already being used by key '%s'.\nAre you sure you want to use it again? (y/N) " "$fingerprint" "$userID" >&2
	    read OK; OK=${OK:=N}
	    if [ "${OK/y/Y}" != 'Y' ] ; then
		failure "Service name not added."
	    fi
	else
	    log info "Key '%s' is already using the service name '%s'." "$fingerprint" "$userID" >&2
	fi
    fi
}

# run command looped over keys
multi_key() {
    local cmd="$1"
    shift
    local keys=$@
    local i=0
    local fprs=($(list_primary_fingerprints <"$HOST_KEY_FILE"))
    local key

    check_no_keys

    if [[ -z "$1" || "$1" == '--all' ]] ; then
	keys="${fprs[@]}"
    fi

    for key in $keys ; do
	if (( i++ > 0 )) ; then
	    echo "##############################"
	fi
	"$cmd" "$key"
    done
}

# show info about the a key
show_key() {
    local id="$1"
    local GNUPGHOME
    local fingerprint
    local tmpssh
    local revokers

    # tmp gpghome dir
    export GNUPGHOME=$(msmktempdir)

    # trap to remove tmp dir if break
    trap "rm -rf $GNUPGHOME" EXIT

    # import the host key into the tmp dir
    gpg --quiet --import <"$HOST_KEY_FILE"

    # get the gpg fingerprint
    if gpg --quiet --list-keys \
	--with-colons --with-fingerprint "$id" \
	| grep '^fpr:' | cut -d: -f10 > "$GNUPGHOME"/fingerprint ; then
	fingerprint=$(cat "$GNUPGHOME"/fingerprint)
    else
	failure "ID '$id' not found."
    fi

    # create the ssh key
    tmpssh="$GNUPGHOME"/ssh_host_key_rsa_pub
    gpg --export "$fingerprint" 2>/dev/null \
	| openpgp2ssh 2>/dev/null >"$tmpssh"

    # list the host key info
    # FIXME: make no-show-keyring work so we don't have to do the grep'ing
    # FIXME: can we show uid validity somehow?
    gpg --list-keys --list-options show-unusable-uids "$fingerprint" 2>/dev/null \
	| grep -v "^${GNUPGHOME}/pubring.gpg$" \
	| egrep -v '^-+$'

    # list revokers, if there are any
    revokers=$(gpg --list-keys --with-colons --fixed-list-mode "$fingerprint" \
	| awk -F: '/^rvk:/{ print $10 }' )
    if [ "$revokers" ] ; then
	echo "The following keys are allowed to revoke this host key:"
	for key in $revokers ; do
	    echo "revoker: $key"
	done
	echo
    fi

    # list the pgp fingerprint
    echo "OpenPGP fingerprint: $fingerprint"

    # list the ssh fingerprint
    echo -n "ssh fingerprint: "
    ssh-keygen -l -f "$tmpssh" | awk '{ print $1, $2, $4 }'

    # remove the tmp file
    trap - EXIT
    rm -rf "$GNUPGHOME"
}

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

# 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}
KEYSERVER=${MONKEYSPHERE_KEYSERVER:=$KEYSERVER}
CHECK_KEYSERVER=${MONKEYSPHERE_CHECK_KEYSERVER:=$CHECK_KEYSERVER}
MONKEYSPHERE_USER=${MONKEYSPHERE_MONKEYSPHERE_USER:=$MONKEYSPHERE_USER}
MONKEYSPHERE_GROUP=$(get_primary_group "$MONKEYSPHERE_USER")
PROMPT=${MONKEYSPHERE_PROMPT:=$PROMPT}

# other variables
GNUPGHOME_HOST=${MONKEYSPHERE_GNUPGHOME_HOST:="${MHDATADIR}"}
LOG_PREFIX=${MONKEYSPHERE_LOG_PREFIX:='ms: '}

# export variables needed in su invocation
export DATE
export LOG_LEVEL
export KEYSERVER
export CHECK_KEYSERVER
export MONKEYSPHERE_USER
export MONKEYSPHERE_GROUP
export PROMPT
export GNUPGHOME_HOST
export GNUPGHOME
export HOST_FINGERPRINT
export LOG_PREFIX

if [ "$#" -eq 0 ] ; then 
    usage
    failure "Please supply a subcommand."
fi

# get subcommand
COMMAND="$1"
shift

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

    'show-keys'|'show-key'|'show'|'s')
	multi_key show_key "$@"
	;;

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

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

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

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

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

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

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

    'update-pgp-pub-file')
	update_pgp_pub_file
	;;

    'version'|'v')
	version
	;;

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

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