# -*-shell-script-*-
# This should be sourced by bash (though we welcome changes to make it POSIX sh compliant)

# Monkeysphere subkey-to-ssh-agent subcommand
#
# The monkeysphere scripts are written by:
# Jameson Rollins <jrollins@finestructure.net>
# Jamie McClelland <jm@mayfirst.org>
# Daniel Kahn Gillmor <dkg@fifthhorseman.net>
#
# They are Copyright 2008-2009, and are all released under the GPL,
# version 3 or later.

# try to add all authentication subkeys to the agent

# FIXME: what if you only want to add one authentication subkey to the
# agent?

subkey_to_ssh_agent() {
    local sshaddresponse=0
    local secretkeys
    local authsubkeys
    local workingdir
    local keysuccess=0
    local subkey
    local publine
    local kname

    # if there's no agent running, don't bother:
    if [ -z "$SSH_AUTH_SOCK" ] || ! type ssh-add >/dev/null ; then
	failure "No ssh-agent available."
    fi

    # and if it looks like it's running, but we can't actually talk to
    # it, bail out:
    ssh-add -l >/dev/null || sshaddresponse="$?"
    if [ "$sshaddresponse" = "2" ]; then
	failure "Could not connect to ssh-agent"
    fi

    # if the MONKEYSPHERE_SUBKEYS_FOR_AGENT variable is set, use the
    # keys specified there
    if [ "$MONKEYSPHERE_SUBKEYS_FOR_AGENT" ] ; then
	authsubkeys="$MONKEYSPHERE_SUBKEYS_FOR_AGENT"

    # otherwise find all authentication-capable subkeys and use those
    else
	# get list of secret keys
	# (to work around bug https://bugs.g10code.com/gnupg/issue945):
	secretkeys=$(gpg_user --list-secret-keys --with-colons --fixed-list-mode \
	    --fingerprint | \
	    grep '^fpr:' | cut -f10 -d: | awk '{ print "0x" $1 "!" }')

	if [ -z "$secretkeys" ]; then
	    failure "You have no secret keys in your keyring!
You might want to run 'gpg --gen-key'."
	fi
    
	authsubkeys=$(gpg_user --list-secret-keys --with-colons --fixed-list-mode \
	    --fingerprint --fingerprint $secretkeys | \
	    cut -f1,5,10,12 -d: | grep -A1 '^ssb:[^:]*::[^:]*a[^:]*$' | \
	    grep '^fpr::' | cut -f3 -d: | sort -u)

	if [ -z "$authsubkeys" ]; then
	    failure "no authentication-capable subkeys available.
You might want to run 'monkeysphere gen-subkey'."
	fi
    fi

    workingdir=$(msmktempdir)
    trap "rm -rf $workingdir" EXIT
    umask 077
    mkfifo "$workingdir/passphrase"

    # FIXME: we're currently allowing any other options to get passed
    # through to ssh-add.  should we limit it to known ones?  For
    # example: -d or -c and/or -t <lifetime> 

    for subkey in $authsubkeys; do
	# test that the subkey has proper capability
	capability=$(gpg_user --list-secret-keys --with-colons --fixed-list-mode \
	    --fingerprint --fingerprint "0x${subkey}!" \
	    | egrep -B 1 "^fpr:::::::::${subkey}:$" | grep "^ssb:" | cut -d: -f12)
	if ! check_capability "$capability" 'a' ; then
	    log error "Did not find authentication-capable subkey with key ID '$subkey'."
	    continue
	fi

	# choose a label by which this key will be known in the agent:
	# we are labelling the key by User ID instead of by
	# fingerprint, but filtering out all / characters to make sure
	# the filename is legit.

	primaryuid=$(gpg_user --with-colons --list-key "0x${subkey}!" | grep '^pub:' | cut -f10 -d: | tr -d /)

	#kname="[monkeysphere] $primaryuid"
	kname="$primaryuid"

	if [ "$1" = '-d' ]; then
	    # we're removing the subkey:
	    gpg_user --export --no-armor "0x${subkey}!" | openpgp2ssh "$subkey" > "$workingdir/$kname"
	    (cd "$workingdir" && ssh-add -d "$kname") || keysuccess="$?"
	else
	    # we're adding the subkey:
	    mkfifo "$workingdir/$kname"
	    gpg_user --passphrase-fd 3 3<"$workingdir/passphrase" \
		--export-options export-reset-subkey-passwd,export-minimal,no-export-attributes \
		--export-secret-subkeys --no-armor "0x${subkey}!" | openpgp2ssh "$subkey" > "$workingdir/$kname" &
	    (cd "$workingdir" && DISPLAY=nosuchdisplay SSH_ASKPASS=/bin/false ssh-add "$@" "$kname" </dev/null )&

	    passphrase_prompt "Enter passphrase for key $kname: " "$workingdir/passphrase"
	    wait %2 || keysuccess="$?"
	fi

	rm -f "$workingdir/$kname"
    done

    trap - EXIT
    rm -rf "$workingdir"

    # FIXME: sort out the return values: we're just returning the
    # failure code of the last authentication subkey which fails.
    # what if more than one authentication subkey fails?
    return "$keysuccess"
}