path: root/src/share/m/update_known_hosts

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

# Monkeysphere update_known_hosts 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 2010, and are all released under the GPL, version
# 3 or later.

# update the known_hosts file for a set of hosts listed on command
# line
update_known_hosts() {
    local returnCode=0
    local fileCheck
    local host
    local newUmask

    # touch the known_hosts file so that the file permission check
    # below won't fail upon not finding the file
    if [ ! -f "$KNOWN_HOSTS" ]; then
    # make sure to create any files or directories with the appropriate write bits turned off:
    newUmask=$(printf "%04o" $(( 0$(umask) | 0022 )) )
    [ -d $(dirname "$KNOWN_HOSTS") ] \
        || (umask "$newUmask" && mkdir -p -m 0700 $(dirname "$KNOWN_HOSTS") ) \
        || failure "Could not create path to known_hosts file '$KNOWN_HOSTS'"
    # make sure to create this file with the appropriate bits turned off:
    (umask "$newUmask" && touch "$KNOWN_HOSTS") \
        || failure "Unable to create known_hosts file '$KNOWN_HOSTS'"
    fi

    # check permissions on the known_hosts file path
    check_key_file_permissions $(whoami) "$KNOWN_HOSTS" \
    || failure "Bad permissions governing known_hosts file '$KNOWN_HOSTS'"

    # create a lockfile on known_hosts:
    lock create "$KNOWN_HOSTS"

    # make temp file
    tmpFile=$(mktemp "${KNOWN_HOSTS}.monkeysphere.XXXXXX")

    # FIXME: we're discarding any pre-existing EXIT trap; is this bad?
    trap "lock remove $KNOWN_HOSTS; rm -f $tmpFile" EXIT

    for host ; do
    FILE_TYPE='known_hosts' process_keys_for_file "$tmpFile" "ssh://${host}"

    # touch the lockfile, for good measure.
    lock touch "$KNOWN_HOSTS"
    done

    # note if the authorized_keys file was updated
    if [ "$(file_hash "$KNOWN_HOSTS")" != "$(file_hash "$tmpFile")" ] ; then
    log debug "known_hosts file updated."
    fi
    mv -f "$tmpFile" "$KNOWN_HOSTS"

    # remove the lockfile and the trap
    lock remove "$KNOWN_HOSTS"

    # remove the trap
    trap - EXIT
}

# process hosts from a known_hosts file
process_known_hosts() {
    local hosts

    # exit if the known_hosts file does not exist
    if [ ! -e "$KNOWN_HOSTS" ] ; then
    failure "known_hosts file '$KNOWN_HOSTS' does not exist."
    fi

    log debug "processing known_hosts file:"
    log debug " $KNOWN_HOSTS"

    hosts=$(meat "$KNOWN_HOSTS" | cut -d ' ' -f 1 | grep -v '^|.*$' | tr , ' ' | tr '\n' ' ')

    if [ -z "$hosts" ] ; then
    log debug "no hosts to process."
    return
    fi

    # take all the hosts from the known_hosts file (first
    # field), grep out all the hashed hosts (lines starting
    # with '|')...
    update_known_hosts $hosts
}