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

# Monkeysphere host diagnostics 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.

# check on the status and validity of the key and public certificates

diagnostics() {

local seckey
local keysfound
local curdate
local warnwindow
local warndate
local create
local expire
local uid
local fingerprint
local badhostkeys
local sshd_config
local problemsfound=0

# FIXME: what's the correct, cross-platform answer?
sshd_config=/etc/ssh/sshd_config
seckey=$(gpg_host --list-secret-keys --fingerprint --with-colons --fixed-list-mode)
keysfound=$(echo "$seckey" | grep -c ^sec:)
curdate=$(date +%s)
# warn when anything is 2 months away from expiration
warnwindow='2 months'
warndate=$(advance_date $warnwindow +%s)

if ! id monkeysphere >/dev/null ; then
    echo "! No monkeysphere user found!  Please create a monkeysphere system user with bash as its shell."
    problemsfound=$(($problemsfound+1))
fi

if ! [ -d "$SYSDATADIR" ] ; then
    echo "! no $SYSDATADIR directory found.  Please create it."
    problemsfound=$(($problemsfound+1))
fi

echo "Checking host GPG key..."
if (( "$keysfound" < 1 )); then
    echo "! No host key found."
    echo " - Recommendation: run 'monkeysphere-host gen-key' or 'monkeysphere-host import-key'"
    problemsfound=$(($problemsfound+1))
elif (( "$keysfound" > 1 )); then
    echo "! More than one host key found?"
    # FIXME: recommend a way to resolve this
    problemsfound=$(($problemsfound+1))
else
    create=$(echo "$seckey" | grep ^sec: | cut -f6 -d:)
    expire=$(echo "$seckey" | grep ^sec: | cut -f7 -d:)
    fingerprint=$(echo "$seckey" | grep ^fpr: | head -n1 | cut -f10 -d:)
    # check for key expiration:
    if [ "$expire" ]; then
	if (( "$expire"  < "$curdate" )); then
	    echo "! Host key is expired."
	    echo " - Recommendation: extend lifetime of key with 'monkeysphere-host extend-key'"
	    problemsfound=$(($problemsfound+1))
	elif (( "$expire" < "$warndate" )); then
	    echo "! Host key expires in less than $warnwindow:" $(advance_date $(( $expire - $curdate )) seconds +%F)
	    echo " - Recommendation: extend lifetime of key with 'monkeysphere-host extend-key'"
	    problemsfound=$(($problemsfound+1))
	fi
    fi

    # and weirdnesses:
    if [ "$create" ] && (( "$create" > "$curdate" )); then
	echo "! Host key was created in the future(?!). Is your clock correct?"
	echo " - Recommendation: Check clock ($(date +%F_%T)); use NTP?"
	problemsfound=$(($problemsfound+1))
    fi
    
    # check for UserID expiration:
    echo "$seckey" | grep ^uid: | cut -d: -f6,7,10 | \
    while IFS=: read create expire uid ; do
	# FIXME: should we be doing any checking on the form
	# of the User ID?  Should we be unmangling it somehow?

	if [ "$create" ] && (( "$create" > "$curdate" )); then
	    echo "! User ID '$uid' was created in the future(?!).  Is your clock correct?"
	    echo " - Recommendation: Check clock ($(date +%F_%T)); use NTP?"
	    problemsfound=$(($problemsfound+1))
	fi
	if [ "$expire" ] ; then
	    if (( "$expire" < "$curdate" )); then
		echo "! User ID '$uid' is expired."
		# FIXME: recommend a way to resolve this
		problemsfound=$(($problemsfound+1))
	    elif (( "$expire" < "$warndate" )); then
		echo "! User ID '$uid' expires in less than $warnwindow:" $(advance_date $(( $expire - $curdate )) seconds +%F)
		# FIXME: recommend a way to resolve this
		problemsfound=$(($problemsfound+1))
	    fi
	fi
    done
	    
# FIXME: verify that the host key is properly published to the
#   keyservers (do this with the non-privileged user)

# FIXME: check that there are valid, non-expired certifying signatures
#   attached to the host key after fetching from the public keyserver
#   (do this with the non-privileged user as well)

# FIXME: propose adding a revoker to the host key if none exist (do we
#   have a way to do that after key generation?)

    # Ensure that the ssh_host_rsa_key file is present and non-empty:
    echo
    echo "Checking host SSH key..."
    if [ ! -s "${SYSDATADIR}/ssh_host_rsa_key" ] ; then
	echo "! The host key as prepared for SSH (${SYSDATADIR}/ssh_host_rsa_key) is missing or empty."
	problemsfound=$(($problemsfound+1))
    else
	if [ $(ls -l "${SYSDATADIR}/ssh_host_rsa_key" | cut -f1 -d\ ) != '-rw-------' ] ; then
	    echo "! Permissions seem wrong for ${SYSDATADIR}/ssh_host_rsa_key -- should be 0600."
	    problemsfound=$(($problemsfound+1))
	fi

	# propose changes needed for sshd_config (if any)
	if ! grep -q "^HostKey[[:space:]]\+${SYSDATADIR}/ssh_host_rsa_key$" "$sshd_config"; then
	    echo "! $sshd_config does not point to the monkeysphere host key (${SYSDATADIR}/ssh_host_rsa_key)."
	    echo " - Recommendation: add a line to $sshd_config: 'HostKey ${SYSDATADIR}/ssh_host_rsa_key'"
	    problemsfound=$(($problemsfound+1))
	fi
	if badhostkeys=$(grep -i '^HostKey' "$sshd_config" | grep -v "^HostKey[[:space:]]\+${SYSDATADIR}/ssh_host_rsa_key$") ; then
	    echo "! $sshd_config refers to some non-monkeysphere host keys:"
	    echo "$badhostkeys"
	    echo " - Recommendation: remove the above HostKey lines from $sshd_config"
	    problemsfound=$(($problemsfound+1))
	fi

        # FIXME: test (with ssh-keyscan?) that the running ssh
        # daemon is actually offering the monkeysphere host key.

    fi
fi

# FIXME: look at the ownership/privileges of the various keyrings,
#    directories housing them, etc (what should those values be?  can
#    we make them as minimal as possible?)


if [ "$problemsfound" -gt 0 ]; then
    echo "When the above $problemsfound issue"$(if [ "$problemsfound" -eq 1 ] ; then echo " is" ; else echo "s are" ; fi)" resolved, please re-run:"
    echo "  monkeysphere-host expert diagnostics"
else
    echo "Everything seems to be in order!"
fi

}