#!/usr/bin/env bash

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

#  * check on the status and validity of the key and public certificates
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 (( "$keysfound" < 1 )); then
    echo "! No host key found."
    echo " - Recommendation: run 'monkeysphere-server gen-key'"
    problemsfound=$(($problemsfound+1))
elif (( "$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"  < "$curdate" )); then
	    echo "! Host key is expired."
	    echo " - Recommendation: extend lifetime of key with 'monkeysphere-server extend-key'"
	    problemsfound=$(($problemsfound+1))
	elif (( "$expire" < "$warndate" )); then
	    echo "! Host key expires in less than $warnwindow:" $(advance_date $(( $expire - $curdate )) seconds +%F)
	    echo " - Recommendation: extend lifetime of key with 'monkeysphere-server extend-key'"
	    problemsfound=$(($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?)

# FIXME: look to see that the ownertrust rules are set properly on the
#    authentication keyring

# FIXME: make sure that at least one identity certifier exists

# FIXME: look at the timestamps on the monkeysphere-generated
# authorized_keys files -- warn if they seem out-of-date.

# FIXME: check for a cronjob that updates monkeysphere-generated
# authorized_keys?

echo
echo "Checking for MonkeySphere-enabled public-key authentication for users ..."
# Ensure that User ID authentication is enabled:
if ! grep -q "^AuthorizedKeysFile[[:space:]]\+${SYSDATADIR}/authorized_keys/%u$" "$sshd_config"; then
    echo "! $sshd_config does not point to monkeysphere authorized keys."
    echo " - Recommendation: add a line to $sshd_config: 'AuthorizedKeysFile ${SYSDATADIR}/authorized_keys/%u'"
    problemsfound=$(($problemsfound+1))
fi
if badauthorizedkeys=$(grep -i '^AuthorizedKeysFile' "$sshd_config" | grep -v "^AuthorizedKeysFile[[:space:]]\+${SYSDATADIR}/authorized_keys/%u$") ; then
    echo "! $sshd_config refers to non-monkeysphere authorized_keys files:"
    echo "$badauthorizedkeys"
    echo " - Recommendation: remove the above AuthorizedKeysFile lines from $sshd_config"
    problemsfound=$(($problemsfound+1))
fi

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-server diagnostics"
else
    echo "Everything seems to be in order!"
fi