# Targets (targets with "*" require the CLIENT variables on the command line):
#   all		Sets up CA
#   add*	Used by 'zip'
#   zip*	Used for making a client cert for a person's own computer
#   ctarball*	Used for making a client cert for a Linux host
#   revoke*	Revoke's a given cert and re-generates the CRL (don't forget to install it on the server)
#   tarball	For installation on the server
#   install_keys  Run on a Linux host after extracting the tarball; specify DEST
#   		  (Don't forget to install and modify the config file.)
#
# The following variables may/must be present on the command line:
#   CLIENT (if building a client; mandatory)
#   CLIENT_REQ_ARGS= (if building a client; used to require a passphrase)
#   SERVER_ID (if building a server; optional)
#   KEY_DEPT (optional; specifies organizationalUnitName and alters config file name)
#   CN (optional; specifies commonName)
#   KEY_DIR (optional)
#   KEY_CONFIG (optional)
#   REQ_ARGS (optional; can be used to pass "-subj 'arg'" -- NOTE QUOTES)
#   CA_ARGS (optional; can be used to pass "-batch")
#
# The following environment variables may/must be present:
#   KEY_ORG (mandatory)
#   SERVER_FQDN (mandatory)
#   KEY_SIZE (optional; do not change after CA is built; edit server/staff.conf)
#
# TO-DO:
#   + add 'remove' target; runs "rm -rf keys/$(CLIENT).* clients/.$(CLIENT)_*stamp clients/$(CLIENT)"
#   + make 'remove' target depnd on 'revoke' target

# == Setup ==
.EXPORT_ALL_VARIABLES:

# must be a single word
CLIENT = someone
# don't use a passphrase
CLIENT_REQ_ARGS = -nodes

SERVER = server
SERVER_ID = $(SERVER)

DEST = /tmp/keys

KEY_CONFIG = openssl.cnf
KEY_DIR = keys
# These might be overriden by an environment variable
KEY_SIZE ?= 2048
KEY_DEPT ?= 
CN ?= 

SERVER_KEY_FILES = $(KEY_DIR)/ca.crt $(KEY_DIR)/$(SERVER_ID).crt $(KEY_DIR)/$(SERVER_ID).key $(KEY_DIR)/banned_certs.crl $(KEY_DIR)/dh$(KEY_SIZE).pem

CLIENT_DEPS = clients/$(CLIENT).conf clients/.$(CLIENT)_stamp


# *** TARGETS ***
.PHONY: all
# make sure all required files exist
all: $(KEY_DIR)/ca.key $(SERVER_KEY_FILES)


# == Client ==
.PHONY: add cc copy_key conf_clean conf_link revoke
# this target generates the following in clients/:
#   + a TLS mode client config file called someone.conf
#   + a directory called someone containing:
#       - a symbolic link called $KEY_ORG.ovpn
#         (it will be called $KEY_DEPT.ovpn if $KEY_DEPT is set)
#       - a keys subdirectory containing symlinks to the client & ca certs and
#         the the client key
# Makes sure that if the .ovpn file is re-created, the zip/tarball will be too.
add: $(CLIENT_DEPS)

clients/$(CLIENT).conf: clients/_template.conf
	@if [ -z "$$SERVER_FQDN" ] ; then echo ERROR: SERVER_FQDN not present in environment 2>&1; exit 3 ; fi
	sed -e "s/<SERVER>/$$SERVER_FQDN/" -e "s/<CLIENT>/$(CLIENT)/" $^ > $@

# -- directory containing links to be archived --
# Use stamp files rather than phony targets to avoid always rebuilding
clients/.$(CLIENT)_stamp: clients/$(CLIENT) \
 clients/.$(CLIENT)_conf-link-stamp clients/.$(CLIENT)_cert-link-stamp
	touch $@

clients/$(CLIENT):
	mkdir -p $@ $@/keys

clients/.$(CLIENT)_cert-link-stamp: $(KEY_DIR)/$(CLIENT).crt $(KEY_DIR)/$(CLIENT).key
	ln -sv --force ../../../$(KEY_DIR)/$(CLIENT).crt ../../../$(KEY_DIR)/$(CLIENT).key clients/$(CLIENT)/keys
	ln -s --force ../../../$(KEY_DIR)/ca.crt clients/$(CLIENT)/keys
	touch $@

conf_link: clients/.$(CLIENT)_conf-link-stamp
clients/.$(CLIENT)_conf-link-stamp: clients/$(CLIENT).conf
	@if [ -z "$$KEY_ORG" ] ; then echo WARNING: KEY_ORG not present in environment ; fi
	ln -s --force ../$(CLIENT).conf "clients/$(CLIENT)/$${KEY_DEPT:-$$KEY_ORG}.ovpn"
	touch $@

# -- real .key and .crt files --
$(KEY_DIR)/$(CLIENT).crt: $(KEY_DIR)/$(CLIENT).csr $(KEY_DIR)/ca.crt $(KEY_DIR)/ca.key
	openssl ca -config $(KEY_CONFIG) $(CA_ARGS) \
	  -in $(KEY_DIR)/$(CLIENT).csr -out $(KEY_DIR)/$(CLIENT).crt

# Generates new .key and .csr files
# -nodes isn't specified here because it might be in $(CLIENT_REQ_ARGS)
$(KEY_DIR)/$(CLIENT).key $(KEY_DIR)/$(CLIENT).csr: $(KEY_DIR)/ca.key
	openssl req -config $(KEY_CONFIG) $(REQ_ARGS) $(CLIENT_REQ_ARGS) \
	  -new -out $(KEY_DIR)/$(CLIENT).csr \
	  -newkey rsa:$(KEY_SIZE) -keyout $(KEY_DIR)/$(CLIENT).key
	chmod 0600 $(KEY_DIR)/$(CLIENT).key

# -- utilities --
# Copies a key and generates a new .csr file
# (This requires the passphrase to be entered, so is little different from
# making a new key)
copy_key: $(KEY_DIR)/$(SOURCE_KEY)
	if ! [ -f "$^" ] ; then echo 'ERROR: $$SOURCE_KEY not set' ; exit 1 ; fi
	cp $(KEY_DIR)/$(SOURCE_KEY) $(KEY_DIR)/$(CLIENT).key
	openssl req -config $(KEY_CONFIG) $(REQ_ARGS) $(CLIENT_REQ_ARGS) \
	  -new -out $(KEY_DIR)/$(CLIENT).csr \
	  -key $(KEY_DIR)/$(CLIENT).key

# Hint: use with CLIENT=\* (but be prepared for warnings)
conf_clean:
	rm -f clients/$(CLIENT)/*.ovpn
	rm -f clients/.$(CLIENT)_conf-link-stamp

# -- revocation --
revoke:
	openssl ca -config $(KEY_CONFIG) -revoke "$(KEY_DIR)/$(CLIENT).crt"
	$(MAKE) tarball

# Goes in 'client-config-dir' setting i.e. /etc/openvpn/clients
# Requires $VPN_IP_START to be set
onespace := $() $()
CN := $(shell [ -f "$(KEY_DIR)/$(CLIENT).crt" ] && openssl x509 -subject -noout -in "$(KEY_DIR)/$(CLIENT).crt" | sed 's/.*CN = \([^,]*\).*/\1/')
Q_CN := $(subst $(onespace),\ ,$(CN))
cc: clients/$(CLIENT)/$(Q_CN)
clients/$(CLIENT)/$(Q_CN):
	if [ -z "$$VPN_IP_START" ] ; then echo '$$VPN_IP_START not set' ; exit 3 ; fi
	raw_index=$$(awk '/CN=$(CN)($$|\/)/ { print $$3 }' keys/index.txt) ; \
	if [ -n "$$raw_index" ] ; then index=$$(printf '%d\n' 0x$$raw_index) ; echo "ifconfig-push $$VPN_IP_START$$((index * 4 + 2)) $$VPN_IP_START$$((index * 4 + 1))" > "$@"  ; else exit 2 ; fi


# == Server ==
$(KEY_DIR)/dh$(KEY_SIZE).pem:
	openssl dhparam -out $(KEY_DIR)/dh$(KEY_SIZE).pem $(KEY_SIZE)

$(KEY_DIR)/$(SERVER_ID).crt: $(KEY_DIR)/$(SERVER_ID).csr $(KEY_DIR)/ca.crt $(KEY_DIR)/ca.key | $(KEY_DIR)/dh$(KEY_SIZE).pem
	openssl ca -config $(KEY_CONFIG) $(CA_ARGS) \
	  -extensions server -days 3650 \
	  -in $(KEY_DIR)/$(SERVER_ID).csr -out $(KEY_DIR)/$(SERVER_ID).crt

$(KEY_DIR)/$(SERVER_ID).key $(KEY_DIR)/$(SERVER_ID).csr: $(KEY_DIR)/ca.key
	CN="$(SERVER_ID)" openssl req -config $(KEY_CONFIG) $(REQ_ARGS) \
	  -new -extensions server -out $(KEY_DIR)/$(SERVER_ID).csr \
	  -newkey rsa:$(KEY_SIZE) -keyout $(KEY_DIR)/$(SERVER_ID).key -nodes
	chmod 0600 $(KEY_DIR)/$(SERVER_ID).key

# updates the CRL whenever index.txt has changed
# (avoids having to generate the CRL every time a cert is revoked,
# but does take the safe option of making $(SERVER_ID).tar.gz transitively dependent
# on $(KEY_DIR)/index.txt)
$(KEY_DIR)/banned_certs.crl: $(KEY_DIR)/ca.key $(KEY_DIR)/index.txt
	[ -L $(KEY_DIR)/crl.pem ] || ln -s banned_certs.crl $(KEY_DIR)/crl.pem
	openssl ca -config $(KEY_CONFIG) \
	  -gencrl -out $(KEY_DIR)/banned_certs.crl


# == distribution archives ==
.phony: zip tarball ctarball
# this target creates a zipfile (no symlinks) for distribution to a client
zip: OpenVPN_$(CLIENT).zip
OpenVPN_$(CLIENT).zip: $(CLIENT_DEPS)
	# zip automatically dereferences symlinks
	(cd clients/$(CLIENT) ;  zip -r - . ) > $@

# this target creates a tarball (no symlinks) for distribution to a client machine
ctarball: OpenVPN_$(CLIENT).tar.gz
OpenVPN_$(CLIENT).tar.gz: $(CLIENT_DEPS)
	cp -p clients/$(CLIENT).conf "/tmp/$${KEY_DEPT:-$${SERVER_FQDN}}_connect.conf"
	tar czhvf $@ -C clients/$(CLIENT) keys -C /tmp "$${KEY_DEPT:-$${SERVER_FQDN}}_connect.conf"
	@rm "/tmp/$${KEY_DEPT:-$${SERVER_FQDN}}_connect.conf"

tarball: $(SERVER_ID).tar.gz
$(SERVER_ID).tar.gz: $(SERVER_ID)/staff.conf $(SERVER_KEY_FILES)
	tar czf $@ -C $(SERVER_ID) staff.conf scripts/routing_on.up -C .. $(SERVER_KEY_FILES)

# Only copy staff.conf if the target is missing, NOT when updated, hence elide
# the source as a dependency
# (Should probably use a pristine copy of server/staff.conf)
$(SERVER_ID)/staff.conf:
	mkdir -p $(SERVER_ID)/scripts
	cp server/staff.conf $@
	cp -p server/scripts/routing_on.up $(SERVER_ID)/scripts


# == CA ==
# Note: $(REQ_ARGS) is not used
$(KEY_DIR)/ca.crt: | $(KEY_DIR) $(KEY_DIR)/ca.key
$(KEY_DIR)/ca.key: | $(KEY_DIR) $(KEY_DIR)/index.txt $(KEY_DIR)/serial
	@echo Creating CA key and certificate
	openssl req -config $(KEY_CONFIG) \
	  -new -x509 -days 3650 -out $(KEY_DIR)/ca.crt \
	  -newkey rsa:$(KEY_SIZE) -keyout $(KEY_DIR)/ca.key -nodes
	chmod 0600 $(KEY_DIR)/ca.key

$(KEY_DIR):
	mkdir -p $(KEY_DIR)

$(KEY_DIR)/index.txt:
	touch $@

$(KEY_DIR)/serial:
	echo 01 > $@


# == Other ==
.PHONY: install_keys
# used to install keys as root for a specific client into a specfic directory
# TO-DO: install the config file too
install_keys:
	install -d "$(DEST)"
	install --mode=644 --preserve-timestamps "$(KEY_DIR)/$(CLIENT).crt" "$(KEY_DIR)/ca.crt" "$(DEST)"
	install --mode=600 --preserve-timestamps "$(KEY_DIR)/$(CLIENT).key" "$(DEST)"