#!/bin/bash

DIR=/config/vpn-management-site
LOGFILE=/var/log/vpn-management-site.log

set -eE

err_report() {
	error="HTTP/1.1 500 Internal server error\n\nserver.sh: Error on line ${1}"
	echo -e error >> ${LOGFILE}
	echo -e error
}

trap 'err_report $LINENO' ERR

# Read first line of HTTP request, set operation var
OP=""
IFS= read -r LINE_NL
LINE=${LINE_NL::-1}
if [[ "${LINE}" == "POST "* ]]; then
	OP="modify_vpn"
elif [[ "${LINE}" == "GET /servers.json"* ]]; then
	OP="get_server_list"
elif [[ "${LINE}" == "GET /"* ]]; then
	OP="get_html"
else
	RESPONSE="HTTP/1.1 400 Bad Request\n\nInvalid HTTP prelude\n${LINE}"
	echo -e $RESPONSE >> ${LOGFILE}
	echo -e $RESPONSE
fi

# Find the content length (nc doesn't send an EOL)
CONTENT_LENGTH=-1
while IFS= read -r LINE_NL; do
	LINE=${LINE_NL::-1}
	if [[ "${LINE}" == "Content-Length:"* ]]; then
		CONTENT_LENGTH=${LINE:16}
	elif [[ "${LINE}" == "" ]]; then
		break
	fi
done

# If the request is about a static resource, just send that
if [[ "${OP}" == "get_html" ]]; then
	HTML=$(cat ${DIR}/index.html)
	RESPONSE="HTTP/1.1 200 OK\nContent-Type: text/html\n\n${HTML}"
	echo -e RESPONSE >> ${LOGFILE}
	echo -e RESPONSE
	exit 0
fi

if [[ "${OP}" == "get_server_list" ]]; then
	JSON=$(cat ${DIR}/servers.json)
	RESPONSE="HTTP/1.1 200 OK\nContent-Type: application/json\n\n${JSON}"
	echo -e RESPONSE >> ${LOGFILE}
	echo -e RESPONSE
	exit 0
fi

# Otherwise the request must be about setting the VPN state
if [[ "${OP}" != "modify_vpn" ]]; then
	echo "Invalid operation ${OP}" >> ${LOGFILE}
	RESPONSE="HTTP/1.1 400 Bad Request\n\n"
	echo -e RESPONSE >> ${LOGFILE}
	echo -e RESPONSE
fi

# Read CONTENT_LENGTH worth of content
IFS= read -n${CONTENT_LENGTH} -d$'\0' -r CONTENT

# Read the action field from the content JSON (either enable or disable)
ACTION=$(echo ${CONTENT} | jq -r .action)

# Make router configuration commands available
source /opt/vyatta/etc/functions/script-template > /dev/null

# If action is disable, disable the openvpn interface
if [[ "${ACTION}" == "disable" ]]; then
	echo "Disabling VPN..." >> ${LOGFILE}
	configure 2>&1 >> ${LOGFILE}
	set interfaces openvpn vtun0 disable 2>&1 >> ${LOGFILE}
	commit 2>&1 >> ${LOGFILE}
	save 2>&1 >> ${LOGFILE}

	RESPONSE="HTTP/1.1 200 OK\n\nVPN disabled"
	echo -e RESPONSE >> ${LOGFILE}
	echo -e RESPONSE
	exit 0
fi

# Otherwise the action must be enable
if [[ "${ACTION}" != "enable" ]]; then
	echo "Invalid action ${ACTION}" >> ${LOGFILE}

	RESPONSE="HTTP/1.1 400 Bad Request\n\nInvalid action ${ACTION}"
	echo -e RESPONSE >> ${LOGFILE}
	echo -e RESPONSE
	exit 1
fi

echo "Enabling VPN..." >> ${LOGFILE}

# Read the VPN server domain and IP from the request content JSON
DOMAIN=$(echo ${CONTENT} | jq -r .domain)
IP=$(echo ${CONTENT} | jq -r .ip)

# Produce an openvpn config
cat > /config/openvpn/vpn.ovpn <<- ENDOUT
client
dev tun
proto udp
remote ${IP} 1194
resolv-retry infinite
remote-random
nobind
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450
persist-key
persist-tun
ping 15
ping-restart 0
ping-timer-rem
reneg-sec 0
comp-lzo no
verify-x509-name CN=${DOMAIN}
remote-cert-tls server
auth-user-pass /config/openvpn/nordvpnauth.txt
route-nopull
verb 3
pull
fast-io
cipher AES-256-CBC
auth SHA512
<ca>
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----
</ca>
key-direction 1
<tls-auth>
#
# 2048 bit OpenVPN static key
#
-----BEGIN OpenVPN Static key V1-----
e685bdaf659a25a200e2b9e39e51ff03
0fc72cf1ce07232bd8b2be5e6c670143
f51e937e670eee09d4f2ea5a6e4e6996
5db852c275351b86fc4ca892d78ae002
d6f70d029bd79c4d1c26cf14e9588033
cf639f8a74809f29f72b9d58f9b8f5fe
fc7938eade40e9fed6cb92184abb2cc1
0eb1a296df243b251df0643d53724cdb
5a92a1d6cb817804c4a9319b57d53be5
80815bcfcb2df55018cc83fc43bc7ff8
2d51f9b88364776ee9d12fc85cc7ea5b
9741c4f598c485316db066d52db4540e
212e1518a9bd4828219e24b20d88f598
a196c9de96012090e333519ae18d3509
9427e7b372d348d352dc4c85e18cd4b9
3f8a56ddb2e64eb67adfc9b337157ff4
-----END OpenVPN Static key V1-----
</tls-auth>
ENDOUT

# Cycle the openvpn interface off and on to force config reload
configure 2>&1 >> ${LOGFILE}
set interfaces openvpn vtun0 disable 2>&1 >> ${LOGFILE}
commit 2>&1 >> ${LOGFILE}
delete interfaces openvpn vtun0 disable 2>&1 >> ${LOGFILE}
commit 2>&1 >> ${LOGFILE}
save 2>&1 >> ${LOGFILE}

# Send OK response
RESPONSE="HTTP/1.1 200 OK\n\nVPN enabled, IP: ${IP}, domain: ${DOMAIN}"
echo -e RESPONSE >> ${LOGFILE}
echo -e RESPONSE
exit 0