#!/bin/bash

# oe-git-proxy is a simple tool to be via GIT_PROXY_COMMAND. It uses BSD netcat
# to make SOCKS5 or HTTPS proxy connections. It uses ALL_PROXY to determine the
# proxy server, protocol, and port. It uses NO_PROXY to skip using the proxy for
# a comma delimited list of hosts, host globs (*.example.com), IPs, or CIDR
# masks (192.168.1.0/24). It is known to work with both bash and dash shells.
#
# BSD netcat is provided by netcat-openbsd on Ubuntu and nc on Fedora.
#
# Example ALL_PROXY values:
# ALL_PROXY=socks://socks.example.com:1080
# ALL_PROXY=https://proxy.example.com:8080
#
# Copyright (c) 2013, Intel Corporation.
# All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# AUTHORS
# Darren Hart <dvhart@linux.intel.com>

# Locate the netcat binary
NC=$(which nc 2>/dev/null)
if [ $? -ne 0 ]; then
	echo "ERROR: nc binary not in PATH"
	exit 1
fi
METHOD=""

# Test for a valid IPV4 quad with optional bitmask
valid_ipv4() {
	echo $1 | egrep -q "^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}(/(3[0-2]|[1-2]?[0-9]))?$"
	return $?
}

# Convert an IPV4 address into a 32bit integer
ipv4_val() {
	IP="$1"
	SHIFT=24
	VAL=0
	for B in ${IP//./ }; do
		VAL=$(($VAL+$(($B<<$SHIFT))))
		SHIFT=$(($SHIFT-8))
	done
	echo "$VAL"
}

# Determine if two IPs are equivalent, or if the CIDR contains the IP
match_ipv4() {
	CIDR=$1
	IP=$2

	if [ -z "${IP%%$CIDR}" ]; then
		return 0
	fi

	# Determine the mask bitlength
	BITS=${CIDR##*/}
	if [ -z "$BITS" ]; then
		return 1
	fi

	IPVAL=$(ipv4_val $IP)
	IP2VAL=$(ipv4_val ${CIDR%%/*})

	# OR in the unmasked bits
	for i in $(seq 0 $((32-$BITS))); do
		IP2VAL=$(($IP2VAL|$((1<<$i))))
		IPVAL=$(($IPVAL|$((1<<$i))))
	done

	if [ $IPVAL -eq $IP2VAL ]; then
		return 0
	fi
	return 1
}

# Test to see if GLOB matches HOST
match_host() {
	HOST=$1
	GLOB=$2

	if [ -z "${HOST%%$GLOB}" ]; then
		return 0
	fi

	# Match by netmask
	if valid_ipv4 $GLOB; then
		HOST_IP=$(gethostip -d $HOST)
		if valid_ipv4 $HOST_IP; then
			match_ipv4 $GLOB $HOST_IP
			if [ $? -eq 0 ]; then
				return 0
			fi
		fi
	fi

	return 1
}

# If no proxy is set, just connect directly
if [ -z "$ALL_PROXY" ]; then
	exec $NC -X connect "$@"
fi

# Connect directly to hosts in NO_PROXY
for H in ${NO_PROXY//,/ }; do
	if match_host $1 $H; then
		METHOD="-X connect"
		break
	fi
done

if [ -z "$METHOD" ]; then
	# strip the protocol and the trailing slash
	PROTO=$(echo $ALL_PROXY | sed -e 's/\([^:]*\):\/\/.*/\1/')
	PROXY=$(echo $ALL_PROXY | sed -e 's/.*:\/\/\([^:]*:[0-9]*\).*/\1/')
	if [ "$PROTO" = "socks" ]; then
		METHOD="-X 5 -x $PROXY"
	elif [ "$PROTO" = "https" ]; then
		METHOD="-X connect -x $PROXY"
	fi
fi

exec $NC $METHOD "$@"