#!/usr/bin/python3
#
# hv_set_ifconfig <config> -- take the hv_kvp_daemon generated configuration
#                             file and apply it to the Ubuntu configuration.
#

# CONFIG example:
# HWADDR=11:22:33:44:55:66
# DEVICE=foo1
# DHCP=yes

# CONFIG example:
# HWADDR=11:22:33:44:55:66
# DEVICE=foo1
# IPADDR=192.168.99.10
# GATEWAY=192.168.99.1
# DNS1=192.168.88.250
# IPADDR2=192.168.99.11
# IPV6ADDR=2001:DB8:99::10
# IPV6NETMASK=64
# IPV6_DEFAULTGW=2001:DB8:99::10

# set interfaces in hv_kvp_daemon style
import fileinput
import sys
import errno
import os
import shutil
import tempfile
import subprocess

if_filename="/etc/network/interfaces"

# Drop our output (XXX?)
sys.stdout = open(os.devnull, 'w')
sys.stderr = open(os.devnull, 'w')

# Confirm we can open the network configuration.
try:
    if_file=open(if_filename,"r+")
except IOError as e:
    exit(e.errno)
else:
    if_file.close()

# Usage: hv_set_ifconfig <config>
if len(sys.argv) != 2 :
    exit(errno.EINVAL)

#
# Here is the format of the ip configuration file:
#
# HWADDR=macaddr
# DEVICE=interface name
# BOOTPROTO=<protocol> (where <protocol> is "dhcp" if DHCP is configured
#                       or "none" if no boot-time protocol should be used)
#
# IPADDR0=ipaddr1
# IPADDR1=ipaddr2
# IPADDRx=ipaddry (where y = x + 1)
#
# NETMASK0=netmask1
# NETMASKx=netmasky (where y = x + 1)
#
# GATEWAY=ipaddr1
# GATEWAYx=ipaddry (where y = x + 1)
#
# DNSx=ipaddrx (where first DNS address is tagged as DNS1 etc)
#
# IPV6 addresses will be tagged as IPV6ADDR, IPV6 gateway will be
# tagged as IPV6_DEFAULTGW and IPV6 NETMASK will be tagged as
# IPV6NETMASK.
#

kvp=dict(line.strip().split("=") for line in fileinput.input())

# Setting the hwaddress to something azure is not expecting is fatal
# to networking.
if not "HWADDR" in kvp :
    exit(errno.EPROTO)

# Confirm we have a device specified.
if not "DEVICE" in kvp :
    exit(1)

output=[]
basename=kvp["DEVICE"]

# DNS entries will go with the first interface and there can be a max
# of three.  These will be emitted with the first interface.
dns = []
for count in (1, 2, 3):
    key = "DNS" + str(count)
    if key in kvp:
        dns += [kvp[key]]
dns_emitted = False

# IPV4 may either be dhcp or static.
if ("DHCP" in kvp and kvp["DHCP"] == "yes") or \
   ("BOOTPROTO" in kvp and kvp["BOOTPROTO"] == "dhcp"):
    output += ["auto " + basename]
    output += ["iface " + basename  + " inet dhcp"]
    output += [""]
else:
    autolist = []
    # Matchup the interface specific lines

    # No real max for the number of interface + aliases ...
    # only required is the address (but mate everything up that comes in.

    # IPv4 -- ensure we sort by numeric suffixes.
    v4names = [ int(name[6:]) for name in kvp.keys() if name.startswith("IPADDR") ]
    v4names.sort()

    for if_count in v4names:
        ifname = basename
        which = str(if_count)

        if if_count:
            ifname += ":" + str(if_count)
            which_gw = which
        else:
            which_gw = ""

        if not ifname in autolist:
            autolist += [ifname]

        output += [ "iface " + ifname + " inet static" ]
        output += [ "\t" + "address " + kvp["IPADDR" + which] ]
        if "NETMASK" + which in kvp:
            output += [ "\tnetmask " + kvp["NETMASK" + which] ]
        if "GATEWAY" + which_gw in kvp:
            output += ["\tgateway " + kvp["GATEWAY" + which_gw]]

        if not dns_emitted:
            dns_emitted = True
            output += ["\tdns-nameservers " + ' '.join(dns)]
        output += [""]

# IPv6 requires a netmask
# If an ipv6 exists, you'll want to turn off /proc/sys/net/ipv6/conf/all/autoconf with
# echo 0 > /proc/sys/net/ipv6/conf/all/autoconf
v6names = [ int(name[8:]) for name in kvp.keys() if name.startswith("IPV6ADDR") ]
v6names.sort()

for if6_count in v6names:
    ifname = basename
    which = str(if6_count)

    if if6_count:
        ifname += ":" + str(if6_count)
        which_gw = which
    else:
        which_gw = ""

    if not ifname in autolist:
        autolist += [ifname]

    if "IPV6NETMASK" + which in kvp:
        output += [ "iface " + ifname + " inet6 static"]
        output += [ "\taddress " + kvp["IPV6ADDR" + which]]
        output += [ "\tnetmask " + kvp["IPV6NETMASK" + which]]
        if "IPV6_DEFAULTGW" + which_gw in kvp:
            output += [ "\tgateway " + kvp["IPV6_DEFAULTGW" + which_gw] ]
        if not dns_emitted:
            dns_emitted = True
            output += ["\tdns-nameservers " + ' '.join(dns)]
        output += [""]

# Mark this new interface for automatic up.
output = ["auto "+" ".join(autolist)] + output

print("===================================")
print(output)
print("===================================")


# Time to clean out the existing interface file

# Markers.
start_mark = "# The following stanza(s) added by hv_set_ifconfig"
end_mark = "#End of hv_set_ifconfig stanzas"

f=open(if_filename,"r")
flines=f.readlines()
f.close()
newfile=[]
pitchstanza=0
inastanza=0
stanza=[]
prev_line=None
for line in flines:
    if line.startswith("auto"):
        if inastanza:
            if not pitchstanza:
                newfile.extend(stanza)
            stanza=[]
        inastanza=0
        newline=""
        autoline=line.strip().split(" ")
        for word in autoline:
            if (not word == basename) and (not word.startswith(basename+":")):
                newline+=word + " "
        newline = newline.strip()
        if not newline == "auto":
            newfile += [newline.strip()]
    elif line.startswith(("iface","mapping","source")):
        '''Read a stanza'''
        '''A Stanza can also start with allow- ie allow-hotplug'''
        if inastanza:
            if not pitchstanza:
                newfile.extend(stanza)
            stanza=[]
        inastanza=1
        pitchstanza=0
        autoline=line.strip().split(" ")
        for word in autoline:
            if (word == basename) or (word.startswith(basename+":")):
                pitchstanza=1
        if not pitchstanza:
            stanza+=[line.strip()]
    elif line.strip() in (start_mark, end_mark):
        if inastanza:
            if not pitchstanza:
                newfile.extend(stanza)
            stanza=[]
        inastanza = 0
        pitchstanza = 0
        # Deduplicate markers.
        if line != prev_line:
            newfile += [line.strip()]
    else:
        if inastanza:
            if not pitchstanza:
                stanza+=[line.strip()]
        else:
            if not pitchstanza:
                newfile += [line.strip()]
    prev_line=line



def emit(line):
    print(line)
    output = line + "\n"
    os.write(fd, output.encode('utf-8'))

# Insert the new output at the end and inside the existing markers if found.
emitted = False
fd, path = tempfile.mkstemp()
for line in newfile:
    if line == end_mark:
        emit("\n".join(output))
        emitted = True
    emit(line)
if not emitted:
    emit(start_mark)
    emit("\n".join(output))
    emit(end_mark)
os.close(fd)

shutil.copy(path,if_filename)
os.chmod(if_filename,0o644)

#print("TMPFILE is at: " + path)
#print("Copied file is at: " + if_filename)

try:
    retcode = subprocess.call("ifdown "+basename , shell=True)
    if retcode < 0:
        print("Child was terminated by signal", -retcode, file=sys.stderr)
    else:
        print("Child returned", retcode, file=sys.stderr)
except OSError as e:
    print("Execution failed:", e, file=sys.stderr)

try:
    retcode = subprocess.call("ifup "+basename , shell=True)
    if retcode < 0:
        print("Child was terminated by signal", -retcode, file=sys.stderr)
    else:
        print("Child returned", retcode, file=sys.stderr)
except OSError as e:
    print("Execution failed:", e, file=sys.stderr)