T792: add TFTP server functionality

1 files changed, 159 insertions, 0 deletions

diff --git a/src/conf_mode/tftp_server.py b/src/conf_mode/tftp_server.py
new file mode 100755
index 000000000..8133ed215
--- /dev/null
+++ b/src/conf_mode/tftp_server.py
@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# 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, see <http://www.gnu.org/licenses/>.
+#
+#
+
+import sys
+import os
+import stat
+import pwd
+
+import jinja2
+import ipaddress
+import netifaces
+
+from vyos.config import Config
+from vyos import ConfigError
+
+config_file = r'/etc/default/tftpd-hpa'
+
+# Please be careful if you edit the template.
+config_tmpl = """
+### Autogenerated by tftp_server.py ###
+
+# See manual at https://linux.die.net/man/8/tftpd
+
+TFTP_USERNAME="tftp"
+TFTP_DIRECTORY="{{ directory }}"
+{% if listen_ipv4 and listen_ipv6 -%}
+TFTP_ADDRESS="{% for a in listen_ipv4 -%}{{ a }}:{{ port }}{{- " --address " if not loop.last -}}{% endfor -%} {% for a in listen_ipv6 %} --address [{{ a }}]:{{ port }}{% endfor -%}"
+{% elif listen_ipv4 -%}
+TFTP_ADDRESS="{% for a in listen_ipv4 -%}{{ a }}:{{ port }}{{- " --address " if not loop.last -}}{% endfor %} -4"
+{% elif listen_ipv6 -%}
+TFTP_ADDRESS="{% for a in listen_ipv6 -%}[{{ a }}]:{{ port }}{{- " --address " if not loop.last -}}{% endfor %} -6"
+{%- endif %}
+
+TFTP_OPTIONS="--secure {% if allow_upload %}--create --umask 002{% endif %}"
+"""
+
+default_config_data = {
+    'directory': '',
+    'allow_upload': False,
+    'port': '69',
+    'listen_ipv4': [],
+    'listen_ipv6': []
+}
+
+# Verify if an IP address is assigned to any interface, IPv4 and IPv6
+def addrok(ipaddr, ipversion):
+    for interface in netifaces.interfaces():
+        # Retrieve IP address of network interfaces
+            if ipversion in netifaces.ifaddresses(interface).keys():
+                for addr in netifaces.ifaddresses(interface)[ipversion]:
+                    if addr['addr'] == ipaddr:
+                        return True
+
+    return False
+
+def get_config():
+    tftpd = default_config_data
+    conf = Config()
+    if not conf.exists('service tftp-server'):
+        return None
+    else:
+        conf.set_level('service tftp-server')
+
+    if conf.exists('directory'):
+        tftpd['directory'] = conf.return_value('directory')
+
+    if conf.exists('allow-upload'):
+        tftpd['allow_upload'] = True
+
+    if conf.exists('port'):
+        tftpd['port'] = conf.return_value('port')
+
+    if conf.exists('listen-address'):
+        for addr in conf.return_values('listen-address'):
+            if (ipaddress.ip_address(addr).version == 4):
+                tftpd['listen_ipv4'].append(addr)
+
+            if (ipaddress.ip_address(addr).version == 6):
+                tftpd['listen_ipv6'].append(addr)
+
+    return tftpd
+
+def verify(tftpd):
+    # bail out early - looks like removal from running config
+    if tftpd is None:
+        return None
+
+    # Configuring allowed clients without a server makes no sense
+    if not tftpd['directory']:
+        raise ConfigError('TFTP root directory must be configured!')
+
+    if not (tftpd['listen_ipv4'] or tftpd['listen_ipv6']):
+        raise ConfigError('TFTP server listen address must be configured!')
+
+    for address in tftpd['listen_ipv4']:
+        if not addrok(address, netifaces.AF_INET):
+            raise ConfigError('TFTP server listen address "{0}" not configured on this system.'.format(address))
+
+    for address in tftpd['listen_ipv6']:
+        if not addrok(address, netifaces.AF_INET6):
+            raise ConfigError('TFTP server listen address "{0}" not configured on this system.'.format(address))
+
+    return None
+
+def generate(tftpd):
+    # bail out early - looks like removal from running config
+    if tftpd is None:
+        return None
+
+    tmpl = jinja2.Template(config_tmpl)
+    config_text = tmpl.render(tftpd)
+    with open(config_file, 'w') as f:
+        f.write(config_text)
+
+    return None
+
+def apply(tftpd):
+    if tftpd is not None:
+
+        tftp_root = tftpd['directory']
+        if not os.path.exists(tftp_root):
+            os.makedirs(tftp_root)
+            os.chmod(tftp_root, stat.S_IRUSR|stat.S_IWUSR|stat.S_IXUSR|stat.S_IRGRP|stat.S_IXGRP|stat.S_IROTH|stat.S_IXOTH)
+            # get uid for user 'snmp'
+            tftp_uid = pwd.getpwnam('tftp').pw_uid
+            os.chown(tftp_root, tftp_uid, -1)
+
+        os.system('sudo systemctl restart tftpd-hpa.service')
+    else:
+        # TFTP server support is removed in the commit
+        os.system('sudo systemctl stop tftpd-hpa.service')
+        os.unlink(config_file)
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        sys.exit(1)