utils: Introduce modem-netns-setup.py

Used to quickly set modem net interfaces into their own net namespace
(named after modem USB ID path).

The idea is that since osmo-gsm-tester ofono modem.py knowns the USB
path from a modem (path yml attr), it can infer the netns from it and
run a ping process inside it.

Related: OS#2308
Change-Id: Iadb2df2974e132044fba1f1bc2db8b559912e4e1

utils/modem-netns-setup.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+# Pau Espin Pedrol <pespin@sysmocom.de>
+# MIT
+
+# manage netns for ofono modems
+
+import os
+import sys
+import subprocess
+import usb.core
+import usb.util
+from pprint import pprint
+
+def get_path_ids(bus, port_numbers):
+    port_numbers = [str(port) for port in port_numbers]
+    ports = '.'.join(port_numbers)
+    return '{}-{}'.format(bus, ports)
+
+def get_usb_dir(bus, port_numbers):
+    return '/sys/bus/usb/devices/' + get_path_ids(bus, port_numbers) + '/'
+
+def get_net_from_usb(bus, port_numbers):
+    net_ifaces = []
+    path = get_usb_dir(bus, port_numbers)
+    path_ids = get_path_ids(bus, port_numbers)
+
+    usb_interfaces = [f for f in os.listdir(path) if f.startswith(path_ids)]
+    for usb_iface in usb_interfaces:
+        listdir = [f for f in os.listdir(path + usb_iface) if f == ('net')]
+        if listdir:
+            # found a net iface
+            net_ifaces += os.listdir(path + usb_iface + '/net/')
+    return net_ifaces
+
+def move_modem_to_netns(usb_path_id, net_li):
+
+        if len(net_li) == 0:
+            print("%s: Device has no net ifaces, skipping" %(usb_path_id))
+            return
+
+        if not os.path.exists("/var/run/netns/%s" % usb_path_id):
+            print("%s: Creating netns" % (usb_path_id))
+            subprocess.check_call(["ip", "netns", "add", usb_path_id])
+        else:
+            print("%s: netns already exists" % (usb_path_id))
+
+        for netif in net_li:
+            print("%s: Moving iface %s to netns" % (usb_path_id, netif))
+            subprocess.check_call(["ip", "link", "set", netif, "netns", usb_path_id])
+            # iface Must be set up AFTER pdp ctx is activated, otherwise we get no DHCP response.
+            #print("%s: Setting up iface %s" % (usb_path_id, netif))
+            #subprocess.check_call(["ip", "netns", "exec", usb_path_id, "ip", "link", "set", "dev", netif, "up"])
+            #subprocess.check_call(["ip", "netns", "exec", usb_path_id, "udhcpc", "-i", netif])
+
+def delete_modem_netns(usb_path_id):
+        if os.path.exists("/var/run/netns/%s" % usb_path_id):
+            print("%s: Deleting netns" % (usb_path_id))
+            subprocess.check_call(["ip", "netns", "delete", usb_path_id])
+        else:
+            print("%s: netns doesn't exist" % (usb_path_id))
+
+def print_help():
+    print("Usage: %s start|stop" % sys.argv[0])
+    exit(1)
+
+
+if __name__ == '__main__':
+
+    if len(sys.argv) != 2:
+        print_help()
+
+    USB_DEVS = [dev for dev in usb.core.find(find_all=True)]
+    RESULT = {}
+    for device in USB_DEVS:
+        result = {}
+        if not device.port_numbers:
+            continue
+
+        usb_path_id = get_path_ids(device.bus, device.port_numbers)
+        net_li = get_net_from_usb(device.bus, device.port_numbers)
+
+        if sys.argv[1] == "start":
+            move_modem_to_netns(usb_path_id, net_li)
+        elif sys.argv[1] == "stop":
+            delete_modem_netns(usb_path_id)
+        else:
+            print_help()