test proper error handling if lo is missing or has no address #957

test/linux.uts

@@ -125,3 +125,50 @@ assert(conf.route.route("192.0.2.43") == ("scapy0.42", "203.0.113.42", "203.0.11
 route_specific = (3221226027, 4294967295, "203.0.113.41", "scapy0.42", "203.0.113.42", 0)
 assert(route_specific in conf.route.routes)
 exit_status = os.system("ip link del name dev scapy0")
+
+= catch looback device missing
+~ linux needs_root
+
+from mock import patch
+
+# can't remove the lo device (or its address without causing trouble) - use some pseudo dummy instead
+
+with patch('scapy.consts.LOOPBACK_NAME', 'scapy_lo_x'):
+    _ = read_routes()
+
+= catch looback device no address assigned
+~ linux needs_root
+
+import os, socket
+from mock import patch
+
+exit_status = os.system("ip link add name scapy_lo type dummy")
+assert(exit_status == 0)
+exit_status = os.system("ip link set dev scapy_lo up")
+assert(exit_status == 0)
+
+with patch('scapy.consts.LOOPBACK_NAME', 'scapy_lo'):
+    _ = read_routes()
+
+exit_status = os.system("ip addr add dev scapy_lo 10.10.0.1/24")
+assert(exit_status == 0)
+
+with patch('scapy.consts.LOOPBACK_NAME', 'scapy_lo'):
+    routes = read_routes()
+
+got_lo_device = False
+for route in routes:
+    dst_int, msk_int, _, if_name, if_addr, _ = route
+    if if_name == 'scapy_lo':
+        got_lo_device = True
+        assert(if_addr == '10.10.0.1')
+        dst_addr = socket.inet_ntoa(struct.pack("!I", dst_int))
+        assert(dst_addr == '10.10.0.0')
+        msk = socket.inet_ntoa(struct.pack("!I", msk_int))
+        assert (msk == '255.255.255.0')
+        break
+
+assert(got_lo_device)
+
+exit_status = os.system("ip link del dev scapy_lo")
+assert(exit_status == 0)