From 69b58836f699ee4a6f283ff1f90a5886c6f460ee Mon Sep 17 00:00:00 2001
From: Jarrod Johnson <jjohnson2@lenovo.com>
Date: Tue, 24 Aug 2021 11:54:13 -0400
Subject: [PATCH] Change to built in neigh fetch

Rather than outsource, slowly,
to ip neigh for this frequent task,
call netlink directly.
---
 confluent_server/confluent/neighutil.py | 58 +++++++++++++++----------
 1 file changed, 35 insertions(+), 23 deletions(-)

diff --git a/confluent_server/confluent/neighutil.py b/confluent_server/confluent/neighutil.py
index 90f85c12..9b9dc7c6 100644
--- a/confluent_server/confluent/neighutil.py
+++ b/confluent_server/confluent/neighutil.py
@@ -19,8 +19,9 @@
 # use ip neigh for the moment
 
 import confluent.util as util
-import eventlet.green.subprocess as subprocess
 import os
+import eventlet.green.socket as socket
+import struct
 
 neightable = {}
 neightime = 0
@@ -33,29 +34,40 @@ _validmac = re.compile('..:..:..:..:..:..')
 def update_neigh():
     global neightable
     global neightime
-    neightable = {}
-    if os.name == 'nt':
-        return
-    ipn = subprocess.Popen(['ip', 'neigh'], stdin=subprocess.PIPE,
-                                 stdout=subprocess.PIPE,
-                                 stderr=subprocess.PIPE)
-    (neighdata, err) = ipn.communicate()
-    neighdata = util.stringify(neighdata)
-    for entry in neighdata.split('\n'):
-        entry = entry.split(' ')
-        if len(entry) < 5 or not entry[4]:
-            continue
-        if entry[0] in ('192.168.0.100', '192.168.70.100', '192.168.70.125'):
-            # Note that these addresses are common static ip addresses
-            # that are hopelessly ambiguous if there are many
-            # so ignore such entries and move on
-            # ideally the system network steers clear of this landmine of
-            # a subnet, but just in case
-            continue
-        if not _validmac.match(entry[4]):
-            continue
-        neightable[entry[0]] = entry[4]
     neightime = os.times()[4]
+    s = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, socket.NETLINK_ROUTE)
+    s.bind((0, 0))
+    # RTM_GETNEIGH
+    nlhdr = b'\x1c\x00\x00\x00\x1e\x00\x01\x03\x00\x00\x00\x00\x00\x00\x00\x00'
+    ndmsg=  b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+    s.sendall(nlhdr + ndmsg)
+    while True:
+        pdata = s.recv(65536)
+        v = memoryview(pdata)
+        if struct.unpack('H', v[4:6])[0] == 3:
+            break
+        while len(v):
+            length, typ = struct.unpack('IH', v[:6])
+            if typ == 28:
+                hlen = struct.calcsize('BIHBB')
+                fam, idx, state, flags, typ = struct.unpack('BIHBB', v[16:16+hlen])
+                if typ == 1:  # only handle unicast entries
+                    curraddr = None
+                    currip = None
+                    rta = v[16+hlen:length]
+                    while len(rta):
+                        rtalen, rtatyp = struct.unpack('HH', rta[:4])
+                        if rtatyp == 2:  # hwaddr
+                            hwlen = rtalen - 4
+                            curraddr = ':'.join(['{:02x}'.format(x) for x in bytearray(rta[4:rtalen].tobytes())])
+                        elif rtatyp == 1:  # ip address
+                            currip = socket.inet_ntop(fam, rta[4:rtalen].tobytes())
+                        rta = rta[rtalen:]
+                        if not rtalen:
+                            if curraddr and currip:
+                                neightable[currip] = curraddr
+                            break
+            v = v[length:]
 
 
 def refresh_neigh():