Remove filename from DHCP reply

filename is ignored if pxeclient anyway.  This will provide a
consistent approach for boot file for dhcp-elsewhere and
fixed ip clients alike.

Also add some TODO about how to enable DHCPREQUEST
processing when the time comes, as today the code skipping
option parsing for DISCOVER packets trips up the ability
to continue.  We must make sure we don't call discovery
handler again for REQUEST after doing so for DISCOVER.

confluent_server/confluent/discovery/protocols/pxe.py

@@ -298,7 +298,10 @@ def snoop(handler, protocol=None):
                     'architecture': disco['arch'],
                     'netinfo': {'ifidx': idx, 'recvip': recv, 'txid': txid},
                     'services': ('pxe-client',)}
-            if disco['uuid']:
+            if disco['uuid']:  #TODO(jjohnson2): need to explictly check for
+                               # discover, so that the parser can go ahead and
+                               # parse the options including uuid to enable
+                               # ACK
                 handler(info)
             consider_discover(info, rqinfo, net4, cfg, rqv)
 
@@ -365,9 +368,6 @@ def check_reply(node, info, packet, sock, cfg, reqview):
     repview[10] = 0x80  # always set broadcast
     repview[28:44] = reqview[28:44]  # copy chaddr field
     repview[20:24] = myipn
-    if info['architecture'] == 'uefi-x64':
-        bootfile = b'confluent/x86_64/ipxe.efi'
-    repview[108:108 + len(bootfile)] = bootfile
     repview[236:240] = b'\x63\x82\x53\x63'
     repview[240:242] = b'\x35\x01'
     if rqtype == 1:  # if discover, then offer
@@ -379,6 +379,10 @@ def check_reply(node, info, packet, sock, cfg, reqview):
     repview[249:255] = b'\x33\x04\x00\x00\x00\xf0'  # fixed short lease time
     repview[255:257] = b'\x61\x11'
     repview[257:274] = packet[97]
+    # Note that sending PXEClient kicks off the proxyDHCP procedure, ignoring
+    # boot filename and such in the DHCP packet
+    # we will simply always do it to provide the boot payload in a consistent
+    # matter to both dhcp-elsewhere and fixed ip clients
     repview[274:285] = b'\x3c\x09PXEClient'
     repview[285] = 0xff  # end of options, should always be last byte
     repview = memoryview(reply)