[DHCPv6] add the NTP Server Option (#4113)

Author: evverx

scapy/layers/dhcp6.py

@@ -116,6 +116,7 @@ def _dhcp6_dispatcher(x, *args, **kargs):
              41: "OPTION_NEW_POSIX_TIMEZONE",  # RFC4833
              42: "OPTION_NEW_TZDB_TIMEZONE",  # RFC4833
              48: "OPTION_LQ_CLIENT_LINK",  # RFC5007
+             56: "OPTION_NTP_SERVER",  # RFC5908
              59: "OPT_BOOTFILE_URL",  # RFC5970
              60: "OPT_BOOTFILE_PARAM",  # RFC5970
              61: "OPTION_CLIENT_ARCH_TYPE",  # RFC5970
@@ -174,6 +175,7 @@ def _dhcp6_dispatcher(x, *args, **kargs):
                      # 46: "DHCP6OptLQClientTime",       #RFC5007
                      # 47: "DHCP6OptLQRelayData",        #RFC5007
                      48: "DHCP6OptLQClientLink",  # RFC5007
+                     56: "DHCP6OptNTPServer",  # RFC5908
                      59: "DHCP6OptBootFileUrl",  # RFC5790
                      60: "DHCP6OptBootFileParam",  # RFC5970
                      61: "DHCP6OptClientArchType",  # RFC5970
@@ -961,6 +963,60 @@ class DHCP6OptLQClientLink(_DHCP6OptGuessPayload):  # RFC5007
                                 length_from=lambda pkt: pkt.optlen)]
 
 
+class DHCP6NTPSubOptSrvAddr(Packet):  # RFC5908 sect 4.1
+    name = "DHCP6 NTP Server Address Suboption"
+    fields_desc = [ShortField("optcode", 1),
+                   ShortField("optlen", 16),
+                   IP6Field("addr", "::")]
+
+    def extract_padding(self, s):
+        return b"", s
+
+
+class DHCP6NTPSubOptMCAddr(Packet):  # RFC5908 sect 4.2
+    name = "DHCP6 NTP Multicast Address Suboption"
+    fields_desc = [ShortField("optcode", 2),
+                   ShortField("optlen", 16),
+                   IP6Field("addr", "::")]
+
+    def extract_padding(self, s):
+        return b"", s
+
+
+class DHCP6NTPSubOptSrvFQDN(Packet):  # RFC5908 sect 4.3
+    name = "DHCP6 NTP Server FQDN Suboption"
+    fields_desc = [ShortField("optcode", 3),
+                   FieldLenField("optlen", None, length_of="fqdn"),
+                   DNSStrField("fqdn", "",
+                               length_from=lambda pkt: pkt.optlen)]
+
+    def extract_padding(self, s):
+        return b"", s
+
+
+_ntp_subopts = {1: DHCP6NTPSubOptSrvAddr,
+                2: DHCP6NTPSubOptMCAddr,
+                3: DHCP6NTPSubOptSrvFQDN}
+
+
+def _ntp_subopt_dispatcher(p, **kwargs):
+    cls = conf.raw_layer
+    if len(p) >= 2:
+        o = struct.unpack("!H", p[:2])[0]
+        cls = _ntp_subopts.get(o, conf.raw_layer)
+    return cls(p, **kwargs)
+
+
+class DHCP6OptNTPServer(_DHCP6OptGuessPayload):  # RFC5908
+    name = "DHCP6 NTP Server Option"
+    fields_desc = [ShortEnumField("optcode", 56, dhcp6opts),
+                   FieldLenField("optlen", None, length_of="ntpserver",
+                                 fmt="!H"),
+                   PacketListField("ntpserver", [],
+                                   _ntp_subopt_dispatcher,
+                                   length_from=lambda pkt: pkt.optlen)]
+
+
 class DHCP6OptBootFileUrl(_DHCP6OptGuessPayload):  # RFC5970
     name = "DHCP6 Boot File URL Option"
     fields_desc = [ShortEnumField("optcode", 59, dhcp6opts),

test/scapy/layers/dhcp6.uts

@@ -1054,6 +1054,81 @@ raw(DHCP6OptLQClientLink(linkaddress=["2001:db8::1", "2001:db8::2"])) == b'\x000
 a = DHCP6OptLQClientLink(b'\x000\x00  \x01\r\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01 \x01\r\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02')
 a.optcode == 48 and a.optlen == 32 and len(a.linkaddress) == 2 and a.linkaddress[0] == "2001:db8::1" and a.linkaddress[1] == "2001:db8::2"
 
+
+############
+############
++ Test DHCP6 Option - NTP Server
+
+= DHCP6NTPSubOptSrvAddr - Basic dissection/instantiation
+b = b'\x00\x01' + b'\x00\x10' + b'\x00' * 16
+assert raw(DHCP6NTPSubOptSrvAddr()) == b
+
+p = DHCP6NTPSubOptSrvAddr(b)
+assert p.optcode == 1 and p.optlen == 16 and p.addr == '::'
+
+= DHCP6NTPSubOptSrvAddr - Dissection/instantiation with specific values
+b = b'\x00\x01' + b'\x00\x10' + b'\x20\x01\x0d\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01'
+assert raw(DHCP6NTPSubOptSrvAddr(addr='2001:db8::1')) == b
+
+p = DHCP6NTPSubOptSrvAddr(b)
+assert p.optcode == 1 and p.optlen == 16 and p.addr == '2001:db8::1'
+
+= DHCP6NTPSubOptMCAddr - Basic dissection/instantiation
+b = b'\x00\x02' + b'\x00\x10' + b'\x00' * 16
+assert raw(DHCP6NTPSubOptMCAddr()) == b
+
+p = DHCP6NTPSubOptMCAddr(b)
+assert p.optcode == 2 and p.optlen == 16 and p.addr == '::'
+
+= DHCP6NTPSubOptMCAddr - Dissection/instantiation with specific values
+b = b'\x00\x02' + b'\x00\x10' + b'\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01'
+assert raw(DHCP6NTPSubOptMCAddr(addr='ff02::101')) == b
+
+p = DHCP6NTPSubOptMCAddr(b)
+assert p.optcode == 2 and p.optlen == 16 and p.addr == 'ff02::101'
+
+= DHCP6NTPSubOptSrvFQDN - Basic dissection/instantiation
+b = b'\x00\x03' + b'\x00\x01' + b'\x00'
+assert raw(DHCP6NTPSubOptSrvFQDN()) == b
+
+p = DHCP6NTPSubOptSrvFQDN(b)
+assert p.optcode == 3 and p.optlen == 1 and p.fqdn == b'.'
+
+= DHCP6NTPSubOptSrvFQDN - Dissection/instantiation with specific values
+b = b'\x00\x03' + b'\x00\x0d' + b'\x07example\x03com\x00'
+assert raw(DHCP6NTPSubOptSrvFQDN(fqdn='example.com')) == b
+
+p = DHCP6NTPSubOptSrvFQDN(b)
+assert p.optcode == 3 and p.optlen == 13 and p.fqdn == b'example.com.'
+
+= DHCP6OptNTPServer - Basic dissection/instantiation
+b = b'\x00\x38' + b'\x00\x00'
+assert raw(DHCP6OptNTPServer()) == b
+
+p = DHCP6OptNTPServer(b)
+assert p.optcode == 56 and p.optlen == 0 and p.ntpserver == []
+
+= DHCP6OptNTPServer - Dissection/instantiation with specific values
+srv_addr = b'\x00\x01' + b'\x00\x10' + b'\x20\x01\x0d\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01'
+mc_addr = b'\x00\x02' + b'\x00\x10' + b'\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01'
+srv_fqdn = b'\x00\x03' + b'\x00\x0d' + b'\x07example\x03com\x00'
+b = b'\x00\x38' + b'\x00\x39' + srv_addr + mc_addr + srv_fqdn
+
+p = DHCP6OptNTPServer(
+    ntpserver=[DHCP6NTPSubOptSrvAddr(addr='2001:db8::1'),
+               DHCP6NTPSubOptMCAddr(addr='ff02::101'),
+               DHCP6NTPSubOptSrvFQDN(fqdn='example.com'),
+               ]
+)
+assert raw(p) == b
+
+p = DHCP6OptNTPServer(b)
+assert p.optcode == 56 and p.optlen == 57 and len(p.ntpserver) == 3
+assert p.ntpserver[0] == DHCP6NTPSubOptSrvAddr(srv_addr)
+assert p.ntpserver[1] == DHCP6NTPSubOptMCAddr(mc_addr)
+assert p.ntpserver[2] == DHCP6NTPSubOptSrvFQDN(srv_fqdn)
+
+
 ############
 ############
 + Test DHCP6 Option - Boot File URL