1 files changed, 147 insertions, 0 deletions
diff --git a/external/construct/protocols/application/dns.py b/external/construct/protocols/application/dns.py
new file mode 100644
index 0000000..8a586ce
--- /dev/null
+++ b/external/construct/protocols/application/dns.py
@@ -0,0 +1,147 @@
+"""
+Domain Name System (TCP/IP protocol stack)
+"""
+from construct import *
+from construct.protocols.layer3.ipv4 import IpAddressAdapter
+from binascii import unhexlify
+import six
+
+
+class DnsStringAdapter(Adapter):
+    def _encode(self, obj, context):
+        parts = obj.split(".")
+        parts.append("")
+        return parts
+    def _decode(self, obj, context):
+        return ".".join(obj[:-1])
+
+dns_record_class = Enum(UBInt16("class"),
+    RESERVED = 0,
+    INTERNET = 1,
+    CHAOS = 3,
+    HESIOD = 4,
+    NONE = 254,
+    ANY = 255,
+)
+
+dns_record_type = Enum(UBInt16("type"),
+    IPv4 = 1,
+    AUTHORITIVE_NAME_SERVER = 2,
+    CANONICAL_NAME = 5,
+    NULL = 10,
+    MAIL_EXCHANGE = 15,
+    TEXT = 16,
+    X25 = 19,
+    ISDN = 20,
+    IPv6 = 28,
+    UNSPECIFIED = 103,
+    ALL = 255,
+)
+
+query_record = Struct("query_record",
+    DnsStringAdapter(
+        RepeatUntil(lambda obj, ctx: obj == "",
+            PascalString("name")
+        )
+    ),
+    dns_record_type,
+    dns_record_class,
+)
+
+rdata = Field("rdata", lambda ctx: ctx.rdata_length)
+
+resource_record = Struct("resource_record",
+    CString("name", terminators = six.b("\xc0\x00")),
+    Padding(1),
+    dns_record_type,
+    dns_record_class,
+    UBInt32("ttl"),
+    UBInt16("rdata_length"),
+    IfThenElse("data", lambda ctx: ctx.type == "IPv4",
+        IpAddressAdapter(rdata),
+        rdata
+    )
+)
+
+dns = Struct("dns",
+    UBInt16("id"),
+    BitStruct("flags",
+        Enum(Bit("type"),
+            QUERY = 0,
+            RESPONSE = 1,
+        ),
+        Enum(Nibble("opcode"),
+            STANDARD_QUERY = 0,
+            INVERSE_QUERY = 1,
+            SERVER_STATUS_REQUEST = 2,
+            NOTIFY = 4,
+            UPDATE = 5,
+        ),
+        Flag("authoritive_answer"),
+        Flag("truncation"),
+        Flag("recurssion_desired"),
+        Flag("recursion_available"),
+        Padding(1),
+        Flag("authenticated_data"),
+        Flag("checking_disabled"),
+        Enum(Nibble("response_code"),
+            SUCCESS = 0,
+            FORMAT_ERROR = 1,
+            SERVER_FAILURE = 2,
+            NAME_DOES_NOT_EXIST = 3,
+            NOT_IMPLEMENTED = 4,
+            REFUSED = 5,
+            NAME_SHOULD_NOT_EXIST = 6,
+            RR_SHOULD_NOT_EXIST = 7,
+            RR_SHOULD_EXIST = 8,
+            NOT_AUTHORITIVE = 9,
+            NOT_ZONE = 10,
+        ),
+    ),
+    UBInt16("question_count"),
+    UBInt16("answer_count"),
+    UBInt16("authority_count"),
+    UBInt16("additional_count"),
+    Array(lambda ctx: ctx.question_count,
+        Rename("questions", query_record),
+    ),
+    Rename("answers", 
+        Array(lambda ctx: ctx.answer_count, resource_record)
+    ),
+    Rename("authorities",
+        Array(lambda ctx: ctx.authority_count, resource_record)
+    ),
+    Array(lambda ctx: ctx.additional_count,
+        Rename("additionals", resource_record),
+    ),
+)
+
+
+if __name__ == "__main__":
+    cap1 = unhexlify(six.b("2624010000010000000000000377777706676f6f676c6503636f6d0000010001"))
+    
+    cap2 = unhexlify(six.b(
+    "2624818000010005000600060377777706676f6f676c6503636f6d0000010001c00c00"
+    "05000100089065000803777777016cc010c02c0001000100000004000440e9b768c02c"
+    "0001000100000004000440e9b793c02c0001000100000004000440e9b763c02c000100"
+    "0100000004000440e9b767c030000200010000a88600040163c030c030000200010000"
+    "a88600040164c030c030000200010000a88600040165c030c030000200010000a88600"
+    "040167c030c030000200010000a88600040161c030c030000200010000a88600040162"
+    "c030c0c00001000100011d0c0004d8ef3509c0d0000100010000ca7c000440e9b309c0"
+    "80000100010000c4c5000440e9a109c0900001000100004391000440e9b709c0a00001"
+    "00010000ca7c000442660b09c0b00001000100000266000440e9a709"
+    ))
+
+    obj = dns.parse(cap1)
+    print (obj)
+    print (repr(dns.build(obj)))
+    
+    print ("-" * 80)
+    
+    obj = dns.parse(cap2)
+    print (obj)
+    print (repr(dns.build(obj)))
+    
+    
+
+