4 files changed, 106 insertions, 0 deletions
diff --git a/external/construct/protocols/layer4/__init__.py b/external/construct/protocols/layer4/__init__.py
new file mode 100644
index 0000000..38693c6
--- /dev/null
+++ b/external/construct/protocols/layer4/__init__.py
@@ -0,0 +1,4 @@
+"""
+layer 4 (transporation) protocols
+"""
+
diff --git a/external/construct/protocols/layer4/isup.py b/external/construct/protocols/layer4/isup.py
new file mode 100644
index 0000000..8111b60
--- /dev/null
+++ b/external/construct/protocols/layer4/isup.py
@@ -0,0 +1,15 @@
+"""
+ISDN User Part (SS7 protocol stack)
+"""
+from construct import *
+
+
+isup_header = Struct("isup_header",
+    Bytes("routing_label", 5),
+    UBInt16("cic"),
+    UBInt8("message_type"),
+    # mandatory fixed parameters
+    # mandatory variable parameters
+    # optional parameters
+)
+
diff --git a/external/construct/protocols/layer4/tcp.py b/external/construct/protocols/layer4/tcp.py
new file mode 100644
index 0000000..44f1bd7
--- /dev/null
+++ b/external/construct/protocols/layer4/tcp.py
@@ -0,0 +1,61 @@
+"""
+Transmission Control Protocol (TCP/IP protocol stack)
+"""
+from construct import *
+from binascii import unhexlify
+import six
+
+
+tcp_header = Struct("tcp_header",
+    UBInt16("source"),
+    UBInt16("destination"),
+    UBInt32("seq"),
+    UBInt32("ack"),
+    EmbeddedBitStruct(
+        ExprAdapter(Nibble("header_length"), 
+            encoder = lambda obj, ctx: obj / 4,
+            decoder = lambda obj, ctx: obj * 4,
+        ),
+        Padding(3),
+        Struct("flags",
+            Flag("ns"),
+            Flag("cwr"),
+            Flag("ece"),
+            Flag("urg"),
+            Flag("ack"),
+            Flag("psh"),
+            Flag("rst"),
+            Flag("syn"),
+            Flag("fin"),
+        ),
+    ),
+    UBInt16("window"),
+    UBInt16("checksum"),
+    UBInt16("urgent"),
+    Field("options", lambda ctx: ctx.header_length - 20),
+)
+
+if __name__ == "__main__":
+    cap = unhexlify(six.b("0db5005062303fb21836e9e650184470c9bc0000"))
+    
+    obj = tcp_header.parse(cap)
+    print (obj)
+    built = tcp_header.build(obj)
+    print (built)
+    assert cap == built
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/external/construct/protocols/layer4/udp.py b/external/construct/protocols/layer4/udp.py
new file mode 100644
index 0000000..42a951e
--- /dev/null
+++ b/external/construct/protocols/layer4/udp.py
@@ -0,0 +1,26 @@
+"""
+User Datagram Protocol (TCP/IP protocol stack)
+"""
+from construct import *
+import six
+from binascii import unhexlify
+
+
+udp_header = Struct("udp_header",
+    Value("header_length", lambda ctx: 8),
+    UBInt16("source"),
+    UBInt16("destination"),
+    ExprAdapter(UBInt16("payload_length"), 
+        encoder = lambda obj, ctx: obj + 8,
+        decoder = lambda obj, ctx: obj - 8,
+    ),
+    UBInt16("checksum"),
+)
+
+if __name__ == "__main__":
+    cap = unhexlify(six.b("0bcc003500280689"))
+    obj = udp_header.parse(cap)
+    print (obj)
+    print (repr(udp_header.build(obj)))
+
+