Add a tlvdata module

confluent/common/tlvdata.py

@@ -0,0 +1,40 @@
+
+import struct
+
+def send_tlvdata(handle, data):
+    if not isintance(type, int):
+        raise Exception()
+    if isinstance(data, str):
+        tl = len(data)
+        if tl < 16777216:
+            #type for string is '0', so we don't need
+            #to xor anything in
+            handle.write(struct.pack("!I", tl))
+        else:
+            raise Exception("String data length exceeds protocol")
+        handle.write(data)
+        handle.flush()
+    elif isinstance(data, dict):  # JSON currently only goes to 4 bytes
+        sdata = json.dumps(data, separators=(',',':'))
+        tl = len(sdata)
+        if tl > 16777215:
+            raise Exception("JSON data exceeds protocol limits")
+        # xor in the type (0b1 << 24)
+        tl |= 16777216
+        handle.write(struct.pack("!I", tl))
+        handle.write(sdata)
+        handle.flush()
+
+def recv_tlvdata(handle):
+    tl = handle.read(4)
+    tl = struct.unpack("!B", tl)[0]
+    if tl & 0b10000000:
+        raise Exception("Protocol Violation, reserved bit set")
+    # 4 byte tlv
+    dlen = tl & 16777215  # 24 ones
+    type = (tl & 2130706432) >> 24  # 7 ones, followed by 24 zeroes
+    if type == 0:
+        return(handle.read(dlen))
+    elif type == 1:
+        sdata = handle.read(dlen)
+        return json.loads(sdata)