Files
clever-show/messaging_lib.py
2019-04-08 18:20:02 +03:00

109 lines
3.7 KiB
Python

import io
import sys
import json
import struct
class Message:
def __init__(self):
self.income_raw = b""
self._jsonheader_len = None
self.jsonheader = None
self.content = None
@staticmethod
def _json_encode(obj, encoding="utf-8"):
return json.dumps(obj, ensure_ascii=False).encode(encoding)
@staticmethod
def _json_decode(json_bytes, encoding="utf-8"):
with io.TextIOWrapper(io.BytesIO(json_bytes), encoding=encoding, newline="") as tiow:
obj = json.load(tiow)
return obj
@classmethod
def create_message(cls, content_bytes, content_type, message_type, content_encoding="utf-8",
additional_headers=None):
jsonheader = {
"byteorder": sys.byteorder,
"content-type": content_type,
"content-encoding": content_encoding,
"content-length": len(content_bytes),
"message-type": message_type,
}
if additional_headers:
jsonheader.update(additional_headers)
jsonheader_bytes = cls._json_encode(jsonheader, "utf-8")
message_hdr = struct.pack(">H", len(jsonheader_bytes))
message = message_hdr + jsonheader_bytes + content_bytes
return message
@classmethod
def create_json_message(cls, contents):
message = cls.create_message(cls._json_encode(contents), "json", "message")
return message
@classmethod
def create_simple_message(cls, command, args=None):
if args is None:
args = {}
message = cls.create_json_message({"command": command, "args": args})
return message
@classmethod
def create_request(cls, requested_value, request_id, args=None):
if args is None:
args = {}
contents = {"requested_value": requested_value,
"requst_id": request_id,
"args": args,
}
message = cls.create_message(cls._json_encode(contents), "json", "request")
return message
def _process_protoheader(self):
header_len = 2
if len(self.income_raw) >= header_len:
self._jsonheader_len = struct.unpack(">H", self.income_raw[:header_len])[0]
self.income_raw = self.income_raw[header_len:]
def _process_jsonheader(self):
header_len = self._jsonheader_len
if len(self.income_raw) >= header_len:
self.jsonheader = self._json_decode(self.income_raw[:header_len], "utf-8")
self.income_raw = self.income_raw[header_len:]
for reqhdr in (
"byteorder",
"content-length",
"content-type",
"content-encoding",
"message-type",
):
if reqhdr not in self.jsonheader:
raise ValueError('Missing required header {}'.format(reqhdr))
def _process_content(self):
content_len = self.jsonheader["content-length"]
if not len(self.income_raw) >= content_len:
return
data = self.income_raw[:content_len]
self.income_raw = self.income_raw[content_len:]
if self.jsonheader["content-type"] == "json":
encoding = self.jsonheader["content-encoding"]
self.content = self._json_decode(data, encoding)
else:
self.content = data
def process_message(self):
if self._jsonheader_len is None:
self._process_protoheader()
if self._jsonheader_len is not None:
if self.jsonheader is None:
self._process_jsonheader()
if self.jsonheader:
if self.content is None:
self._process_content()