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65 lines
1.7 KiB
65 lines
1.7 KiB
from dataclasses import dataclass
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from typing import List, Optional
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MAX_MESSAGE_SIZE = 512
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EXPECTED_ARG_COUNT = {
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"NICK": 1,
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"USER": 4,
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"JOIN": 1,
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"PRIVMSG": 2,
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}
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class ParsingError(Exception):
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message: Optional[str]
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def __init__(self, message: Optional[str] = None) -> None:
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self.message = message
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@dataclass
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class Message:
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cmd: str
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args: List[str]
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prefix: str = "localhost"
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def encode(self) -> bytes:
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prefix = self.prefix
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if prefix != "":
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prefix = f":{prefix} "
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# TODO: Raise exception if formatted message exceeds 512 bytes
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return f"{prefix}{self.cmd} {' '.join(self.args)}\r\n".encode("utf-8")
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def parse_message(raw: bytes) -> Message:
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if len(raw) > MAX_MESSAGE_SIZE:
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raise ParsingError(
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f"Message is {len(raw)} bytes, larger than allowed {MAX_MESSAGE_SIZE}"
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)
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if not raw.endswith(b"\r\n"):
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raise ParsingError("Message does not terminate in CRLF")
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tokens: List[str] = []
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raw_tokens: List[str] = raw.decode("utf-8").split(" ")
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for i, token in enumerate(raw_tokens):
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if token.startswith(":"):
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trailing = token[1:] + " " + " ".join(raw_tokens[i + 1 :])
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tokens.append(trailing)
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break
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tokens.append(token)
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if len(tokens) == 0:
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raise ParsingError("Message has no command")
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cmd = tokens[0].upper()
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if cmd in EXPECTED_ARG_COUNT and EXPECTED_ARG_COUNT[cmd] != len(tokens) - 1:
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raise ParsingError(
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f"{cmd} had {len(tokens)-1} arguments, expected {EXPECTED_ARG_COUNT[cmd]}"
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)
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tokens[-1] = tokens[-1].strip()
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return Message(cmd=tokens[0], args=tokens[1:])
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