tlslp.protocol

Shared protocol helpers for the TLS client and server.

The challenge protocol is newline-delimited UTF-8:

  • Every outbound message is a str that is UTF-8 encoded and ends with "\n".

  • Every inbound message is read until a trailing newline is seen, then decoded as UTF-8 and returned without the newline.

  • Multiline payloads are intentionally unsupported: a peer must send exactly one logical command per line.

This module raises: - ProtocolError when the peer violates message framing/encoding rules (non-bytes from socket, invalid UTF-8, line too long, etc.). - TransportError for network/TLS failures (timeouts, disconnects, OS errors).

Functions

receive_message(secure_sock)

Receive one newline-delimited UTF-8 message.

send_message(string_to_send, secure_sock)

Send one newline-delimited UTF-8 message.

Exceptions

ProtocolError

Peer violated the newline-delimited UTF-8 protocol.

TransportError

Network/TLS error while sending/receiving.
exception tlslp.protocol.ProtocolError

Bases: ValueError

Peer violated the newline-delimited UTF-8 protocol.

exception tlslp.protocol.TransportError

Bases: RuntimeError

Network/TLS error while sending/receiving.

tlslp.protocol.receive_message(secure_sock: socket) → str

Receive one newline-delimited UTF-8 message.

Reads from the socket until a newline byte is observed, then decodes as UTF-8 and returns the string without the trailing newline.

Parameters:

secure_sock (socket.socket) – Connected socket (plain or TLS-wrapped) to read from.

Returns:

The decoded message with the trailing newline removed.

Return type:

(str)

Raises:

  • ProtocolError – If the peer sends non-bytes, invalid UTF-8, or a line that exceeds MAX_LINE_LENGTH.

  • TransportError – If the peer closes the connection, a timeout occurs, or another network/TLS/OS error happens.

Examples

>>> import socket
>>> a, b = socket.socketpair()
>>> try:
...     a.sendall(b"HELLOBACK\n")
...     receive_message(b)
... finally:
...     a.close(); b.close()
'HELLOBACK'
tlslp.protocol.send_message(string_to_send: str, secure_sock: socket) → None

Send one newline-delimited UTF-8 message.

The function guarantees: - the payload is a str (otherwise ProtocolError), - it ends with a newline (adds one if missing), - it can be encoded as UTF-8, - it is fully transmitted using sendall.

Parameters:

  • string_to_send (str) – Message to send (with or without a trailing "\n").

  • secure_sock (socket.socket) – Connected socket (plain or TLS-wrapped) to send on.

Raises:

  • ProtocolError – If the payload is not a str or cannot be UTF-8 encoded.

  • TransportError – If the underlying socket/TLS layer fails while sending.

Examples

>>> import socket
>>> a, b = socket.socketpair()
>>> try:
...     send_message("HELLO", a)
...     b.recv(16)
... finally:
...     a.close(); b.close()
b'HELLO\n'