Read exactly five bytes for the TLS record header, unpack the content type, version, and length, then keep receiving until you’ve collected the promised payload length.
from fixtures.local_targets import HeartbleedFixtureSocket, parse_tls_record_header, recvall, tls_client_hello
sock = HeartbleedFixtureSocket()
sock.send(tls_client_hello())
content_type, version, length = parse_tls_record_header(sock.recv(5))
payload = recvall(sock, length)
print(content_type, hex(version), payload[:1])22 0x302 b'\x0e'The solution reads the fixed five-byte TLS header first, then reads exactly the payload length promised by that header. That pattern matters because TCP gives you a stream of bytes, not tidy message-sized chunks.
Here’s what’s happening: the header tells us how much more to read. If we pretend one recv() always returns the whole payload, the code may work in a toy case and then betray us in real protocol work.
References: Python socket, struct.unpack(), and RFC 5246.