... in most cases instead of 'struct connectdata *' but in some cases in
addition to.
- We mostly operate on transfers and not connections.
- We need the transfer handle to log, store data and more. Everything in
libcurl is driven by a transfer (the CURL * in the public API).
- This work clarifies and separates the transfers from the connections
better.
- We should avoid "conn->data". Since individual connections can be used
by many transfers when multiplexing, making sure that conn->data
points to the current and correct transfer at all times is difficult
and has been notoriously error-prone over the years. The goal is to
ultimately remove the conn->data pointer for this reason.
Closes#6425
Factor out common I/O loop as bearssl_run_until, which reads/writes TLS
records until the desired engine state is reached. This is now used for
the handshake, read, write, and close.
Match OpenSSL SSL_write behavior, and don't return the number of bytes
written until the corresponding records have been completely flushed
across the socket. This involves keeping track of the length of data
buffered into the TLS engine, and assumes that when CURLE_AGAIN is
returned, the write function will be called again with the same data
and length arguments. This is the same requirement of SSL_write.
Handle TLS close notify as EOF when reading by returning 0.
Closes https://github.com/curl/curl/pull/4748
