Use TCP_NODELAY on TLS sockets to speed up the TLS handshake.#1214
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wcawijngaards
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Better speed on the handshake may improved DNS lookup latency. The code looks fine, for setting the nodelay option.
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- Merge #1214: Use TCP_NODELAY on TLS sockets to speed up the TLS handshake.
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Setting TCP_NODELAY on TLS sockets speeds up the TLS handshake.
Also noted on https://docs.openssl.org/3.4/man3/SSL_connect/#notes.
It was observed that during the handshake the server waits before sending more handshake data for the client ACK (Nagle's algorithm), which is delayed because the client waits for more data before ACKing (delayed ACK).
Old versions of OSes don't seem to experience the handshake delay (e.g., Ubuntu 20.04).
Tested with the same compiled versions of Unbound and OpenSSL across OS versions.
Maybe something changed in the kernel (or the kernel configuration) but couldn't pinpoint anything in particular.
Fixes #1045, #1185, #1202.