net: count application bytes in read_bytes for TLS

[moonchen]

On TLS connections, net.read_bytes was only counting some bytes for the handshake, and none of the incoming ciphertext. This is neither intuitive nor consistent with net.write_bytes.

The fix for now is to make it symmetric with net.write_bytes. Count the plaintext bytes for TLS. This means not counting the handshake bytes.

For a long term fix, I plan to add more comprehensive metrics for TLS.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adjusts net.read_bytes accounting on TLS connections to count decrypted application payload bytes (plaintext), making it symmetric with net.write_bytes, and updates documentation to reflect the clarified semantics.

Changes:

• Move net.read_bytes / net.read_bytes_count increments from raw socket reads to post-decryption reads in SSLNetVConnection.
• Stop counting TLS handshake / record-layer bytes toward net.read_bytes.
• Document that read_bytes/write_bytes represent application-layer plaintext for TLS connections.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/iocore/net/SSLNetVConnection.cc	Shifts read-byte metrics to count decrypted payload instead of raw network bytes for TLS.
doc/admin-guide/monitoring/statistics/core/network-io.en.rst	Documents TLS plaintext semantics for read_bytes and write_bytes.

[moonchen]

[approve ci Clang-Analyzer]