JA3 hash computation and filtration

[krizhanovsky]

Motivation

JA3 is a popular client identification, including for DDoS mitigation. Also required for #1381.

Scope

Compute the JA3 hash on the Tempesta TLS layer and implement a rate limiter for each of the JA3 hash. This must be an on-the-fly reconfigurable option, proposed configuration format:

ja3 {
    <hash value> <connections per second> <TLS records per second>;
}

e.g. (0 unlimited, default):

ja3 {
    e7d705a3286e19ea42f587b344ee6865 0 10;
    6734f37431670b3ab4292b8f60f29984 10 100;
}

Multi-layer JA4 hashes

UPDATE ja4 provides hashes for TCP, TLS, HTTP and even destination measures, so we should move with ja4 and configure which layers should be computed with the hash.

Testing

Please write a test or create a new testing issue for this.

Documentation

Update https://tempesta-tech.com/knowledge-base/Tempesta-TLS/ .