nostr relay: Rate Limiting

To enable rate limiting, add rate_limits to your config file, like this:

rate_limits:
    global:
        EVENT: 1000/s
    ip:
        EVENT: 1/minute
        REQ: 10/s

The rate limiter keeps track of global and per/ip rate limits, per message-type.

The syntax for each option is: frequency/interval

The options for interval are hour, minute, second (or h, m, s)

So, to allow each ip to add 100 events per hour, but only 1 event per second:

rate_limits:
    ip:
        EVENT: 100/hour,1/sec

Or you can cap the global limit for events, and allow individual connections to exceed the rate:

rate_limits:
    global:
        EVENT: 1000/min
    ip:
        EVENT: 100/s

== Per/IP Exemptions ==

To exempt or restrict certain addresses from rate limits:

rate_limits:
    ip:
        EVENT: 100/hour,10/sec
    127.0.0.1:
        EVENT: 100/sec
    8.8.8.8:
        EVENT: -1/sec

In this case, 8.8.8.8 would never be limited.

== Custom Rate Limiter Class ==

You can also customize rate limiting with your own class:

rate_limiter_class: my_custom_module.MyRateLimiter
rate_limits:
    arbitrary_option: foo

The rate_limits dict will be passed to your rate limiter instance. It must implement two methods: is_limited(ip_address, message) and cleanup()