mre / rate-limits

Parse HTTP Rate-Limit headers of different vendors

rate-limits

A crate for parsing HTTP rate limit headers as per the IETF draft. Inofficial implementations like the Github rate limit headers are also supported on a best effort basis. See vendor list for support.

use indoc::indoc;
use std::str::FromStr;
use time::{OffsetDateTime, Duration};
use rate_limits::{Vendor, RateLimit, ResetTime, Headers};

let headers = indoc! {"
    x-ratelimit-limit: 5000
    x-ratelimit-remaining: 4987
    x-ratelimit-reset: 1350085394
"};

assert_eq!(
    RateLimit::new(headers).unwrap(),
    RateLimit::Rfc6585(Headers {
        limit: 5000,
        remaining: 4987,
        reset: ResetTime::DateTime(
            OffsetDateTime::from_unix_timestamp(1350085394).unwrap()
        ),
        window: Some(Duration::HOUR),
        vendor: Vendor::Github
    }),
);

Also takes the Retry-After header into account when calculating the reset time.

http::HeaderMap is supported as well:

use std::str::FromStr;
use time::{OffsetDateTime, Duration};
use rate_limits::{Vendor, RateLimit, ResetTime, Headers};
use http::header::HeaderMap;

let mut headers = HeaderMap::new();
headers.insert("X-RATELIMIT-LIMIT", "5000".parse().unwrap());
headers.insert("X-RATELIMIT-REMAINING", "4987".parse().unwrap());
headers.insert("X-RATELIMIT-RESET", "1350085394".parse().unwrap());

assert_eq!(
    RateLimit::new(headers).unwrap(),
    RateLimit::Rfc6585(Headers {
        limit: 5000,
        remaining: 4987,
        reset: ResetTime::DateTime(
            OffsetDateTime::from_unix_timestamp(1350085394).unwrap()
        ),
        window: Some(Duration::HOUR),
        vendor: Vendor::Github
    }),
);

Further development

There is a new IETF draft which supersedes the old "polli" draft. It introduces a new RateLimit-Policy header which specifies the rate limit quota policy. The goal is to support this new draft in this crate as well.

Other resources:

• Examples of HTTP API Rate Limiting HTTP Response

License: Apache-2.0/MIT