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real_ip: Remove Heroku router workaround #10249

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Merged
merged 1 commit into from
Dec 20, 2024
Merged

real_ip: Remove Heroku router workaround #10249

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63 changes: 17 additions & 46 deletions src/real_ip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,50 +38,21 @@ fn is_cloud_front_ip(ip: &IpAddr) -> bool {
.any(|trusted_proxy| trusted_proxy.contains(*ip))
}

/// Extracts the client IP address from the `X-Forwarded-For` header.
///
/// This function will return the last valid non-CloudFront IP address in the
/// `X-Forwarded-For` header, if any.
pub fn process_xff_headers(headers: &HeaderMap) -> Option<IpAddr> {
let mut xff_iter = headers.get_all(X_FORWARDED_FOR).iter();
let Some(first_header) = xff_iter.next() else {
debug!(target: "real_ip", "No X-Forwarded-For header found");
return None;
};

let has_more_headers = xff_iter.next().is_some();
if has_more_headers {
// This only happens for requests going directly to crates-io.herokuapp.com,
// since AWS CloudFront automatically merges these headers into one.
//
// The Heroku router has a bug where it currently (2023-10-25) appends
// the connecting IP to the **first** header instead of the last.
//
// In this specific scenario we will read the IP from the first header,
// instead of the last, to work around the Heroku bug. We also don't
// have to care about the trusted proxies, since the request was
// apparently sent to Heroku directly.

debug!(target: "real_ip", ?first_header, "Multiple X-Forwarded-For headers found, using the first one due to Heroku bug");

parse_xff_header(first_header)
.into_iter()
.filter_map(|r| r.ok())
.next_back()
} else {
// If the request came in through CloudFront we only get a single,
// merged header.
//
// If the request came in through Heroku and only had a single header
// originally, then we also only get a single header.
//
// In this case return the right-most IP address that is not in the list
// of IPs from trusted proxies (i.e. CloudFront).

debug!(target: "real_ip", ?first_header, "Single X-Forwarded-For header found");

parse_xff_header(first_header)
.into_iter()
.filter_map(|r| r.ok())
.filter(|ip| !is_cloud_front_ip(ip))
.next_back()
}
headers
.get_all(X_FORWARDED_FOR)
.iter()
.flat_map(|header| {
parse_xff_header(header)
.into_iter()
.filter_map(|r| r.ok())
.filter(|ip| !is_cloud_front_ip(ip))
})
.next_back()
}

/// Parses the content of an `X-Forwarded-For` header into a
Expand Down Expand Up @@ -142,11 +113,11 @@ mod tests {
test(vec![b"1.1.1.1, 130.176.118.147"], Some("1.1.1.1"));
test(vec![b"1.1.1.1, 2.2.2.2, 130.176.118.147"], Some("2.2.2.2"));

// Heroku workaround
test(vec![b"1.1.1.1, 2.2.2.2", b"3.3.3.3"], Some("2.2.2.2"));
// Multiple headers behavior
test(vec![b"1.1.1.1, 2.2.2.2", b"3.3.3.3"], Some("3.3.3.3"));
test(
vec![b"1.1.1.1, 130.176.118.147", b"3.3.3.3"],
Some("130.176.118.147"),
Some("3.3.3.3"),
);
}

Expand Down