rama-http-backend 0.4.0

error types and utilities for rama
Documentation 
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use std::fmt;

use rama_core::error::BoxError;
use rama_http_types::{StatusCode, Version};
use rama_net::client::{ConnectionError, ConnectionErrorDomain, ConnectionErrorKind};

#[derive(Debug)]
/// error that can be returned in case a http proxy
/// did not manage to establish a connection
pub enum HttpProxyError {
    /// Proxy Authentication Required
    ///
    /// (Proxy returned HTTP 407)
    AuthRequired,
    /// Proxy is Unavailable
    ///
    /// (Proxy returned HTTP 503)
    Unavailable,
    /// I/O error happened as part of HTTP Proxy Connection Establishment
    ///
    /// (e.g. some kind of TCP error)
    Transport(BoxError),
    /// The configured HTTP version cannot establish a CONNECT tunnel.
    InvalidVersion(Version),
    /// The proxy rejected CONNECT with an unexpected response status.
    Rejected(StatusCode),
}

impl fmt::Display for HttpProxyError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::AuthRequired => {
                write!(f, "http proxy error: proxy auth required (http 407)")
            }
            Self::Unavailable => {
                write!(f, "http proxy error: proxy unavailable (http 503)")
            }
            Self::Transport(error) => {
                write!(f, "http proxy error: transport error: I/O [{error}]")
            }
            Self::InvalidVersion(version) => {
                write!(f, "http proxy error: invalid CONNECT version: {version:?}")
            }
            Self::Rejected(status) => {
                write!(f, "http proxy error: CONNECT rejected with status {status}")
            }
        }
    }
}

impl From<HttpProxyError> for ConnectionError {
    fn from(error: HttpProxyError) -> Self {
        let (domain, kind) = match &error {
            HttpProxyError::AuthRequired => (
                ConnectionErrorDomain::Transport,
                ConnectionErrorKind::Authentication,
            ),
            HttpProxyError::Unavailable | HttpProxyError::Transport(_) => (
                ConnectionErrorDomain::Transport,
                ConnectionErrorKind::Unavailable,
            ),
            HttpProxyError::Rejected(_) => (
                ConnectionErrorDomain::Transport,
                ConnectionErrorKind::Rejected,
            ),
            HttpProxyError::InvalidVersion(_) => (
                ConnectionErrorDomain::Local,
                ConnectionErrorKind::InvalidInput,
            ),
        };

        Self::new(error, domain, kind)
    }
}

impl From<std::io::Error> for HttpProxyError {
    fn from(value: std::io::Error) -> Self {
        Self::Transport(value.into())
    }
}

impl std::error::Error for HttpProxyError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        let Self::Transport(err) = self else {
            return None;
        };

        // filter out generic io errors,
        // but do allow custom errors (e.g. because IP is blocked)
        let err_ref = err.source().unwrap_or_else(|| err.as_ref());
        if err_ref.is::<std::io::Error>() {
            Some(self)
        } else {
            Some(err_ref)
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn classifies_proxy_responses() {
        let error = ConnectionError::from(HttpProxyError::AuthRequired);
        assert_eq!(error.domain(), ConnectionErrorDomain::Transport);
        assert_eq!(error.kind(), ConnectionErrorKind::Authentication);

        let error = ConnectionError::from(HttpProxyError::Unavailable);
        assert_eq!(error.domain(), ConnectionErrorDomain::Transport);
        assert_eq!(error.kind(), ConnectionErrorKind::Unavailable);

        let error = ConnectionError::from(HttpProxyError::Rejected(StatusCode::BAD_GATEWAY));
        assert_eq!(error.domain(), ConnectionErrorDomain::Transport);
        assert_eq!(error.kind(), ConnectionErrorKind::Rejected);

        let error = ConnectionError::from(HttpProxyError::InvalidVersion(Version::HTTP_3));
        assert_eq!(error.domain(), ConnectionErrorDomain::Local);
        assert_eq!(error.kind(), ConnectionErrorKind::InvalidInput);
    }
}