netring 0.11.0

High-performance zero-copy packet I/O for Linux (AF_PACKET TPACKET_V3 + AF_XDP)
Documentation 
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//! Error types for netring.

/// All errors returned by netring.
#[derive(Debug, thiserror::Error)]
pub enum Error {
    /// Failed to create the AF_PACKET socket.
    #[error("socket creation failed")]
    Socket(#[source] std::io::Error),

    /// `mmap` of the ring buffer failed.
    #[error("mmap failed")]
    Mmap(#[source] std::io::Error),

    /// Configuration is invalid (e.g., block_size not power of 2).
    #[error("invalid configuration: {0}")]
    Config(String),

    /// The named network interface does not exist.
    #[error("interface not found: {0}")]
    InterfaceNotFound(String),

    /// `bind` to the interface failed.
    #[error("bind failed")]
    Bind(#[source] std::io::Error),

    /// A `setsockopt` call failed.
    #[error("setsockopt({option}) failed")]
    SockOpt {
        /// The socket option that failed (e.g., `"PACKET_VERSION"`).
        option: &'static str,
        /// The underlying OS error.
        #[source]
        source: std::io::Error,
    },

    /// Insufficient privileges — typically missing `CAP_NET_RAW`.
    #[error("insufficient privileges (need CAP_NET_RAW)")]
    PermissionDenied,

    /// Generic I/O error.
    #[error(transparent)]
    Io(#[from] std::io::Error),

    /// XDP loader error (only present when the `xdp-loader` feature is enabled).
    #[cfg(feature = "xdp-loader")]
    #[error("XDP loader: {0}")]
    Loader(String),

    /// BPF filter construction failed (e.g., oversize program,
    /// conflicting fragments). Bubbled up from
    /// [`BpfFilter::new`](crate::BpfFilter::new) and the typed builder.
    #[error("BPF filter: {0}")]
    Bpf(#[from] crate::config::BuildError),
}

/// Convenience alias used throughout the crate.
pub type Result<T> = std::result::Result<T, Error>;

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

    #[test]
    fn error_is_send_sync() {
        fn assert_send_sync<T: Send + Sync>() {}
        assert_send_sync::<Error>();
    }

    #[test]
    fn from_io_error() {
        let io_err = std::io::Error::other("test");
        let err: Error = io_err.into();
        assert!(matches!(err, Error::Io(_)));
    }

    #[test]
    fn display_variants() {
        let e = Error::Config("bad block_size".into());
        assert_eq!(e.to_string(), "invalid configuration: bad block_size");

        let e = Error::InterfaceNotFound("eth99".into());
        assert_eq!(e.to_string(), "interface not found: eth99");

        let e = Error::PermissionDenied;
        assert!(e.to_string().contains("CAP_NET_RAW"));

        let io_err = std::io::Error::other("fail");
        let e = Error::SockOpt {
            option: "PACKET_VERSION",
            source: io_err,
        };
        assert!(e.to_string().contains("PACKET_VERSION"));
    }
}