bgpkit_parser/parser/bgp/attributes/

mod.rs

mod attr_01_origin;
mod attr_02_17_as_path;
mod attr_03_next_hop;
mod attr_04_med;
mod attr_05_local_pref;
mod attr_07_18_aggregator;
mod attr_08_communities;
mod attr_09_originator;
mod attr_10_13_cluster;
mod attr_14_15_nlri;
mod attr_16_25_extended_communities;
mod attr_23_tunnel_encap;
mod attr_29_linkstate;
mod attr_32_large_communities;
mod attr_35_otc;

use bytes::{Buf, BufMut, Bytes, BytesMut};
use log::{debug, warn};
use std::net::IpAddr;

use crate::models::*;

use crate::error::{BgpValidationWarning, ParserError};
use crate::parser::bgp::attributes::attr_01_origin::{encode_origin, parse_origin};
use crate::parser::bgp::attributes::attr_02_17_as_path::encode_as_path;
pub(crate) use crate::parser::bgp::attributes::attr_02_17_as_path::parse_as_path;
use crate::parser::bgp::attributes::attr_03_next_hop::{encode_next_hop, parse_next_hop};
use crate::parser::bgp::attributes::attr_04_med::{encode_med, parse_med};
use crate::parser::bgp::attributes::attr_05_local_pref::{encode_local_pref, parse_local_pref};
use crate::parser::bgp::attributes::attr_07_18_aggregator::{encode_aggregator, parse_aggregator};
use crate::parser::bgp::attributes::attr_08_communities::{
    encode_regular_communities, parse_regular_communities,
};
use crate::parser::bgp::attributes::attr_09_originator::{
    encode_originator_id, parse_originator_id,
};
use crate::parser::bgp::attributes::attr_10_13_cluster::{encode_clusters, parse_clusters};
use crate::parser::bgp::attributes::attr_14_15_nlri::encode_nlri;
pub(crate) use crate::parser::bgp::attributes::attr_14_15_nlri::parse_nlri;
use crate::parser::bgp::attributes::attr_16_25_extended_communities::{
    encode_extended_communities, encode_ipv6_extended_communities, parse_extended_community,
    parse_ipv6_extended_community,
};
use crate::parser::bgp::attributes::attr_23_tunnel_encap::{
    encode_tunnel_encapsulation_attribute, parse_tunnel_encapsulation_attribute,
};
use crate::parser::bgp::attributes::attr_29_linkstate::{
    encode_link_state_attribute, parse_link_state_attribute,
};
use crate::parser::bgp::attributes::attr_32_large_communities::{
    encode_large_communities, parse_large_communities,
};
use crate::parser::bgp::attributes::attr_35_otc::{
    encode_only_to_customer, parse_only_to_customer,
};
use crate::parser::ReadUtils;

/// Validate attribute flags according to RFC 4271 and RFC 7606
fn validate_attribute_flags(
    attr_type: AttrType,
    flags: AttrFlags,
    warnings: &mut Vec<BgpValidationWarning>,
) {
    let expected_flags = match attr_type {
        // Well-known mandatory attributes
        AttrType::ORIGIN | AttrType::AS_PATH | AttrType::NEXT_HOP => AttrFlags::TRANSITIVE,
        // Well-known discretionary attributes
        AttrType::ATOMIC_AGGREGATE => AttrFlags::TRANSITIVE,
        // Optional non-transitive attributes
        AttrType::MULTI_EXIT_DISCRIMINATOR
        | AttrType::ORIGINATOR_ID
        | AttrType::CLUSTER_LIST
        | AttrType::MP_REACHABLE_NLRI
        | AttrType::MP_UNREACHABLE_NLRI => AttrFlags::OPTIONAL,
        // Optional transitive attributes
        AttrType::AGGREGATOR
        | AttrType::AS4_AGGREGATOR
        | AttrType::AS4_PATH
        | AttrType::COMMUNITIES
        | AttrType::EXTENDED_COMMUNITIES
        | AttrType::IPV6_ADDRESS_SPECIFIC_EXTENDED_COMMUNITIES
        | AttrType::LARGE_COMMUNITIES
        | AttrType::ONLY_TO_CUSTOMER => AttrFlags::OPTIONAL | AttrFlags::TRANSITIVE,
        // LOCAL_PREFERENCE is well-known mandatory for IBGP
        AttrType::LOCAL_PREFERENCE => AttrFlags::TRANSITIVE,
        // Unknown or development attributes
        _ => return, // Don't validate unknown attributes
    };

    // Check if flags match expected (ignoring EXTENDED and PARTIAL flags for this check)
    let relevant_flags = flags & (AttrFlags::OPTIONAL | AttrFlags::TRANSITIVE);
    if relevant_flags != expected_flags {
        warnings.push(BgpValidationWarning::AttributeFlagsError {
            attr_type,
            expected_flags: expected_flags.bits(),
            actual_flags: relevant_flags.bits(),
        });
    }

    // Check partial flag constraint
    if flags.contains(AttrFlags::PARTIAL) {
        match attr_type {
            // Partial bit MUST be 0 for well-known attributes and optional non-transitive
            AttrType::ORIGIN
            | AttrType::AS_PATH
            | AttrType::NEXT_HOP
            | AttrType::LOCAL_PREFERENCE
            | AttrType::ATOMIC_AGGREGATE
            | AttrType::MULTI_EXIT_DISCRIMINATOR
            | AttrType::ORIGINATOR_ID
            | AttrType::CLUSTER_LIST
            | AttrType::MP_REACHABLE_NLRI
            | AttrType::MP_UNREACHABLE_NLRI => {
                warnings.push(BgpValidationWarning::AttributeFlagsError {
                    attr_type,
                    expected_flags: expected_flags.bits(),
                    actual_flags: flags.bits(),
                });
            }
            _ => {} // Partial is OK for optional transitive attributes
        }
    }
}

/// Check if an attribute type is well-known mandatory
fn is_well_known_mandatory(attr_type: AttrType) -> bool {
    matches!(
        attr_type,
        AttrType::ORIGIN | AttrType::AS_PATH | AttrType::NEXT_HOP | AttrType::LOCAL_PREFERENCE
    )
}

pub(crate) struct AttributeValidationState {
    warnings: Vec<BgpValidationWarning>,
    attr_mask: [u64; 4],
}

impl AttributeValidationState {
    pub(crate) fn new() -> Self {
        Self {
            warnings: Vec::new(),
            attr_mask: [0; 4],
        }
    }

    fn has_raw_attr(&self, attr: u8) -> bool {
        (self.attr_mask[(attr / 64) as usize] & (1u64 << (attr % 64))) != 0
    }

    pub(crate) fn has_attr(&self, attr_type: AttrType) -> bool {
        self.has_raw_attr(u8::from(attr_type))
    }

    fn set_attr(&mut self, attr: u8) {
        self.attr_mask[(attr / 64) as usize] |= 1u64 << (attr % 64);
    }

    pub(crate) fn observe_header(
        &mut self,
        raw_attr_type: u8,
        attr_type: AttrType,
        flags: AttrFlags,
        length: usize,
    ) -> bool {
        if self.has_raw_attr(raw_attr_type) {
            self.warnings
                .push(BgpValidationWarning::DuplicateAttribute { attr_type });
        }
        self.set_attr(raw_attr_type);

        validate_attribute_flags(attr_type, flags, &mut self.warnings);
        validate_attribute_length(attr_type, length, &mut self.warnings);

        flags.contains(AttrFlags::PARTIAL)
    }

    pub(crate) fn observe_parse_error(
        &mut self,
        attr_type: AttrType,
        partial: bool,
        error: &ParserError,
    ) {
        if partial {
            self.warnings
                .push(BgpValidationWarning::PartialAttributeError {
                    attr_type,
                    reason: error.to_string(),
                });
            debug!("PARTIAL attribute error: {}", error);
        } else if is_well_known_mandatory(attr_type) {
            self.warnings
                .push(BgpValidationWarning::MalformedAttributeList {
                    reason: format!(
                        "Well-known mandatory attribute {} parsing failed: {}",
                        u8::from(attr_type),
                        error
                    ),
                });
            debug!(
                "Well-known mandatory attribute parsing failed, treating as withdraw: {}",
                error
            );
        } else {
            self.warnings
                .push(BgpValidationWarning::OptionalAttributeError {
                    attr_type,
                    reason: error.to_string(),
                });
            debug!("Optional attribute error, discarding: {}", error);
        }
    }

    pub(crate) fn check_mandatory_attributes(
        &mut self,
        is_announcement: bool,
        has_standard_nlri: bool,
    ) {
        if !is_announcement {
            return;
        }

        if !self.has_attr(AttrType::ORIGIN) {
            self.warnings
                .push(BgpValidationWarning::MissingWellKnownAttribute {
                    attr_type: AttrType::ORIGIN,
                });
        }

        if !self.has_attr(AttrType::AS_PATH) {
            self.warnings
                .push(BgpValidationWarning::MissingWellKnownAttribute {
                    attr_type: AttrType::AS_PATH,
                });
        }

        let has_mp_reach = self.has_attr(AttrType::MP_REACHABLE_NLRI);
        if (has_standard_nlri || !has_mp_reach) && !self.has_attr(AttrType::NEXT_HOP) {
            self.warnings
                .push(BgpValidationWarning::MissingWellKnownAttribute {
                    attr_type: AttrType::NEXT_HOP,
                });
        }
    }

    pub(crate) fn finish(self) -> (Vec<BgpValidationWarning>, [u64; 4]) {
        (self.warnings, self.attr_mask)
    }
}

/// Validate attribute length constraints
fn validate_attribute_length(
    attr_type: AttrType,
    length: usize,
    warnings: &mut Vec<BgpValidationWarning>,
) {
    let expected_length = match attr_type {
        AttrType::ORIGIN => Some(1),
        AttrType::NEXT_HOP => Some(4), // IPv4 next hop
        AttrType::MULTI_EXIT_DISCRIMINATOR => Some(4),
        AttrType::LOCAL_PREFERENCE => Some(4),
        AttrType::ATOMIC_AGGREGATE => Some(0),
        AttrType::ORIGINATOR_ID => Some(4),
        AttrType::ONLY_TO_CUSTOMER => Some(4),
        // Variable length attributes - no fixed constraint
        AttrType::AS_PATH
        | AttrType::AS4_PATH
        | AttrType::AGGREGATOR
        | AttrType::AS4_AGGREGATOR
        | AttrType::COMMUNITIES
        | AttrType::EXTENDED_COMMUNITIES
        | AttrType::IPV6_ADDRESS_SPECIFIC_EXTENDED_COMMUNITIES
        | AttrType::LARGE_COMMUNITIES
        | AttrType::CLUSTER_LIST
        | AttrType::MP_REACHABLE_NLRI
        | AttrType::MP_UNREACHABLE_NLRI => None,
        _ => None, // Unknown attributes
    };

    if let Some(expected) = expected_length {
        if length != expected {
            warnings.push(BgpValidationWarning::AttributeLengthError {
                attr_type,
                expected_length: Some(expected),
                actual_length: length,
            });
        }
    }
}

/// Parse BGP attributes given a slice of u8 and some options.
///
/// The `data: &[u8]` contains the entirety of the attributes bytes, therefore the size of
/// the slice is the total byte length of the attributes section of the message.
pub fn parse_attributes(
    mut data: Bytes,
    asn_len: &AsnLength,
    add_path: bool,
    afi: Option<Afi>,
    safi: Option<Safi>,
    prefixes: Option<&[NetworkPrefix]>,
) -> Result<Attributes, ParserError> {
    // Estimate capacity from data size: each attribute is at least 3 bytes
    // (flag + type + length). Cap at 256 to avoid over-allocation for corrupted data.
    let estimated_attrs = (data.remaining() / 3).min(256);
    let mut attributes: Vec<Attribute> = Vec::with_capacity(estimated_attrs.max(8));
    let mut validation = AttributeValidationState::new();

    while data.remaining() >= 3 {
        // each attribute is at least 3 bytes: flag(1) + type(1) + length(1)
        // thus the while loop condition is set to be at least 3 bytes to read.

        // has content to read
        let flag = AttrFlags::from_bits_retain(data.read_u8()?);
        let attr_type = data.read_u8()?;
        let attr_length = match flag.contains(AttrFlags::EXTENDED) {
            false => data.read_u8()? as usize,
            true => data.read_u16()? as usize,
        };

        debug!(
            "reading attribute: type -- {:?}, length -- {}",
            &attr_type, attr_length
        );

        let parsed_attr_type = AttrType::from(attr_type);

        let partial = validation.observe_header(attr_type, parsed_attr_type, flag, attr_length);

        let attr_type = match parsed_attr_type {
            attr_type @ AttrType::Unknown(unknown_type) => {
                // skip pass the remaining bytes of this attribute
                let bytes = data.read_n_bytes(attr_length)?;
                let attr_value = match get_deprecated_attr_type(unknown_type) {
                    Some(t) => {
                        debug!("deprecated attribute type: {} - {}", unknown_type, t);
                        AttributeValue::Deprecated(AttrRaw { attr_type, bytes })
                    }
                    None => {
                        debug!("unknown attribute type: {}", unknown_type);
                        AttributeValue::Unknown(AttrRaw { attr_type, bytes })
                    }
                };

                assert_eq!(attr_type, attr_value.attr_type());
                attributes.push(Attribute {
                    value: attr_value,
                    flag,
                });
                continue;
            }
            t => t,
        };

        let bytes_left = data.remaining();

        if data.remaining() < attr_length {
            warn!(
                "{:?} attribute encodes a length ({}) that is longer than the remaining attribute data ({}). Skipping remaining attribute data for BGP message",
                attr_type, attr_length, bytes_left
            );
            // break and return already parsed attributes
            break;
        }

        // we know data has enough bytes to read, so we can split the bytes into a new Bytes object
        data.has_n_remaining(attr_length)?;
        let mut attr_data = data.split_to(attr_length);

        let attr = match attr_type {
            AttrType::ORIGIN => parse_origin(attr_data),
            AttrType::AS_PATH => {
                parse_as_path(attr_data, asn_len).map(|path| AttributeValue::AsPath {
                    path,
                    is_as4: false,
                })
            }
            AttrType::NEXT_HOP => parse_next_hop(attr_data, &afi),
            AttrType::MULTI_EXIT_DISCRIMINATOR => parse_med(attr_data),
            AttrType::LOCAL_PREFERENCE => parse_local_pref(attr_data),
            AttrType::ATOMIC_AGGREGATE => Ok(AttributeValue::AtomicAggregate),
            AttrType::AGGREGATOR => {
                parse_aggregator(attr_data, asn_len).map(|(asn, id)| AttributeValue::Aggregator {
                    asn,
                    id,
                    is_as4: false,
                })
            }
            AttrType::ORIGINATOR_ID => parse_originator_id(attr_data),
            AttrType::CLUSTER_LIST => parse_clusters(attr_data),
            AttrType::MP_REACHABLE_NLRI => {
                parse_nlri(attr_data, &afi, &safi, &prefixes, true, add_path)
            }
            AttrType::MP_UNREACHABLE_NLRI => {
                parse_nlri(attr_data, &afi, &safi, &prefixes, false, add_path)
            }
            AttrType::AS4_PATH => parse_as_path(attr_data, &AsnLength::Bits32)
                .map(|path| AttributeValue::AsPath { path, is_as4: true }),
            AttrType::AS4_AGGREGATOR => {
                parse_aggregator(attr_data, &AsnLength::Bits32).map(|(asn, id)| {
                    AttributeValue::Aggregator {
                        asn,
                        id,
                        is_as4: true,
                    }
                })
            }

            // communities
            AttrType::COMMUNITIES => parse_regular_communities(attr_data),
            AttrType::LARGE_COMMUNITIES => parse_large_communities(attr_data),
            AttrType::EXTENDED_COMMUNITIES => parse_extended_community(attr_data),
            AttrType::IPV6_ADDRESS_SPECIFIC_EXTENDED_COMMUNITIES => {
                parse_ipv6_extended_community(attr_data)
            }
            AttrType::DEVELOPMENT => {
                let mut value = vec![];
                for _i in 0..attr_length {
                    value.push(attr_data.read_u8()?);
                }
                Ok(AttributeValue::Development(value))
            }
            AttrType::ONLY_TO_CUSTOMER => parse_only_to_customer(attr_data),
            AttrType::TUNNEL_ENCAPSULATION => parse_tunnel_encapsulation_attribute(attr_data),
            AttrType::BGP_LS_ATTRIBUTE => parse_link_state_attribute(attr_data),
            _ => Err(ParserError::Unsupported(format!(
                "unsupported attribute type: {attr_type:?}"
            ))),
        };

        match attr {
            Ok(value) => {
                assert_eq!(attr_type, value.attr_type());
                attributes.push(Attribute { value, flag });
            }
            Err(e) => {
                validation.observe_parse_error(attr_type, partial, &e);
                continue;
            }
        };
    }

    let (validation_warnings, attr_mask) = validation.finish();
    Ok(Attributes {
        inner: attributes,
        validation_warnings,
        attr_mask,
    })
}

impl Attribute {
    pub fn encode(&self, asn_len: AsnLength) -> Bytes {
        let mut bytes = BytesMut::new();

        let flag = self.flag.bits();
        let type_code = self.value.attr_type().into();

        bytes.put_u8(flag);
        bytes.put_u8(type_code);

        let value_bytes = match &self.value {
            AttributeValue::Origin(v) => encode_origin(v),
            AttributeValue::AsPath { path, is_as4 } => {
                let four_byte = match is_as4 {
                    true => AsnLength::Bits32,
                    false => match asn_len.is_four_byte() {
                        true => AsnLength::Bits32,
                        false => AsnLength::Bits16,
                    },
                };
                encode_as_path(path, four_byte)
            }
            AttributeValue::NextHop(v) => encode_next_hop(v),
            AttributeValue::MultiExitDiscriminator(v) => encode_med(*v),
            AttributeValue::LocalPreference(v) => encode_local_pref(*v),
            AttributeValue::OnlyToCustomer(v) => encode_only_to_customer(v.into()),
            AttributeValue::AtomicAggregate => Bytes::default(),
            AttributeValue::Aggregator { asn, id, is_as4: _ } => {
                encode_aggregator(asn, &IpAddr::from(*id))
            }
            AttributeValue::Communities(v) => encode_regular_communities(v),
            AttributeValue::ExtendedCommunities(v) => encode_extended_communities(v),
            AttributeValue::LargeCommunities(v) => encode_large_communities(v),
            AttributeValue::Ipv6AddressSpecificExtendedCommunities(v) => {
                encode_ipv6_extended_communities(v)
            }
            AttributeValue::OriginatorId(v) => encode_originator_id(&IpAddr::from(*v)),
            AttributeValue::Clusters(v) => encode_clusters(v),
            AttributeValue::MpReachNlri(v) => {
                // Infer ADD-PATH from presence of path_id in any labeled prefix
                let add_path = v
                    .labeled_prefixes
                    .as_ref()
                    .is_some_and(|prefixes| prefixes.iter().any(|p| p.path_id.is_some()));
                encode_nlri(v, true, add_path).unwrap_or_else(|e| {
                    log::warn!("Failed to encode MP_REACH_NLRI: {}", e);
                    Bytes::new()
                })
            }
            AttributeValue::MpUnreachNlri(v) => {
                // Withdrawals don't use ADD-PATH encoding per RFC 8277
                encode_nlri(v, false, false).unwrap_or_else(|e| {
                    log::warn!("Failed to encode MP_UNREACH_NLRI: {}", e);
                    Bytes::new()
                })
            }
            AttributeValue::LinkState(v) => encode_link_state_attribute(v),
            AttributeValue::TunnelEncapsulation(v) => encode_tunnel_encapsulation_attribute(v),
            AttributeValue::Development(v) => Bytes::from(v.to_owned()),
            AttributeValue::Deprecated(v) => Bytes::from(v.bytes.to_owned()),
            AttributeValue::Unknown(v) => Bytes::from(v.bytes.to_owned()),
            AttributeValue::Aigp(_v) => {
                // AIGP encoding not yet implemented - return empty bytes
                Bytes::new()
            }
            AttributeValue::AttrSet(_v) => {
                // ATTR_SET encoding not yet implemented - return empty bytes
                Bytes::new()
            }
        };

        match self.is_extended() {
            false => {
                bytes.put_u8(value_bytes.len() as u8);
            }
            true => {
                bytes.put_u16(value_bytes.len() as u16);
            }
        }
        bytes.extend(value_bytes);
        bytes.freeze()
    }
}

impl Attributes {
    pub fn encode(&self, asn_len: AsnLength) -> Bytes {
        let mut bytes = BytesMut::new();
        for attr in &self.inner {
            bytes.extend(attr.encode(asn_len));
        }
        bytes.freeze()
    }
}

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

    #[test]
    fn test_unknwon_attribute_type() {
        let data = Bytes::from(vec![0x40, 0xFE, 0x00]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;
        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes);
        assert!(attributes.is_ok());
        let attributes = attributes.unwrap();
        assert_eq!(attributes.inner.len(), 1);
        assert_eq!(
            attributes.inner[0].value.attr_type(),
            AttrType::Unknown(254)
        );
    }

    #[test]
    fn test_rfc7606_attribute_flags_error() {
        // Create an ORIGIN attribute with wrong flags (should be transitive, not optional)
        let data = Bytes::from(vec![0x80, 0x01, 0x01, 0x00]); // Optional flag set incorrectly
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();

        // Should have validation warning for incorrect flags
        assert!(attributes.has_validation_warnings());
        let warnings = attributes.validation_warnings();
        // Will have attribute flags error + missing mandatory attributes
        assert!(!warnings.is_empty());

        match &warnings[0] {
            BgpValidationWarning::AttributeFlagsError { attr_type, .. } => {
                assert_eq!(*attr_type, AttrType::ORIGIN);
            }
            _ => panic!("Expected AttributeFlagsError warning"),
        }
    }

    #[test]
    fn test_rfc7606_missing_mandatory_attribute() {
        // Attributes with only LOCAL_PREF (missing ORIGIN, AS_PATH, NEXT_HOP)
        let data = Bytes::from(vec![
            0x40, 0x05, 0x04, 0x00, 0x00, 0x00, 0x64, // LOCAL_PREF = 100
        ]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let mut attributes =
            parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();
        // Manually trigger mandatory check as an announcement with standard NLRI
        attributes.check_mandatory_attributes(true, true);

        // Should have warnings for missing mandatory attributes
        assert!(attributes.has_validation_warnings());
        let warnings = attributes.validation_warnings();
        // LOCAL_PREF is not a withdrawal, so ORIGIN, AS_PATH, NEXT_HOP are required
        assert_eq!(warnings.len(), 3); // ORIGIN, AS_PATH, NEXT_HOP

        for warning in warnings {
            match warning {
                BgpValidationWarning::MissingWellKnownAttribute { attr_type } => {
                    assert!(matches!(
                        attr_type,
                        AttrType::ORIGIN | AttrType::AS_PATH | AttrType::NEXT_HOP
                    ));
                }
                _ => panic!("Expected MissingWellKnownAttribute warning"),
            }
        }
    }

    #[test]
    fn test_mp_reach_no_next_hop() {
        // Attributes with MP_REACH_NLRI (missing ORIGIN, AS_PATH)
        // MP_REACH_NLRI is type 14 (0x0E).
        // We just need a dummy MP_REACH_NLRI.
        let data = Bytes::from(vec![
            0x80, 0x0E, 0x06, 0x00, 0x01, 0x01, // AFI=1, SAFI=1
            0x00, // Next Hop Len = 0 (invalid for parsing, but enough to trigger logic)
            0x00, // Reserved
            0x00, // NLRI
        ]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let mut attributes =
            parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();
        // Manually trigger mandatory check as an announcement but NO standard NLRI (MP only)
        attributes.check_mandatory_attributes(true, false);

        // Should NOT have NEXT_HOP warning because MP_REACH_NLRI is present and has_standard_nlri is false
        let warnings = attributes.validation_warnings();
        let has_next_hop_warning = warnings.iter().any(|w| {
            matches!(
                w,
                BgpValidationWarning::MissingWellKnownAttribute {
                    attr_type: AttrType::NEXT_HOP
                }
            )
        });
        assert!(!has_next_hop_warning);
    }

    #[test]
    fn test_pure_withdrawal_no_warnings() {
        // Empty attributes - pure withdrawal
        let data = Bytes::from(vec![]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let mut attributes =
            parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();
        // Manually trigger mandatory check as a withdrawal
        attributes.check_mandatory_attributes(false, false);

        // Should have NO warnings
        assert!(!attributes.has_validation_warnings());

        // Attributes with only MP_UNREACH_NLRI - pure withdrawal
        let data = Bytes::from(vec![
            0x80, 0x0F, 0x03, 0x00, 0x01, 0x01, // AFI=1, SAFI=1
        ]);
        let mut attributes =
            parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();
        attributes.check_mandatory_attributes(false, false);
        assert!(!attributes.has_validation_warnings());
    }

    #[test]
    fn test_rfc7606_duplicate_attribute() {
        // Create two ORIGIN attributes
        let data = Bytes::from(vec![
            0x40, 0x01, 0x01, 0x00, // First ORIGIN attribute
            0x40, 0x01, 0x01, 0x01, // Second ORIGIN attribute (duplicate)
        ]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();

        // Should have warning for duplicate attribute
        assert!(attributes.has_validation_warnings());
        let warnings = attributes.validation_warnings();

        // Should have at least one duplicate attribute warning
        let has_duplicate_warning = warnings
            .iter()
            .any(|w| matches!(w, BgpValidationWarning::DuplicateAttribute { .. }));
        assert!(has_duplicate_warning);
    }

    #[test]
    fn test_attribute_type_boundaries() {
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        // Required attributes for valid BGP message
        const REQUIRED_ATTRS: &[u8] = &[
            0x40, 0x01, 0x01, 0x00, // origin
            0x40, 0x02, 0x00, // as_path
            0x40, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04, // next_hop
        ];

        // Test highest (development) attribute type
        let mut data = REQUIRED_ATTRS.to_vec();
        data.extend_from_slice(&[0x40, 0xFF, 0x01, 0x00]); // development
        let data = Bytes::from(data);

        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();

        assert!(attributes.has_attr(AttrType::DEVELOPMENT));
        assert!(!attributes.has_validation_warnings());

        // Test lowest (reserved) attribute type
        let mut data = REQUIRED_ATTRS.to_vec();
        data.extend_from_slice(&[0x40, 0x00, 0x01, 0x01]); // reserved
        let data = Bytes::from(data);

        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();

        // There is a validation warning about the reserved attribute
        assert!(attributes.validation_warnings.iter().any(|vw| {
            matches!(vw, BgpValidationWarning::OptionalAttributeError { attr_type, reason:_ } if *attr_type == AttrType::RESERVED)
        }));
    }

    #[test]
    fn test_rfc7606_attribute_length_error() {
        // Create an ORIGIN attribute with wrong length (should be 1 byte, not 2)
        let data = Bytes::from(vec![0x40, 0x01, 0x02, 0x00, 0x01]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        let attributes = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes).unwrap();

        // Should have warning for incorrect attribute length
        assert!(attributes.has_validation_warnings());
        let warnings = attributes.validation_warnings();

        let has_length_warning = warnings
            .iter()
            .any(|w| matches!(w, BgpValidationWarning::AttributeLengthError { .. }));
        assert!(has_length_warning);
    }

    #[test]
    fn test_rfc7606_no_session_reset() {
        // Test that parsing continues even with multiple errors
        let data = Bytes::from(vec![
            0x80, 0x01, 0x02, 0x00, 0x01, // Wrong flags and length for ORIGIN
            0x40, 0x01, 0x01, 0x00, // Duplicate ORIGIN
            0x40, 0xFF, 0x01, 0x00, // Unknown attribute
        ]);
        let asn_len = AsnLength::Bits16;
        let add_path = false;
        let afi = None;
        let safi = None;
        let prefixes = None;

        // Should not panic or return error - RFC 7606 requires continued parsing
        let result = parse_attributes(data, &asn_len, add_path, afi, safi, prefixes);
        assert!(result.is_ok());

        let attributes = result.unwrap();
        assert!(attributes.has_validation_warnings());

        // Should have multiple warnings but parsing should continue
        let warnings = attributes.validation_warnings();
        assert!(!warnings.is_empty());
    }
}