Method parseAttributes

Server/src/bgp/UpdateMsg.cpp:248–308

* Parses the BGP attributes in the update * * \details * Parses all attributes. Decoded values are updated in 'parsed_data' * * \param [in] data Pointer to the start of the prefixes to be parsed * \param [in] len Length of the data in bytes to be read * \param [out] parsed_data Reference to parsed_update_data; will be updated with all parsed data */

 * \param [out]  parsed_data    Reference to parsed_update_data; will be updated with all parsed data
 */
void UpdateMsg::parseAttributes(u_char *data, uint16_t len, parsed_update_data &parsed_data) {
    /*
     * Per RFC4271 Section 4.3, flat indicates if the length is 1 or 2 octets
     */
    u_char   attr_flags;
    u_char   attr_type;
    uint16_t attr_len;

    if (len == 0)
        return;

    else if (len < 3) {
        LOG_WARN("%s: rtr=%s: Cannot parse the attributes due to the data being too short, error in update message. len=%d",
                peer_addr.c_str(), router_addr.c_str(), len);
        return;
    }

    /*
     * Iterate through all attributes and parse them
     */
    for (int read_size=0;  read_size < len; read_size += 2) {
        attr_flags = *data++;
        attr_type = *data++;

        // Check if the length field is 1 or two bytes
        if (ATTR_FLAG_EXTENDED(attr_flags)) {
            SELF_DEBUG("%s: rtr=%s: extended length path attribute bit set for an entry", peer_addr.c_str(), router_addr.c_str());

            memcpy(&attr_len, data, 2); data += 2; read_size += 2;
            bgp::SWAP_BYTES(&attr_len);

        } else {
            attr_len = *data++;
            read_size++;
        }

        SELF_DEBUG("%s: rtr=%s: attribute type = %d len_sz = %d",
                peer_addr.c_str(), router_addr.c_str(), attr_type, attr_len);

        // Get the attribute data, if we have any; making sure to not overrun buffer
        if (attr_len > 0 and (read_size + attr_len) <= len ) {
            // Data pointer is currently at the data position of the attribute

            /*
             * Parse data based on attribute type
             */
            parseAttrData(attr_type, attr_len, data, parsed_data);
            data        += attr_len;
            read_size   += attr_len;

            SELF_DEBUG("%s: rtr=%s: parsed attr type=%d, size=%hu", peer_addr.c_str(), router_addr.c_str(),
                        attr_type, attr_len);

        } else if (attr_len) {
            LOG_NOTICE("%s: rtr=%s: Attribute data len of %hu is larger than available data in update message of %hu",
                    peer_addr.c_str(), router_addr.c_str(), attr_len, (len - read_size));
            return;
        }