Method parseBgpHeader

Server/src/bgp/parseBGP.cpp:288–340

* Parses the BGP common header * * \details * This method will parse the bgp common header and will upload the global * c_hdr structure, instance data pointer, and remaining bytes of message. * The return value of this method will be the BGP message type. * * \param [in] data Pointer to the raw BGP message header * \param [in] size length of t

 * \returns BGP message type
 */
u_char parseBGP::parseBgpHeader(u_char *data, size_t size) {
    bzero(&common_hdr, sizeof(common_hdr));

    /*
     * Error out if data size is not large enough for common header
     */
    if (size < BGP_MSG_HDR_LEN) {
        LOG_WARN("%s: rtr=%s: BGP message is being parsed is %d but expected at least %d in size",
                p_entry->peer_addr, router_addr.c_str(), size, BGP_MSG_HDR_LEN);
        return 0;
    }

    memcpy(&common_hdr, data, BGP_MSG_HDR_LEN);

    // Change length to host byte order
    bgp::SWAP_BYTES(&common_hdr.len);

    // Update remaining bytes left of the message
    data_bytes_remaining = common_hdr.len - BGP_MSG_HDR_LEN;

    /*
     * Error out if the remaining size of the BGP message is grater than passed bgp message buffer
     *      It is expected that the passed bgp message buffer holds the complete BGP message to be parsed
     */
    if (common_hdr.len > size) {
        LOG_WARN("%s: rtr=%s: BGP message size of %hu is greater than passed data buffer, cannot parse the BGP message",
                p_entry->peer_addr, router_addr.c_str(), common_hdr.len, size);
    }

    SELF_DEBUG("%s: rtr=%s: BGP hdr len = %u, type = %d", p_entry->peer_addr, router_addr.c_str(), common_hdr.len, common_hdr.type);

    /*
     * Validate the message type as being allowed/accepted
     */
    switch (common_hdr.type) {
        case BGP_MSG_UPDATE         : // Update Message
        case BGP_MSG_NOTIFICATION   : // Notification message
        case BGP_MSG_OPEN           : // OPEN message
            // Message(s) are allowed - calling method will request further parsing of the bgp message type
            break;

        case BGP_MSG_ROUTE_REFRESH: // Route Refresh message
            LOG_NOTICE("%s: rtr=%s: Received route refresh, nothing to do with this message currently.",
                        p_entry->peer_addr, router_addr.c_str());
            break;

        default :
            SELF_DEBUG("%s: rtr=%s: Unsupported BGP message type = %d", p_entry->peer_addr, router_addr.c_str(), common_hdr.type);
            break;
    }

    return common_hdr.type;
}

/**
 * Update the Database with the parsed updated data