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/* Copyright (c) 2010 People Power Co.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
* - Neither the name of the People Power Corporation nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* PEOPLE POWER CO. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE
*
*/
/** Operations that should be supported for each option that can be
* configured through an LCP-style automaton negotiation.
*
* @note We currently do not support options that can appear multiple
* times in a single request.
*
* @author Peter A. Bigot <pab@peoplepowerco.com> */
interface PppProtocolOption {
/** Return the option type code for this option within its protocol.
*
* This is primarily used to detect unrecognized options: a default
* implementation is defined that returns option 0, which is an
* illegal option value. Upon detection of this situation, the
* configuration processing implementation will generate a
* Configure-Reject message. */
command uint8_t getType ();
/** Return TRUE iff the option should be added to outgoing
* Configure-Request messages.
*
* If the option is negotiable, appendRequest will invoked to append
* the proposed local value to the outgoing request message.
*
* @note Negotiability of remote values for options is indicated by
* the return value of considerRequest. */
command bool isNegotiable ();
/** Set whether the local value of the option should be negotiated,
* based on protocol activity.
*
* Option negotiation is set to FALSE upon receipt of a
* Configure-Reject message identifying the option, and upon a
* Reject return from considerRequest. It is set to TRUE upon
* receipt of a non-Reject return from considerRequest. */
command void setNegotiable (bool is_negotiable);
/** Determine whether the proposed remote value is acceptable to the
* protocol.
* @return PppControlProtocolCode_Configure{Ack,Nak,Reject},
* depending on whether the option value specified at dp is
* acceptable to this end of the link. */
command uint8_t considerRequest (const uint8_t* dp,
const uint8_t* dpe);
/** Add a proposed local value to a message. The option type and
* length fields are already incorporated; only the data portion is
* to be stored. */
command uint8_t* appendRequest (uint8_t* dp,
const uint8_t* dpe);
/** Add an alternative suggestion to a Nak message. The option type
* and length fields are already reserved; only the data portion is
* to be stored.
*
* If the option cannot express an acceptable alternative within the
* buffer indicated by dp to dpe, the command should return a null
* pointer. Otherwise, the command should return a pointer just
* past the last octet of its proposed alternative.
*
* @param sp The value in the Configure-Request message, in case
* that's useful when proposing an alternative
*
* @param spe Indidates the end of the requested option value
*
* @param dp Where the proposed alternative should be stored
*
* @param dpe The limit up to which the proposed alternative may be
* written. */
command uint8_t* appendNakValue (const uint8_t* sp,
const uint8_t* spe,
uint8_t* dp,
const uint8_t* dpe);
/** Completely reset the option prior to a new negotiation sequence.
*
* This brings things back to their power-up default, and is
* executed when the link goes down. It re-enables options for
* negotiation, and restores default proposed local and remote
* values. */
command void reset ();
/** Set (reset) the option's local value.
*
* The set operation is invoked on each option present in a received
* Configure-Ack message (i.e., this node requested the value). The
* reset operation is invoked prior to transmission of a
* Configure-Request (need permission for value).
*
* @param dp Start of the option value. If passed as a null
* pointer, option is reset to its default.
*
* @param dpe First octet past option value. */
command void setLocal (const uint8_t* dp,
const uint8_t* dpe);
/** Process a proposed alternative local value.
*
* This operation is invoked when the remote sends a Configure-Nak
* in response to local's Configure-Request. Generally, the
* response should be to replace the original local value with the
* value proposed by the peer, or to mark the option non-negotiable.
*
* @param dp Start of the option value.
*
* @param dpe First octet past option value. */
command void processNakValue (const uint8_t* dp,
const uint8_t* dpe);
/** Set (reset) the option's remote value.
*
* The set operation is invoked on each option present in a
* transmitted Configure-Ack message (i.e., the remote node
* requested the value). This is done after transmission. The
* reset operation is invoked upon receipt of a Configure-Request.
*
* @param dp Start of the option value. If passed as a null
* pointer, option is reset to its default.
*
* @param dpe First octet past option value. */
command void setRemote (const uint8_t* dp,
const uint8_t* dpe);
}
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