/* Copyright (c) 2017 - 2020 LiteSpeed Technologies Inc.  See LICENSE. */
/*
 * lsquic_trans_params.h -- Transport parameters types and functions.
 */

#ifndef LSQUIC_TRANS_PARAMS_H
#define LSQUIC_TRANS_PARAMS_H 1

/* Transport parameters are grouped by the type of their values: numeric,
 * empty, and custom.
 *
 * The enum values are arbitrary.  The literal transport parameter ID
 * *values* (e.g. 0x1057 for loss bits) are not exposed by the API.
 */
enum transport_param_id
{
    /*
     * Numeric transport parameters that have default values:
     */
    TPI_MAX_IDLE_TIMEOUT,
    TPI_MAX_PACKET_SIZE,
    TPI_INIT_MAX_DATA,
    TPI_INIT_MAX_STREAM_DATA_BIDI_LOCAL,
    TPI_INIT_MAX_STREAM_DATA_BIDI_REMOTE,
    TPI_INIT_MAX_STREAM_DATA_UNI,
    TPI_INIT_MAX_STREAMS_BIDI,
    TPI_INIT_MAX_STREAMS_UNI,
    TPI_ACK_DELAY_EXPONENT,
    TPI_MAX_ACK_DELAY,
    TPI_ACTIVE_CONNECTION_ID_LIMIT,         MAX_NUM_WITH_DEF_TPI = TPI_ACTIVE_CONNECTION_ID_LIMIT,

    /*
     * Numeric transport parameters without default values:
     */
    TPI_MIN_ACK_DELAY,
    TPI_LOSS_BITS,                          MAX_NUMERIC_TPI = TPI_LOSS_BITS,

    /*
     * Empty transport parameters:
     */
    TPI_TIMESTAMPS,
    TPI_DISABLE_ACTIVE_MIGRATION,           MAX_EMPTY_TPI = TPI_DISABLE_ACTIVE_MIGRATION,

    /*
     * Custom handlers:
     */
    TPI_PREFERRED_ADDRESS,
    TPI_ORIGINAL_CONNECTION_ID,
#if LSQUIC_TEST_QUANTUM_READINESS
    /* https://github.com/quicwg/base-drafts/wiki/Quantum-Readiness-test */
#define QUANTUM_READY_SZ 1200
    TPI_QUANTUM_READINESS,
#endif
    TPI_STATELESS_RESET_TOKEN,              LAST_TPI = TPI_STATELESS_RESET_TOKEN
};


struct transport_params
{
    /* Which transport parameters values are set: */
    unsigned                tp_set;

    /* Which transport parameters were present (set by the decoder): */
    unsigned                tp_decoded;

    uint64_t                tp_numerics[MAX_NUMERIC_TPI + 1];

#define tp_init_max_stream_data_bidi_local  tp_numerics[TPI_INIT_MAX_STREAM_DATA_BIDI_LOCAL]
#define tp_init_max_stream_data_bidi_remote tp_numerics[TPI_INIT_MAX_STREAM_DATA_BIDI_REMOTE]
#define tp_init_max_stream_data_uni         tp_numerics[TPI_INIT_MAX_STREAM_DATA_UNI]
#define tp_init_max_data                    tp_numerics[TPI_INIT_MAX_DATA]
#define tp_max_idle_timeout                 tp_numerics[TPI_MAX_IDLE_TIMEOUT]
#define tp_init_max_streams_bidi            tp_numerics[TPI_INIT_MAX_STREAMS_BIDI]
#define tp_init_max_streams_uni             tp_numerics[TPI_INIT_MAX_STREAMS_UNI]
#define tp_max_packet_size                  tp_numerics[TPI_MAX_PACKET_SIZE]
#define tp_ack_delay_exponent               tp_numerics[TPI_ACK_DELAY_EXPONENT]
#define tp_max_ack_delay                    tp_numerics[TPI_MAX_ACK_DELAY]
#define tp_active_connection_id_limit       tp_numerics[TPI_ACTIVE_CONNECTION_ID_LIMIT]
#define tp_loss_bits                        tp_numerics[TPI_LOSS_BITS]

    uint8_t     tp_stateless_reset_token[IQUIC_SRESET_TOKEN_SZ];
    struct {
        uint8_t         ipv4_addr[4];
        uint16_t        ipv4_port;
        uint8_t         ipv6_addr[16];
        uint16_t        ipv6_port;
        lsquic_cid_t    cid;
        uint8_t         srst[IQUIC_SRESET_TOKEN_SZ];
    }           tp_preferred_address;
    lsquic_cid_t    tp_original_cid;
};

#define TP_DEF_MAX_PACKET_SIZE 65527
#define TP_DEF_ACK_DELAY_EXP 3
#define TP_DEF_INIT_MAX_STREAMS_UNI 0
#define TP_DEF_INIT_MAX_STREAMS_BIDI 0
#define TP_DEF_INIT_MAX_DATA 0
#define TP_DEF_DISABLE_ACTIVE_MIGRATION 0
#define TP_DEF_INIT_MAX_STREAM_DATA_BIDI_LOCAL 0
#define TP_DEF_INIT_MAX_STREAM_DATA_BIDI_REMOTE 0
#define TP_DEF_INIT_MAX_STREAM_DATA_UNI 0
#define TP_DEF_MAX_IDLE_TIMEOUT 0
#define TP_DEF_MAX_ACK_DELAY 25
#define TP_DEF_ACTIVE_CONNECTION_ID_LIMIT 2

/* [draft-ietf-quic-transport-18], Section 18.1 */
#define TP_MAX_MAX_ACK_DELAY ((1u << 14) - 1)

#define TP_DEFAULT_VALUES                                                             \
    .tp_set = ((1 << (MAX_NUM_WITH_DEF_TPI + 1)) - 1),                                \
    .tp_active_connection_id_limit        =  TP_DEF_ACTIVE_CONNECTION_ID_LIMIT,       \
    .tp_max_idle_timeout                  =  TP_DEF_MAX_IDLE_TIMEOUT,                 \
    .tp_max_ack_delay                     =  TP_DEF_MAX_ACK_DELAY,                    \
    .tp_max_packet_size                   =  TP_DEF_MAX_PACKET_SIZE,                  \
    .tp_ack_delay_exponent                =  TP_DEF_ACK_DELAY_EXP,                    \
    .tp_init_max_streams_bidi             =  TP_DEF_INIT_MAX_STREAMS_BIDI,            \
    .tp_init_max_streams_uni              =  TP_DEF_INIT_MAX_STREAMS_UNI,             \
    .tp_init_max_data                     =  TP_DEF_INIT_MAX_DATA,                    \
    .tp_init_max_stream_data_bidi_local   =  TP_DEF_INIT_MAX_STREAM_DATA_BIDI_LOCAL,  \
    .tp_init_max_stream_data_bidi_remote  =  TP_DEF_INIT_MAX_STREAM_DATA_BIDI_REMOTE, \
    .tp_init_max_stream_data_uni          =  TP_DEF_INIT_MAX_STREAM_DATA_UNI

#define TP_INITIALIZER() (struct transport_params) { TP_DEFAULT_VALUES }

int
lsquic_tp_encode (const struct transport_params *, int is_server,
                  unsigned char *buf, size_t bufsz);

int
lsquic_tp_decode (const unsigned char *buf, size_t bufsz,
    /* This argument specifies whose transport parameters we are parsing.  If
     * true, we are parsing parameters sent by the server; if false, we are
     * parsing parameteres sent by the client.
     */
                  int is_server,
                  struct transport_params *);

int
lsquic_tp_encode_id25 (const struct transport_params *, int is_server,
                  unsigned char *buf, size_t bufsz);

int
lsquic_tp_decode_id25 (const unsigned char *buf, size_t bufsz,
                  int is_server, struct transport_params *);

void
lsquic_tp_to_str (const struct transport_params *params, char *buf, size_t sz);

int
lsquic_tp_has_pref_ipv4 (const struct transport_params *);

int
lsquic_tp_has_pref_ipv6 (const struct transport_params *);

#endif