/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * This SCTP implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * Written or modified by:
 *   La Monte H.P. Yarroll <piggy@acm.org>
 *   Karl Knutson          <karl@athena.chicago.il.us>
 *   Randall Stewart       <randall@stewart.chicago.il.us>
 *   Ken Morneau           <kmorneau@cisco.com>
 *   Qiaobing Xie          <qxie1@motorola.com>
 *   Xingang Guo           <xingang.guo@intel.com>
 *   Sridhar Samudrala     <samudrala@us.ibm.com>
 *   Daisy Chang           <daisyc@us.ibm.com>
 */

#ifndef __sctp_constants_h__
#define __sctp_constants_h__

#include <linux/sctp.h>
#include <linux/ipv6.h> /* For ipv6hdr. */
#include <net/tcp_states.h>  /* For TCP states used in sctp_sock_state_t */

/* Value used for stream negotiation. */
enum { SCTP_MAX_STREAM = 0xffff };
enum { SCTP_DEFAULT_OUTSTREAMS = 10 };
enum { SCTP_DEFAULT_INSTREAMS = SCTP_MAX_STREAM };

/* Since CIDs are sparse, we need all four of the following
 * symbols.  CIDs are dense through SCTP_CID_BASE_MAX.
 */
#define SCTP_CID_BASE_MAX               SCTP_CID_SHUTDOWN_COMPLETE

#define SCTP_NUM_BASE_CHUNK_TYPES       (SCTP_CID_BASE_MAX + 1)

#define SCTP_NUM_ADDIP_CHUNK_TYPES      2

#define SCTP_NUM_PRSCTP_CHUNK_TYPES     1

#define SCTP_NUM_AUTH_CHUNK_TYPES       1

#define SCTP_NUM_CHUNK_TYPES            (SCTP_NUM_BASE_CHUNK_TYPES + \
                                         SCTP_NUM_ADDIP_CHUNK_TYPES +\
                                         SCTP_NUM_PRSCTP_CHUNK_TYPES +\
                                         SCTP_NUM_AUTH_CHUNK_TYPES)

/* These are the different flavours of event.  */
typedef enum {

        SCTP_EVENT_T_CHUNK = 1,
        SCTP_EVENT_T_TIMEOUT,
        SCTP_EVENT_T_OTHER,
        SCTP_EVENT_T_PRIMITIVE

} sctp_event_t;

/* As a convenience for the state machine, we append SCTP_EVENT_* and
 * SCTP_ULP_* to the list of possible chunks.
 */

typedef enum {
        SCTP_EVENT_TIMEOUT_NONE = 0,
        SCTP_EVENT_TIMEOUT_T1_COOKIE,
        SCTP_EVENT_TIMEOUT_T1_INIT,
        SCTP_EVENT_TIMEOUT_T2_SHUTDOWN,
        SCTP_EVENT_TIMEOUT_T3_RTX,
        SCTP_EVENT_TIMEOUT_T4_RTO,
        SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD,
        SCTP_EVENT_TIMEOUT_HEARTBEAT,
        SCTP_EVENT_TIMEOUT_SACK,
        SCTP_EVENT_TIMEOUT_AUTOCLOSE,
} sctp_event_timeout_t;

#define SCTP_EVENT_TIMEOUT_MAX          SCTP_EVENT_TIMEOUT_AUTOCLOSE
#define SCTP_NUM_TIMEOUT_TYPES          (SCTP_EVENT_TIMEOUT_MAX + 1)

typedef enum {
        SCTP_EVENT_NO_PENDING_TSN = 0,
        SCTP_EVENT_ICMP_PROTO_UNREACH,
} sctp_event_other_t;

#define SCTP_EVENT_OTHER_MAX            SCTP_EVENT_ICMP_PROTO_UNREACH
#define SCTP_NUM_OTHER_TYPES            (SCTP_EVENT_OTHER_MAX + 1)

/* These are primitive requests from the ULP.  */
typedef enum {
        SCTP_PRIMITIVE_ASSOCIATE = 0,
        SCTP_PRIMITIVE_SHUTDOWN,
        SCTP_PRIMITIVE_ABORT,
        SCTP_PRIMITIVE_SEND,
        SCTP_PRIMITIVE_REQUESTHEARTBEAT,
        SCTP_PRIMITIVE_ASCONF,
} sctp_event_primitive_t;

#define SCTP_EVENT_PRIMITIVE_MAX        SCTP_PRIMITIVE_ASCONF
#define SCTP_NUM_PRIMITIVE_TYPES        (SCTP_EVENT_PRIMITIVE_MAX + 1)

/* We define here a utility type for manipulating subtypes.
 * The subtype constructors all work like this:
 *
 *      sctp_subtype_t foo = SCTP_ST_CHUNK(SCTP_CID_INIT);
 */

typedef union {
        sctp_cid_t chunk;
        sctp_event_timeout_t timeout;
        sctp_event_other_t other;
        sctp_event_primitive_t primitive;
} sctp_subtype_t;

#define SCTP_SUBTYPE_CONSTRUCTOR(_name, _type, _elt) \
static inline sctp_subtype_t    \
SCTP_ST_## _name (_type _arg)           \
{ sctp_subtype_t _retval; _retval._elt = _arg; return _retval; }

SCTP_SUBTYPE_CONSTRUCTOR(CHUNK,         sctp_cid_t,             chunk)
SCTP_SUBTYPE_CONSTRUCTOR(TIMEOUT,       sctp_event_timeout_t,   timeout)
SCTP_SUBTYPE_CONSTRUCTOR(OTHER,         sctp_event_other_t,     other)
SCTP_SUBTYPE_CONSTRUCTOR(PRIMITIVE,     sctp_event_primitive_t, primitive)


#define sctp_chunk_is_data(a) (a->chunk_hdr->type == SCTP_CID_DATA)

/* Calculate the actual data size in a data chunk */
#define SCTP_DATA_SNDSIZE(c) ((int)((unsigned long)(c->chunk_end)\
                                - (unsigned long)(c->chunk_hdr)\
                                - sizeof(sctp_data_chunk_t)))

/* Internal error codes */
typedef enum {

        SCTP_IERROR_NO_ERROR            = 0,
        SCTP_IERROR_BASE                = 1000,
        SCTP_IERROR_NO_COOKIE,
        SCTP_IERROR_BAD_SIG,
        SCTP_IERROR_STALE_COOKIE,
        SCTP_IERROR_NOMEM,
        SCTP_IERROR_MALFORMED,
        SCTP_IERROR_BAD_TAG,
        SCTP_IERROR_BIG_GAP,
        SCTP_IERROR_DUP_TSN,
        SCTP_IERROR_HIGH_TSN,
        SCTP_IERROR_IGNORE_TSN,
        SCTP_IERROR_NO_DATA,
        SCTP_IERROR_BAD_STREAM,
        SCTP_IERROR_BAD_PORTS,
        SCTP_IERROR_AUTH_BAD_HMAC,
        SCTP_IERROR_AUTH_BAD_KEYID,
        SCTP_IERROR_PROTO_VIOLATION,
        SCTP_IERROR_ERROR,
        SCTP_IERROR_ABORT,
} sctp_ierror_t;



/* SCTP state defines for internal state machine */
typedef enum {

        SCTP_STATE_CLOSED               = 0,
        SCTP_STATE_COOKIE_WAIT          = 1,
        SCTP_STATE_COOKIE_ECHOED        = 2,
        SCTP_STATE_ESTABLISHED          = 3,
        SCTP_STATE_SHUTDOWN_PENDING     = 4,
        SCTP_STATE_SHUTDOWN_SENT        = 5,
        SCTP_STATE_SHUTDOWN_RECEIVED    = 6,
        SCTP_STATE_SHUTDOWN_ACK_SENT    = 7,

} sctp_state_t;

#define SCTP_STATE_MAX                  SCTP_STATE_SHUTDOWN_ACK_SENT
#define SCTP_STATE_NUM_STATES           (SCTP_STATE_MAX + 1)

/* These are values for sk->state.
 * For a UDP-style SCTP socket, the states are defined as follows
 * - A socket in SCTP_SS_CLOSED state indicates that it is not willing to
 *   accept new associations, but it can initiate the creation of new ones.
 * - A socket in SCTP_SS_LISTENING state indicates that it is willing to
 *   accept new  associations and can initiate the creation of new ones.
 * - A socket in SCTP_SS_ESTABLISHED state indicates that it is a peeled off
 *   socket with one association.
 * For a TCP-style SCTP socket, the states are defined as follows
 * - A socket in SCTP_SS_CLOSED state indicates that it is not willing to
 *   accept new associations, but it can initiate the creation of new ones.
 * - A socket in SCTP_SS_LISTENING state indicates that it is willing to
 *   accept new associations, but cannot initiate the creation of new ones.
 * - A socket in SCTP_SS_ESTABLISHED state indicates that it has a single 
 *   association.
 */
typedef enum {
        SCTP_SS_CLOSED         = TCP_CLOSE,
        SCTP_SS_LISTENING      = TCP_LISTEN,
        SCTP_SS_ESTABLISHING   = TCP_SYN_SENT,
        SCTP_SS_ESTABLISHED    = TCP_ESTABLISHED,
        SCTP_SS_CLOSING        = TCP_CLOSING,
} sctp_sock_state_t;

/* These functions map various type to printable names.  */
const char *sctp_cname(const sctp_subtype_t);   /* chunk types */
const char *sctp_oname(const sctp_subtype_t);   /* other events */
const char *sctp_tname(const sctp_subtype_t);   /* timeouts */
const char *sctp_pname(const sctp_subtype_t);   /* primitives */

/* This is a table of printable names of sctp_state_t's.  */
extern const char *const sctp_state_tbl[];
extern const char *const sctp_evttype_tbl[];
extern const char *const sctp_status_tbl[];

/* Maximum chunk length considering padding requirements. */
enum { SCTP_MAX_CHUNK_LEN = ((1<<16) - sizeof(__u32)) };

/* Encourage Cookie-Echo bundling by pre-fragmenting chunks a little
 * harder (until reaching ESTABLISHED state).
 */
enum { SCTP_ARBITRARY_COOKIE_ECHO_LEN = 200 };

/* Guess at how big to make the TSN mapping array.
 * We guarantee that we can handle at least this big a gap between the
 * cumulative ACK and the highest TSN.  In practice, we can often
 * handle up to twice this value.
 *
 * NEVER make this more than 32767 (2^15-1).  The Gap Ack Blocks in a
 * SACK (see  section 3.3.4) are only 16 bits, so 2*SCTP_TSN_MAP_SIZE
 * must be less than 65535 (2^16 - 1), or we will have overflow
 * problems creating SACK's.
 */
#define SCTP_TSN_MAP_INITIAL BITS_PER_LONG
#define SCTP_TSN_MAP_INCREMENT SCTP_TSN_MAP_INITIAL
#define SCTP_TSN_MAP_SIZE 4096

/* We will not record more than this many duplicate TSNs between two
 * SACKs.  The minimum PMTU is 576.  Remove all the headers and there
 * is enough room for 131 duplicate reports.  Round down to the
 * nearest power of 2.
 */
enum { SCTP_MIN_PMTU = 576 };
enum { SCTP_MAX_DUP_TSNS = 16 };
enum { SCTP_MAX_GABS = 16 };

/* Heartbeat interval - 30 secs */
#define SCTP_DEFAULT_TIMEOUT_HEARTBEAT  (30*1000)

/* Delayed sack timer - 200ms */
#define SCTP_DEFAULT_TIMEOUT_SACK       (200)

/* RTO.Initial              - 3  seconds
 * RTO.Min                  - 1  second
 * RTO.Max                  - 60 seconds
 * RTO.Alpha                - 1/8
 * RTO.Beta                 - 1/4
 */
#define SCTP_RTO_INITIAL        (3 * 1000)
#define SCTP_RTO_MIN            (1 * 1000)
#define SCTP_RTO_MAX            (60 * 1000)

#define SCTP_RTO_ALPHA          3   /* 1/8 when converted to right shifts. */
#define SCTP_RTO_BETA           2   /* 1/4 when converted to right shifts. */

/* Maximum number of new data packets that can be sent in a burst.  */
#define SCTP_DEFAULT_MAX_BURST          4

#define SCTP_CLOCK_GRANULARITY  1       /* 1 jiffy */

#define SCTP_DEFAULT_COOKIE_LIFE        (60 * 1000) /* 60 seconds */

#define SCTP_DEFAULT_MINWINDOW  1500    /* default minimum rwnd size */
#define SCTP_DEFAULT_MAXWINDOW  65535   /* default rwnd size */
#define SCTP_DEFAULT_RWND_SHIFT  4      /* by default, update on 1/16 of
                                         * rcvbuf, which is 1/8 of initial
                                         * window
                                         */
#define SCTP_DEFAULT_MAXSEGMENT 1500    /* MTU size, this is the limit
                                         * to which we will raise the P-MTU.
                                         */
#define SCTP_DEFAULT_MINSEGMENT 512     /* MTU size ... if no mtu disc */

#define SCTP_SECRET_SIZE 32             /* Number of octets in a 256 bits. */

#define SCTP_SIGNATURE_SIZE 20          /* size of a SLA-1 signature */

#define SCTP_COOKIE_MULTIPLE 32 /* Pad out our cookie to make our hash
                                 * functions simpler to write.
                                 */

/* These return values describe the success or failure of a number of
 * routines which form the lower interface to SCTP_outqueue.
 */
typedef enum {
        SCTP_XMIT_OK,
        SCTP_XMIT_PMTU_FULL,
        SCTP_XMIT_RWND_FULL,
        SCTP_XMIT_DELAY,
} sctp_xmit_t;

/* These are the commands for manipulating transports.  */
typedef enum {
        SCTP_TRANSPORT_UP,
        SCTP_TRANSPORT_DOWN,
        SCTP_TRANSPORT_PF,
} sctp_transport_cmd_t;

/* These are the address scopes defined mainly for IPv4 addresses
 * based on draft of SCTP IPv4 scoping <draft-stewart-tsvwg-sctp-ipv4-00.txt>.
 * These scopes are hopefully generic enough to be used on scoping both
 * IPv4 and IPv6 addresses in SCTP.
 * At this point, the IPv6 scopes will be mapped to these internal scopes
 * as much as possible.
 */
typedef enum {
        SCTP_SCOPE_GLOBAL,              /* IPv4 global addresses */
        SCTP_SCOPE_PRIVATE,             /* IPv4 private addresses */
        SCTP_SCOPE_LINK,                /* IPv4 link local address */
        SCTP_SCOPE_LOOPBACK,            /* IPv4 loopback address */
        SCTP_SCOPE_UNUSABLE,            /* IPv4 unusable addresses */
} sctp_scope_t;

typedef enum {
        SCTP_SCOPE_POLICY_DISABLE,      /* Disable IPv4 address scoping */
        SCTP_SCOPE_POLICY_ENABLE,       /* Enable IPv4 address scoping */
        SCTP_SCOPE_POLICY_PRIVATE,      /* Follow draft but allow IPv4 private addresses */
        SCTP_SCOPE_POLICY_LINK,         /* Follow draft but allow IPv4 link local addresses */
} sctp_scope_policy_t;

/* Based on IPv4 scoping <draft-stewart-tsvwg-sctp-ipv4-00.txt>,
 * SCTP IPv4 unusable addresses: 0.0.0.0/8, 224.0.0.0/4, 198.18.0.0/24,
 * 192.88.99.0/24.
 * Also, RFC 8.4, non-unicast addresses are not considered valid SCTP
 * addresses.
 */
#define IS_IPV4_UNUSABLE_ADDRESS(a)         \
        ((htonl(INADDR_BROADCAST) == a) ||  \
         ipv4_is_multicast(a) ||            \
         ipv4_is_zeronet(a) ||              \
         ipv4_is_test_198(a) ||             \
         ipv4_is_anycast_6to4(a))

/* Flags used for the bind address copy functions.  */
#define SCTP_ADDR6_ALLOWED      0x00000001      /* IPv6 address is allowed by
                                                   local sock family */
#define SCTP_ADDR4_PEERSUPP     0x00000002      /* IPv4 address is supported by
                                                   peer */
#define SCTP_ADDR6_PEERSUPP     0x00000004      /* IPv6 address is supported by
                                                   peer */

/* Reasons to retransmit. */
typedef enum {
        SCTP_RTXR_T3_RTX,
        SCTP_RTXR_FAST_RTX,
        SCTP_RTXR_PMTUD,
        SCTP_RTXR_T1_RTX,
} sctp_retransmit_reason_t;

/* Reasons to lower cwnd. */
typedef enum {
        SCTP_LOWER_CWND_T3_RTX,
        SCTP_LOWER_CWND_FAST_RTX,
        SCTP_LOWER_CWND_ECNE,
        SCTP_LOWER_CWND_INACTIVE,
} sctp_lower_cwnd_t;


/* SCTP-AUTH Necessary constants */

/* SCTP-AUTH, Section 3.3
 *
 *  The following Table 2 shows the currently defined values for HMAC
 *  identifiers.
 *
 *  +-----------------+--------------------------+
 *  | HMAC Identifier | Message Digest Algorithm |
 *  +-----------------+--------------------------+
 *  | 0               | Reserved                 |
 *  | 1               | SHA-1 defined in [8]     |
 *  | 2               | Reserved                 |
 *  | 3               | SHA-256 defined in [8]   |
 *  +-----------------+--------------------------+
 */
enum {
        SCTP_AUTH_HMAC_ID_RESERVED_0,
        SCTP_AUTH_HMAC_ID_SHA1,
        SCTP_AUTH_HMAC_ID_RESERVED_2,
#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
        SCTP_AUTH_HMAC_ID_SHA256,
#endif
        __SCTP_AUTH_HMAC_MAX
};

#define SCTP_AUTH_HMAC_ID_MAX   __SCTP_AUTH_HMAC_MAX - 1
#define SCTP_AUTH_NUM_HMACS     __SCTP_AUTH_HMAC_MAX
#define SCTP_SHA1_SIG_SIZE 20
#define SCTP_SHA256_SIG_SIZE 32

/*  SCTP-AUTH, Section 3.2
 *     The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH chunks
 *     MUST NOT be listed in the CHUNKS parameter
 */
#define SCTP_NUM_NOAUTH_CHUNKS  4
#define SCTP_AUTH_MAX_CHUNKS    (SCTP_NUM_CHUNK_TYPES - SCTP_NUM_NOAUTH_CHUNKS)

/* SCTP-AUTH Section 6.1
 * The RANDOM parameter MUST contain a 32 byte random number.
 */
#define SCTP_AUTH_RANDOM_LENGTH 32

#endif /* __sctp_constants_h__ */