/* 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
 *
 * These are definitions needed by the state machine.
 *
 * 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 addresses:
 *    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>
 *    Xingang Guo <xingang.guo@intel.com>
 *    Jon Grimm <jgrimm@us.ibm.com>
 *    Dajiang Zhang <dajiang.zhang@nokia.com>
 *    Sridhar Samudrala <sri@us.ibm.com>
 *    Daisy Chang <daisyc@us.ibm.com>
 *    Ardelle Fan <ardelle.fan@intel.com>
 *    Kevin Gao <kevin.gao@intel.com>
 */

#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <net/sctp/command.h>
#include <net/sctp/sctp.h>

#ifndef __sctp_sm_h__
#define __sctp_sm_h__

/*
 * Possible values for the disposition are:
 */
typedef enum {
        SCTP_DISPOSITION_DISCARD,        /* No further processing.  */
        SCTP_DISPOSITION_CONSUME,        /* Process return values normally.  */
        SCTP_DISPOSITION_NOMEM,          /* We ran out of memory--recover.  */
        SCTP_DISPOSITION_DELETE_TCB,     /* Close the association.  */
        SCTP_DISPOSITION_ABORT,          /* Close the association NOW.  */
        SCTP_DISPOSITION_VIOLATION,      /* The peer is misbehaving.  */
        SCTP_DISPOSITION_NOT_IMPL,       /* This entry is not implemented.  */
        SCTP_DISPOSITION_ERROR,          /* This is plain old user error.  */
        SCTP_DISPOSITION_BUG,            /* This is a bug.  */
} sctp_disposition_t;

typedef struct {
        int name;
        int action;
} sctp_sm_command_t;

typedef sctp_disposition_t (sctp_state_fn_t) (struct net *,
                                              const struct sctp_endpoint *,
                                              const struct sctp_association *,
                                              const sctp_subtype_t type,
                                              void *arg,
                                              sctp_cmd_seq_t *);
typedef void (sctp_timer_event_t) (unsigned long);
typedef struct {
        sctp_state_fn_t *fn;
        const char *name;
} sctp_sm_table_entry_t;

/* A naming convention of "sctp_sf_xxx" applies to all the state functions
 * currently in use.
 */

/* Prototypes for generic state functions. */
sctp_state_fn_t sctp_sf_not_impl;
sctp_state_fn_t sctp_sf_bug;

/* Prototypes for gener timer state functions. */
sctp_state_fn_t sctp_sf_timer_ignore;

/* Prototypes for chunk state functions. */
sctp_state_fn_t sctp_sf_do_9_1_abort;
sctp_state_fn_t sctp_sf_cookie_wait_abort;
sctp_state_fn_t sctp_sf_cookie_echoed_abort;
sctp_state_fn_t sctp_sf_shutdown_pending_abort;
sctp_state_fn_t sctp_sf_shutdown_sent_abort;
sctp_state_fn_t sctp_sf_shutdown_ack_sent_abort;
sctp_state_fn_t sctp_sf_do_5_1B_init;
sctp_state_fn_t sctp_sf_do_5_1C_ack;
sctp_state_fn_t sctp_sf_do_5_1D_ce;
sctp_state_fn_t sctp_sf_do_5_1E_ca;
sctp_state_fn_t sctp_sf_do_4_C;
sctp_state_fn_t sctp_sf_eat_data_6_2;
sctp_state_fn_t sctp_sf_eat_data_fast_4_4;
sctp_state_fn_t sctp_sf_eat_sack_6_2;
sctp_state_fn_t sctp_sf_operr_notify;
sctp_state_fn_t sctp_sf_t1_init_timer_expire;
sctp_state_fn_t sctp_sf_t1_cookie_timer_expire;
sctp_state_fn_t sctp_sf_t2_timer_expire;
sctp_state_fn_t sctp_sf_t4_timer_expire;
sctp_state_fn_t sctp_sf_t5_timer_expire;
sctp_state_fn_t sctp_sf_sendbeat_8_3;
sctp_state_fn_t sctp_sf_beat_8_3;
sctp_state_fn_t sctp_sf_backbeat_8_3;
sctp_state_fn_t sctp_sf_do_9_2_final;
sctp_state_fn_t sctp_sf_do_9_2_shutdown;
sctp_state_fn_t sctp_sf_do_9_2_shut_ctsn;
sctp_state_fn_t sctp_sf_do_ecn_cwr;
sctp_state_fn_t sctp_sf_do_ecne;
sctp_state_fn_t sctp_sf_ootb;
sctp_state_fn_t sctp_sf_pdiscard;
sctp_state_fn_t sctp_sf_violation;
sctp_state_fn_t sctp_sf_discard_chunk;
sctp_state_fn_t sctp_sf_do_5_2_1_siminit;
sctp_state_fn_t sctp_sf_do_5_2_2_dupinit;
sctp_state_fn_t sctp_sf_do_5_2_3_initack;
sctp_state_fn_t sctp_sf_do_5_2_4_dupcook;
sctp_state_fn_t sctp_sf_unk_chunk;
sctp_state_fn_t sctp_sf_do_8_5_1_E_sa;
sctp_state_fn_t sctp_sf_cookie_echoed_err;
sctp_state_fn_t sctp_sf_do_asconf;
sctp_state_fn_t sctp_sf_do_asconf_ack;
sctp_state_fn_t sctp_sf_do_9_2_reshutack;
sctp_state_fn_t sctp_sf_eat_fwd_tsn;
sctp_state_fn_t sctp_sf_eat_fwd_tsn_fast;
sctp_state_fn_t sctp_sf_eat_auth;

/* Prototypes for primitive event state functions.  */
sctp_state_fn_t sctp_sf_do_prm_asoc;
sctp_state_fn_t sctp_sf_do_prm_send;
sctp_state_fn_t sctp_sf_do_9_2_prm_shutdown;
sctp_state_fn_t sctp_sf_cookie_wait_prm_shutdown;
sctp_state_fn_t sctp_sf_cookie_echoed_prm_shutdown;
sctp_state_fn_t sctp_sf_do_9_1_prm_abort;
sctp_state_fn_t sctp_sf_cookie_wait_prm_abort;
sctp_state_fn_t sctp_sf_cookie_echoed_prm_abort;
sctp_state_fn_t sctp_sf_shutdown_pending_prm_abort;
sctp_state_fn_t sctp_sf_shutdown_sent_prm_abort;
sctp_state_fn_t sctp_sf_shutdown_ack_sent_prm_abort;
sctp_state_fn_t sctp_sf_error_closed;
sctp_state_fn_t sctp_sf_error_shutdown;
sctp_state_fn_t sctp_sf_ignore_primitive;
sctp_state_fn_t sctp_sf_do_prm_requestheartbeat;
sctp_state_fn_t sctp_sf_do_prm_asconf;

/* Prototypes for other event state functions.  */
sctp_state_fn_t sctp_sf_do_no_pending_tsn;
sctp_state_fn_t sctp_sf_do_9_2_start_shutdown;
sctp_state_fn_t sctp_sf_do_9_2_shutdown_ack;
sctp_state_fn_t sctp_sf_ignore_other;
sctp_state_fn_t sctp_sf_cookie_wait_icmp_abort;

/* Prototypes for timeout event state functions.  */
sctp_state_fn_t sctp_sf_do_6_3_3_rtx;
sctp_state_fn_t sctp_sf_do_6_2_sack;
sctp_state_fn_t sctp_sf_autoclose_timer_expire;

/* Prototypes for utility support functions.  */
__u8 sctp_get_chunk_type(struct sctp_chunk *chunk);
const sctp_sm_table_entry_t *sctp_sm_lookup_event(struct net *,
                                            sctp_event_t,
                                            sctp_state_t,
                                            sctp_subtype_t);
int sctp_chunk_iif(const struct sctp_chunk *);
struct sctp_association *sctp_make_temp_asoc(const struct sctp_endpoint *,
                                             struct sctp_chunk *,
                                             gfp_t gfp);
__u32 sctp_generate_verification_tag(void);
void sctp_populate_tie_tags(__u8 *cookie, __u32 curTag, __u32 hisTag);

/* Prototypes for chunk-building functions.  */
struct sctp_chunk *sctp_make_init(const struct sctp_association *,
                             const struct sctp_bind_addr *,
                             gfp_t gfp, int vparam_len);
struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *,
                                 const struct sctp_chunk *,
                                 const gfp_t gfp,
                                 const int unkparam_len);
struct sctp_chunk *sctp_make_cookie_echo(const struct sctp_association *,
                                    const struct sctp_chunk *);
struct sctp_chunk *sctp_make_cookie_ack(const struct sctp_association *,
                                   const struct sctp_chunk *);
struct sctp_chunk *sctp_make_cwr(const struct sctp_association *,
                                 const __u32 lowest_tsn,
                                 const struct sctp_chunk *);
struct sctp_chunk * sctp_make_datafrag_empty(struct sctp_association *,
                                        const struct sctp_sndrcvinfo *sinfo,
                                        int len, const __u8 flags,
                                        __u16 ssn);
struct sctp_chunk *sctp_make_ecne(const struct sctp_association *,
                                  const __u32);
struct sctp_chunk *sctp_make_sack(const struct sctp_association *);
struct sctp_chunk *sctp_make_shutdown(const struct sctp_association *asoc,
                                      const struct sctp_chunk *chunk);
struct sctp_chunk *sctp_make_shutdown_ack(const struct sctp_association *asoc,
                                          const struct sctp_chunk *);
struct sctp_chunk *sctp_make_shutdown_complete(const struct sctp_association *,
                                          const struct sctp_chunk *);
void sctp_init_cause(struct sctp_chunk *, __be16 cause, size_t);
struct sctp_chunk *sctp_make_abort(const struct sctp_association *,
                              const struct sctp_chunk *,
                              const size_t hint);
struct sctp_chunk *sctp_make_abort_no_data(const struct sctp_association *,
                                      const struct sctp_chunk *,
                                      __u32 tsn);
struct sctp_chunk *sctp_make_abort_user(const struct sctp_association *,
                                        struct msghdr *, size_t msg_len);
struct sctp_chunk *sctp_make_abort_violation(const struct sctp_association *,
                                   const struct sctp_chunk *,
                                   const __u8 *,
                                   const size_t );
struct sctp_chunk *sctp_make_violation_paramlen(const struct sctp_association *,
                                   const struct sctp_chunk *,
                                   struct sctp_paramhdr *);
struct sctp_chunk *sctp_make_violation_max_retrans(const struct sctp_association *,
                                                   const struct sctp_chunk *);
struct sctp_chunk *sctp_make_heartbeat(const struct sctp_association *,
                                  const struct sctp_transport *);
struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *,
                                      const struct sctp_chunk *,
                                      const void *payload,
                                      const size_t paylen);
struct sctp_chunk *sctp_make_op_error(const struct sctp_association *,
                                 const struct sctp_chunk *chunk,
                                 __be16 cause_code,
                                 const void *payload,
                                 size_t paylen,
                                 size_t reserve_tail);

struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *,
                                              union sctp_addr *,
                                              struct sockaddr *,
                                              int, __be16);
struct sctp_chunk *sctp_make_asconf_set_prim(struct sctp_association *asoc,
                                             union sctp_addr *addr);
bool sctp_verify_asconf(const struct sctp_association *asoc,
                        struct sctp_chunk *chunk, bool addr_param_needed,
                        struct sctp_paramhdr **errp);
struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
                                       struct sctp_chunk *asconf);
int sctp_process_asconf_ack(struct sctp_association *asoc,
                            struct sctp_chunk *asconf_ack);
struct sctp_chunk *sctp_make_fwdtsn(const struct sctp_association *asoc,
                                    __u32 new_cum_tsn, size_t nstreams,
                                    struct sctp_fwdtsn_skip *skiplist);
struct sctp_chunk *sctp_make_auth(const struct sctp_association *asoc);

void sctp_chunk_assign_tsn(struct sctp_chunk *);
void sctp_chunk_assign_ssn(struct sctp_chunk *);

/* Prototypes for statetable processing. */

int sctp_do_sm(struct net *net, sctp_event_t event_type, sctp_subtype_t subtype,
               sctp_state_t state,
               struct sctp_endpoint *,
               struct sctp_association *asoc,
               void *event_arg,
               gfp_t gfp);

/* 2nd level prototypes */
void sctp_generate_t3_rtx_event(unsigned long peer);
void sctp_generate_heartbeat_event(unsigned long peer);
void sctp_generate_proto_unreach_event(unsigned long peer);

void sctp_ootb_pkt_free(struct sctp_packet *);

struct sctp_association *sctp_unpack_cookie(const struct sctp_endpoint *,
                                       const struct sctp_association *,
                                       struct sctp_chunk *,
                                       gfp_t gfp, int *err,
                                       struct sctp_chunk **err_chk_p);
int sctp_addip_addr_config(struct sctp_association *, sctp_param_t,
                           struct sockaddr_storage*, int);

/* 3rd level prototypes */
__u32 sctp_generate_tag(const struct sctp_endpoint *);
__u32 sctp_generate_tsn(const struct sctp_endpoint *);

/* Extern declarations for major data structures.  */
extern sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES];


/* Get the size of a DATA chunk payload. */
static inline __u16 sctp_data_size(struct sctp_chunk *chunk)
{
        __u16 size;

        size = ntohs(chunk->chunk_hdr->length);
        size -= sizeof(sctp_data_chunk_t);

        return size;
}

/* Compare two TSNs */

/* RFC 1982 - Serial Number Arithmetic
 *
 * 2. Comparison
 *  Then, s1 is said to be equal to s2 if and only if i1 is equal to i2,
 *  in all other cases, s1 is not equal to s2.
 *
 * s1 is said to be less than s2 if, and only if, s1 is not equal to s2,
 * and
 *
 *      (i1 < i2 and i2 - i1 < 2^(SERIAL_BITS - 1)) or
 *      (i1 > i2 and i1 - i2 > 2^(SERIAL_BITS - 1))
 *
 * s1 is said to be greater than s2 if, and only if, s1 is not equal to
 * s2, and
 *
 *      (i1 < i2 and i2 - i1 > 2^(SERIAL_BITS - 1)) or
 *      (i1 > i2 and i1 - i2 < 2^(SERIAL_BITS - 1))
 */

/*
 * RFC 2960
 *  1.6 Serial Number Arithmetic
 *
 * Comparisons and arithmetic on TSNs in this document SHOULD use Serial
 * Number Arithmetic as defined in [RFC1982] where SERIAL_BITS = 32.
 */

enum {
        TSN_SIGN_BIT = (1<<31)
};

static inline int TSN_lt(__u32 s, __u32 t)
{
        return ((s) - (t)) & TSN_SIGN_BIT;
}

static inline int TSN_lte(__u32 s, __u32 t)
{
        return ((s) == (t)) || (((s) - (t)) & TSN_SIGN_BIT);
}

/* Compare two SSNs */

/*
 * RFC 2960
 *  1.6 Serial Number Arithmetic
 *
 * Comparisons and arithmetic on Stream Sequence Numbers in this document
 * SHOULD use Serial Number Arithmetic as defined in [RFC1982] where
 * SERIAL_BITS = 16.
 */
enum {
        SSN_SIGN_BIT = (1<<15)
};

static inline int SSN_lt(__u16 s, __u16 t)
{
        return ((s) - (t)) & SSN_SIGN_BIT;
}

static inline int SSN_lte(__u16 s, __u16 t)
{
        return ((s) == (t)) || (((s) - (t)) & SSN_SIGN_BIT);
}

/*
 * ADDIP 3.1.1
 * The valid range of Serial Number is from 0 to 4294967295 (2**32 - 1). Serial
 * Numbers wrap back to 0 after reaching 4294967295.
 */
enum {
        ADDIP_SERIAL_SIGN_BIT = (1<<31)
};

static inline int ADDIP_SERIAL_gte(__u16 s, __u16 t)
{
        return ((s) == (t)) || (((t) - (s)) & ADDIP_SERIAL_SIGN_BIT);
}

/* Check VTAG of the packet matches the sender's own tag. */
static inline int
sctp_vtag_verify(const struct sctp_chunk *chunk,
                 const struct sctp_association *asoc)
{
        /* RFC 2960 Sec 8.5 When receiving an SCTP packet, the endpoint
         * MUST ensure that the value in the Verification Tag field of
         * the received SCTP packet matches its own Tag. If the received
         * Verification Tag value does not match the receiver's own
         * tag value, the receiver shall silently discard the packet...
         */
        if (ntohl(chunk->sctp_hdr->vtag) == asoc->c.my_vtag)
                return 1;

        return 0;
}

/* Check VTAG of the packet matches the sender's own tag and the T bit is
 * not set, OR its peer's tag and the T bit is set in the Chunk Flags.
 */
static inline int
sctp_vtag_verify_either(const struct sctp_chunk *chunk,
                        const struct sctp_association *asoc)
{
        /* RFC 2960 Section 8.5.1, sctpimpguide Section 2.41
         *
         * B) The receiver of a ABORT MUST accept the packet
         *    if the Verification Tag field of the packet matches its own tag
         *    and the T bit is not set
         *    OR
         *    it is set to its peer's tag and the T bit is set in the Chunk
         *    Flags.
         *    Otherwise, the receiver MUST silently discard the packet
         *    and take no further action.
         *
         * C) The receiver of a SHUTDOWN COMPLETE shall accept the packet
         *    if the Verification Tag field of the packet matches its own tag
         *    and the T bit is not set
         *    OR
         *    it is set to its peer's tag and the T bit is set in the Chunk
         *    Flags.
         *    Otherwise, the receiver MUST silently discard the packet
         *    and take no further action.  An endpoint MUST ignore the
         *    SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
         */
        if ((!sctp_test_T_bit(chunk) &&
             (ntohl(chunk->sctp_hdr->vtag) == asoc->c.my_vtag)) ||
            (sctp_test_T_bit(chunk) && asoc->c.peer_vtag &&
             (ntohl(chunk->sctp_hdr->vtag) == asoc->c.peer_vtag))) {
                return 1;
        }

        return 0;
}

#endif /* __sctp_sm_h__ */