structs.h

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	 */
	__u16		my_port;

	__u8 prsctp_capable;

	/* Padding for future use */
	__u8 padding;  		

	__u32 adaptation_ind;

	__u8 auth_random[sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH];
	__u8 auth_hmacs[SCTP_AUTH_NUM_HMACS + 2];
	__u8 auth_chunks[sizeof(sctp_paramhdr_t) + SCTP_AUTH_MAX_CHUNKS];

	/* This is a shim for my peer's INIT packet, followed by
	 * a copy of the raw address list of the association.
	 * The length of the raw address list is saved in the
	 * raw_addr_list_len field, which will be used at the time when
	 * the association TCB is re-constructed from the cookie.
	 */
	__u32 raw_addr_list_len;
	struct sctp_init_chunk peer_init[0];
};


/* The format of our cookie that we send to our peer. */
struct sctp_signed_cookie {
	__u8 signature[SCTP_SECRET_SIZE];
	__u32 __pad;		/* force sctp_cookie alignment to 64 bits */
	struct sctp_cookie c;
} __attribute__((packed));

/* This is another convenience type to allocate memory for address
 * params for the maximum size and pass such structures around
 * internally.
 */
union sctp_addr_param {
	struct sctp_paramhdr p;
	struct sctp_ipv4addr_param v4;
	struct sctp_ipv6addr_param v6;
};

/* A convenience type to allow walking through the various
 * parameters and avoid casting all over the place.
 */
union sctp_params {
	void *v;
	struct sctp_paramhdr *p;
	struct sctp_cookie_preserve_param *life;
	struct sctp_hostname_param *dns;
	struct sctp_cookie_param *cookie;
	struct sctp_supported_addrs_param *sat;
	struct sctp_ipv4addr_param *v4;
	struct sctp_ipv6addr_param *v6;
	union sctp_addr_param *addr;
	struct sctp_adaptation_ind_param *aind;
	struct sctp_supported_ext_param *ext;
	struct sctp_random_param *random;
	struct sctp_chunks_param *chunks;
	struct sctp_hmac_algo_param *hmac_algo;
};

/* RFC 2960.  Section 3.3.5 Heartbeat.
 *    Heartbeat Information: variable length
 *    The Sender-specific Heartbeat Info field should normally include
 *    information about the sender's current time when this HEARTBEAT
 *    chunk is sent and the destination transport address to which this
 *    HEARTBEAT is sent (see Section 8.3).
 */
typedef struct sctp_sender_hb_info {
	struct sctp_paramhdr param_hdr;
	union sctp_addr daddr;
	unsigned long sent_at;
	__u64 hb_nonce;
} __attribute__((packed)) sctp_sender_hb_info_t;

/*
 *  RFC 2960 1.3.2 Sequenced Delivery within Streams
 *
 *  The term "stream" is used in SCTP to refer to a sequence of user
 *  messages that are to be delivered to the upper-layer protocol in
 *  order with respect to other messages within the same stream.  This is
 *  in contrast to its usage in TCP, where it refers to a sequence of
 *  bytes (in this document a byte is assumed to be eight bits).
 *  ...
 *
 *  This is the structure we use to track both our outbound and inbound
 *  SSN, or Stream Sequence Numbers.
 */

struct sctp_stream {
	__u16 *ssn;
	unsigned int len;
};

struct sctp_ssnmap {
	struct sctp_stream in;
	struct sctp_stream out;
	int malloced;
};

struct sctp_ssnmap *sctp_ssnmap_new(__u16 in, __u16 out,
				    gfp_t gfp);
void sctp_ssnmap_free(struct sctp_ssnmap *map);
void sctp_ssnmap_clear(struct sctp_ssnmap *map);

/* What is the current SSN number for this stream? */
static inline __u16 sctp_ssn_peek(struct sctp_stream *stream, __u16 id)
{
	return stream->ssn[id];
}

/* Return the next SSN number for this stream.	*/
static inline __u16 sctp_ssn_next(struct sctp_stream *stream, __u16 id)
{
	return stream->ssn[id]++;
}

/* Skip over this ssn and all below. */
static inline void sctp_ssn_skip(struct sctp_stream *stream, __u16 id, 
				 __u16 ssn)
{
	stream->ssn[id] = ssn+1;
}
              
/*
 * Pointers to address related SCTP functions.
 * (i.e. things that depend on the address family.)
 */
struct sctp_af {
	int		(*sctp_xmit)	(struct sk_buff *skb,
					 struct sctp_transport *,
					 int ipfragok);
	int		(*setsockopt)	(struct sock *sk,
					 int level,
					 int optname,
					 char __user *optval,
					 int optlen);
	int		(*getsockopt)	(struct sock *sk,
					 int level,
					 int optname,
					 char __user *optval,
					 int __user *optlen);
	int		(*compat_setsockopt)	(struct sock *sk,
					 int level,
					 int optname,
					 char __user *optval,
					 int optlen);
	int		(*compat_getsockopt)	(struct sock *sk,
					 int level,
					 int optname,
					 char __user *optval,
					 int __user *optlen);
	struct dst_entry *(*get_dst)	(struct sctp_association *asoc,
					 union sctp_addr *daddr,
					 union sctp_addr *saddr);
	void		(*get_saddr)	(struct sctp_association *asoc,
					 struct dst_entry *dst,
					 union sctp_addr *daddr,
					 union sctp_addr *saddr);
	void		(*copy_addrlist) (struct list_head *,
					  struct net_device *);
	void		(*dst_saddr)	(union sctp_addr *saddr,
					 struct dst_entry *dst,
					 __be16 port);
	int		(*cmp_addr)	(const union sctp_addr *addr1,
					 const union sctp_addr *addr2);
	void		(*addr_copy)	(union sctp_addr *dst,
					 union sctp_addr *src);
	void		(*from_skb)	(union sctp_addr *,
					 struct sk_buff *skb,
					 int saddr);
	void		(*from_sk)	(union sctp_addr *,
					 struct sock *sk);
	void		(*to_sk_saddr)	(union sctp_addr *,
					 struct sock *sk);
	void		(*to_sk_daddr)	(union sctp_addr *,
					 struct sock *sk);
	void		(*from_addr_param) (union sctp_addr *,
					    union sctp_addr_param *,
					    __be16 port, int iif);
	int		(*to_addr_param) (const union sctp_addr *,
					  union sctp_addr_param *); 
	int		(*addr_valid)	(union sctp_addr *,
					 struct sctp_sock *,
					 const struct sk_buff *);
	sctp_scope_t	(*scope) (union sctp_addr *);
	void		(*inaddr_any)	(union sctp_addr *, __be16);
	int		(*is_any)	(const union sctp_addr *);
	int		(*available)	(union sctp_addr *,
					 struct sctp_sock *);
	int		(*skb_iif)	(const struct sk_buff *sk);
	int		(*is_ce)	(const struct sk_buff *sk);
	void		(*seq_dump_addr)(struct seq_file *seq,
					 union sctp_addr *addr);
	__u16		net_header_len;
	int		sockaddr_len;
	sa_family_t	sa_family;
	struct list_head list;
};

struct sctp_af *sctp_get_af_specific(sa_family_t);
int sctp_register_af(struct sctp_af *);

/* Protocol family functions. */
struct sctp_pf {
	void (*event_msgname)(struct sctp_ulpevent *, char *, int *);
	void (*skb_msgname)  (struct sk_buff *, char *, int *);
	int  (*af_supported) (sa_family_t, struct sctp_sock *);
	int  (*cmp_addr) (const union sctp_addr *,
			  const union sctp_addr *,
			  struct sctp_sock *);
	int  (*bind_verify) (struct sctp_sock *, union sctp_addr *);
	int  (*send_verify) (struct sctp_sock *, union sctp_addr *);
	int  (*supported_addrs)(const struct sctp_sock *, __be16 *);
	struct sock *(*create_accept_sk) (struct sock *sk,
					  struct sctp_association *asoc);
	void (*addr_v4map) (struct sctp_sock *, union sctp_addr *);
	struct sctp_af *af;
};


/* Structure to track chunk fragments that have been acked, but peer
 * fragments of the same message have not.
 */
struct sctp_datamsg {
	/* Chunks waiting to be submitted to lower layer. */
	struct list_head chunks;
	/* Chunks that have been transmitted. */
	struct list_head track;
	/* Reference counting. */
	atomic_t refcnt;
	/* When is this message no longer interesting to the peer? */
	unsigned long expires_at;
	/* Did the messenge fail to send? */
	int send_error;
	char send_failed;
	/* Control whether chunks from this message can be abandoned. */
	char can_abandon;
};

struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *,
					    struct sctp_sndrcvinfo *,
					    struct msghdr *, int len);
void sctp_datamsg_put(struct sctp_datamsg *);
void sctp_datamsg_free(struct sctp_datamsg *);
void sctp_datamsg_track(struct sctp_chunk *);
void sctp_chunk_fail(struct sctp_chunk *, int error);
int sctp_chunk_abandoned(struct sctp_chunk *);

/* RFC2960 1.4 Key Terms
 *
 * o Chunk: A unit of information within an SCTP packet, consisting of
 * a chunk header and chunk-specific content.
 *
 * As a matter of convenience, we remember the SCTP common header for
 * each chunk as well as a few other header pointers...
 */
struct sctp_chunk {
	struct list_head list;

	atomic_t refcnt;

	/* This is our link to the per-transport transmitted list.  */
	struct list_head transmitted_list;

	/* This field is used by chunks that hold fragmented data.
	 * For the first fragment this is the list that holds the rest of
	 * fragments. For the remaining fragments, this is the link to the
	 * frag_list maintained in the first fragment.
	 */
	struct list_head frag_list;

	/* This points to the sk_buff containing the actual data.  */
	struct sk_buff *skb;

	/* These are the SCTP headers by reverse order in a packet.
	 * Note that some of these may happen more than once.  In that
	 * case, we point at the "current" one, whatever that means
	 * for that level of header.
	 */

	/* We point this at the FIRST TLV parameter to chunk_hdr.  */
	union sctp_params param_hdr;
	union {
		__u8 *v;
		struct sctp_datahdr *data_hdr;
		struct sctp_inithdr *init_hdr;
		struct sctp_sackhdr *sack_hdr;
		struct sctp_heartbeathdr *hb_hdr;
		struct sctp_sender_hb_info *hbs_hdr;
		struct sctp_shutdownhdr *shutdown_hdr;
		struct sctp_signed_cookie *cookie_hdr;
		struct sctp_ecnehdr *ecne_hdr;
		struct sctp_cwrhdr *ecn_cwr_hdr;
		struct sctp_errhdr *err_hdr;
		struct sctp_addiphdr *addip_hdr;
		struct sctp_fwdtsn_hdr *fwdtsn_hdr;
		struct sctp_authhdr *auth_hdr;
	} subh;

	__u8 *chunk_end;

	struct sctp_chunkhdr *chunk_hdr;
	struct sctphdr *sctp_hdr;

	/* This needs to be recoverable for SCTP_SEND_FAILED events. */
	struct sctp_sndrcvinfo sinfo;

	/* Which association does this belong to?  */
	struct sctp_association *asoc;

	/* What endpoint received this chunk? */
	struct sctp_ep_common *rcvr;

	/* We fill this in if we are calculating RTT. */
	unsigned long sent_at;

	/* What is the origin IP address for this chunk?  */
	union sctp_addr source;
	/* Destination address for this chunk. */
	union sctp_addr dest;

	/* For outbound message, track all fragments for SEND_FAILED. */
	struct sctp_datamsg *msg;

	/* For an inbound chunk, this tells us where it came from.
	 * For an outbound chunk, it tells us where we'd like it to
	 * go.	It is NULL if we have no preference.
	 */
	struct sctp_transport *transport;

	/* SCTP-AUTH:  For the special case inbound processing of COOKIE-ECHO
	 * we need save a pointer to the AUTH chunk, since the SCTP-AUTH
	 * spec violates the principle premis that all chunks are processed
	 * in order.
	 */
	struct sk_buff *auth_chunk;

	__u8 rtt_in_progress;	/* Is this chunk used for RTT calculation? */
	__u8 resent;		/* Has this chunk ever been retransmitted. */
	__u8 has_tsn;		/* Does this chunk have a TSN yet? */
	__u8 has_ssn;		/* Does this chunk have a SSN yet? */
	__u8 singleton;		/* Was this the only chunk in the packet? */
	__u8 end_of_packet;	/* Was this the last chunk in the packet? */
	__u8 ecn_ce_done;	/* Have we processed the ECN CE bit? */
	__u8 pdiscard;		/* Discard the whole packet now? */
	__u8 tsn_gap_acked;	/* Is this chunk acked by a GAP ACK? */
	__s8 fast_retransmit;	 /* Is this chunk fast retransmitted? */
	__u8 tsn_missing_report; /* Data chunk missing counter. */
	__u8 data_accepted; 	/* At least 1 chunk in this packet accepted */
	__u8 auth;		/* IN: was auth'ed | OUT: needs auth */
};

void sctp_chunk_hold(struct sctp_chunk *);
void sctp_chunk_put(struct sctp_chunk *);
int sctp_user_addto_chunk(struct sctp_chunk *chunk, int off, int len,
			  struct iovec *data);
void sctp_chunk_free(struct sctp_chunk *);
void  *sctp_addto_chunk(struct sctp_chunk *, int len, const void *data);
struct sctp_chunk *sctp_chunkify(struct sk_buff *,
				 const struct sctp_association *,
				 struct sock *);
void sctp_init_addrs(struct sctp_chunk *, union sctp_addr *,
		     union sctp_addr *);
const union sctp_addr *sctp_source(const struct sctp_chunk *chunk);

/* This is a structure for holding either an IPv6 or an IPv4 address.  */
struct sctp_sockaddr_entry {
	struct list_head list;
	struct rcu_head	rcu;
	union sctp_addr a;
	__u8 use_as_src;
	__u8 valid;
};

typedef struct sctp_chunk *(sctp_packet_phandler_t)(struct sctp_association *);

/* This structure holds lists of chunks as we are assembling for
 * transmission.
 */
struct sctp_packet {
	/* These are the SCTP header values (host order) for the packet. */
	__u16 source_port;
	__u16 destination_port;
	__u32 vtag;

	/* This contains the payload chunks.  */
	struct list_head chunk_list;

	/* This is the overhead of the sctp and ip headers. */
	size_t overhead;
	/* This is the total size of all chunks INCLUDING padding.  */