protocol.c

在linux环境下的流控制传输协议（sctp）的源代码

	.get_saddr	   = sctp_v4_get_saddr,
	.copy_addrlist	   = sctp_v4_copy_addrlist,
	.from_skb	   = sctp_v4_from_skb,
	.from_sk	   = sctp_v4_from_sk,
	.to_sk_saddr	   = sctp_v4_to_sk_saddr,
	.to_sk_daddr	   = sctp_v4_to_sk_daddr,
	.from_addr_param   = sctp_v4_from_addr_param,
	.to_addr_param	   = sctp_v4_to_addr_param,
	.dst_saddr	   = sctp_v4_dst_saddr,
	.cmp_addr	   = sctp_v4_cmp_addr,
	.addr_valid	   = sctp_v4_addr_valid,
	.inaddr_any	   = sctp_v4_inaddr_any,
	.is_any		   = sctp_v4_is_any,
	.available	   = sctp_v4_available,
	.scope		   = sctp_v4_scope,
	.skb_iif	   = sctp_v4_skb_iif,
	.is_ce		   = sctp_v4_is_ce,
	.seq_dump_addr	   = sctp_v4_seq_dump_addr,
	.net_header_len	   = sizeof(struct iphdr),
	.sockaddr_len	   = sizeof(struct sockaddr_in),
#ifdef CONFIG_COMPAT
	.compat_setsockopt = compat_ip_setsockopt,
	.compat_getsockopt = compat_ip_getsockopt,
#endif
};

struct sctp_pf *sctp_get_pf_specific(sa_family_t family) {

	switch (family) {
	case PF_INET:
		return sctp_pf_inet_specific;
	case PF_INET6:
		return sctp_pf_inet6_specific;
	default:
		return NULL;
	}
}

/* Register the PF specific function table.  */
int sctp_register_pf(struct sctp_pf *pf, sa_family_t family)
{
	switch (family) {
	case PF_INET:
		if (sctp_pf_inet_specific)
			return 0;
		sctp_pf_inet_specific = pf;
		break;
	case PF_INET6:
		if (sctp_pf_inet6_specific)
			return 0;
		sctp_pf_inet6_specific = pf;
		break;
	default:
		return 0;
	}
	return 1;
}

static int __init init_sctp_mibs(void)
{
	sctp_statistics[0] = alloc_percpu(struct sctp_mib);
	if (!sctp_statistics[0])
		return -ENOMEM;
	sctp_statistics[1] = alloc_percpu(struct sctp_mib);
	if (!sctp_statistics[1]) {
		free_percpu(sctp_statistics[0]);
		return -ENOMEM;
	}
	return 0;

}

static void cleanup_sctp_mibs(void)
{
	free_percpu(sctp_statistics[0]);
	free_percpu(sctp_statistics[1]);
}

static void sctp_v4_pf_init(void)
{
	/* Initialize the SCTP specific PF functions. */
	sctp_register_pf(&sctp_pf_inet, PF_INET);
	sctp_register_af(&sctp_af_inet);
}

static void sctp_v4_pf_exit(void)
{
	list_del(&sctp_af_inet.list);
}

static int sctp_v4_protosw_init(void)
{
	int rc;

	rc = proto_register(&sctp_prot, 1);
	if (rc)
		return rc;

	/* Register SCTP(UDP and TCP style) with socket layer.  */
	inet_register_protosw(&sctp_seqpacket_protosw);
	inet_register_protosw(&sctp_stream_protosw);

	return 0;
}

static void sctp_v4_protosw_exit(void)
{
	inet_unregister_protosw(&sctp_stream_protosw);
	inet_unregister_protosw(&sctp_seqpacket_protosw);
	proto_unregister(&sctp_prot);
}

static int sctp_v4_add_protocol(void)
{
	/* Register notifier for inet address additions/deletions. */
	register_inetaddr_notifier(&sctp_inetaddr_notifier);

	/* Register SCTP with inet layer.  */
	if (inet_add_protocol(&sctp_protocol, IPPROTO_SCTP) < 0)
		return -EAGAIN;

	return 0;
}

static void sctp_v4_del_protocol(void)
{
	inet_del_protocol(&sctp_protocol, IPPROTO_SCTP);
	unregister_inetaddr_notifier(&sctp_inetaddr_notifier);
}

/* Initialize the universe into something sensible.  */
SCTP_STATIC __init int sctp_init(void)
{
	int i;
	int status = -EINVAL;
	unsigned long goal;
	unsigned long limit;
	int max_share;
	int order;

	/* SCTP_DEBUG sanity check. */
	if (!sctp_sanity_check())
		goto out;

	/* Allocate bind_bucket and chunk caches. */
	status = -ENOBUFS;
	sctp_bucket_cachep = kmem_cache_create("sctp_bind_bucket",
					       sizeof(struct sctp_bind_bucket),
					       0, SLAB_HWCACHE_ALIGN,
					       NULL);
	if (!sctp_bucket_cachep)
		goto out;

	sctp_chunk_cachep = kmem_cache_create("sctp_chunk",
					       sizeof(struct sctp_chunk),
					       0, SLAB_HWCACHE_ALIGN,
					       NULL);
	if (!sctp_chunk_cachep)
		goto err_chunk_cachep;

	/* Allocate and initialise sctp mibs.  */
	status = init_sctp_mibs();
	if (status)
		goto err_init_mibs;

	/* Initialize proc fs directory.  */
	status = sctp_proc_init();
	if (status)
		goto err_init_proc;

	/* Initialize object count debugging.  */
	sctp_dbg_objcnt_init();

	/*
	 * 14. Suggested SCTP Protocol Parameter Values
	 */
	/* The following protocol parameters are RECOMMENDED:  */
	/* RTO.Initial              - 3  seconds */
	sctp_rto_initial		= SCTP_RTO_INITIAL;
	/* RTO.Min                  - 1  second */
	sctp_rto_min	 		= SCTP_RTO_MIN;
	/* RTO.Max                 -  60 seconds */
	sctp_rto_max 			= SCTP_RTO_MAX;
	/* RTO.Alpha                - 1/8 */
	sctp_rto_alpha	        	= SCTP_RTO_ALPHA;
	/* RTO.Beta                 - 1/4 */
	sctp_rto_beta			= SCTP_RTO_BETA;

	/* Valid.Cookie.Life        - 60  seconds */
	sctp_valid_cookie_life		= SCTP_DEFAULT_COOKIE_LIFE;

	/* Whether Cookie Preservative is enabled(1) or not(0) */
	sctp_cookie_preserve_enable 	= 1;

	/* Max.Burst		    - 4 */
	sctp_max_burst 			= SCTP_DEFAULT_MAX_BURST;

	/* Association.Max.Retrans  - 10 attempts
	 * Path.Max.Retrans         - 5  attempts (per destination address)
	 * Max.Init.Retransmits     - 8  attempts
	 */
	sctp_max_retrans_association 	= 10;
	sctp_max_retrans_path		= 5;
	sctp_max_retrans_init		= 8;

	/* Sendbuffer growth	    - do per-socket accounting */
	sctp_sndbuf_policy		= 0;

	/* Rcvbuffer growth	    - do per-socket accounting */
	sctp_rcvbuf_policy		= 0;

	/* HB.interval              - 30 seconds */
	sctp_hb_interval		= SCTP_DEFAULT_TIMEOUT_HEARTBEAT;

	/* delayed SACK timeout */
	sctp_sack_timeout		= SCTP_DEFAULT_TIMEOUT_SACK;

	/* Implementation specific variables. */

	/* Initialize default stream count setup information. */
	sctp_max_instreams    		= SCTP_DEFAULT_INSTREAMS;
	sctp_max_outstreams   		= SCTP_DEFAULT_OUTSTREAMS;

	/* Initialize handle used for association ids. */
	idr_init(&sctp_assocs_id);

	/* Set the pressure threshold to be a fraction of global memory that
	 * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
	 * memory, with a floor of 128 pages.
	 * Note this initalizes the data in sctpv6_prot too
	 * Unabashedly stolen from tcp_init
	 */
	limit = min(num_physpages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
	limit = (limit * (num_physpages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
	limit = max(limit, 128UL);
	sysctl_sctp_mem[0] = limit / 4 * 3;
	sysctl_sctp_mem[1] = limit;
	sysctl_sctp_mem[2] = sysctl_sctp_mem[0] * 2;

	/* Set per-socket limits to no more than 1/128 the pressure threshold*/
	limit = (sysctl_sctp_mem[1]) << (PAGE_SHIFT - 7);
	max_share = min(4UL*1024*1024, limit);

	sysctl_sctp_rmem[0] = PAGE_SIZE; /* give each asoc 1 page min */
	sysctl_sctp_rmem[1] = (1500 *(sizeof(struct sk_buff) + 1));
	sysctl_sctp_rmem[2] = max(sysctl_sctp_rmem[1], max_share);

	sysctl_sctp_wmem[0] = SK_MEM_QUANTUM;
	sysctl_sctp_wmem[1] = 16*1024;
	sysctl_sctp_wmem[2] = max(64*1024, max_share);

	/* Size and allocate the association hash table.
	 * The methodology is similar to that of the tcp hash tables.
	 */
	if (num_physpages >= (128 * 1024))
		goal = num_physpages >> (22 - PAGE_SHIFT);
	else
		goal = num_physpages >> (24 - PAGE_SHIFT);

	for (order = 0; (1UL << order) < goal; order++)
		;

	do {
		sctp_assoc_hashsize = (1UL << order) * PAGE_SIZE /
					sizeof(struct sctp_hashbucket);
		if ((sctp_assoc_hashsize > (64 * 1024)) && order > 0)
			continue;
		sctp_assoc_hashtable = (struct sctp_hashbucket *)
					__get_free_pages(GFP_ATOMIC, order);
	} while (!sctp_assoc_hashtable && --order > 0);
	if (!sctp_assoc_hashtable) {
		printk(KERN_ERR "SCTP: Failed association hash alloc.\n");
		status = -ENOMEM;
		goto err_ahash_alloc;
	}
	for (i = 0; i < sctp_assoc_hashsize; i++) {
		rwlock_init(&sctp_assoc_hashtable[i].lock);
		INIT_HLIST_HEAD(&sctp_assoc_hashtable[i].chain);
	}

	/* Allocate and initialize the endpoint hash table.  */
	sctp_ep_hashsize = 64;
	sctp_ep_hashtable = (struct sctp_hashbucket *)
		kmalloc(64 * sizeof(struct sctp_hashbucket), GFP_KERNEL);
	if (!sctp_ep_hashtable) {
		printk(KERN_ERR "SCTP: Failed endpoint_hash alloc.\n");
		status = -ENOMEM;
		goto err_ehash_alloc;
	}
	for (i = 0; i < sctp_ep_hashsize; i++) {
		rwlock_init(&sctp_ep_hashtable[i].lock);
		INIT_HLIST_HEAD(&sctp_ep_hashtable[i].chain);
	}

	/* Allocate and initialize the SCTP port hash table.  */
	do {
		sctp_port_hashsize = (1UL << order) * PAGE_SIZE /
					sizeof(struct sctp_bind_hashbucket);
		if ((sctp_port_hashsize > (64 * 1024)) && order > 0)
			continue;
		sctp_port_hashtable = (struct sctp_bind_hashbucket *)
					__get_free_pages(GFP_ATOMIC, order);
	} while (!sctp_port_hashtable && --order > 0);
	if (!sctp_port_hashtable) {
		printk(KERN_ERR "SCTP: Failed bind hash alloc.");
		status = -ENOMEM;
		goto err_bhash_alloc;
	}
	for (i = 0; i < sctp_port_hashsize; i++) {
		spin_lock_init(&sctp_port_hashtable[i].lock);
		INIT_HLIST_HEAD(&sctp_port_hashtable[i].chain);
	}

	printk(KERN_INFO "SCTP: Hash tables configured "
			 "(established %d bind %d)\n",
		sctp_assoc_hashsize, sctp_port_hashsize);

	/* Disable ADDIP by default. */
	sctp_addip_enable = 0;
	sctp_addip_noauth = 0;

	/* Enable PR-SCTP by default. */
	sctp_prsctp_enable = 1;

	/* Disable AUTH by default. */
	sctp_auth_enable = 0;

	sctp_sysctl_register();

	INIT_LIST_HEAD(&sctp_address_families);
	sctp_v4_pf_init();
	sctp_v6_pf_init();

	/* Initialize the local address list. */
	INIT_LIST_HEAD(&sctp_local_addr_list);
	spin_lock_init(&sctp_local_addr_lock);
	sctp_get_local_addr_list();

	status = sctp_v4_protosw_init();

	if (status)
		goto err_protosw_init;

	status = sctp_v6_protosw_init();
	if (status)
		goto err_v6_protosw_init;

	/* Initialize the control inode/socket for handling OOTB packets.  */
	if ((status = sctp_ctl_sock_init())) {
		printk (KERN_ERR
			"SCTP: Failed to initialize the SCTP control sock.\n");
		goto err_ctl_sock_init;
	}

	status = sctp_v4_add_protocol();
	if (status)
		goto err_add_protocol;

	/* Register SCTP with inet6 layer.  */
	status = sctp_v6_add_protocol();
	if (status)
		goto err_v6_add_protocol;

	status = 0;
out:
	return status;
err_v6_add_protocol:
	sctp_v6_del_protocol();
err_add_protocol:
	sctp_v4_del_protocol();
	sock_release(sctp_ctl_socket);
err_ctl_sock_init:
	sctp_v6_protosw_exit();
err_v6_protosw_init:
	sctp_v4_protosw_exit();
err_protosw_init:
	sctp_free_local_addr_list();
	sctp_v4_pf_exit();
	sctp_v6_pf_exit();
	sctp_sysctl_unregister();
	list_del(&sctp_af_inet.list);
	free_pages((unsigned long)sctp_port_hashtable,
		   get_order(sctp_port_hashsize *
			     sizeof(struct sctp_bind_hashbucket)));
err_bhash_alloc:
	kfree(sctp_ep_hashtable);
err_ehash_alloc:
	free_pages((unsigned long)sctp_assoc_hashtable,
		   get_order(sctp_assoc_hashsize *
			     sizeof(struct sctp_hashbucket)));
err_ahash_alloc:
	sctp_dbg_objcnt_exit();
	sctp_proc_exit();
err_init_proc:
	cleanup_sctp_mibs();
err_init_mibs:
	kmem_cache_destroy(sctp_chunk_cachep);
err_chunk_cachep:
	kmem_cache_destroy(sctp_bucket_cachep);
	goto out;
}

/* Exit handler for the SCTP protocol.  */
SCTP_STATIC __exit void sctp_exit(void)
{
	/* BUG.  This should probably do something useful like clean
	 * up all the remaining associations and all that memory.
	 */

	/* Unregister with inet6/inet layers. */
	sctp_v6_del_protocol();
	sctp_v4_del_protocol();

	/* Free the control endpoint.  */
	sock_release(sctp_ctl_socket);

	/* Free protosw registrations */
	sctp_v6_protosw_exit();
	sctp_v4_protosw_exit();

	/* Free the local address list.  */
	sctp_free_local_addr_list();

	/* Unregister with socket layer. */
	sctp_v6_pf_exit();
	sctp_v4_pf_exit();

	sctp_sysctl_unregister();
	list_del(&sctp_af_inet.list);

	free_pages((unsigned long)sctp_assoc_hashtable,
		   get_order(sctp_assoc_hashsize *
			     sizeof(struct sctp_hashbucket)));
	kfree(sctp_ep_hashtable);
	free_pages((unsigned long)sctp_port_hashtable,
		   get_order(sctp_port_hashsize *
			     sizeof(struct sctp_bind_hashbucket)));

	sctp_dbg_objcnt_exit();
	sctp_proc_exit();
	cleanup_sctp_mibs();

	kmem_cache_destroy(sctp_chunk_cachep);
	kmem_cache_destroy(sctp_bucket_cachep);
}

module_init(sctp_init);
module_exit(sctp_exit);

/*
 * __stringify doesn't likes enums, so use IPPROTO_SCTP value (132) directly.
 */
MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-132");
MODULE_ALIAS("net-pf-" __stringify(PF_INET6) "-proto-132");
MODULE_AUTHOR("Linux Kernel SCTP developers <[e-mail]>");
MODULE_DESCRIPTION("Support for the SCTP protocol (RFC2960)");
MODULE_LICENSE("GPL");