ip_vs_sync.c

linux-2.6.15.6

/*
 * IPVS         An implementation of the IP virtual server support for the
 *              LINUX operating system.  IPVS is now implemented as a module
 *              over the NetFilter framework. IPVS can be used to build a
 *              high-performance and highly available server based on a
 *              cluster of servers.
 *
 * Version:     $Id: ip_vs_sync.c,v 1.13 2003/06/08 09:31:19 wensong Exp $
 *
 * Authors:     Wensong Zhang <[e-mail]>
 *
 * ip_vs_sync:  sync connection info from master load balancer to backups
 *              through multicast
 *
 * Changes:
 *	Alexandre Cassen	:	Added master & backup support at a time.
 *	Alexandre Cassen	:	Added SyncID support for incoming sync
 *					messages filtering.
 *	Justin Ossevoort	:	Fix endian problem on sync message size.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/net.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/igmp.h>                 /* for ip_mc_join_group */

#include <net/ip.h>
#include <net/sock.h>
#include <asm/uaccess.h>                /* for get_fs and set_fs */

#include <net/ip_vs.h>

#define IP_VS_SYNC_GROUP 0xe0000051    /* multicast addr - 224.0.0.81 */
#define IP_VS_SYNC_PORT  8848          /* multicast port */


/*
 *	IPVS sync connection entry
 */
struct ip_vs_sync_conn {
	__u8			reserved;

	/* Protocol, addresses and port numbers */
	__u8			protocol;       /* Which protocol (TCP/UDP) */
	__u16			cport;
	__u16                   vport;
	__u16                   dport;
	__u32                   caddr;          /* client address */
	__u32                   vaddr;          /* virtual address */
	__u32                   daddr;          /* destination address */

	/* Flags and state transition */
	__u16                   flags;          /* status flags */
	__u16                   state;          /* state info */

	/* The sequence options start here */
};

struct ip_vs_sync_conn_options {
	struct ip_vs_seq        in_seq;         /* incoming seq. struct */
	struct ip_vs_seq        out_seq;        /* outgoing seq. struct */
};

#define IP_VS_SYNC_CONN_TIMEOUT (3*60*HZ)
#define SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
#define FULL_CONN_SIZE  \
(sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))


/*
  The master mulitcasts messages to the backup load balancers in the
  following format.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Count Conns  |    SyncID     |            Size               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                    IPVS Sync Connection (1)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            .                                  |
      |                            .                                  |
      |                            .                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                    IPVS Sync Connection (n)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/

#define SYNC_MESG_HEADER_LEN	4

struct ip_vs_sync_mesg {
	__u8                    nr_conns;
	__u8                    syncid;
	__u16                   size;

	/* ip_vs_sync_conn entries start here */
};

/* the maximum length of sync (sending/receiving) message */
static int sync_send_mesg_maxlen;
static int sync_recv_mesg_maxlen;

struct ip_vs_sync_buff {
	struct list_head        list;
	unsigned long           firstuse;

	/* pointers for the message data */
	struct ip_vs_sync_mesg  *mesg;
	unsigned char           *head;
	unsigned char           *end;
};


/* the sync_buff list head and the lock */
static LIST_HEAD(ip_vs_sync_queue);
static DEFINE_SPINLOCK(ip_vs_sync_lock);

/* current sync_buff for accepting new conn entries */
static struct ip_vs_sync_buff   *curr_sb = NULL;
static DEFINE_SPINLOCK(curr_sb_lock);

/* ipvs sync daemon state */
volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
volatile int ip_vs_master_syncid = 0;
volatile int ip_vs_backup_syncid = 0;

/* multicast interface name */
char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];

/* multicast addr */
static struct sockaddr_in mcast_addr;


static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
{
	spin_lock(&ip_vs_sync_lock);
	list_add_tail(&sb->list, &ip_vs_sync_queue);
	spin_unlock(&ip_vs_sync_lock);
}

static inline struct ip_vs_sync_buff * sb_dequeue(void)
{
	struct ip_vs_sync_buff *sb;

	spin_lock_bh(&ip_vs_sync_lock);
	if (list_empty(&ip_vs_sync_queue)) {
		sb = NULL;
	} else {
		sb = list_entry(ip_vs_sync_queue.next,
				struct ip_vs_sync_buff,
				list);
		list_del(&sb->list);
	}
	spin_unlock_bh(&ip_vs_sync_lock);

	return sb;
}

static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
{
	struct ip_vs_sync_buff *sb;

	if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
		return NULL;

	if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
		kfree(sb);
		return NULL;
	}
	sb->mesg->nr_conns = 0;
	sb->mesg->syncid = ip_vs_master_syncid;
	sb->mesg->size = 4;
	sb->head = (unsigned char *)sb->mesg + 4;
	sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
	sb->firstuse = jiffies;
	return sb;
}

static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
{
	kfree(sb->mesg);
	kfree(sb);
}

/*
 *	Get the current sync buffer if it has been created for more
 *	than the specified time or the specified time is zero.
 */
static inline struct ip_vs_sync_buff *
get_curr_sync_buff(unsigned long time)
{
	struct ip_vs_sync_buff *sb;

	spin_lock_bh(&curr_sb_lock);
	if (curr_sb && (time == 0 ||
			time_before(jiffies - curr_sb->firstuse, time))) {
		sb = curr_sb;
		curr_sb = NULL;
	} else
		sb = NULL;
	spin_unlock_bh(&curr_sb_lock);
	return sb;
}


/*
 *      Add an ip_vs_conn information into the current sync_buff.
 *      Called by ip_vs_in.
 */
void ip_vs_sync_conn(struct ip_vs_conn *cp)
{
	struct ip_vs_sync_mesg *m;
	struct ip_vs_sync_conn *s;
	int len;

	spin_lock(&curr_sb_lock);
	if (!curr_sb) {
		if (!(curr_sb=ip_vs_sync_buff_create())) {
			spin_unlock(&curr_sb_lock);
			IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
			return;
		}
	}

	len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
		SIMPLE_CONN_SIZE;
	m = curr_sb->mesg;
	s = (struct ip_vs_sync_conn *)curr_sb->head;

	/* copy members */
	s->protocol = cp->protocol;
	s->cport = cp->cport;
	s->vport = cp->vport;
	s->dport = cp->dport;
	s->caddr = cp->caddr;
	s->vaddr = cp->vaddr;
	s->daddr = cp->daddr;
	s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
	s->state = htons(cp->state);
	if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
		struct ip_vs_sync_conn_options *opt =
			(struct ip_vs_sync_conn_options *)&s[1];
		memcpy(opt, &cp->in_seq, sizeof(*opt));
	}

	m->nr_conns++;
	m->size += len;
	curr_sb->head += len;

	/* check if there is a space for next one */
	if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
		sb_queue_tail(curr_sb);
		curr_sb = NULL;
	}
	spin_unlock(&curr_sb_lock);

	/* synchronize its controller if it has */
	if (cp->control)
		ip_vs_sync_conn(cp->control);
}


/*
 *      Process received multicast message and create the corresponding
 *      ip_vs_conn entries.
 */
static void ip_vs_process_message(const char *buffer, const size_t buflen)
{
	struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
	struct ip_vs_sync_conn *s;
	struct ip_vs_sync_conn_options *opt;
	struct ip_vs_conn *cp;
	char *p;
	int i;

	/* Convert size back to host byte order */
	m->size = ntohs(m->size);

	if (buflen != m->size) {
		IP_VS_ERR("bogus message\n");
		return;
	}

	/* SyncID sanity check */
	if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
		IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
			  m->syncid);
		return;
	}

	p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
	for (i=0; i<m->nr_conns; i++) {
		unsigned flags;

		s = (struct ip_vs_sync_conn *)p;
		flags = ntohs(s->flags);
		if (!(flags & IP_VS_CONN_F_TEMPLATE))
			cp = ip_vs_conn_in_get(s->protocol,
					       s->caddr, s->cport,
					       s->vaddr, s->vport);
		else
			cp = ip_vs_ct_in_get(s->protocol,
					       s->caddr, s->cport,
					       s->vaddr, s->vport);
		if (!cp) {
			cp = ip_vs_conn_new(s->protocol,
					    s->caddr, s->cport,
					    s->vaddr, s->vport,
					    s->daddr, s->dport,
					    flags, NULL);
			if (!cp) {
				IP_VS_ERR("ip_vs_conn_new failed\n");
				return;
			}
			cp->state = ntohs(s->state);
		} else if (!cp->dest) {
			/* it is an entry created by the synchronization */
			cp->state = ntohs(s->state);
			cp->flags = flags | IP_VS_CONN_F_HASHED;
		}	/* Note that we don't touch its state and flags
			   if it is a normal entry. */

		if (flags & IP_VS_CONN_F_SEQ_MASK) {
			opt = (struct ip_vs_sync_conn_options *)&s[1];
			memcpy(&cp->in_seq, opt, sizeof(*opt));
			p += FULL_CONN_SIZE;
		} else
			p += SIMPLE_CONN_SIZE;

		atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
		cp->timeout = IP_VS_SYNC_CONN_TIMEOUT;
		ip_vs_conn_put(cp);

		if (p > buffer+buflen) {
			IP_VS_ERR("bogus message\n");
			return;
		}
	}
}


/*
 *      Setup loopback of outgoing multicasts on a sending socket
 */
static void set_mcast_loop(struct sock *sk, u_char loop)
{
	struct inet_sock *inet = inet_sk(sk);

	/* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
	lock_sock(sk);
	inet->mc_loop = loop ? 1 : 0;
	release_sock(sk);
}

/*
 *      Specify TTL for outgoing multicasts on a sending socket
 */
static void set_mcast_ttl(struct sock *sk, u_char ttl)
{
	struct inet_sock *inet = inet_sk(sk);

	/* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
	lock_sock(sk);
	inet->mc_ttl = ttl;
	release_sock(sk);
}

/*
 *      Specifiy default interface for outgoing multicasts
 */
static int set_mcast_if(struct sock *sk, char *ifname)
{
	struct net_device *dev;
	struct inet_sock *inet = inet_sk(sk);

	if ((dev = __dev_get_by_name(ifname)) == NULL)
		return -ENODEV;

	if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
		return -EINVAL;

	lock_sock(sk);
	inet->mc_index = dev->ifindex;
	/*  inet->mc_addr  = 0; */
	release_sock(sk);

	return 0;
}


/*
 *	Set the maximum length of sync message according to the
 *	specified interface's MTU.
 */
static int set_sync_mesg_maxlen(int sync_state)
{
	struct net_device *dev;
	int num;

	if (sync_state == IP_VS_STATE_MASTER) {
		if ((dev = __dev_get_by_name(ip_vs_master_mcast_ifn)) == NULL)
			return -ENODEV;

		num = (dev->mtu - sizeof(struct iphdr) -
		       sizeof(struct udphdr) -
		       SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
		sync_send_mesg_maxlen =
			SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
		IP_VS_DBG(7, "setting the maximum length of sync sending "
			  "message %d.\n", sync_send_mesg_maxlen);
	} else if (sync_state == IP_VS_STATE_BACKUP) {
		if ((dev = __dev_get_by_name(ip_vs_backup_mcast_ifn)) == NULL)
			return -ENODEV;

		sync_recv_mesg_maxlen = dev->mtu -
			sizeof(struct iphdr) - sizeof(struct udphdr);
		IP_VS_DBG(7, "setting the maximum length of sync receiving "
			  "message %d.\n", sync_recv_mesg_maxlen);
	}

	return 0;
}


/*
 *      Join a multicast group.
 *      the group is specified by a class D multicast address 224.0.0.0/8
 *      in the in_addr structure passed in as a parameter.
 */
static int
join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
{
	struct ip_mreqn mreq;
	struct net_device *dev;
	int ret;

	memset(&mreq, 0, sizeof(mreq));
	memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));

	if ((dev = __dev_get_by_name(ifname)) == NULL)
		return -ENODEV;
	if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
		return -EINVAL;