sys/netinet/ip_dummynet.h

/*
 * Copyright (c) 1998-2002 Luigi Rizzo, Universita` di Pisa
 * Portions Copyright (c) 2000 Akamba Corp.
 * All rights reserved
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: head/sys/netinet/ip_dummynet.h 96077 2002-05-05 21:27:47Z luigi $
 */

#ifndef _IP_DUMMYNET_H
#define _IP_DUMMYNET_H

/*
 * Definition of dummynet data structures. In the structures, I decided
 * not to use the macros in <sys/queue.h> in the hope of making the code
 * easier to port to other architectures. The type of lists and queue we
 * use here is pretty simple anyways.
 */

/*
 * We start with a heap, which is used in the scheduler to decide when
 * to transmit packets etc.
 *
 * The key for the heap is used for two different values:
 *
 * 1. timer ticks- max 10K/second, so 32 bits are enough;
 *
 * 2. virtual times. These increase in steps of len/x, where len is the
 *    packet length, and x is either the weight of the flow, or the
 *    sum of all weights.
 *    If we limit to max 1000 flows and a max weight of 100, then
 *    x needs 17 bits. The packet size is 16 bits, so we can easily
 *    overflow if we do not allow errors.
 * So we use a key "dn_key" which is 64 bits. Some macros are used to
 * compare key values and handle wraparounds.
 * MAX64 returns the largest of two key values.
 * MY_M is used as a shift count when doing fixed point arithmetic
 * (a better name would be useful...).
 */
typedef u_int64_t dn_key ;      /* sorting key */
#define DN_KEY_LT(a,b)     ((int64_t)((a)-(b)) < 0)
#define DN_KEY_LEQ(a,b)    ((int64_t)((a)-(b)) <= 0)
#define DN_KEY_GT(a,b)     ((int64_t)((a)-(b)) > 0)
#define DN_KEY_GEQ(a,b)    ((int64_t)((a)-(b)) >= 0)
#define MAX64(x,y)  (( (int64_t) ( (y)-(x) )) > 0 ) ? (y) : (x)
#define MY_M	16 /* number of left shift to obtain a larger precision */

/*
 * XXX With this scaling, max 1000 flows, max weight 100, 1Gbit/s, the
 * virtual time wraps every 15 days.
 */

/*
 * The OFFSET_OF macro is used to return the offset of a field within
 * a structure. It is used by the heap management routines.
 */
#define OFFSET_OF(type, field) ((int)&( ((type *)0)->field) )

/*
 * A heap entry is made of a key and a pointer to the actual
 * object stored in the heap.
 * The heap is an array of dn_heap_entry entries, dynamically allocated.
 * Current size is "size", with "elements" actually in use.
 * The heap normally supports only ordered insert and extract from the top.
 * If we want to extract an object from the middle of the heap, we
 * have to know where the object itself is located in the heap (or we
 * need to scan the whole array). To this purpose, an object has a
 * field (int) which contains the index of the object itself into the
 * heap. When the object is moved, the field must also be updated.
 * The offset of the index in the object is stored in the 'offset'
 * field in the heap descriptor. The assumption is that this offset
 * is non-zero if we want to support extract from the middle.
 */
struct dn_heap_entry {
    dn_key key ;	/* sorting key. Topmost element is smallest one */
    void *object ;	/* object pointer */
} ;

struct dn_heap {
    int size ;
    int elements ;
    int offset ; /* XXX if > 0 this is the offset of direct ptr to obj */
    struct dn_heap_entry *p ;	/* really an array of "size" entries */
} ;

/*
 * MT_DUMMYNET is a new (fake) mbuf type that is prepended to the
 * packet when it comes out of a pipe. The definition
 * ought to go in /sys/sys/mbuf.h but here it is less intrusive.
 */

#define MT_DUMMYNET MT_CONTROL

/*
 * struct dn_pkt identifies a packet in the dummynet queue. The
 * first part is really an m_hdr for implementation purposes, and some
 * fields are saved there. When passing the packet back to the ip_input/
 * ip_output()/bdg_forward, the struct is prepended to the mbuf chain with type
 * MT_DUMMYNET, and contains the pointer to the matching rule.
 *
 * Note: there is no real need to make this structure contain an m_hdr,
 * in the future this should be changed to a normal data structure.
 */
struct dn_pkt {
    struct m_hdr hdr ;
#define dn_next	hdr.mh_nextpkt	/* next element in queue */
#define DN_NEXT(x)	(struct dn_pkt *)(x)->dn_next
#define dn_m	hdr.mh_next	/* packet to be forwarded */
#define dn_dir	hdr.mh_flags	/* action when pkt extracted from a queue */
#define DN_TO_IP_OUT	1
#define DN_TO_IP_IN	2
#define DN_TO_BDG_FWD	3

    dn_key  output_time;	/* when the pkt is due for delivery	*/
    struct ifnet *ifp;		/* interface, for ip_output		*/
    struct sockaddr_in *dn_dst ;
    struct route ro;		/* route, for ip_output. MUST COPY	*/
    int flags ;			/* flags, for ip_output (IPv6 ?)	*/
};

/*
 * Overall structure of dummynet (with WF2Q+):

In dummynet, packets are selected with the firewall rules, and passed
to two different objects: PIPE or QUEUE.

A QUEUE is just a queue with configurable size and queue management
policy. It is also associated with a mask (to discriminate among
different flows), a weight (used to give different shares of the
bandwidth to different flows) and a "pipe", which essentially
supplies the transmit clock for all queues associated with that
pipe.

A PIPE emulates a fixed-bandwidth link, whose bandwidth is
configurable.  The "clock" for a pipe can come from either an
internal timer, or from the transmit interrupt of an interface.
A pipe is also associated with one (or more, if masks are used)
queue, where all packets for that pipe are stored.

The bandwidth available on the pipe is shared by the queues
associated with that pipe (only one in case the packet is sent
to a PIPE) according to the WF2Q+ scheduling algorithm and the
configured weights.

In general, incoming packets are stored in the appropriate queue,
which is then placed into one of a few heaps managed by a scheduler
to decide when the packet should be extracted.
The scheduler (a function called dummynet()) is run at every timer
tick, and grabs queues from the head of the heaps when they are
ready for processing.

There are three data structures definining a pipe and associated queues:

 + dn_pipe, which contains the main configuration parameters related
   to delay and bandwidth;
 + dn_flow_set, which contains WF2Q+ configuration, flow
   masks, plr and RED configuration;
 + dn_flow_queue, which is the per-flow queue (containing the packets)

Multiple dn_flow_set can be linked to the same pipe, and multiple
dn_flow_queue can be linked to the same dn_flow_set.
All data structures are linked in a linear list which is used for
housekeeping purposes.

During configuration, we create and initialize the dn_flow_set
and dn_pipe structures (a dn_pipe also contains a dn_flow_set).

At runtime: packets are sent to the appropriate dn_flow_set (either
WFQ ones, or the one embedded in the dn_pipe for fixed-rate flows),
which in turn dispatches them to the appropriate dn_flow_queue
(created dynamically according to the masks).

The transmit clock for fixed rate flows (ready_event()) selects the
dn_flow_queue to be used to transmit the next packet. For WF2Q,
wfq_ready_event() extract a pipe which in turn selects the right
flow using a number of heaps defined into the pipe itself.

 *
 */

/*
 * per flow queue. This contains the flow identifier, the queue
 * of packets, counters, and parameters used to support both RED and
 * WF2Q+.
 *
 * A dn_flow_queue is created and initialized whenever a packet for
 * a new flow arrives.
 */
struct dn_flow_queue {
    struct dn_flow_queue *next ;
    struct ipfw_flow_id id ;

    struct dn_pkt *head, *tail ;	/* queue of packets */
    u_int len ;
    u_int len_bytes ;
    long numbytes ;		/* credit for transmission (dynamic queues) */

    u_int64_t tot_pkts ;	/* statistics counters	*/
    u_int64_t tot_bytes ;
    u_int32_t drops ;

    int hash_slot ;		/* debugging/diagnostic */

    /* RED parameters */
    int avg ;                   /* average queue length est. (scaled) */
    int count ;                 /* arrivals since last RED drop */
    int random ;                /* random value (scaled) */
    u_int32_t q_time ;          /* start of queue idle time */

    /* WF2Q+ support */
    struct dn_flow_set *fs ;	/* parent flow set */
    int heap_pos ;		/* position (index) of struct in heap */
    dn_key sched_time ;		/* current time when queue enters ready_heap */

    dn_key S,F ;		/* start time, finish time */
    /*
     * Setting F < S means the timestamp is invalid. We only need
     * to test this when the queue is empty.
     */
} ;

/*
 * flow_set descriptor. Contains the "template" parameters for the
 * queue configuration, and pointers to the hash table of dn_flow_queue's.
 *
 * The hash table is an array of lists -- we identify the slot by
 * hashing the flow-id, then scan the list looking for a match.
 * The size of the hash table (buckets) is configurable on a per-queue
 * basis.
 *
 * A dn_flow_set is created whenever a new queue or pipe is created (in the
 * latter case, the structure is located inside the struct dn_pipe).
 */
struct dn_flow_set {
    struct dn_flow_set *next; /* next flow set in all_flow_sets list */

    u_short fs_nr ;             /* flow_set number       */
    u_short flags_fs;
#define DN_HAVE_FLOW_MASK	0x0001
#define DN_IS_RED		0x0002
#define DN_IS_GENTLE_RED	0x0004
#define DN_QSIZE_IS_BYTES	0x0008	/* queue size is measured in bytes */
#define DN_IS_PIPE		0x4000
#define DN_IS_QUEUE		0x8000

    struct dn_pipe *pipe ;	/* pointer to parent pipe */
    u_short parent_nr ;		/* parent pipe#, 0 if local to a pipe */

    int weight ;		/* WFQ queue weight */
    int qsize ;			/* queue size in slots or bytes */
    int plr ;			/* pkt loss rate (2^31-1 means 100%) */

    struct ipfw_flow_id flow_mask ;

    /* hash table of queues onto this flow_set */
    int rq_size ;		/* number of slots */
    int rq_elements ;		/* active elements */
    struct dn_flow_queue **rq;	/* array of rq_size entries */

    u_int32_t last_expired ;	/* do not expire too frequently */
    int backlogged ;		/* #active queues for this flowset */

        /* RED parameters */
#define SCALE_RED               16
#define SCALE(x)                ( (x) << SCALE_RED )
#define SCALE_VAL(x)            ( (x) >> SCALE_RED )
#define SCALE_MUL(x,y)          ( ( (x) * (y) ) >> SCALE_RED )
    int w_q ;			/* queue weight (scaled) */
    int max_th ;		/* maximum threshold for queue (scaled) */
    int min_th ;		/* minimum threshold for queue (scaled) */
    int max_p ;			/* maximum value for p_b (scaled) */
    u_int c_1 ;			/* max_p/(max_th-min_th) (scaled) */
    u_int c_2 ;			/* max_p*min_th/(max_th-min_th) (scaled) */
    u_int c_3 ;			/* for GRED, (1-max_p)/max_th (scaled) */
    u_int c_4 ;			/* for GRED, 1 - 2*max_p (scaled) */
    u_int * w_q_lookup ;	/* lookup table for computing (1-w_q)^t */
    u_int lookup_depth ;	/* depth of lookup table */
    int lookup_step ;		/* granularity inside the lookup table */
    int lookup_weight ;		/* equal to (1-w_q)^t / (1-w_q)^(t+1) */
    int avg_pkt_size ;		/* medium packet size */
    int max_pkt_size ;		/* max packet size */
} ;

/*
 * Pipe descriptor. Contains global parameters, delay-line queue,
 * and the flow_set used for fixed-rate queues.
 *
 * For WF2Q+ support it also has 3 heaps holding dn_flow_queue:
 *   not_eligible_heap, for queues whose start time is higher
 *	than the virtual time. Sorted by start time.
 *   scheduler_heap, for queues eligible for scheduling. Sorted by
 *	finish time.
 *   idle_heap, all flows that are idle and can be removed. We
 *	do that on each tick so we do not slow down too much
 *	operations during forwarding.
 *
 */
struct dn_pipe {		/* a pipe */
    struct dn_pipe *next ;

    int	pipe_nr ;		/* number	*/
    int bandwidth;		/* really, bytes/tick.	*/
    int	delay ;			/* really, ticks	*/

    struct	dn_pkt *head, *tail ;	/* packets in delay line */

    /* WF2Q+ */
    struct dn_heap scheduler_heap ; /* top extract - key Finish time*/
    struct dn_heap not_eligible_heap; /* top extract- key Start time */
    struct dn_heap idle_heap ; /* random extract - key Start=Finish time */

    dn_key V ;			/* virtual time */
    int sum;			/* sum of weights of all active sessions */
    int numbytes;		/* bits I can transmit (more or less). */

    dn_key sched_time ;		/* time pipe was scheduled in ready_heap */

    /*
     * When the tx clock come from an interface (if_name[0] != '\0'), its name
     * is stored below, whereas the ifp is filled when the rule is configured.
     */
    char if_name[16];
    struct ifnet *ifp ;
    int ready ; /* set if ifp != NULL and we got a signal from it */

    struct dn_flow_set fs ; /* used with fixed-rate flows */
};

#ifdef _KERNEL
typedef	int ip_dn_ctl_t(struct sockopt *); /* raw_ip.c */
typedef	void ip_dn_ruledel_t(void *); /* ip_fw.c */
typedef	int ip_dn_io_t(int pipe, int dir, struct mbuf *m,
	struct ifnet *ifp, struct route *ro, struct sockaddr_in * dst,
	struct ip_fw *rule, int flags); /* ip_{in,out}put.c, bridge.c */
extern	ip_dn_ctl_t *ip_dn_ctl_ptr;
extern	ip_dn_ruledel_t *ip_dn_ruledel_ptr;
extern	ip_dn_io_t *ip_dn_io_ptr;
#define	DUMMYNET_LOADED	(ip_dn_io_ptr != NULL)
#endif

#endif /* _IP_DUMMYNET_H */