/*
 * linux/include/linux/sunrpc/svc.h
 *
 * RPC server declarations.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */


#ifndef SUNRPC_SVC_H
#define SUNRPC_SVC_H

#include <linux/in.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/wait.h>
#include <linux/mm.h>

/*
 * RPC service.
 *
 * An RPC service is a ``daemon,'' possibly multithreaded, which
 * receives and processes incoming RPC messages.
 * It has one or more transport sockets associated with it, and maintains
 * a list of idle threads waiting for input.
 *
 * We currently do not support more than one RPC program per daemon.
 */
struct svc_serv {
	struct list_head	sv_threads;	/* idle server threads */
	struct list_head	sv_sockets;	/* pending sockets */
	struct svc_program *	sv_program;	/* RPC program */
	struct svc_stat *	sv_stats;	/* RPC statistics */
	spinlock_t		sv_lock;
	unsigned int		sv_nrthreads;	/* # of server threads */
	unsigned int		sv_bufsz;	/* datagram buffer size */
	unsigned int		sv_xdrsize;	/* XDR buffer size */

	struct list_head	sv_permsocks;	/* all permanent sockets */
	struct list_head	sv_tempsocks;	/* all temporary sockets */
	int			sv_tmpcnt;	/* count of temporary sockets */

	char *			sv_name;	/* service name */
#ifndef __GENKSYMS__
	void			(*sv_shutdown)(struct svc_serv *serv);
						/* Callback to use when last
						 * thread exits.
						 */
	unsigned int		sv_maxconn;	/* max connections allowed or
						 * '0' causing max to be based
						 * on number of threads. */
#endif
};

/*
 * Maximum payload size supported by a kernel RPC server.
 * This is use to determine the max number of pages nfsd is
 * willing to return in a single READ operation.
 *
 * These happen to all be powers of 2, which is not strictly
 * necessary but helps enforce the real limitation, which is
 * that they should be multiples of PAGE_CACHE_SIZE.
 *
 * For UDP transports, a block plus NFS,RPC, and UDP headers
 * has to fit into the IP datagram limit of 64K.  The largest
 * feasible number for all known page sizes is probably 48K,
 * but we choose 32K here.  This is the same as the historical
 * Linux limit; someone who cares more about NFS/UDP performance
 * can test a larger number.
 *
 * For TCP transports we have more freedom.  A size of 1MB is
 * chosen to match the client limit.  Other OSes are known to
 * have larger limits, but those numbers are probably beyond
 * the point of diminishing returns.
 */
#define RPCSVC_MAXPAYLOAD	(1*1024*1024u)
#define RPCSVC_MAXPAYLOAD_TCP	RPCSVC_MAXPAYLOAD
#define RPCSVC_MAXPAYLOAD_UDP	(32*1024u)
#define OLD_RPCSVC_MAXPAYLOAD	(64*1024u)

extern u32 svc_max_payload(const struct svc_rqst *rqstp);

/*
 * RPC Requsts and replies are stored in one or more pages.
 * We maintain an array of pages for each server thread.
 * Requests are copied into these pages as they arrive.  Remaining
 * pages are available to write the reply into.
 *
 * Pages are sent using ->sendpage so each server thread needs to
 * allocate more to replace those used in sending.  To help keep track
 * of these pages we have a receive list where all pages initialy live,
 * and a send list where pages are moved to when there are to be part
 * of a reply.
 *
 * We use xdr_buf for holding responses as it fits well with NFS
 * read responses (that have a header, and some data pages, and possibly
 * a tail) and means we can share some client side routines.
 *
 * The xdr_buf.head kvec always points to the first page in the rq_*pages
 * list.  The xdr_buf.pages pointer points to the second page on that
 * list.  xdr_buf.tail points to the end of the first page.
 * This assumes that the non-page part of an rpc reply will fit
 * in a page - NFSd ensures this.  lockd also has no trouble.
 *
 * Each request/reply pair can have at most one "payload", plus two pages,
 * one for the request, and one for the reply.
 */
#define RPCSVC_MAXPAGES		((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE + 2)
#define OLD_RPCSVC_MAXPAGES	((OLD_RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE + 2)

static inline u32 svc_getu32(struct kvec *iov)
{
	u32 val, *vp;
	vp = iov->iov_base;
	val = *vp++;
	iov->iov_base = (void*)vp;
	iov->iov_len -= sizeof(u32);
	return val;
}

static inline void svc_ungetu32(struct kvec *iov)
{
	u32 *vp = (u32 *)iov->iov_base;
	iov->iov_base = (void *)(vp - 1);
	iov->iov_len += sizeof(*vp);
}

static inline void svc_putu32(struct kvec *iov, u32 val)
{
	u32 *vp = iov->iov_base + iov->iov_len;
	*vp = val;
	iov->iov_len += sizeof(u32);
}

	
/*
 * The context of a single thread, including the request currently being
 * processed.
 */
struct svc_rqst {
	struct list_head	rq_list;	/* idle list */
	struct svc_sock *	rq_sock;	/* socket */
	struct sockaddr_in	rq_addr;	/* peer address */
	int			rq_addrlen;

	struct svc_serv *	rq_server;	/* RPC service definition */
	struct svc_procedure *	rq_procinfo;	/* procedure info */
	struct auth_ops *	rq_authop;	/* authentication flavour */
	struct svc_cred		rq_cred;	/* auth info */
	struct sk_buff *	rq_skbuff;	/* fast recv inet buffer */
	struct svc_deferred_req*rq_deferred;	/* deferred request we are replaying */

	struct xdr_buf		rq_arg;
	struct xdr_buf		rq_res;
#ifdef __GENKSYMS__
	struct page *		rq_argpages[OLD_RPCSVC_MAXPAGES];
	struct page *		rq_respages[OLD_RPCSVC_MAXPAGES];
#else
	struct page *		rq_argpages_UNUSED[OLD_RPCSVC_MAXPAGES];
	struct page *		rq_respages_UNUSED[OLD_RPCSVC_MAXPAGES];
#endif
	int			rq_restailpage;
	short			rq_argused;	/* pages used for argument */
	short			rq_arghi;	/* pages available in argument page list */
	short			rq_resused;	/* pages used for result */

	u32			rq_xid;		/* transmission id */
	u32			rq_prog;	/* program number */
	u32			rq_vers;	/* program version */
	u32			rq_proc;	/* procedure number */
	u32			rq_prot;	/* IP protocol */
	unsigned short
				rq_secure  : 1;	/* secure port */


	__u32			rq_daddr;	/* dest addr of request - reply from here */

	void *			rq_argp;	/* decoded arguments */
	void *			rq_resp;	/* xdr'd results */
	void *			rq_auth_data;	/* flavor-specific data */

	int			rq_reserved;	/* space on socket outq
						 * reserved for this request
						 */

	struct cache_req	rq_chandle;	/* handle passed to caches for 
						 * request delaying 
						 */
	/* Catering to nfsd */
	struct auth_domain *	rq_client;	/* RPC peer info */
	struct svc_cacherep *	rq_cacherep;	/* cache info */
	struct knfsd_fh *	rq_reffh;	/* Referrence filehandle, used to
						 * determine what device number
						 * to report (real or virtual)
						 */
	int			rq_sendfile_ok; /* turned off in gss privacy
						 * to prevent encrypting page
						 * cache pages */
	wait_queue_head_t	rq_wait;	/* synchronization */
#ifndef __GENKSYMS__
	u32			rq_flavor;	/* pseudoflavor */
	struct auth_domain *	rq_gssclient;	/* "gss/"-style peer info */
	struct page *		rq_pages[RPCSVC_MAXPAGES];
	struct page *		*rq_respages;	/* points into rq_pages */
	struct kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
#endif
};

/*
 * Check buffer bounds after decoding arguments
 */
static inline int
xdr_argsize_check(struct svc_rqst *rqstp, u32 *p)
{
	char *cp = (char *)p;
	struct kvec *vec = &rqstp->rq_arg.head[0];
	return cp >= (char*)vec->iov_base
		&& cp <= (char*)vec->iov_base + vec->iov_len;
}

static inline int
xdr_ressize_check(struct svc_rqst *rqstp, u32 *p)
{
	struct kvec *vec = &rqstp->rq_res.head[0];
	char *cp = (char*)p;

	vec->iov_len = cp - (char*)vec->iov_base;

	return vec->iov_len <= PAGE_SIZE;
}

static inline void svc_free_res_pages(struct svc_rqst *rqstp)
{
	while (rqstp->rq_resused) {
		struct page **pp = (rqstp->rq_respages +
				    --rqstp->rq_resused);
		if (*pp) {
			put_page(*pp);
			*pp = NULL;
		}
	}
}

static inline void
svc_shutdown(struct svc_serv *serv, void (*shutdown)(struct svc_serv *serv))
{
	if (serv)
		serv->sv_shutdown = shutdown;
}

struct svc_deferred_req {
	u32			prot;	/* protocol (UDP or TCP) */
	struct sockaddr_in	addr;
	struct svc_sock		*svsk;	/* where reply must go */
	u32			daddr;	/* where reply must come from */
	struct cache_deferred_req handle;
	int			argslen;
	u32			args[0];
};

/*
 * List of RPC programs on the same transport endpoint
 */
struct svc_program {
	struct svc_program *	pg_next;	/* other programs (same xprt) */
	u32			pg_prog;	/* program number */
	unsigned int		pg_lovers;	/* lowest version */
	unsigned int		pg_hivers;	/* lowest version */
	unsigned int		pg_nvers;	/* number of versions */
	struct svc_version **	pg_vers;	/* version array */
	char *			pg_name;	/* service name */
	char *			pg_class;	/* class name: services sharing authentication */
	struct svc_stat *	pg_stats;	/* rpc statistics */
	int			(*pg_authenticate)(struct svc_rqst *);
};

/*
 * RPC program version
 */
struct svc_version {
	u32			vs_vers;	/* version number */
	u32			vs_nproc;	/* number of procedures */
	struct svc_procedure *	vs_proc;	/* per-procedure info */
	u32			vs_xdrsize;	/* xdrsize needed for this version */

	/* Override dispatch function (e.g. when caching replies).
	 * A return value of 0 means drop the request. 
	 * vs_dispatch == NULL means use default dispatcher.
	 */
	int			(*vs_dispatch)(struct svc_rqst *, u32 *);
};

/*
 * RPC procedure info
 */
typedef int	(*svc_procfunc)(struct svc_rqst *, void *argp, void *resp);
struct svc_procedure {
	svc_procfunc		pc_func;	/* process the request */
	kxdrproc_t		pc_decode;	/* XDR decode args */
	kxdrproc_t		pc_encode;	/* XDR encode result */
	kxdrproc_t		pc_release;	/* XDR free result */
	unsigned int		pc_argsize;	/* argument struct size */
	unsigned int		pc_ressize;	/* result struct size */
	unsigned int		pc_count;	/* call count */
	unsigned int		pc_cachetype;	/* cache info (NFS) */
	unsigned int		pc_xdrressize;	/* maximum size of XDR reply */
};

/*
 * This is the RPC server thread function prototype
 */
typedef void		(*svc_thread_fn)(struct svc_rqst *);

/*
 * Function prototypes.
 */
struct svc_serv *  svc_create(struct svc_program *, unsigned int);
int		   svc_create_thread(svc_thread_fn, struct svc_serv *);
void		   svc_exit_thread(struct svc_rqst *);
void		   svc_destroy(struct svc_serv *);
int		   svc_process(struct svc_serv *, struct svc_rqst *);
int		   svc_register(struct svc_serv *, int, unsigned short);
void		   svc_wake_up(struct svc_serv *);
void		   svc_reserve(struct svc_rqst *rqstp, int space);

/*
 * When we want to reduce the size of the reserved space in the response
 * buffer, we need to take into account the size of any checksum data that
 * may be at the end of the packet. This is difficult to determine exactly
 * for all cases without actually generating the checksum, so we just use a
 * static value.
 */
static inline void 
svc_reserve_auth(struct svc_rqst *rqstp, int space)
{
	int			added_space = 0;

	switch(rqstp->rq_authop->flavour) {
		case RPC_AUTH_GSS:
			added_space = RPC_MAX_AUTH_SIZE;
	}
	return svc_reserve(rqstp, space + added_space);
}

#endif /* SUNRPC_SVC_H */