/*
   * iSCSI over TCP/IP Data-Path lib
   *
   * Copyright (C) 2008 Mike Christie
   * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
   * maintained by open-iscsi@googlegroups.com
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published
   * by the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   * General Public License for more details.
   *
   * See the file COPYING included with this distribution for more details.
   */
  
  #ifndef LIBISCSI_TCP_H
  #define LIBISCSI_TCP_H
  
  #include <scsi/libiscsi.h>
  
  struct iscsi_tcp_conn;
  struct iscsi_segment;
  struct sk_buff;
  struct hash_desc;
  
  typedef int iscsi_segment_done_fn_t(struct iscsi_tcp_conn *,
  				    struct iscsi_segment *);
  
  struct iscsi_segment {
  	unsigned char		*data;
  	unsigned int		size;
  	unsigned int		copied;
  	unsigned int		total_size;
  	unsigned int		total_copied;
  
  	struct hash_desc	*hash;

  	unsigned char		padbuf[ISCSI_PAD_LEN];

  	unsigned char		recv_digest[ISCSI_DIGEST_SIZE];
  	unsigned char		digest[ISCSI_DIGEST_SIZE];
  	unsigned int		digest_len;
  
  	struct scatterlist	*sg;
  	void			*sg_mapped;
  	unsigned int		sg_offset;

  	bool			atomic_mapped;

  
  	iscsi_segment_done_fn_t	*done;
  };

  /* Socket connection receive helper */

  struct iscsi_tcp_recv {
  	struct iscsi_hdr	*hdr;
  	struct iscsi_segment	segment;
  
  	/* Allocate buffer for BHS + AHS */
  	uint32_t		hdr_buf[64];
  
  	/* copied and flipped values */
  	int			datalen;
  };
  
  struct iscsi_tcp_conn {
  	struct iscsi_conn	*iscsi_conn;
  	void			*dd_data;
  	int			stop_stage;	/* conn_stop() flag: *
  						 * stop to recover,  *
  						 * stop to terminate */
  	/* control data */
  	struct iscsi_tcp_recv	in;		/* TCP receive context */
  	/* CRC32C (Rx) LLD should set this is they do not offload */
  	struct hash_desc	*rx_hash;
  };
  
  struct iscsi_tcp_task {
  	uint32_t		exp_datasn;	/* expected target's R2TSN/DataSN */
  	int			data_offset;
  	struct iscsi_r2t_info	*r2t;		/* in progress solict R2T */
  	struct iscsi_pool	r2tpool;

  	struct kfifo		r2tqueue;

  	void			*dd_data;
  };
  
  enum {
  	ISCSI_TCP_SEGMENT_DONE,		/* curr seg has been processed */
  	ISCSI_TCP_SKB_DONE,		/* skb is out of data */
  	ISCSI_TCP_CONN_ERR,		/* iscsi layer has fired a conn err */
  	ISCSI_TCP_SUSPENDED,		/* conn is suspended */
  };
  
  extern void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn);
  extern int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
  			      unsigned int offset, bool offloaded, int *status);
  extern void iscsi_tcp_cleanup_task(struct iscsi_task *task);
  extern int iscsi_tcp_task_init(struct iscsi_task *task);
  extern int iscsi_tcp_task_xmit(struct iscsi_task *task);
  
  /* segment helpers */
  extern int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn);

  extern int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
  				  struct iscsi_segment *segment, int recv,

  				  unsigned copied);
  extern void iscsi_tcp_segment_unmap(struct iscsi_segment *segment);
  
  extern void iscsi_segment_init_linear(struct iscsi_segment *segment,
  				      void *data, size_t size,
  				      iscsi_segment_done_fn_t *done,
  				      struct hash_desc *hash);
  extern int
  iscsi_segment_seek_sg(struct iscsi_segment *segment,
  		      struct scatterlist *sg_list, unsigned int sg_count,
  		      unsigned int offset, size_t size,
  		      iscsi_segment_done_fn_t *done, struct hash_desc *hash);
  
  /* digest helpers */
  extern void iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr,
  				  size_t hdrlen,
  				  unsigned char digest[ISCSI_DIGEST_SIZE]);
  extern struct iscsi_cls_conn *
  iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
  		     uint32_t conn_idx);
  extern void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn);
  
  /* misc helpers */
  extern int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session);
  extern void iscsi_tcp_r2tpool_free(struct iscsi_session *session);

  extern int iscsi_tcp_set_max_r2t(struct iscsi_conn *conn, char *buf);

  extern void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
  				     struct iscsi_stats *stats);
  #endif /* LIBISCSI_TCP_H */