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/*
 * RFC 3720 (iSCSI) protocol data types
 *
 * Copyright (C) 2005 Dmitry Yusupov
 * Copyright (C) 2005 Alex Aizman
 * maintained by open-iscsi@googlegroups.com
 */

#ifndef ISCSI_PROTO_H
#define ISCSI_PROTO_H

#include <linux/types.h>
#include <scsi/scsi.h>

#define ISCSI_DRAFT20_VERSION	0x00

/* default iSCSI listen port for incoming connections */
#define ISCSI_LISTEN_PORT	3260

/* iSCSI header length */
#define ISCSI_HDR_LEN		48

/* iSCSI CRC32C length */
#define ISCSI_CRC_LEN		4

/* Padding word length */
#define ISCSI_PAD_LEN		4

/*
 * Serial Number Arithmetic, 32 bits, RFC1982
 */

static inline int iscsi_sna_lt(u32 n1, u32 n2)
{
	return (s32)(n1 - n2) < 0;
}

static inline int iscsi_sna_lte(u32 n1, u32 n2)
{
	return (s32)(n1 - n2) <= 0;
}

static inline int iscsi_sna_gt(u32 n1, u32 n2)
{
	return (s32)(n1 - n2) > 0;
}

static inline int iscsi_sna_gte(u32 n1, u32 n2)
{
	return (s32)(n1 - n2) >= 0;
}

/*
 * useful common(control and data paths) macro
 */
#define ntoh24(p) (((p)[0] << 16) | ((p)[1] << 8) | ((p)[2]))
#define hton24(p, v) { \
        p[0] = (((v) >> 16) & 0xFF); \
        p[1] = (((v) >> 8) & 0xFF); \
        p[2] = ((v) & 0xFF); \
}
#define zero_data(p) {p[0]=0;p[1]=0;p[2]=0;}

/* initiator tags; opaque for target */
typedef uint32_t __bitwise itt_t;
/* below makes sense only for initiator that created this tag */
#define build_itt(itt, age) ((__force itt_t)\
	((itt) | ((age) << ISCSI_AGE_SHIFT)))
#define get_itt(itt) ((__force uint32_t)(itt_t)(itt) & ISCSI_ITT_MASK)
#define RESERVED_ITT ((__force itt_t)0xffffffff)

/*
 * iSCSI Template Message Header
 */
struct iscsi_hdr {
	uint8_t		opcode;
	uint8_t		flags;		/* Final bit */
	uint8_t		rsvd2[2];
	uint8_t		hlength;	/* AHSs total length */
	uint8_t		dlength[3];	/* Data length */
	struct scsi_lun	lun;
	itt_t		itt;		/* Initiator Task Tag, opaque for target */
	__be32		ttt;		/* Target Task Tag */
	__be32		statsn;
	__be32		exp_statsn;
	__be32		max_statsn;
	uint8_t		other[12];
};

/************************* RFC 3720 Begin *****************************/

#define ISCSI_RESERVED_TAG		0xffffffff

/* Opcode encoding bits */
#define ISCSI_OP_RETRY			0x80
#define ISCSI_OP_IMMEDIATE		0x40
#define ISCSI_OPCODE_MASK		0x3F

/* Initiator Opcode values */
#define ISCSI_OP_NOOP_OUT		0x00
#define ISCSI_OP_SCSI_CMD		0x01
#define ISCSI_OP_SCSI_TMFUNC		0x02
#define ISCSI_OP_LOGIN			0x03
#define ISCSI_OP_TEXT			0x04
#define ISCSI_OP_SCSI_DATA_OUT		0x05
#define ISCSI_OP_LOGOUT			0x06
#define ISCSI_OP_SNACK			0x10

#define ISCSI_OP_VENDOR1_CMD		0x1c
#define ISCSI_OP_VENDOR2_CMD		0x1d
#define ISCSI_OP_VENDOR3_CMD		0x1e
#define ISCSI_OP_VENDOR4_CMD		0x1f

/* Target Opcode values */
#define ISCSI_OP_NOOP_IN		0x20
#define ISCSI_OP_SCSI_CMD_RSP		0x21
#define ISCSI_OP_SCSI_TMFUNC_RSP	0x22
#define ISCSI_OP_LOGIN_RSP		0x23
#define ISCSI_OP_TEXT_RSP		0x24
#define ISCSI_OP_SCSI_DATA_IN		0x25
#define ISCSI_OP_LOGOUT_RSP		0x26
#define ISCSI_OP_R2T			0x31
#define ISCSI_OP_ASYNC_EVENT		0x32
#define ISCSI_OP_REJECT			0x3f

struct iscsi_ahs_hdr {
	__be16 ahslength;
	uint8_t ahstype;
	uint8_t ahspec[5];
};

#define ISCSI_AHSTYPE_CDB		1
#define ISCSI_AHSTYPE_RLENGTH		2
#define ISCSI_CDB_SIZE			16

/* iSCSI PDU Header */
struct iscsi_scsi_req {
	uint8_t opcode;
	uint8_t flags;
	__be16 rsvd2;
	uint8_t hlength;
	uint8_t dlength[3];
	struct scsi_lun lun;
	itt_t	 itt;	/* Initiator Task Tag */
	__be32 data_length;
	__be32 cmdsn;
	__be32 exp_statsn;
	uint8_t cdb[ISCSI_CDB_SIZE];	/* SCSI Command Block */
	/* Additional Data (Command Dependent) */
};

/* Command PDU flags */
#define ISCSI_FLAG_CMD_FINAL		0x80
#define ISCSI_FLAG_CMD_READ		0x40
#define ISCSI_FLAG_CMD_WRITE		0x20
#define ISCSI_FLAG_CMD_ATTR_MASK	0x07	/* 3 bits */

/* SCSI Command Attribute values */
#define ISCSI_ATTR_UNTAGGED		0
#define ISCSI_ATTR_SIMPLE		1
#define ISCSI_ATTR_ORDERED		2
#define ISCSI_ATTR_HEAD_OF_QUEUE	3
#define ISCSI_ATTR_ACA			4

struct iscsi_rlength_ahdr {
	__be16 ahslength;
	uint8_t ahstype;
	uint8_t reserved;
	__be32 read_length;
};

/