/*******************************************************************************
 * Filename:  target_core_fabric_lib.c
 *
 * This file contains generic high level protocol identifier and PR
 * handlers for TCM fabric modules
 *
 * (c) Copyright 2010-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@linux-iscsi.org>
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

/*
 * See SPC4, section 7.5 "Protocol specific parameters" for details
 * on the formats implemented in this file.
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <asm/unaligned.h>

#include <scsi/scsi_proto.h>

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>

#include "target_core_internal.h"
#include "target_core_pr.h"


static int sas_get_pr_transport_id(
        struct se_node_acl *nacl,
        int *format_code,
        unsigned char *buf)
{
        int ret;

        /* Skip over 'naa. prefix */
        ret = hex2bin(&buf[4], &nacl->initiatorname[4], 8);
        if (ret) {
                pr_debug("%s: invalid hex string\n", __func__);
                return ret;
        }

        return 24;
}

static int fc_get_pr_transport_id(
        struct se_node_acl *se_nacl,
        int *format_code,
        unsigned char *buf)
{
        unsigned char *ptr;
        int i, ret;
        u32 off = 8;

        /*
         * We convert the ASCII formatted N Port name into a binary
         * encoded TransportID.
         */
        ptr = &se_nacl->initiatorname[0];
        for (i = 0; i < 23; ) {
                if (!strncmp(&ptr[i], ":", 1)) {
                        i++;
                        continue;
                }
                ret = hex2bin(&buf[off++], &ptr[i], 1);
                if (ret < 0) {
                        pr_debug("%s: invalid hex string\n", __func__);
                        return ret;
                }
                i += 2;
        }
        /*
         * The FC Transport ID is a hardcoded 24-byte length
         */
        return 24;
}

static int sbp_get_pr_transport_id(
        struct se_node_acl *nacl,
        int *format_code,
        unsigned char *buf)
{
        int ret;

        ret = hex2bin(&buf[8], nacl->initiatorname, 8);
        if (ret) {
                pr_debug("%s: invalid hex string\n", __func__);
                return ret;
        }

        return 24;
}

static int srp_get_pr_transport_id(
        struct se_node_acl *nacl,
        int *format_code,
        unsigned char *buf)
{
        const char *p;
        unsigned len, count, leading_zero_bytes;
        int rc;

        p = nacl->initiatorname;
        if (strncasecmp(p, "0x", 2) == 0)
                p += 2;
        len = strlen(p);
        if (len % 2)
                return -EINVAL;

        count = min(len / 2, 16U);
        leading_zero_bytes = 16 - count;
        memset(buf + 8, 0, leading_zero_bytes);
        rc = hex2bin(buf + 8 + leading_zero_bytes, p, count);
        if (rc < 0) {
                pr_debug("hex2bin failed for %s: %d\n", p, rc);
                return rc;
        }

        return 24;
}

static int iscsi_get_pr_transport_id(
        struct se_node_acl *se_nacl,
        struct t10_pr_registration *pr_reg,
        int *format_code,
        unsigned char *buf)
{
        u32 off = 4, padding = 0;
        int isid_len;
        u16 len = 0;

        spin_lock_irq(&se_nacl->nacl_sess_lock);
        /*
         * Only null terminate the last field.
         *
         * From spc4r37 section 7.6.4.6: TransportID for initiator ports using
         * SCSI over iSCSI.
         *
         * Table 507 TPID=0 Initiator device TransportID
         *
         * The null-terminated, null-padded (see 4.3.2) ISCSI NAME field shall
         * contain the iSCSI name of an iSCSI initiator node (see RFC 7143).
         * The first ISCSI NAME field byte containing an ASCII null character
         * terminates the ISCSI NAME field without regard for the specified
         * length of the iSCSI TransportID or the contents of the ADDITIONAL
         * LENGTH field.
         */
        len = sprintf(&buf[off], "%s", se_nacl->initiatorname);
        off += len;
        if ((*format_code == 1) && (pr_reg->isid_present_at_reg)) {
                /*
                 * Set FORMAT CODE 01b for iSCSI Initiator port TransportID
                 * format.
                 */
                buf[0] |= 0x40;
                /*
                 * From spc4r37 Section 7.6.4.6
                 *
                 * Table 508 TPID=1 Initiator port TransportID.
                 *
                 * The ISCSI NAME field shall not be null-terminated
                 * (see 4.3.2) and shall not be padded.
                 *
                 * The SEPARATOR field shall contain the five ASCII
                 * characters ",i,0x".
                 *
                 * The null-terminated, null-padded ISCSI INITIATOR SESSION ID
                 * field shall contain the iSCSI initiator session identifier
                 * (see RFC 3720) in the form of ASCII characters that are the
                 * hexadecimal digits converted from the binary iSCSI initiator
                 * session identifier value. The first ISCSI INITIATOR SESSION
                 * ID field byte containing an ASCII null character terminates
                 * the ISCSI INITIATOR SESSION ID field without regard for the
                 * specified length of the iSCSI TransportID or the contents
                 * of the ADDITIONAL LENGTH field.
                 */
                buf[off++] = 0x2c; /* ASCII Character: "," */
                buf[off++] = 0x69; /* ASCII Character: "i" */
                buf[off++] = 0x2c; /* ASCII Character: "," */
                buf[off++] = 0x30; /* ASCII Character: "0" */
                buf[off++] = 0x78; /* ASCII Character: "x" */
                len += 5;

                isid_len = sprintf(buf + off, "%s", pr_reg->pr_reg_isid);
                off += isid_len;
                len += isid_len;
        }
        buf[off] = '\0';
        len += 1;
        spin_unlock_irq(&se_nacl->nacl_sess_lock);
        /*
         * The ADDITIONAL LENGTH field specifies the number of bytes that follow
         * in the TransportID. The additional length shall be at least 20 and
         * shall be a multiple of four.
        */
        padding = ((-len) & 3);
        if (padding != 0)
                len += padding;

        put_unaligned_be16(len, &buf[2]);
        /*
         * Increment value for total payload + header length for
         * full status descriptor
         */
        len += 4;

        return len;
}

static int iscsi_get_pr_transport_id_len(
        struct se_node_acl *se_nacl,
        struct t10_pr_registration *pr_reg,
        int *format_code)
{
        u32 len = 0, padding = 0;

        spin_lock_irq(&se_nacl->nacl_sess_lock);
        len = strlen(se_nacl->initiatorname);
        /*
         * Add extra byte for NULL terminator
         */
        len++;
        /*
         * If there is ISID present with the registration, use format code:
         * 01b: iSCSI Initiator port TransportID format
         *
         * If there is not an active iSCSI session, use format code:
         * 00b: iSCSI Initiator device TransportID format
         */
        if (pr_reg->isid_present_at_reg) {
                len += 5; /* For ",i,0x" ASCII separator */
                len += strlen(pr_reg->pr_reg_isid);
                *format_code = 1;
        } else
                *format_code = 0;
        spin_unlock_irq(&se_nacl->nacl_sess_lock);
        /*
         * The ADDITIONAL LENGTH field specifies the number of bytes that follow
         * in the TransportID. The additional length shall be at least 20 and
         * shall be a multiple of four.
         */
        padding = ((-len) & 3);
        if (padding != 0)
                len += padding;
        /*
         * Increment value for total payload + header length for
         * full status descriptor
         */
        len += 4;

        return len;
}

static char *iscsi_parse_pr_out_transport_id(
        struct se_portal_group *se_tpg,
        char *buf,
        u32 *out_tid_len,
        char **port_nexus_ptr)
{
        char *p;
        int i;
        u8 format_code = (buf[0] & 0xc0);
        /*
         * Check for FORMAT CODE 00b or 01b from spc4r17, section 7.5.4.6:
         *
         *       TransportID for initiator ports using SCSI over iSCSI,
         *       from Table 388 -- iSCSI TransportID formats.
         *
         *    00b     Initiator port is identified using the world wide unique
         *            SCSI device name of the iSCSI initiator
         *            device containing the initiator port (see table 389).
         *    01b     Initiator port is identified using the world wide unique
         *            initiator port identifier (see table 390).10b to 11b
         *            Reserved
         */
        if ((format_code != 0x00) && (format_code != 0x40)) {
                pr_err("Illegal format code: 0x%02x for iSCSI"
                        " Initiator Transport ID\n", format_code);
                return NULL;
        }
        /*
         * If the caller wants the TransportID Length, we set that value for the
         * entire iSCSI Tarnsport ID now.
         */
        if (out_tid_len) {
                /* The shift works thanks to integer promotion rules */
                *out_tid_len = get_unaligned_be16(&buf[2]);
                /* Add four bytes for iSCSI Transport ID header */
                *out_tid_len += 4;
        }

        /*
         * Check for ',i,0x' separator between iSCSI Name and iSCSI Initiator
         * Session ID as defined in Table 390 - iSCSI initiator port TransportID
         * format.
         */
        if (format_code == 0x40) {
                p = strstr(&buf[4], ",i,0x");
                if (!p) {
                        pr_err("Unable to locate \",i,0x\" separator"
                                " for Initiator port identifier: %s\n",
                                &buf[4]);
                        return NULL;
                }
                *p = '\0'; /* Terminate iSCSI Name */
                p += 5; /* Skip over ",i,0x" separator */

                *port_nexus_ptr = p;
                /*
                 * Go ahead and do the lower case conversion of the received
                 * 12 ASCII characters representing the ISID in the TransportID
                 * for comparison against the running iSCSI session's ISID from
                 * iscsi_target.c:lio_sess_get_initiator_sid()
                 */
                for (i = 0; i < 12; i++) {
                        /*
                         * The first ISCSI INITIATOR SESSION ID field byte
                         * containing an ASCII null character terminates the
                         * ISCSI INITIATOR SESSION ID field without regard for
                         * the specified length of the iSCSI TransportID or the
                         * contents of the ADDITIONAL LENGTH field.
                         */
                        if (*p == '\0')
                                break;

                        if (isdigit(*p)) {
                                p++;
                                continue;
                        }
                        *p = tolower(*p);
                        p++;
                }
        } else
                *port_nexus_ptr = NULL;

        return &buf[4];
}

int target_get_pr_transport_id_len(struct se_node_acl *nacl,
                struct t10_pr_registration *pr_reg, int *format_code)
{
        switch (nacl->se_tpg->proto_id) {
        case SCSI_PROTOCOL_FCP:
        case SCSI_PROTOCOL_SBP:
        case SCSI_PROTOCOL_SRP:
        case SCSI_PROTOCOL_SAS:
                break;
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_get_pr_transport_id_len(nacl, pr_reg, format_code);
        default:
                pr_err("Unknown proto_id: 0x%02x\n", nacl->se_tpg->proto_id);
                return -EINVAL;
        }

        /*
         * Most transports use a fixed length 24 byte identifier.
         */
        *format_code = 0;
        return 24;
}

int target_get_pr_transport_id(struct se_node_acl *nacl,
                struct t10_pr_registration *pr_reg, int *format_code,
                unsigned char *buf)
{
        switch (nacl->se_tpg->proto_id) {
        case SCSI_PROTOCOL_SAS:
                return sas_get_pr_transport_id(nacl, format_code, buf);
        case SCSI_PROTOCOL_SBP:
                return sbp_get_pr_transport_id(nacl, format_code, buf);
        case SCSI_PROTOCOL_SRP:
                return srp_get_pr_transport_id(nacl, format_code, buf);
        case SCSI_PROTOCOL_FCP:
                return fc_get_pr_transport_id(nacl, format_code, buf);
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_get_pr_transport_id(nacl, pr_reg, format_code,
                                buf);
        default:
                pr_err("Unknown proto_id: 0x%02x\n", nacl->se_tpg->proto_id);
                return -EINVAL;
        }
}

const char *target_parse_pr_out_transport_id(struct se_portal_group *tpg,
                char *buf, u32 *out_tid_len, char **port_nexus_ptr)
{
        u32 offset;

        switch (tpg->proto_id) {
        case SCSI_PROTOCOL_SAS:
                /*
                 * Assume the FORMAT CODE 00b from spc4r17, 7.5.4.7 TransportID
                 * for initiator ports using SCSI over SAS Serial SCSI Protocol.
                 */
                offset = 4;
                break;
        case SCSI_PROTOCOL_SBP:
        case SCSI_PROTOCOL_SRP:
        case SCSI_PROTOCOL_FCP:
                offset = 8;
                break;
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_parse_pr_out_transport_id(tpg, buf, out_tid_len,
                                        port_nexus_ptr);
        default:
                pr_err("Unknown proto_id: 0x%02x\n", tpg->proto_id);
                return NULL;
        }

        *port_nexus_ptr = NULL;
        *out_tid_len = 24;
        return buf + offset;
}