/*
 <:copyright-BRCM:2016:DUAL/GPL:standard

 Broadcom Proprietary and Confidential.(c) 2016 Broadcom
 All Rights Reserved

 Unless you and Broadcom execute a separate written software license
 agreement governing use of this software, this software is licensed
 to you under the terms of the GNU General Public License version 2
 (the "GPL"), available at http://www.broadcom.com/licenses/GPLv2.php,
 with the following added to such license:

 As a special exception, the copyright holders of this software give
 you permission to link this software with independent modules, and
 to copy and distribute the resulting executable under terms of your
 choice, provided that you also meet, for each linked independent
 module, the terms and conditions of the license of that module.
 An independent module is a module which is not derived from this
 software.  The special exception does not apply to any modifications
 of the software.

 Not withstanding the above, under no circumstances may you combine
 this software in any way with any other Broadcom software provided
 under a license other than the GPL, without Broadcom's express prior
 written consent.

 :>
 */

#include "bcmos_system.h"
#include "bcmolt_model_types.h"
#include "bcmolt_api.h"
#include "oam_defs.h"
#include "bcmolt_math.h"
#include <encrypt_oam.h>

static const bcmos_mac_address slow_prot_mcast_mac =
{
    .u8 = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x02 }
};

static uint8_t oam_buffer[OAM_MAX_PACKET_SIZE];

static bcmos_bool oam_var_add_tlv_header(bcmolt_buf *buf, oam_var_branch branch, uint16_t leaf, uint8_t len)
{
    bcmos_bool ok = BCMOS_TRUE;
    uint8_t *snap = bcmolt_buf_snap_get(buf);

    ok = ok && (len <= OAM_MAX_TLV_LENGTH);
    ok = ok && bcmolt_buf_write_u8(buf, (uint8_t) branch);
    ok = ok && bcmolt_buf_write_u16_be(buf, leaf);
    ok = ok && bcmolt_buf_write_u8(buf, oam_var_tlv_length_encode(len));
    ok = ok && (bcmolt_buf_get_remaining_size(buf) >= len);
    if (!ok)
    {
        bcmolt_buf_snap_restore(buf, snap);
    }
    return ok;
}

static bcmos_bool dpoe_encrypt_tlv_add(bcmolt_buf *oambuf, uint16_t period, dpoe_encrypt_mode mode)
{
    bcmos_bool ok = BCMOS_TRUE;

    // encryption mode TLV
    ok = ok && oam_var_add_tlv_header(oambuf, OAM_VAR_BRANCH_DPOE_ATTRIBUTE, (uint16_t) OAM_DPOE_ATTR_ENCRYPT_MODE, 1);
    ok = ok && bcmolt_buf_write_u8(oambuf, (uint8_t) mode);

    /* Key Expiry Time TLV */
    ok = ok && oam_var_add_tlv_header(oambuf, OAM_VAR_BRANCH_DPOE_ATTRIBUTE, (uint16_t) OAM_DPOE_ATTR_KEY_EXPIRY_TIME, 2);
    ok = ok && bcmolt_buf_write_u16_be(oambuf, period);

    return ok;
}

static bcmos_bool oam_pdu_build_common(bcmos_mac_address pon_mac, bcmolt_buf *outbuf)
{
    bcmos_bool ok = BCMOS_TRUE;

    ok = ok && bcmolt_buf_write_mac_address(outbuf, slow_prot_mcast_mac);        // DA
    ok = ok && bcmolt_buf_write_mac_address(outbuf, pon_mac);                    // SA
    ok = ok && bcmolt_buf_write_u16_be(outbuf, ETHERTYPE_SLOWPROTOCOLS);         // Type
    ok = ok && bcmolt_buf_write_u8(outbuf, (uint8_t) SLOW_PROTOCOL_SUBTYPE_OAM); // Subtype

    return ok;
}

/* Sends OAM frame 'frame' to a link via the inject frame operation */
static bcmos_bool oam_pdu_transmit(const hde_key* hde_link, uint8_t *frame, uint16_t len)
{
    bcmolt_ethernet_frame_unmasked oam_frame;
    bcmolt_epon_link_inject_frame  inject_frame;

    oam_frame.frame_octets.len = len;
    oam_frame.frame_octets.val = frame;
    bcmolt_epon_link_key link_key =
    {
        .epon_ni = hde_link->epon_ni,
        .mac_address = hde_link->mac_addr
    };

    BCMOLT_PROXY_INIT(&inject_frame, epon_link, inject_frame, link_key);
    BCMOLT_PROXY_PROP_SET(&inject_frame, epon_link, inject_frame, frame, oam_frame);
    if (bcmolt_proxy_send(hde_link->device_id, &inject_frame.hdr) != BCM_ERR_OK)
    {
        return BCMOS_FALSE;
    }

    return BCMOS_TRUE;
}

static bcmos_bool oam_var_get_next(bcmolt_buf *buf, oam_var_generic *oamvar)
{
    bcmos_bool ok = BCMOS_TRUE;
    uint8_t branch = OAM_VAR_BRANCH_TERMINATION;

    memset(oamvar, 0, sizeof(*oamvar));
    ok = ok && (bcmolt_buf_get_remaining_size(buf) != 0);
    ok = ok && bcmolt_buf_read_u8(buf, &branch); // Read the branch.
    if (ok)
    {
        switch (branch)
        {
        case OAM_VAR_BRANCH_ATTRIBUTE:
        case OAM_VAR_BRANCH_ACTION:
        case OAM_VAR_BRANCH_DPOE_ACT:
        case OAM_VAR_BRANCH_DPOE_ATTRIBUTE:
        case OAM_VAR_BRANCH_DPOE_OBJECT:
            oamvar->branch = (oam_var_branch) branch;
            ok = ok && bcmolt_buf_read_u16_be(buf, &oamvar->leaf); // Read leaf
            ok = ok && bcmolt_buf_read_u8(buf, &oamvar->width); // Read Width
            oamvar->value = bcmolt_buf_snap_get(buf); // Keep the position of value
            oamvar->width = oam_var_tlv_length_encode(oamvar->width); // Re-encode width via OAM spec
            ok = ok && bcmolt_buf_skip(buf, oamvar->width); // Skip a 'width' amount
            break;

        case OAM_VAR_BRANCH_TERMINATION:
        default:
            ok = BCMOS_FALSE;
            break;
        }
    }

    ok = ok && bcmolt_buf_skip(buf, oamvar->width);
    return ok;
}

/* Loops through 'oam_resp' looking for the provided branch/leaf. If found it will return it. */
static bcmos_bool oam_var_get_branch_leaf(uint8_t *oam_resp, uint32_t oam_resp_len, oam_var_branch branch, uint16_t leaf, oam_var_generic *oam_var)
{
    bcmolt_buf buf;
    oam_var_generic var;

    bcmolt_buf_init(&buf, oam_resp_len, oam_resp, (bcmos_endian) BCMOLT_BUF_ENDIAN_FIXED);

    while (oam_var_get_next(&buf, &var)) // Keep going through all OAM vars.
    {
        if ((var.branch == branch) && (var.leaf == leaf)) // Check to see it is the one we are looking for.
        {
            *oam_var = var;
            return BCMOS_TRUE;
        }
    }
    return BCMOS_FALSE;
}

static bcmos_bool oam_parse_to_dpoe_opcode(bcmolt_buf *buf, oam_dpoe_opcode opcode)
{
    bcmos_bool ok = BCMOS_TRUE;
    uint24_t dpoe_oui = { .low_hi = { .hi = 0x00, .mid = 0x10, .low = 0x00 } };
    uint16_t u16;
    uint8_t u8;
    uint24_t u24;
    ok = ok && bcmolt_buf_skip(buf, 12); // Skip both mac addresses
    ok = ok && bcmolt_buf_read_u16_be(buf, &u16); // Read ethertype
    ok = ok && u16 == ETHERTYPE_SLOWPROTOCOLS; // Make sure it is slow protocol
    ok = ok && bcmolt_buf_read_u8(buf, &u8); // Read the subtype
    ok = ok && u8 == SLOW_PROTOCOL_SUBTYPE_OAM; // Make sure it is OAM
    ok = ok && bcmolt_buf_skip(buf, 2); // Skip flags
    ok = ok && bcmolt_buf_read_u8(buf, &u8); // Read the code
    ok = ok && u8 == OAM_PDU_CODE_ORG_EXT; // Make sure it is organization specific
    ok = ok && bcmolt_buf_read_u24(buf, &u24); // Read the OUI
    ok = ok && memcmp(&dpoe_oui, &u24, sizeof(uint24_t)) == 0; // Make sure it is the DPoE OUI
    ok = ok && bcmolt_buf_read_u8(buf, &u8); // Read the opcode
    ok = ok && opcode == u8; // Make sure it matches the provided opcode
    return ok;
}

bcmos_errno dpoe_encrypt_oam_set_request_send(const hde_key *hde_link, uint16_t period, dpoe_encrypt_mode encrypt_mode, bcmos_mac_address pon_mac)
{
    // send the encrypt mode and key expiry time TLVs to ONU.
    bcmolt_buf buf;
    ieee_oui dpoe_oui = { { 0x00, 0x10, 0x00 } };
    bcmos_bool ok = BCMOS_TRUE;

    memset(oam_buffer, 0, sizeof(oam_buffer));

    bcmolt_buf_init(&buf, OAM_MAX_PACKET_SIZE, oam_buffer, BCMOLT_BUF_ENDIAN_FIXED);
    ok = ok && oam_pdu_build_common(pon_mac, &buf);
    ok = ok && bcmolt_buf_write_u16_be(&buf, (uint16_t) OAM_PDU_FLAG_SEND_ANY); /* write flags */
    ok = ok && bcmolt_buf_write_u8(&buf, (uint8_t) OAM_PDU_CODE_ORG_EXT); /* write  code */
    ok = ok && bcmolt_buf_write(&buf, dpoe_oui.byte, 3); /* write oui */
    ok = ok && bcmolt_buf_write_u8(&buf, OAM_DPOE_OPCODE_SET_REQUEST); /* write opcode */
    ok = ok && dpoe_encrypt_tlv_add(&buf, period, encrypt_mode); /* write encryption TLVs */
    ok = ok && bcmolt_buf_write_u16_be(&buf, 0); /* write END */
    ok = ok && oam_pdu_transmit(hde_link, oam_buffer, MAX(bcmolt_buf_get_used(&buf), 60)); /* Send it */

    if (!ok)
    {
        return BCM_ERR_NOMEM;
    }
    else
    {
        return BCM_ERR_OK;
    }
    return ok;
}

bcmos_errno dpoe_encrypt_oam_parse_set_response(const bcmolt_u8_list_u32 *frame, uint8_t *encrypt_mode_response, uint8_t *key_expiry_response)
{
    oam_var_generic encrypt_mode;
    oam_var_generic key_expiry_time;
    bcmolt_buf buf;
    bcmolt_buf_init(&buf, frame->len, frame->val, BCMOLT_BUF_ENDIAN_FIXED);

    // Move the OAM buffer forward to the opcode
    if (!oam_parse_to_dpoe_opcode(&buf, OAM_DPOE_OPCODE_SET_RESPONSE))
    {
        return BCM_ERR_PARSE;
    }

    // Check for encrypt mode TLV
    if (!oam_var_get_branch_leaf(
        bcmolt_buf_snap_get(&buf),
        bcmolt_buf_get_remaining_size(&buf),
        OAM_VAR_BRANCH_DPOE_ATTRIBUTE,
        OAM_DPOE_ATTR_ENCRYPT_MODE,
        &encrypt_mode))
    {
        return BCM_ERR_PARSE;
    }

    // Check for key expiry time TLV
    if (!oam_var_get_branch_leaf(
        bcmolt_buf_snap_get(&buf),
        bcmolt_buf_get_remaining_size(&buf),
        OAM_VAR_BRANCH_DPOE_ATTRIBUTE,
        OAM_DPOE_ATTR_KEY_EXPIRY_TIME,
        &key_expiry_time))
    {
        return BCM_ERR_PARSE;
    }

    *encrypt_mode_response = encrypt_mode.width;
    *key_expiry_response = key_expiry_time.width;
    return BCM_ERR_OK;
}

bcmos_errno dpoe_encrypt_oam_parse_new_key(const bcmolt_u8_list_u32 *frame, uint8_t *new_key, bcmolt_epon_key_choice *key_choice)
{
    bcmos_bool ok = BCMOS_TRUE;
    uint8_t key_number;
    uint8_t key_length;
    bcmolt_buf buf;
    bcmolt_buf_init(&buf, frame->len, frame->val, BCMOLT_BUF_ENDIAN_FIXED);
    ok = oam_parse_to_dpoe_opcode(&buf, OAM_DPOE_OPCODE_KEY_EXCHANGE);
    ok = ok && bcmolt_buf_read_u8(&buf, &key_number); // Read key number
    ok = ok && bcmolt_buf_read_u8(&buf, &key_length); // Read key length
    ok = ok && key_length == 16; // Make sure the key is 16 byte length
    ok = ok && bcmolt_buf_read(&buf, new_key, 16); // Read the key

    if (!ok)
    {
        return BCM_ERR_PARSE;
    }

    if (key_number == 0)
    {
        *key_choice = BCMOLT_EPON_KEY_CHOICE_KEY_0;
    }
    else if (key_number == 1)
    {
        *key_choice = BCMOLT_EPON_KEY_CHOICE_KEY_1;
    }
    else
    {
        return BCM_ERR_PARSE;
    }

    return BCM_ERR_OK;
}