boot/boot_serial/src/boot_serial.c

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
#include <assert.h>
#include <stddef.h>
#include <inttypes.h>
#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <limits.h>

#include "sysflash/sysflash.h"

#include "bootutil/bootutil_log.h"

#ifdef __ZEPHYR__
#include <zephyr/sys/reboot.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/sys/__assert.h>
#include <zephyr/drivers/flash.h>
#include <zephyr/kernel.h>
#include <zephyr/sys/crc.h>
#include <zephyr/sys/base64.h>
#include <hal/hal_flash.h>
#elif __ESPRESSIF__
#include <bootloader_utility.h>
#include <esp_rom_sys.h>
#include <esp_crc.h>
#include <endian.h>
#include <mbedtls/base64.h>
#else
#include <bsp/bsp.h>
#include <hal/hal_system.h>
#include <hal/hal_flash.h>
#include <os/endian.h>
#include <os/os_cputime.h>
#include <crc/crc16.h>
#include <base64/base64.h>
#endif /* __ZEPHYR__ */

#include <zcbor_decode.h>
#include <zcbor_encode.h>
#include "zcbor_bulk.h"

#include <flash_map_backend/flash_map_backend.h>
#include <os/os.h>
#include <os/os_malloc.h>

#include <bootutil/image.h>
#include <bootutil/bootutil.h>

#include "boot_serial/boot_serial.h"
#include "boot_serial_priv.h"
#include "mcuboot_config/mcuboot_config.h"

#ifdef MCUBOOT_ERASE_PROGRESSIVELY
#include "bootutil_priv.h"
#endif

#ifdef MCUBOOT_ENC_IMAGES
#include "boot_serial/boot_serial_encryption.h"
#endif

#include "bootutil/boot_hooks.h"

BOOT_LOG_MODULE_DECLARE(mcuboot);

#ifndef ARRAY_SIZE
#define ARRAY_SIZE ZCBOR_ARRAY_SIZE
#endif

#ifndef MCUBOOT_SERIAL_MAX_RECEIVE_SIZE
#define MCUBOOT_SERIAL_MAX_RECEIVE_SIZE 512
#endif

#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
#define BOOT_SERIAL_IMAGE_STATE_SIZE_MAX 48
#else
#define BOOT_SERIAL_IMAGE_STATE_SIZE_MAX 0
#endif
#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
#define BOOT_SERIAL_HASH_SIZE_MAX 36
#else
#define BOOT_SERIAL_HASH_SIZE_MAX 0
#endif

#define BOOT_SERIAL_OUT_MAX     ((128 + BOOT_SERIAL_IMAGE_STATE_SIZE_MAX + \
                                  BOOT_SERIAL_HASH_SIZE_MAX) * BOOT_IMAGE_NUMBER)

#define BOOT_SERIAL_FRAME_MTU   124 /* 127 - pkt start (2 bytes) and stop (1 byte) */

#ifdef __ZEPHYR__
/* base64 lib encodes data to null-terminated string */
#define BASE64_ENCODE_SIZE(in_size) ((((((in_size) - 1) / 3) * 4) + 4) + 1)

#define CRC16_INITIAL_CRC       0       /* what to seed crc16 with */
#define CRC_CITT_POLYMINAL 0x1021

#define ntohs(x) sys_be16_to_cpu(x)
#define htons(x) sys_cpu_to_be16(x)
#elif __ESPRESSIF__
#define BASE64_ENCODE_SIZE(in_size) ((((((in_size) - 1) / 3) * 4) + 4) + 1)
#define CRC16_INITIAL_CRC       0       /* what to seed crc16 with */

#define ntohs(x) be16toh(x)
#define htons(x) htobe16(x)

#define base64_decode mbedtls_base64_decode
#define base64_encode mbedtls_base64_encode
#endif

#if (BOOT_IMAGE_NUMBER > 1)
#define IMAGES_ITER(x) for ((x) = 0; (x) < BOOT_IMAGE_NUMBER; ++(x))
#else
#define IMAGES_ITER(x)
#endif

static char in_buf[MCUBOOT_SERIAL_MAX_RECEIVE_SIZE + 1];
static char dec_buf[MCUBOOT_SERIAL_MAX_RECEIVE_SIZE + 1];
const struct boot_uart_funcs *boot_uf;
static struct nmgr_hdr *bs_hdr;
static bool bs_entry;

static char bs_obuf[BOOT_SERIAL_OUT_MAX];

static void boot_serial_output(void);

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
static int boot_serial_get_hash(const struct image_header *hdr,
                                const struct flash_area *fap, uint8_t *hash);
#endif

static zcbor_state_t cbor_state[2];

void reset_cbor_state(void)
{
    zcbor_new_encode_state(cbor_state, 2, (uint8_t *)bs_obuf,
        sizeof(bs_obuf), 0);
}

/**
 * Function that processes MGMT_GROUP_ID_PERUSER mcumgr group and may be
 * used to process any groups that have not been processed by generic boot
 * serial implementation.
 *
 * @param[in] hdr -- the decoded header of mcumgr message;
 * @param[in] buffer -- buffer with first mcumgr message;
 * @param[in] len -- length of of data in buffer;
 * @param[out] *cs -- object with encoded response.
 *
 * @return 0 on success; non-0 error code otherwise.
 */
extern int bs_peruser_system_specific(const struct nmgr_hdr *hdr,
                                      const char *buffer,
                                      int len, zcbor_state_t *cs);

#define zcbor_tstr_put_lit_cast(state, string) \
	zcbor_tstr_encode_ptr(state, (char *)string, sizeof(string) - 1)

#ifndef MCUBOOT_USE_SNPRINTF
/*
 * Convert version into string without use of snprintf().
 */
static int
u32toa(char *tgt, uint32_t val)
{
    char *dst;
    uint32_t d = 1;
    uint32_t dgt;
    int n = 0;

    dst = tgt;
    while (val / d >= 10) {
        d *= 10;
    }
    while (d) {
        dgt = val / d;
        val %= d;
        d /= 10;
        if (n || dgt > 0 || d == 0) {
            *dst++ = dgt + '0';
            ++n;
        }
    }
    *dst = '\0';

    return dst - tgt;
}

/*
 * dst has to be able to fit "255.255.65535.4294967295" (25 characters).
 */
static void
bs_list_img_ver(char *dst, int maxlen, struct image_version *ver)
{
    int off;

    off = u32toa(dst, ver->iv_major);
    dst[off++] = '.';
    off += u32toa(dst + off, ver->iv_minor);
    dst[off++] = '.';
    off += u32toa(dst + off, ver->iv_revision);

    if (ver->iv_build_num != 0) {
        dst[off++] = '.';
        off += u32toa(dst + off, ver->iv_build_num);
    }
}
#else
/*
 * dst has to be able to fit "255.255.65535.4294967295" (25 characters).
 */
static void
bs_list_img_ver(char *dst, int maxlen, struct image_version *ver)
{
   int len;

   len = snprintf(dst, maxlen, "%hu.%hu.%hu", (uint16_t)ver->iv_major,
                  (uint16_t)ver->iv_minor, ver->iv_revision);

   if (ver->iv_build_num != 0 && len > 0 && len < maxlen) {
      snprintf(&dst[len], (maxlen - len), "%u", ver->iv_build_num);
   }
}
#endif /* !MCUBOOT_USE_SNPRINTF */

/*
 * List images.
 */
static void
bs_list(char *buf, int len)
{
    struct image_header hdr;
    uint32_t slot, area_id;
    const struct flash_area *fap;
    uint8_t image_index;
#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
    uint8_t hash[32];
#endif

    zcbor_map_start_encode(cbor_state, 1);
    zcbor_tstr_put_lit_cast(cbor_state, "images");
    zcbor_list_start_encode(cbor_state, 5);
    image_index = 0;
    IMAGES_ITER(image_index) {
#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
        int swap_status = boot_swap_type_multi(image_index);
#endif

        for (slot = 0; slot < 2; slot++) {
            FIH_DECLARE(fih_rc, FIH_FAILURE);
            uint8_t tmpbuf[64];

#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
            bool active = false;
            bool confirmed = false;
            bool pending = false;
            bool permanent = false;
#endif

            area_id = flash_area_id_from_multi_image_slot(image_index, slot);
            if (flash_area_open(area_id, &fap)) {
                continue;
            }

            int rc = BOOT_HOOK_CALL(boot_read_image_header_hook,
                                    BOOT_HOOK_REGULAR, image_index, slot, &hdr);
            if (rc == BOOT_HOOK_REGULAR)
            {
                flash_area_read(fap, 0, &hdr, sizeof(hdr));
            }

            if (hdr.ih_magic == IMAGE_MAGIC)
            {
                BOOT_HOOK_CALL_FIH(boot_image_check_hook,
                                   FIH_BOOT_HOOK_REGULAR,
                                   fih_rc, image_index, slot);
                if (FIH_EQ(fih_rc, FIH_BOOT_HOOK_REGULAR))
                {
#ifdef MCUBOOT_ENC_IMAGES
                    if (IS_ENCRYPTED(&hdr)) {
                        FIH_CALL(boot_image_validate_encrypted, fih_rc, fap,
                                 &hdr, tmpbuf, sizeof(tmpbuf));
                    } else {
#endif
                        FIH_CALL(bootutil_img_validate, fih_rc, NULL, 0, &hdr,
                                 fap, tmpbuf, sizeof(tmpbuf), NULL, 0, NULL);
#ifdef MCUBOOT_ENC_IMAGES
                    }
#endif
                }
            }

            if (FIH_NOT_EQ(fih_rc, FIH_SUCCESS)) {
                flash_area_close(fap);
                continue;
            }

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
            /* Retrieve SHA256 hash of image for identification */
            rc = boot_serial_get_hash(&hdr, fap, hash);
#endif

            flash_area_close(fap);
            zcbor_map_start_encode(cbor_state, 20);

#if (BOOT_IMAGE_NUMBER > 1)
            zcbor_tstr_put_lit_cast(cbor_state, "image");
            zcbor_uint32_put(cbor_state, image_index);
#endif

#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
            if (swap_status == BOOT_SWAP_TYPE_NONE) {
                if (slot == BOOT_PRIMARY_SLOT) {
                    confirmed = true;
                    active = true;
                }
            } else if (swap_status == BOOT_SWAP_TYPE_TEST) {
                if (slot == BOOT_PRIMARY_SLOT) {
                    confirmed = true;
                } else {
                    pending = true;
                }
            } else if (swap_status == BOOT_SWAP_TYPE_PERM) {
                if (slot == BOOT_PRIMARY_SLOT) {
                    confirmed = true;
                } else {
                    pending = true;
                    permanent = true;
                }
            } else if (swap_status == BOOT_SWAP_TYPE_REVERT) {
                if (slot == BOOT_PRIMARY_SLOT) {
                    active = true;
                } else {
                    confirmed = true;
                }
            }

            if (!(hdr.ih_flags & IMAGE_F_NON_BOOTABLE)) {
                zcbor_tstr_put_lit_cast(cbor_state, "bootable");
                zcbor_bool_put(cbor_state, true);
            }

            if (confirmed) {
                zcbor_tstr_put_lit_cast(cbor_state, "confirmed");
                zcbor_bool_put(cbor_state, true);
            }

            if (active) {
                zcbor_tstr_put_lit_cast(cbor_state, "active");
                zcbor_bool_put(cbor_state, true);
            }

            if (pending) {
                zcbor_tstr_put_lit_cast(cbor_state, "pending");
                zcbor_bool_put(cbor_state, true);
            }

            if (permanent) {
                zcbor_tstr_put_lit_cast(cbor_state, "permanent");
                zcbor_bool_put(cbor_state, true);
            }
#endif

            zcbor_tstr_put_lit_cast(cbor_state, "slot");
            zcbor_uint32_put(cbor_state, slot);

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
            if (rc == 0) {
                zcbor_tstr_put_lit_cast(cbor_state, "hash");
                zcbor_bstr_encode_ptr(cbor_state, hash, sizeof(hash));
            }
#endif

            zcbor_tstr_put_lit_cast(cbor_state, "version");

            bs_list_img_ver((char *)tmpbuf, sizeof(tmpbuf), &hdr.ih_ver);

            zcbor_tstr_encode_ptr(cbor_state, (char *)tmpbuf, strlen((char *)tmpbuf));
            zcbor_map_end_encode(cbor_state, 20);
        }
    }
    zcbor_list_end_encode(cbor_state, 5);
    zcbor_map_end_encode(cbor_state, 1);
    boot_serial_output();
}

#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
/*
 * Set image state.
 */
static void
bs_set(char *buf, int len)
{
    /*
     * Expected data format.
     * {
     *   "confirm":<true for confirm, false for test>
     *   "hash":<hash of image (OPTIONAL for single image only)>
     * }
     */
    uint8_t image_index = 0;
    size_t decoded = 0;
    uint8_t hash[32];
    bool confirm;
    struct zcbor_string img_hash;
    bool ok;
    int rc;

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
    bool found = false;
#endif

    zcbor_state_t zsd[4];
    zcbor_new_state(zsd, sizeof(zsd) / sizeof(zcbor_state_t), (uint8_t *)buf, len, 1);

    struct zcbor_map_decode_key_val image_set_state_decode[] = {
        ZCBOR_MAP_DECODE_KEY_DECODER("confirm", zcbor_bool_decode, &confirm),
#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
        ZCBOR_MAP_DECODE_KEY_DECODER("hash", zcbor_bstr_decode, &img_hash),
#endif
    };

    ok = zcbor_map_decode_bulk(zsd, image_set_state_decode, ARRAY_SIZE(image_set_state_decode),
                               &decoded) == 0;

    if (!ok) {
        rc = MGMT_ERR_EINVAL;
        goto out;
    }

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
    if ((img_hash.len != sizeof(hash) && img_hash.len != 0) ||
        (img_hash.len == 0 && BOOT_IMAGE_NUMBER > 1)) {
        /* Hash is required and was not provided or is invalid size */
        rc = MGMT_ERR_EINVAL;
        goto out;
    }

    if (img_hash.len != 0) {
        for (image_index = 0; image_index < BOOT_IMAGE_NUMBER; ++image_index) {
            struct image_header hdr;
            uint32_t area_id;
            const struct flash_area *fap;
            uint8_t tmpbuf[64];

            area_id = flash_area_id_from_multi_image_slot(image_index, 1);
            if (flash_area_open(area_id, &fap)) {
                BOOT_LOG_ERR("Failed to open flash area ID %d", area_id);
                continue;
            }

            rc = BOOT_HOOK_CALL(boot_read_image_header_hook,
                                BOOT_HOOK_REGULAR, image_index, 1, &hdr);
            if (rc == BOOT_HOOK_REGULAR)
            {
                flash_area_read(fap, 0, &hdr, sizeof(hdr));
            }

            if (hdr.ih_magic == IMAGE_MAGIC)
            {
                FIH_DECLARE(fih_rc, FIH_FAILURE);

                BOOT_HOOK_CALL_FIH(boot_image_check_hook,
                                   FIH_BOOT_HOOK_REGULAR,
                                   fih_rc, image_index, 1);
                if (FIH_EQ(fih_rc, FIH_BOOT_HOOK_REGULAR))
                {
#ifdef MCUBOOT_ENC_IMAGES
                    if (IS_ENCRYPTED(&hdr)) {
                        FIH_CALL(boot_image_validate_encrypted, fih_rc, fap,
                                 &hdr, tmpbuf, sizeof(tmpbuf));
                    } else {
#endif
                        FIH_CALL(bootutil_img_validate, fih_rc, NULL, 0, &hdr,
                                 fap, tmpbuf, sizeof(tmpbuf), NULL, 0, NULL);
#ifdef MCUBOOT_ENC_IMAGES
                    }
#endif
                }

                if (FIH_NOT_EQ(fih_rc, FIH_SUCCESS)) {
                    continue;
                }
            }

            /* Retrieve SHA256 hash of image for identification */
            rc = boot_serial_get_hash(&hdr, fap, hash);
            flash_area_close(fap);

            if (rc == 0 && memcmp(hash, img_hash.value, sizeof(hash)) == 0) {
                /* Hash matches, set this slot for test or confirmation */
                found = true;
                break;
            }
        }

        if (!found) {
            /* Image was not found with specified hash */
            BOOT_LOG_ERR("Did not find image with specified hash");
            rc = MGMT_ERR_ENOENT;
            goto out;
        }
    }
#endif

    rc = boot_set_pending_multi(image_index, confirm);

out:
    if (rc == 0) {
        /* Success - return updated list of images */
        bs_list(buf, len);
    } else {
        /* Error code, only return the error */
        zcbor_map_start_encode(cbor_state, 10);
        zcbor_tstr_put_lit_cast(cbor_state, "rc");
        zcbor_int32_put(cbor_state, rc);
        zcbor_map_end_encode(cbor_state, 10);

        boot_serial_output();
    }
}
#endif

/*
 * Send rc code only.
 */
static void
bs_rc_rsp(int rc_code)
{
    zcbor_map_start_encode(cbor_state, 10);
    zcbor_tstr_put_lit_cast(cbor_state, "rc");
    zcbor_int32_put(cbor_state, rc_code);
    zcbor_map_end_encode(cbor_state, 10);
    boot_serial_output();
}

static void
bs_list_set(uint8_t op, char *buf, int len)
{
    if (op == NMGR_OP_READ) {
        bs_list(buf, len);
    } else {
#ifdef MCUBOOT_SERIAL_IMG_GRP_IMAGE_STATE
        bs_set(buf, len);
#else
        bs_rc_rsp(MGMT_ERR_ENOTSUP);
#endif
    }
}

#ifdef MCUBOOT_ERASE_PROGRESSIVELY
/** Erases range of flash, aligned to sector size
 *
 * Function will erase all sectors withing [start, end] range; it does not check
 * the @p start for alignment, and it will use @p end to find boundaries of las
 * sector to erase. Function returns offset of the first byte past the last
 * erased sector, so basically offset of next sector to be erased if needed.
 * The function is intended to be called iteratively with previously returned
 * offset as @p start.
 *
 * @param   start starting offset, aligned to sector offset;
 * @param   end ending offset, maybe anywhere within sector;
 *
 * @retval On success: offset of the first byte past last erased sector;
 *         On failure: -EINVAL.
 */
static off_t erase_range(const struct flash_area *fap, off_t start, off_t end)
{
    struct flash_sector sect;
    size_t size;
    int rc;

    if (end >= flash_area_get_size(fap)) {
        return -EINVAL;
    }

    if (end < start) {
        return start;
    }

    if (flash_area_get_sector(fap, end, &sect)) {
        return -EINVAL;
    }

    size = flash_sector_get_off(&sect) + flash_sector_get_size(&sect) - start;
    BOOT_LOG_INF("Erasing range 0x%jx:0x%jx", (intmax_t)start,
		 (intmax_t)(start + size - 1));

    rc = flash_area_erase(fap, start, size);
    if (rc != 0) {
        BOOT_LOG_ERR("Error %d while erasing range", rc);
        return -EINVAL;
    }

    return start + size;
}
#endif

/*
 * Image upload request.
 */
static void
bs_upload(char *buf, int len)
{
    static size_t img_size;             /* Total image size, held for duration of upload */
    static uint32_t curr_off;           /* Expected current offset */
    const uint8_t *img_chunk = NULL;    /* Pointer to buffer with received image chunk */
    size_t img_chunk_len = 0;           /* Length of received image chunk */
    size_t img_chunk_off = SIZE_MAX;    /* Offset of image chunk within image  */
    uint8_t rem_bytes;                  /* Reminder bytes after aligning chunk write to
                                         * to flash alignment */
    uint32_t img_num_tmp = UINT_MAX;    /* Temp variable for image number */
    static uint32_t img_num = 0;
    size_t img_size_tmp = SIZE_MAX;     /* Temp variable for image size */
    const struct flash_area *fap = NULL;
    int rc;
    struct zcbor_string img_chunk_data;
    size_t decoded = 0;
    bool ok;
#ifdef MCUBOOT_ERASE_PROGRESSIVELY
    static off_t not_yet_erased = 0;    /* Offset of next byte to erase; writes to flash
                                         * are done in consecutive manner and erases are done
                                         * to allow currently received chunk to be written;
                                         * this state variable holds information where last
                                         * erase has stopped to let us know whether erase
                                         * is needed to be able to write current chunk.
                                         */
    static struct flash_sector status_sector;
#endif

    zcbor_state_t zsd[4];
    zcbor_new_state(zsd, sizeof(zsd) / sizeof(zcbor_state_t), (uint8_t *)buf, len, 1);

    struct zcbor_map_decode_key_val image_upload_decode[] = {
        ZCBOR_MAP_DECODE_KEY_DECODER("image", zcbor_uint32_decode, &img_num_tmp),
        ZCBOR_MAP_DECODE_KEY_DECODER("data", zcbor_bstr_decode, &img_chunk_data),
        ZCBOR_MAP_DECODE_KEY_DECODER("len", zcbor_size_decode, &img_size_tmp),
        ZCBOR_MAP_DECODE_KEY_DECODER("off", zcbor_size_decode, &img_chunk_off),
    };

    ok = zcbor_map_decode_bulk(zsd, image_upload_decode, ARRAY_SIZE(image_upload_decode),
                               &decoded) == 0;

    if (!ok) {
        goto out_invalid_data;
    }

    img_chunk = img_chunk_data.value;
    img_chunk_len = img_chunk_data.len;

    /*
     * Expected data format.
     * {
     *   "image":<image number in a multi-image set (OPTIONAL)>
     *   "data":<image data>
     *   "len":<image len>
     *   "off":<current offset of image data>
     * }
     */

    if (img_chunk_off == SIZE_MAX || img_chunk == NULL) {
        /*
         * Offset must be set in every block.
         */
        goto out_invalid_data;
    }

    /* Use image number only from packet with offset == 0. */
    if (img_chunk_off == 0) {
        if (img_num_tmp != UINT_MAX) {
            img_num = img_num_tmp;
        } else {
            img_num = 0;
        }
    }

#if !defined(MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD)
    rc = flash_area_open(flash_area_id_from_multi_image_slot(img_num, 0), &fap);
#else
    rc = flash_area_open(flash_area_id_from_direct_image(img_num), &fap);
#endif
    if (rc) {
        rc = MGMT_ERR_EINVAL;
        goto out;
    }

    if (img_chunk_off == 0) {
        /* Receiving chunk with 0 offset resets the upload state; this basically
         * means that upload has started from beginning.
         */
        const size_t area_size = flash_area_get_size(fap);

        curr_off = 0;
#ifdef MCUBOOT_ERASE_PROGRESSIVELY
        /* Get trailer sector information; this is done early because inability to get
         * that sector information means that upload will not work anyway.
         * TODO: This is single occurrence issue, it should get detected during tests
         * and fixed otherwise you are deploying broken mcuboot.
         */
        if (flash_area_get_sector(fap, boot_status_off(fap), &status_sector)) {
            rc = MGMT_ERR_EUNKNOWN;
            BOOT_LOG_ERR("Unable to determine flash sector of the image trailer");
            goto out;
         }
#endif

#if defined(MCUBOOT_VALIDATE_PRIMARY_SLOT_ONCE)
        /* We are using swap state at end of flash area to store validation
         * result. Make sure the user cannot write it from an image to skip validation.
         */
        if (img_size_tmp > (area_size - BOOT_MAGIC_SZ)) {
            goto out_invalid_data;
        }
#else
        if (img_size_tmp > area_size) {
            goto out_invalid_data;
        }

#endif

#ifndef MCUBOOT_ERASE_PROGRESSIVELY
        /* Non-progressive erase erases entire image slot when first chunk of
         * an image is received.
         */
        rc = flash_area_erase(fap, 0, area_size);
        if (rc) {
            goto out_invalid_data;
        }
#else
        not_yet_erased = 0;
#endif

        img_size = img_size_tmp;
    } else if (img_chunk_off != curr_off) {
        /* If received chunk offset does not match expected one jump, pretend
         * success and jump to out; out will respond to client with success
         * and request the expected offset, held by curr_off.
         */
        rc = 0;
        goto out;
    } else if (curr_off + img_chunk_len > img_size) {
        rc = MGMT_ERR_EINVAL;
        goto out;
    }

#ifdef MCUBOOT_ERASE_PROGRESSIVELY
    /* Progressive erase will erase enough flash, aligned to sector size,
     * as needed for the current chunk to be written.
     */
    not_yet_erased = erase_range(fap, not_yet_erased,
                                 curr_off + img_chunk_len - 1);

    if (not_yet_erased < 0) {
        rc = MGMT_ERR_EINVAL;
        goto out;
    }
#endif

    /* Writes are aligned to flash write alignment, so may drop a few bytes
     * from the end of the buffer; we will request these bytes again with
     * new buffer by responding with request for offset after the last aligned
     * write.
     */
    rem_bytes = img_chunk_len % flash_area_align(fap);
    img_chunk_len -= rem_bytes;

    if (curr_off + img_chunk_len + rem_bytes < img_size) {
        rem_bytes = 0;
    }

    BOOT_LOG_INF("Writing at 0x%x until 0x%x", curr_off, curr_off + img_chunk_len);
    /* Write flash aligned chunk, note that img_chunk_len now holds aligned length */
#if defined(MCUBOOT_SERIAL_UNALIGNED_BUFFER_SIZE) && MCUBOOT_SERIAL_UNALIGNED_BUFFER_SIZE > 0
    if (flash_area_align(fap) > 1 &&
        (((size_t)img_chunk) & (flash_area_align(fap) - 1)) != 0) {
        /* Buffer address incompatible with write address, use buffer to write */
        uint8_t write_size = MCUBOOT_SERIAL_UNALIGNED_BUFFER_SIZE;
        uint8_t wbs_aligned[MCUBOOT_SERIAL_UNALIGNED_BUFFER_SIZE];

        while (img_chunk_len >= flash_area_align(fap)) {
            if (write_size > img_chunk_len) {
                write_size = img_chunk_len;
            }

            memset(wbs_aligned, flash_area_erased_val(fap), sizeof(wbs_aligned));
            memcpy(wbs_aligned, img_chunk, write_size);

            rc = flash_area_write(fap, curr_off, wbs_aligned, write_size);

            if (rc != 0) {
                goto out;
            }

            curr_off += write_size;
            img_chunk += write_size;
            img_chunk_len -= write_size;
        }
    } else {
        rc = flash_area_write(fap, curr_off, img_chunk, img_chunk_len);
    }
#else
    rc = flash_area_write(fap, curr_off, img_chunk, img_chunk_len);
#endif

    if (rc == 0 && rem_bytes) {
        /* Non-zero rem_bytes means that last chunk needs alignment; the aligned
         * part, in the img_chunk_len - rem_bytes count bytes, has already been
         * written by the above write, so we are left with the rem_bytes.
         */
        uint8_t wbs_aligned[BOOT_MAX_ALIGN];

        memset(wbs_aligned, flash_area_erased_val(fap), sizeof(wbs_aligned));
        memcpy(wbs_aligned, img_chunk + img_chunk_len, rem_bytes);

        rc = flash_area_write(fap, curr_off + img_chunk_len, wbs_aligned,
                              flash_area_align(fap));
    }

    if (rc == 0) {
        curr_off += img_chunk_len + rem_bytes;
        if (curr_off == img_size) {
#ifdef MCUBOOT_ERASE_PROGRESSIVELY
            /* Assure that sector for image trailer was erased. */
            /* Check whether it was erased during previous upload. */
            off_t start = flash_sector_get_off(&status_sector);

            if (erase_range(fap, start, start) < 0) {
                rc = MGMT_ERR_EUNKNOWN;
                goto out;
            }
#endif
            rc = BOOT_HOOK_CALL(boot_serial_uploaded_hook, 0, img_num, fap,
                                img_size);
            if (rc) {
                BOOT_LOG_ERR("Error %d post upload hook", rc);
                goto out;
            }
        }
    } else {
    out_invalid_data:
        rc = MGMT_ERR_EINVAL;
    }

out:
    BOOT_LOG_INF("RX: 0x%x", rc);
    zcbor_map_start_encode(cbor_state, 10);
    zcbor_tstr_put_lit_cast(cbor_state, "rc");
    zcbor_int32_put(cbor_state, rc);
    if (rc == 0) {
        zcbor_tstr_put_lit_cast(cbor_state, "off");
        zcbor_uint32_put(cbor_state, curr_off);
    }
    zcbor_map_end_encode(cbor_state, 10);

    boot_serial_output();

#ifdef MCUBOOT_ENC_IMAGES
    /* Check if this upload was for the primary slot */
#if !defined(MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD)
    if (flash_area_id_from_multi_image_slot(img_num, 0) == FLASH_AREA_IMAGE_PRIMARY(0))
#else
    if (flash_area_id_from_direct_image(img_num) == FLASH_AREA_IMAGE_PRIMARY(0))
#endif
    {
        if (curr_off == img_size) {
            /* Last sector received, now start a decryption on the image if it is encrypted */
            rc = boot_handle_enc_fw(fap);
        }
    }
#endif

    flash_area_close(fap);
}

#ifdef MCUBOOT_BOOT_MGMT_ECHO
static void
bs_echo(char *buf, int len)
{
    struct zcbor_string value = { 0 };
    struct zcbor_string key;
    bool ok;
    uint32_t rc = MGMT_ERR_EINVAL;

    zcbor_state_t zsd[4];
    zcbor_new_state(zsd, sizeof(zsd) / sizeof(zcbor_state_t), (uint8_t *)buf, len, 1);

    if (!zcbor_map_start_decode(zsd)) {
        goto out;
    }

    do {
        ok = zcbor_tstr_decode(zsd, &key);

        if (ok) {
            if (key.len == 1 && *key.value == 'd') {
                ok = zcbor_tstr_decode(zsd, &value);
                break;
            }

            ok = zcbor_any_skip(zsd, NULL);
        }
    } while (ok);

    if (!ok || !zcbor_map_end_decode(zsd)) {
        goto out;
    }

    zcbor_map_start_encode(cbor_state, 10);
    zcbor_tstr_put_term(cbor_state, "r");
    if (zcbor_tstr_encode(cbor_state, &value) && zcbor_map_end_encode(cbor_state, 10)) {
        boot_serial_output();
        return;
    } else {
        rc = MGMT_ERR_ENOMEM;
    }

out:
    reset_cbor_state();
    bs_rc_rsp(rc);
}
#endif

/*
 * Reset, and (presumably) boot to newly uploaded image. Flush console
 * before restarting.
 */
static void
bs_reset(char *buf, int len)
{
    int rc = BOOT_HOOK_CALL(boot_reset_request_hook, 0, false);
    if (rc == BOOT_RESET_REQUEST_HOOK_BUSY) {
	rc = MGMT_ERR_EBUSY;
    } else {
        /* Currently whatever else is returned it is just converted
         * to 0/no error. Boot serial starts accepting "force" parameter
         * in command this needs to change.
         */
         rc = 0;
    }
    bs_rc_rsp(rc);

    if (rc == 0) {
#ifdef __ZEPHYR__
#ifdef CONFIG_MULTITHREADING
        k_sleep(K_MSEC(250));
#else
        k_busy_wait(250000);
#endif
        sys_reboot(SYS_REBOOT_COLD);
#elif __ESPRESSIF__
        esp_rom_delay_us(250000);
        bootloader_reset();
#else
        os_cputime_delay_usecs(250000);
        hal_system_reset();
#endif
    }
}

/*
 * Parse incoming line of input from console.
 * Expect newtmgr protocol with serial transport.
 */
void
boot_serial_input(char *buf, int len)
{
    struct nmgr_hdr *hdr;

    hdr = (struct nmgr_hdr *)buf;
    if (len < sizeof(*hdr) ||
      (hdr->nh_op != NMGR_OP_READ && hdr->nh_op != NMGR_OP_WRITE) ||
      (ntohs(hdr->nh_len) < len - sizeof(*hdr))) {
        return;
    }
    bs_hdr = hdr;
    hdr->nh_group = ntohs(hdr->nh_group);

    buf += sizeof(*hdr);
    len -= sizeof(*hdr);

    reset_cbor_state();

    /*
     * Limited support for commands.
     */
    if (hdr->nh_group == MGMT_GROUP_ID_IMAGE) {
        switch (hdr->nh_id) {
        case IMGMGR_NMGR_ID_STATE:
            bs_list_set(hdr->nh_op, buf, len);
            break;
        case IMGMGR_NMGR_ID_UPLOAD:
            bs_upload(buf, len);
            break;
        default:
            bs_rc_rsp(MGMT_ERR_ENOTSUP);
            break;
        }
    } else if (hdr->nh_group == MGMT_GROUP_ID_DEFAULT) {
        switch (hdr->nh_id) {
        case NMGR_ID_ECHO:
#ifdef MCUBOOT_BOOT_MGMT_ECHO
            bs_echo(buf, len);
#endif
            break;
        case NMGR_ID_CONS_ECHO_CTRL:
            bs_rc_rsp(0);
            break;
        case NMGR_ID_RESET:
            bs_reset(buf, len);
            break;
        default:
            bs_rc_rsp(MGMT_ERR_ENOTSUP);
            break;
        }
    } else if (MCUBOOT_PERUSER_MGMT_GROUP_ENABLED == 1) {
        if (bs_peruser_system_specific(hdr, buf, len, cbor_state) == 0) {
            boot_serial_output();
        }
    } else {
        bs_rc_rsp(MGMT_ERR_ENOTSUP);
    }
#ifdef MCUBOOT_SERIAL_WAIT_FOR_DFU
    bs_entry = true;
#endif
}

static void
boot_serial_output(void)
{
    char *data;
    int len, out;
    uint16_t crc;
    uint16_t totlen;
    char pkt_cont[2] = { SHELL_NLIP_DATA_START1, SHELL_NLIP_DATA_START2 };
    char pkt_start[2] = { SHELL_NLIP_PKT_START1, SHELL_NLIP_PKT_START2 };
    char buf[BOOT_SERIAL_OUT_MAX + sizeof(*bs_hdr) + sizeof(crc) + sizeof(totlen)];
    char encoded_buf[BASE64_ENCODE_SIZE(sizeof(buf))];

    data = bs_obuf;
    len = (uintptr_t)cbor_state->payload_mut - (uintptr_t)bs_obuf;

    bs_hdr->nh_op++;
    bs_hdr->nh_flags = 0;
    bs_hdr->nh_len = htons(len);
    bs_hdr->nh_group = htons(bs_hdr->nh_group);

#ifdef __ZEPHYR__
    crc =  crc16_itu_t(CRC16_INITIAL_CRC, (uint8_t *)bs_hdr, sizeof(*bs_hdr));
    crc =  crc16_itu_t(crc, data, len);
#elif __ESPRESSIF__
    /* For ESP32 it was used the CRC API in rom/crc.h */
    crc =  ~esp_crc16_be(~CRC16_INITIAL_CRC, (uint8_t *)bs_hdr, sizeof(*bs_hdr));
    crc =  ~esp_crc16_be(~crc, (uint8_t *)data, len);
#else
    crc = crc16_ccitt(CRC16_INITIAL_CRC, bs_hdr, sizeof(*bs_hdr));
    crc = crc16_ccitt(crc, data, len);
#endif
    crc = htons(crc);

    totlen = len + sizeof(*bs_hdr) + sizeof(crc);
    totlen = htons(totlen);

    memcpy(buf, &totlen, sizeof(totlen));
    totlen = sizeof(totlen);
    memcpy(&buf[totlen], bs_hdr, sizeof(*bs_hdr));
    totlen += sizeof(*bs_hdr);
    memcpy(&buf[totlen], data, len);
    totlen += len;
    memcpy(&buf[totlen], &crc, sizeof(crc));
    totlen += sizeof(crc);
#ifdef __ZEPHYR__
    size_t enc_len;
    base64_encode(encoded_buf, sizeof(encoded_buf), &enc_len, buf, totlen);
    totlen = enc_len;
#elif __ESPRESSIF__
    size_t enc_len;
    base64_encode((unsigned char *)encoded_buf, sizeof(encoded_buf), &enc_len, (unsigned char *)buf, totlen);
    totlen = enc_len;
#else
    totlen = base64_encode(buf, totlen, encoded_buf, 1);
#endif

    out = 0;
    while (out < totlen) {
        if (out == 0) {
            boot_uf->write(pkt_start, sizeof(pkt_start));
        } else {
            boot_uf->write(pkt_cont, sizeof(pkt_cont));
        }

        len = MIN(BOOT_SERIAL_FRAME_MTU, totlen - out);
        boot_uf->write(&encoded_buf[out], len);

        out += len;

        boot_uf->write("\n", 1);
    }

    BOOT_LOG_INF("TX");
}

/*
 * Returns 1 if full packet has been received.
 */
static int
boot_serial_in_dec(char *in, int inlen, char *out, int *out_off, int maxout)
{
    int rc;
    uint16_t crc;
    uint16_t len;

#ifdef __ZEPHYR__
    int err;
    err = base64_decode( &out[*out_off], maxout - *out_off, &rc, in, inlen - 2);
    if (err) {
        return -1;
    }
#elif __ESPRESSIF__
    int err;
    err = base64_decode((unsigned char *)&out[*out_off], maxout - *out_off, (size_t *)&rc, (unsigned char *)in, inlen);
    if (err) {
        return -1;
    }
#else
    if (*out_off + base64_decode_len(in) >= maxout) {
        return -1;
    }
    rc = base64_decode(in, &out[*out_off]);
    if (rc < 0) {
        return -1;
    }
#endif

    *out_off += rc;
    if (*out_off <= sizeof(uint16_t)) {
        return 0;
    }

    len = ntohs(*(uint16_t *)out);
    if (len != *out_off - sizeof(uint16_t)) {
        return 0;
    }

    if (len > *out_off - sizeof(uint16_t)) {
        len = *out_off - sizeof(uint16_t);
    }

    out += sizeof(uint16_t);
#ifdef __ZEPHYR__
    crc = crc16_itu_t(CRC16_INITIAL_CRC, out, len);
#elif __ESPRESSIF__
    crc = ~esp_crc16_be(~CRC16_INITIAL_CRC, (uint8_t *)out, len);
#else
    crc = crc16_ccitt(CRC16_INITIAL_CRC, out, len);
#endif
    if (crc || len <= sizeof(crc)) {
        return 0;
    }
    *out_off -= sizeof(crc);
    out[*out_off] = '\0';

    return 1;
}

/*
 * Task which waits reading console, expecting to get image over
 * serial port.
 */
static void
boot_serial_read_console(const struct boot_uart_funcs *f,int timeout_in_ms)
{
    int rc;
    int off;
    int dec_off = 0;
    int full_line;
    int max_input;
    int elapsed_in_ms = 0;

    boot_uf = f;
    max_input = sizeof(in_buf);

    off = 0;
    while (timeout_in_ms > 0 || bs_entry) {
        /*
         * Don't enter CPU idle state here if timeout based serial recovery is
         * used as otherwise the boot process hangs forever, waiting for input
         * from serial console (if single-thread mode is used).
         */
#ifndef MCUBOOT_SERIAL_WAIT_FOR_DFU
        MCUBOOT_CPU_IDLE();
#endif
        MCUBOOT_WATCHDOG_FEED();
#ifdef MCUBOOT_SERIAL_WAIT_FOR_DFU
        uint32_t start = k_uptime_get_32();
#endif
        rc = f->read(in_buf + off, sizeof(in_buf) - off, &full_line);
        if (rc <= 0 && !full_line) {
            goto check_timeout;
        }
        off += rc;
        if (!full_line) {
            if (off == max_input) {
                /*
                 * Full line, no newline yet. Reset the input buffer.
                 */
                off = 0;
            }
            goto check_timeout;
        }
        if (in_buf[0] == SHELL_NLIP_PKT_START1 &&
          in_buf[1] == SHELL_NLIP_PKT_START2) {
            dec_off = 0;
            rc = boot_serial_in_dec(&in_buf[2], off - 2, dec_buf, &dec_off, max_input);
        } else if (in_buf[0] == SHELL_NLIP_DATA_START1 &&
          in_buf[1] == SHELL_NLIP_DATA_START2) {
            rc = boot_serial_in_dec(&in_buf[2], off - 2, dec_buf, &dec_off, max_input);
        }

        /* serve errors: out of decode memory, or bad encoding */
        if (rc == 1) {
            boot_serial_input(&dec_buf[2], dec_off - 2);
        }
        off = 0;
check_timeout:
        /* Subtract elapsed time */
#ifdef MCUBOOT_SERIAL_WAIT_FOR_DFU
        elapsed_in_ms = (k_uptime_get_32() - start);
#endif
        timeout_in_ms -= elapsed_in_ms;
    }
}

/*
 * Task which waits reading console, expecting to get image over
 * serial port.
 */
void
boot_serial_start(const struct boot_uart_funcs *f)
{
    bs_entry = true;
    boot_serial_read_console(f,0);
}

#ifdef MCUBOOT_SERIAL_WAIT_FOR_DFU
/*
 * Task which waits reading console for a certain amount of timeout.
 * If within this timeout no mcumgr command is received, the function is
 * returning, else the serial boot is never exited
 */
void
boot_serial_check_start(const struct boot_uart_funcs *f, int timeout_in_ms)
{
    bs_entry = false;
    boot_serial_read_console(f,timeout_in_ms);
}
#endif

#ifdef MCUBOOT_SERIAL_IMG_GRP_HASH
/* Function to find the hash of an image, returns 0 on success. */
static int boot_serial_get_hash(const struct image_header *hdr,
                                const struct flash_area *fap, uint8_t *hash)
{
    struct image_tlv_iter it;
    uint32_t offset;
    uint16_t len;
    uint16_t type;
    int rc;

    /* Manifest data is concatenated to the end of the image.
     * It is encoded in TLV format.
     */
    rc = bootutil_tlv_iter_begin(&it, hdr, fap, IMAGE_TLV_ANY, false);
    if (rc) {
        return -1;
    }

    /* Traverse through the TLV area to find the image hash TLV. */
    while (true) {
        rc = bootutil_tlv_iter_next(&it, &offset, &len, &type);
        if (rc < 0) {
            return -1;
        } else if (rc > 0) {
            break;
        }

        if (type == IMAGE_TLV_SHA256) {
            /* Get the image's hash value from the manifest section. */
            if (len != 32) {
                return -1;
            }

            rc = flash_area_read(fap, offset, hash, len);
            if (rc) {
                return -1;
            }

            return 0;
        }
    }

    return -1;
}
#endif