/*
 * Copyright 1994, 1995, 2000 Neil Russell.
 * (See License)
 * Copyright 2000, 2001 DENX Software Engineering, Wolfgang Denk, wd@denx.de
 * Copyright 2011 Comelit Group SpA,
 *                Luca Ceresoli <luca.ceresoli@comelit.it>
 */
#include <common.h>
#include <command.h>
#include <display_options.h>
#include <efi_loader.h>
#include <env.h>
#include <image.h>
#include <lmb.h>
#include <log.h>
#include <mapmem.h>
#include <net.h>
#include <net6.h>
#include <asm/global_data.h>
#include <net/tftp.h>
#include "bootp.h"

DECLARE_GLOBAL_DATA_PTR;

/* Well known TFTP port # */
#define WELL_KNOWN_PORT 69
/* Millisecs to timeout for lost pkt */
#define TIMEOUT         5000UL
/* Number of "loading" hashes per line (for checking the image size) */
#define HASHES_PER_LINE 65

/*
 *      TFTP operations.
 */
#define TFTP_RRQ        1
#define TFTP_WRQ        2
#define TFTP_DATA       3
#define TFTP_ACK        4
#define TFTP_ERROR      5
#define TFTP_OACK       6

static ulong timeout_ms = TIMEOUT;
static int timeout_count_max = (CONFIG_NET_RETRY_COUNT * 2);
static ulong time_start;   /* Record time we started tftp */
static struct in6_addr tftp_remote_ip6;

/*
 * These globals govern the timeout behavior when attempting a connection to a
 * TFTP server. tftp_timeout_ms specifies the number of milliseconds to
 * wait for the server to respond to initial connection. Second global,
 * tftp_timeout_count_max, gives the number of such connection retries.
 * tftp_timeout_count_max must be non-negative and tftp_timeout_ms must be
 * positive. The globals are meant to be set (and restored) by code needing
 * non-standard timeout behavior when initiating a TFTP transfer.
 */
ulong tftp_timeout_ms = TIMEOUT;
int tftp_timeout_count_max = (CONFIG_NET_RETRY_COUNT * 2);

enum {
        TFTP_ERR_UNDEFINED           = 0,
        TFTP_ERR_FILE_NOT_FOUND      = 1,
        TFTP_ERR_ACCESS_DENIED       = 2,
        TFTP_ERR_DISK_FULL           = 3,
        TFTP_ERR_UNEXPECTED_OPCODE   = 4,
        TFTP_ERR_UNKNOWN_TRANSFER_ID  = 5,
        TFTP_ERR_FILE_ALREADY_EXISTS = 6,
        TFTP_ERR_OPTION_NEGOTIATION = 8,
};

static struct in_addr tftp_remote_ip;
/* The UDP port at their end */
static int      tftp_remote_port;
/* The UDP port at our end */
static int      tftp_our_port;
static int      timeout_count;
/* packet sequence number */
static ulong    tftp_cur_block;
/* last packet sequence number received */
static ulong    tftp_prev_block;
/* count of sequence number wraparounds */
static ulong    tftp_block_wrap;
/* memory offset due to wrapping */
static ulong    tftp_block_wrap_offset;
static int      tftp_state;
static ulong    tftp_load_addr;
#ifdef CONFIG_LMB
static ulong    tftp_load_size;
#endif
#ifdef CONFIG_TFTP_TSIZE
/* The file size reported by the server */
static int      tftp_tsize;
/* The number of hashes we printed */
static short    tftp_tsize_num_hash;
#endif
/* The window size negotiated */
static ushort   tftp_windowsize;
/* Next block to send ack to */
static ushort   tftp_next_ack;
/* Last nack block we send */
static ushort   tftp_last_nack;
#ifdef CONFIG_CMD_TFTPPUT
/* 1 if writing, else 0 */
static int      tftp_put_active;
/* 1 if we have sent the last block */
static int      tftp_put_final_block_sent;
#else
#define tftp_put_active 0
#endif

#define STATE_SEND_RRQ  1
#define STATE_DATA      2
#define STATE_TOO_LARGE 3
#define STATE_BAD_MAGIC 4
#define STATE_OACK      5
#define STATE_RECV_WRQ  6
#define STATE_SEND_WRQ  7
#define STATE_INVALID_OPTION    8

/* default TFTP block size */
#define TFTP_BLOCK_SIZE         512
#define TFTP_MTU_BLOCKSIZE6 (CONFIG_TFTP_BLOCKSIZE - 20)
/* sequence number is 16 bit */
#define TFTP_SEQUENCE_SIZE      ((ulong)(1<<16))

#define DEFAULT_NAME_LEN        (8 + 4 + 1)
static char default_filename[DEFAULT_NAME_LEN];

#ifndef CONFIG_TFTP_FILE_NAME_MAX_LEN
#define MAX_LEN 128
#else
#define MAX_LEN CONFIG_TFTP_FILE_NAME_MAX_LEN
#endif

static char tftp_filename[MAX_LEN];

/* 512 is poor choice for ethernet, MTU is typically 1500.
 * Minus eth.hdrs thats 1468.  Can get 2x better throughput with
 * almost-MTU block sizes.  At least try... fall back to 512 if need be.
 * (but those using CONFIG_IP_DEFRAG may want to set a larger block in cfg file)
 */

/* When windowsize is defined to 1,
 * tftp behaves the same way as it was
 * never declared
 */
#ifdef CONFIG_TFTP_WINDOWSIZE
#define TFTP_WINDOWSIZE CONFIG_TFTP_WINDOWSIZE
#else
#define TFTP_WINDOWSIZE 1
#endif

static unsigned short tftp_block_size = TFTP_BLOCK_SIZE;
static unsigned short tftp_block_size_option = CONFIG_TFTP_BLOCKSIZE;
static unsigned short tftp_window_size_option = TFTP_WINDOWSIZE;

static inline int store_block(int block, uchar *src, unsigned int len)
{
        ulong offset = block * tftp_block_size + tftp_block_wrap_offset -
                        tftp_block_size;
        ulong newsize = offset + len;
        ulong store_addr = tftp_load_addr + offset;
        void *ptr;

#ifdef CONFIG_LMB
        ulong end_addr = tftp_load_addr + tftp_load_size;

        if (!end_addr)
                end_addr = ULONG_MAX;

        if (store_addr < tftp_load_addr ||
            store_addr + len > end_addr) {
                puts("\nTFTP error: ");
                puts("trying to overwrite reserved memory...\n");
                return -1;
        }
#endif
        ptr = map_sysmem(store_addr, len);
        memcpy(ptr, src, len);
        unmap_sysmem(ptr);

        if (net_boot_file_size < newsize)
                net_boot_file_size = newsize;

        return 0;
}

/* Clear our state ready for a new transfer */
static void new_transfer(void)
{
        tftp_prev_block = 0;
        tftp_block_wrap = 0;
        tftp_block_wrap_offset = 0;
#ifdef CONFIG_CMD_TFTPPUT
        tftp_put_final_block_sent = 0;
#endif
}

#ifdef CONFIG_CMD_TFTPPUT
/**
 * Load the next block from memory to be sent over tftp.
 *
 * @param block Block number to send
 * @param dst   Destination buffer for data
 * @param len   Number of bytes in block (this one and every other)
 * Return: number of bytes loaded
 */
static int load_block(unsigned block, uchar *dst, unsigned len)
{
        /* We may want to get the final block from the previous set */
        ulong offset = block * tftp_block_size + tftp_block_wrap_offset -
                       tftp_block_size;
        ulong tosend = len;

        tosend = min(net_boot_file_size - offset, tosend);
        (void)memcpy(dst, (void *)(image_save_addr + offset), tosend);
        debug("%s: block=%u, offset=%lu, len=%u, tosend=%lu\n", __func__,
              block, offset, len, tosend);
        return tosend;
}
#endif

static void tftp_send(void);
static void tftp_timeout_handler(void);

/**********************************************************************/

static void show_block_marker(void)
{
        ulong pos;

#ifdef CONFIG_TFTP_TSIZE
        if (tftp_tsize) {
                pos = tftp_cur_block * tftp_block_size +
                        tftp_block_wrap_offset;
                if (pos > tftp_tsize)
                        pos = tftp_tsize;

                while (tftp_tsize_num_hash < pos * 50 / tftp_tsize) {
                        putc('#');
                        tftp_tsize_num_hash++;
                }
        } else
#endif
        {
                pos = (tftp_cur_block - 1) +
                        (tftp_block_wrap * TFTP_SEQUENCE_SIZE);
                if ((pos % 10) == 0)
                        putc('#');
                else if (((pos + 1) % (10 * HASHES_PER_LINE)) == 0)
                        puts("\n\t ");
        }
}

/**
 * restart the current transfer due to an error
 *
 * @param msg   Message to print for user
 */
static void restart(const char *msg)
{
        printf("\n%s; starting again\n", msg);
        net_start_again();
}

/*
 * Check if the block number has wrapped, and update progress
 *
 * TODO: The egregious use of global variables in this file should be tidied.
 */
static void update_block_number(void)
{
        /*
         * RFC1350 specifies that the first data packet will
         * have sequence number 1. If we receive a sequence
         * number of 0 this means that there was a wrap
         * around of the (16 bit) counter.
         */
        if (tftp_cur_block == 0 && tftp_prev_block != 0) {
                tftp_block_wrap++;
                tftp_block_wrap_offset += tftp_block_size * TFTP_SEQUENCE_SIZE;
                timeout_count = 0; /* we've done well, reset the timeout */
        }
        show_block_marker();
}

/* The TFTP get or put is complete */
static void tftp_complete(void)
{
#ifdef CONFIG_TFTP_TSIZE
        /* Print hash marks for the last packet received */
        while (tftp_tsize && tftp_tsize_num_hash < 49) {
                putc('#');
                tftp_tsize_num_hash++;
        }
        puts("  ");
        print_size(tftp_tsize, "");
#endif
        time_start = get_timer(time_start);
        if (time_start > 0) {
                puts("\n\t ");  /* Line up with "Loading: " */
                print_size(net_boot_file_size /
                        time_start * 1000, "/s");
        }
        puts("\ndone\n");
        if (IS_ENABLED(CONFIG_CMD_BOOTEFI)) {
                if (!tftp_put_active)
                        efi_set_bootdev("Net", "", tftp_filename,
                                        map_sysmem(tftp_load_addr, 0),
                                        net_boot_file_size);
        }
        net_set_state(NETLOOP_SUCCESS);
}

static void tftp_send(void)
{
        uchar *pkt;
        uchar *xp;
        int len = 0;
        ushort *s;
        bool err_pkt = false;

        /*
         *      We will always be sending some sort of packet, so
         *      cobble together the packet headers now.
         */
        if (IS_ENABLED(CONFIG_IPV6) && use_ip6)
                pkt = net_tx_packet + net_eth_hdr_size() +
                      IP6_HDR_SIZE + UDP_HDR_SIZE;
        else
                pkt = net_tx_packet + net_eth_hdr_size() + IP_UDP_HDR_SIZE;

        switch (tftp_state) {
        case STATE_SEND_RRQ:
        case STATE_SEND_WRQ:
                xp = pkt;
                s = (ushort *)pkt;
#ifdef CONFIG_CMD_TFTPPUT
                *s++ = htons(tftp_state == STATE_SEND_RRQ ? TFTP_RRQ :
                        TFTP_WRQ);
#else
                *s++ = htons(TFTP_RRQ);
#endif
                pkt = (uchar *)s;
                strcpy((char *)pkt, tftp_filename);
                pkt += strlen(tftp_filename) + 1;
                strcpy((char *)pkt, "octet");
                pkt += 5 /*strlen("octet")*/ + 1;
                strcpy((char *)pkt, "timeout");
                pkt += 7 /*strlen("timeout")*/ + 1;
                sprintf((char *)pkt, "%lu", timeout_ms / 1000);
                debug("send option \"timeout %s\"\n", (char *)pkt);
                pkt += strlen((char *)pkt) + 1;
#ifdef CONFIG_TFTP_TSIZE
                pkt += sprintf((char *)pkt, "tsize%c%u%c",
                                0, net_boot_file_size, 0);
#endif
                /* try for more effic. blk size */
                pkt += sprintf((char *)pkt, "blksize%c%d%c",
                                0, tftp_block_size_option, 0);

                /* try for more effic. window size.
                 * Implemented only for tftp get.
                 * Don't bother sending if it's 1
                 */
                if (tftp_state == STATE_SEND_RRQ && tftp_window_size_option > 1)
                        pkt += sprintf((char *)pkt, "windowsize%c%d%c",
                                        0, tftp_window_size_option, 0);
                len = pkt - xp;
                break;

        case STATE_OACK:

        case STATE_RECV_WRQ:
        case STATE_DATA:
                xp = pkt;
                s = (ushort *)pkt;
                s[0] = htons(TFTP_ACK);
                s[1] = htons(tftp_cur_block);
                pkt = (uchar *)(s + 2);
#ifdef CONFIG_CMD_TFTPPUT
                if (tftp_put_active) {
                        int toload = tftp_block_size;
                        int loaded = load_block(tftp_cur_block, pkt, toload);

                        s[0] = htons(TFTP_DATA);
                        pkt += loaded;
                        tftp_put_final_block_sent = (loaded < toload);
                }
#endif
                len = pkt - xp;
                break;

        case STATE_TOO_LARGE:
                xp = pkt;
                s = (ushort *)pkt;
                *s++ = htons(TFTP_ERROR);
                        *s++ = htons(3);

                pkt = (uchar *)s;
                strcpy((char *)pkt, "File too large");
                pkt += 14 /*strlen("File too large")*/ + 1;
                len = pkt - xp;
                err_pkt = true;
                break;

        case STATE_BAD_MAGIC:
                xp = pkt;
                s = (ushort *)pkt;
                *s++ = htons(TFTP_ERROR);
                *s++ = htons(2);
                pkt = (uchar *)s;
                strcpy((char *)pkt, "File has bad magic");
                pkt += 18 /*strlen("File has bad magic")*/ + 1;
                len = pkt - xp;
                err_pkt = true;
                break;

        case STATE_INVALID_OPTION:
                xp = pkt;
                s = (ushort *)pkt;
                *s++ = htons(TFTP_ERROR);
                *s++ = htons(TFTP_ERR_OPTION_NEGOTIATION);
                pkt = (uchar *)s;
                strcpy((char *)pkt, "Option Negotiation Failed");
                /* strlen("Option Negotiation Failed") + NULL*/
                pkt += 25 + 1;
                len = pkt - xp;
                err_pkt = true;
                break;
        }

        if (IS_ENABLED(CONFIG_IPV6) && use_ip6)
                net_send_udp_packet6(net_server_ethaddr,
                                     &tftp_remote_ip6,
                                     tftp_remote_port,
                                     tftp_our_port, len);
        else
                net_send_udp_packet(net_server_ethaddr, tftp_remote_ip,
                                    tftp_remote_port, tftp_our_port, len);

        if (err_pkt)
                net_set_state(NETLOOP_FAIL);
}

#ifdef CONFIG_CMD_TFTPPUT
static void icmp_handler(unsigned type, unsigned code, unsigned dest,
                         struct in_addr sip, unsigned src, uchar *pkt,
                         unsigned len)
{
        if (type == ICMP_NOT_REACH && code == ICMP_NOT_REACH_PORT) {
                /* Oh dear the other end has gone away */
                restart("TFTP server died");
        }
}
#endif

static void tftp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
                         unsigned src, unsigned len)
{
        __be16 proto;
        __be16 *s;
        int i;
        u16 timeout_val_rcvd;

        if (dest != tftp_our_port) {
                        return;
        }
        if (tftp_state != STATE_SEND_RRQ && src != tftp_remote_port &&
            tftp_state != STATE_RECV_WRQ && tftp_state != STATE_SEND_WRQ)
                return;

        if (len < 2)
                return;
        len -= 2;
        /* warning: don't use increment (++) in ntohs() macros!! */
        s = (__be16 *)pkt;
        proto = *s++;
        pkt = (uchar *)s;
        switch (ntohs(proto)) {
        case TFTP_RRQ:
                break;

        case TFTP_ACK:
#ifdef CONFIG_CMD_TFTPPUT
                if (tftp_put_active) {
                        if (tftp_put_final_block_sent) {
                                tftp_complete();
                        } else {
                                /*
                                 * Move to the next block. We want our block
                                 * count to wrap just like the other end!
                                 */
                                int block = ntohs(*s);
                                int ack_ok = (tftp_cur_block == block);

                                tftp_prev_block = tftp_cur_block;
                                tftp_cur_block = (unsigned short)(block + 1);
                                update_block_number();
                                if (ack_ok)
                                        tftp_send(); /* Send next data block */
                        }
                }
#endif
                break;

        default:
                break;

#ifdef CONFIG_CMD_TFTPSRV
        case TFTP_WRQ:
                debug("Got WRQ\n");
                tftp_remote_ip = sip;
                tftp_remote_port = src;
                tftp_our_port = 1024 + (get_timer(0) % 3072);
                new_transfer();
                tftp_send(); /* Send ACK(0) */
                break;
#endif

        case TFTP_OACK:
                debug("Got OACK: ");
                for (i = 0; i < len; i++) {
                        if (pkt[i] == '\0')
                                debug(" ");
                        else
                                debug("%c", pkt[i]);
                }
                debug("\n");
                tftp_state = STATE_OACK;
                tftp_remote_port = src;
                /*
                 * Check for 'blksize' option.
                 * Careful: "i" is signed, "len" is unsigned, thus
                 * something like "len-8" may give a *huge* number
                 */
                for (i = 0; i+8 < len; i++) {
                        if (strcasecmp((char *)pkt + i, "blksize") == 0) {
                                tftp_block_size = (unsigned short)
                                        dectoul((char *)pkt + i + 8, NULL);
                                debug("Blocksize oack: %s, %d\n",
                                      (char *)pkt + i + 8, tftp_block_size);
                                if (tftp_block_size > tftp_block_size_option) {
                                        printf("Invalid blk size(=%d)\n",
                                               tftp_block_size);
                                        tftp_state = STATE_INVALID_OPTION;
                                }
                        }
                        if (strcasecmp((char *)pkt + i, "timeout") == 0) {
                                timeout_val_rcvd = (unsigned short)
                                        dectoul((char *)pkt + i + 8, NULL);
                                debug("Timeout oack: %s, %d\n",
                                      (char *)pkt + i + 8, timeout_val_rcvd);
                                if (timeout_val_rcvd != (timeout_ms / 1000)) {
                                        printf("Invalid timeout val(=%d s)\n",
                                               timeout_val_rcvd);
                                        tftp_state = STATE_INVALID_OPTION;
                                }
                        }
#ifdef CONFIG_TFTP_TSIZE
                        if (strcasecmp((char *)pkt + i, "tsize") == 0) {
                                tftp_tsize = dectoul((char *)pkt + i + 6,
                                                     NULL);
                                debug("size = %s, %d\n",
                                      (char *)pkt + i + 6, tftp_tsize);
                        }
#endif
                        if (strcasecmp((char *)pkt + i,  "windowsize") == 0) {
                                tftp_windowsize =
                                        dectoul((char *)pkt + i + 11, NULL);
                                debug("windowsize = %s, %d\n",
                                      (char *)pkt + i + 11, tftp_windowsize);
                        }
                }

                tftp_next_ack = tftp_windowsize;

#ifdef CONFIG_CMD_TFTPPUT
                if (tftp_put_active && tftp_state == STATE_OACK) {
                        /* Get ready to send the first block */
                        tftp_state = STATE_DATA;
                        tftp_cur_block++;
                }
#endif
                tftp_send(); /* Send ACK or first data block */
                break;
        case TFTP_DATA:
                if (len < 2)
                        return;
                len -= 2;

                if (ntohs(*(__be16 *)pkt) != (ushort)(tftp_cur_block + 1)) {
                        debug("Received unexpected block: %d, expected: %d\n",
                              ntohs(*(__be16 *)pkt),
                              (ushort)(tftp_cur_block + 1));
                        /*
                         * Only ACK if the block count received is greater than
                         * the expected block count, otherwise skip ACK.
                         * (required to properly handle the server retransmitting
                         *  the window)
                         */
                        if ((ushort)(tftp_cur_block + 1) - (short)(ntohs(*(__be16 *)pkt)) > 0)
                                break;
                        /*
                         * If one packet is dropped most likely
                         * all other buffers in the window
                         * that will arrive will cause a sending NACK.
                         * This just overwellms the server, let's just send one.
                         */
                        if (tftp_last_nack != tftp_cur_block) {
                                tftp_send();
                                tftp_last_nack = tftp_cur_block;
                                tftp_next_ack = (ushort)(tftp_cur_block +
                                                         tftp_windowsize);
                        }
                        break;
                }

                tftp_cur_block++;
                tftp_cur_block %= TFTP_SEQUENCE_SIZE;

                if (tftp_state == STATE_SEND_RRQ) {
                        debug("Server did not acknowledge any options!\n");
                        tftp_next_ack = tftp_windowsize;
                }

                if (tftp_state == STATE_SEND_RRQ || tftp_state == STATE_OACK ||
                    tftp_state == STATE_RECV_WRQ) {
                        /* first block received */
                        tftp_state = STATE_DATA;
                        tftp_remote_port = src;
                        new_transfer();

                        if (tftp_cur_block != 1) {      /* Assertion */
                                puts("\nTFTP error: ");
                                printf("First block is not block 1 (%ld)\n",
                                       tftp_cur_block);
                                puts("Starting again\n\n");
                                net_start_again();
                                break;
                        }
                }

                if (tftp_cur_block == tftp_prev_block) {
                        /* Same block again; ignore it. */
                        break;
                }

                update_block_number();
                tftp_prev_block = tftp_cur_block;
                timeout_count_max = tftp_timeout_count_max;
                net_set_timeout_handler(timeout_ms, tftp_timeout_handler);

                if (store_block(tftp_cur_block, pkt + 2, len)) {
                        eth_halt();
                        net_set_state(NETLOOP_FAIL);
                        break;
                }

                if (len < tftp_block_size) {
                        tftp_send();
                        tftp_complete();
                        break;
                }

                /*
                 *      Acknowledge the block just received, which will prompt
                 *      the remote for the next one.
                 */
                if (tftp_cur_block == tftp_next_ack) {
                        tftp_send();
                        tftp_next_ack += tftp_windowsize;
                }
                break;

        case TFTP_ERROR:
                printf("\nTFTP error: '%s' (%d)\n",
                       pkt + 2, ntohs(*(__be16 *)pkt));

                switch (ntohs(*(__be16 *)pkt)) {
                case TFTP_ERR_FILE_NOT_FOUND:
                case TFTP_ERR_ACCESS_DENIED:
                        puts("Not retrying...\n");
                        eth_halt();
                        net_set_state(NETLOOP_FAIL);
                        break;
                case TFTP_ERR_UNDEFINED:
                case TFTP_ERR_DISK_FULL:
                case TFTP_ERR_UNEXPECTED_OPCODE:
                case TFTP_ERR_UNKNOWN_TRANSFER_ID:
                case TFTP_ERR_FILE_ALREADY_EXISTS:
                default:
                        puts("Starting again\n\n");
                        net_start_again();
                        break;
                }
                break;
        }
}


static void tftp_timeout_handler(void)
{
        if (++timeout_count > timeout_count_max) {
                restart("Retry count exceeded");
        } else {
                puts("T ");
                net_set_timeout_handler(timeout_ms, tftp_timeout_handler);
                if (tftp_state != STATE_RECV_WRQ)
                        tftp_send();
        }
}

/* Initialize tftp_load_addr and tftp_load_size from image_load_addr and lmb */
static int tftp_init_load_addr(void)
{
#ifdef CONFIG_LMB
        struct lmb lmb;
        phys_size_t max_size;

        lmb_init_and_reserve(&lmb, gd->bd, (void *)gd->fdt_blob);

        max_size = lmb_get_free_size(&lmb, image_load_addr);
        if (!max_size)
                return -1;

        tftp_load_size = max_size;
#endif
        tftp_load_addr = image_load_addr;
        return 0;
}

static int saved_tftp_block_size_option;
static void sanitize_tftp_block_size_option(enum proto_t protocol)
{
        int cap, max_defrag;

        switch (protocol) {
        case TFTPGET:
                max_defrag = config_opt_enabled(CONFIG_IP_DEFRAG, CONFIG_NET_MAXDEFRAG, 0);
                if (max_defrag) {
                        /* Account for IP, UDP and TFTP headers. */
                        cap = max_defrag - (20 + 8 + 4);
                        /* RFC2348 sets a hard upper limit. */
                        cap = min(cap, 65464);
                        break;
                }
                /*
                 * If not CONFIG_IP_DEFRAG, cap at the same value as
                 * for tftp put, namely normal MTU minus protocol
                 * overhead.
                 */
                fallthrough;
        case TFTPPUT:
        default:
                /*
                 * U-Boot does not support IP fragmentation on TX, so
                 * this must be small enough that it fits normal MTU
                 * (and small enough that it fits net_tx_packet which
                 * has room for PKTSIZE_ALIGN bytes).
                 */
                cap = 1468;
        }
        if (tftp_block_size_option > cap) {
                printf("Capping tftp block size option to %d (was %d)\n",
                       cap, tftp_block_size_option);
                saved_tftp_block_size_option = tftp_block_size_option;
                tftp_block_size_option = cap;
        }
}

void tftp_start(enum proto_t protocol)
{
        __maybe_unused char *ep;             /* Environment pointer */

        if (saved_tftp_block_size_option) {
                tftp_block_size_option = saved_tftp_block_size_option;
                saved_tftp_block_size_option = 0;
        }

        if (IS_ENABLED(CONFIG_NET_TFTP_VARS)) {

                /*
                 * Allow the user to choose TFTP blocksize and timeout.
                 * TFTP protocol has a minimal timeout of 1 second.
                 */

                ep = env_get("tftpblocksize");
                if (ep != NULL)
                        tftp_block_size_option = simple_strtol(ep, NULL, 10);

                ep = env_get("tftpwindowsize");
                if (ep != NULL)
                        tftp_window_size_option = simple_strtol(ep, NULL, 10);

                ep = env_get("tftptimeout");
                if (ep != NULL)
                        timeout_ms = simple_strtol(ep, NULL, 10);

                if (timeout_ms < 1000) {
                        printf("TFTP timeout (%ld ms) too low, set min = 1000 ms\n",
                               timeout_ms);
                        timeout_ms = 1000;
                }

                ep = env_get("tftptimeoutcountmax");
                if (ep != NULL)
                        tftp_timeout_count_max = simple_strtol(ep, NULL, 10);

                if (tftp_timeout_count_max < 0) {
                        printf("TFTP timeout count max (%d ms) negative, set to 0\n",
                               tftp_timeout_count_max);
                        tftp_timeout_count_max = 0;
                }
        }

        sanitize_tftp_block_size_option(protocol);

        debug("TFTP blocksize = %i, TFTP windowsize = %d timeout = %ld ms\n",
              tftp_block_size_option, tftp_window_size_option, timeout_ms);

        if (IS_ENABLED(CONFIG_IPV6))
                tftp_remote_ip6 = net_server_ip6;

        tftp_remote_ip = net_server_ip;
        if (!net_parse_bootfile(&tftp_remote_ip, tftp_filename, MAX_LEN)) {
                sprintf(default_filename, "%02X%02X%02X%02X.img",
                        net_ip.s_addr & 0xFF,
                        (net_ip.s_addr >>  8) & 0xFF,
                        (net_ip.s_addr >> 16) & 0xFF,
                        (net_ip.s_addr >> 24) & 0xFF);

                strncpy(tftp_filename, default_filename, DEFAULT_NAME_LEN);
                tftp_filename[DEFAULT_NAME_LEN - 1] = 0;

                printf("*** Warning: no boot file name; using '%s'\n",
                       tftp_filename);
        }

        if (IS_ENABLED(CONFIG_IPV6)) {
                if (use_ip6) {
                        char *s, *e;
                        size_t len;

                        s = strchr(net_boot_file_name, '[');
                        e = strchr(net_boot_file_name, ']');
                        len = e - s;
                        if (s && e) {
                                string_to_ip6(s + 1, len - 1, &tftp_remote_ip6);
                                strlcpy(tftp_filename, e + 2, MAX_LEN);
                        } else {
                                strlcpy(tftp_filename, net_boot_file_name, MAX_LEN);
                                tftp_filename[MAX_LEN - 1] = 0;
                        }
                }
        }

        printf("Using %s device\n", eth_get_name());

        if (IS_ENABLED(CONFIG_IPV6) && use_ip6) {
                printf("TFTP from server %pI6c; our IP address is %pI6c",
                       &tftp_remote_ip6, &net_ip6);

                if (tftp_block_size_option > TFTP_MTU_BLOCKSIZE6)
                        tftp_block_size_option = TFTP_MTU_BLOCKSIZE6;
        } else {
                printf("TFTP %s server %pI4; our IP address is %pI4",
#ifdef CONFIG_CMD_TFTPPUT
               protocol == TFTPPUT ? "to" : "from",
#else
               "from",
#endif
               &tftp_remote_ip, &net_ip);
        }

        /* Check if we need to send across this subnet */
        if (IS_ENABLED(CONFIG_IPV6) && use_ip6) {
                if (!ip6_addr_in_subnet(&net_ip6, &tftp_remote_ip6,
                                        net_prefix_length))
                        printf("; sending through gateway %pI6c",
                               &net_gateway6);
        } else if (net_gateway.s_addr && net_netmask.s_addr) {
                struct in_addr our_net;
                struct in_addr remote_net;

                our_net.s_addr = net_ip.s_addr & net_netmask.s_addr;
                remote_net.s_addr = tftp_remote_ip.s_addr & net_netmask.s_addr;
                if (our_net.s_addr != remote_net.s_addr)
                        printf("; sending through gateway %pI4", &net_gateway);
        }
        putc('\n');

        printf("Filename '%s'.", tftp_filename);

        if (net_boot_file_expected_size_in_blocks) {
                printf(" Size is 0x%x Bytes = ",
                       net_boot_file_expected_size_in_blocks << 9);
                print_size(net_boot_file_expected_size_in_blocks << 9, "");
        }

        putc('\n');
#ifdef CONFIG_CMD_TFTPPUT
        tftp_put_active = (protocol == TFTPPUT);
        if (tftp_put_active) {
                printf("Save address: 0x%lx\n", image_save_addr);
                printf("Save size:    0x%lx\n", image_save_size);
                net_boot_file_size = image_save_size;
                puts("Saving: *\b");
                tftp_state = STATE_SEND_WRQ;
                new_transfer();
        } else
#endif
        {
                if (tftp_init_load_addr()) {
                        eth_halt();
                        net_set_state(NETLOOP_FAIL);
                        puts("\nTFTP error: ");
                        puts("trying to overwrite reserved memory...\n");
                        return;
                }
                printf("Load address: 0x%lx\n", tftp_load_addr);
                puts("Loading: *\b");
                tftp_state = STATE_SEND_RRQ;
        }

        time_start = get_timer(0);
        timeout_count_max = tftp_timeout_count_max;

        net_set_timeout_handler(timeout_ms, tftp_timeout_handler);
        net_set_udp_handler(tftp_handler);
#ifdef CONFIG_CMD_TFTPPUT
        net_set_icmp_handler(icmp_handler);
#endif
        tftp_remote_port = WELL_KNOWN_PORT;
        timeout_count = 0;
        /* Use a pseudo-random port unless a specific port is set */
        tftp_our_port = 1024 + (get_timer(0) % 3072);

#ifdef CONFIG_TFTP_PORT
        ep = env_get("tftpdstp");
        if (ep != NULL)
                tftp_remote_port = simple_strtol(ep, NULL, 10);
        ep = env_get("tftpsrcp");
        if (ep != NULL)
                tftp_our_port = simple_strtol(ep, NULL, 10);
#endif
        tftp_cur_block = 0;
        tftp_windowsize = 1;
        tftp_last_nack = 0;
        /* zero out server ether in case the server ip has changed */
        memset(net_server_ethaddr, 0, 6);
        /* Revert tftp_block_size to dflt */
        tftp_block_size = TFTP_BLOCK_SIZE;
#ifdef CONFIG_TFTP_TSIZE
        tftp_tsize = 0;
        tftp_tsize_num_hash = 0;
#endif

        tftp_send();
}

#ifdef CONFIG_CMD_TFTPSRV
void tftp_start_server(void)
{
        tftp_filename[0] = 0;

        if (tftp_init_load_addr()) {
                eth_halt();
                net_set_state(NETLOOP_FAIL);
                puts("\nTFTP error: trying to overwrite reserved memory...\n");
                return;
        }
        printf("Using %s device\n", eth_get_name());
        printf("Listening for TFTP transfer on %pI4\n", &net_ip);
        printf("Load address: 0x%lx\n", tftp_load_addr);

        puts("Loading: *\b");

        timeout_count_max = tftp_timeout_count_max;
        timeout_count = 0;
        timeout_ms = TIMEOUT;
        net_set_timeout_handler(timeout_ms, tftp_timeout_handler);

        /* Revert tftp_block_size to dflt */
        tftp_block_size = TFTP_BLOCK_SIZE;
        tftp_cur_block = 0;
        tftp_our_port = WELL_KNOWN_PORT;
        tftp_windowsize = 1;
        tftp_next_ack = tftp_windowsize;

#ifdef CONFIG_TFTP_TSIZE
        tftp_tsize = 0;
        tftp_tsize_num_hash = 0;
#endif

        tftp_state = STATE_RECV_WRQ;
        net_set_udp_handler(tftp_handler);

        /* zero out server ether in case the server ip has changed */
        memset(net_server_ethaddr, 0, 6);
}

#endif /* CONFIG_CMD_TFTPSRV */