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/*
* wip, a small TCP/IP stack.
* Copyright (C) 2025 Xavier Del Campo Romero
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
#include <wip/wip.h>
#include <wip/prv/io.h>
#include <wip/prv/log.h>
#include <wip/prv/icmp.h>
#include <wip/prv/icmp/routines.h>
#include <wip/prv/icmp/types.h>
#include <stddef.h>
#include <string.h>
struct read
{
const void *buf;
size_t n;
struct wip_icmp *icmp;
};
static int io_read(void *const buf, const size_t n, void *const user)
{
const struct read *const r = user;
const size_t ret = n > r->n ? r->n : n;
memcpy(buf, r->buf, ret);
return ret;
}
static enum wip_state readbuf(struct wip_sm_io *const io, const void *const buf,
const size_t n, struct wip_icmp *const icmp)
{
struct wip_cfg cfg = {0};
struct read r;
r.buf = buf;
r.n = n;
r.icmp = icmp;
cfg.read = io_read;
cfg.user = &r;
return wip_io_read_c(&cfg, io);
}
enum wip_state get_payload(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
const struct wip_cfg *const cfg = &w->cfg;
const size_t nsz = icmp->read + n;
char *const nbuf = cfg->realloc(icmp->buf, nsz, cfg->user);
size_t i;
if (!nbuf)
return WIP_FATAL;
memcpy(nbuf + icmp->read, buf, n);
icmp->buf = nbuf;
icmp->read += n;
*r = n;
for (i = icmp->read; i < nsz; i++)
icmp->checksum += *(const char *)icmp->buf;
wip_log("ICMP data={");
for (i = 0; i < icmp->read; i++)
{
wip_log("%#hhx", *((const char *)icmp->buf + i));
if (i + 1 < icmp->read)
wip_log(", ");
}
wip_log("}\n");
wip_log("calculated checksum: %#hx, expected checksum: %#hx\n",
icmp->checksum, wip_be16(&icmp->exp_checksum));
return WIP_OK;
}
enum wip_state get_seqnum(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
const enum wip_state state = readbuf(&icmp->io, buf, n, icmp);
if (state)
return state;
else
{
struct wip_sm_io io = {0};
io.buf = &icmp->seqnum;
io.n = sizeof icmp->seqnum;
icmp->io = io;
}
wip_log("got seqnum: %#x\n", wip_be16(&icmp->seqnum));
icmp->checksum += wip_be16(&icmp->seqnum);
icmp->next = get_payload;
*r = sizeof icmp->seqnum;
return WIP_AGAIN;
}
enum wip_state get_id(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
const enum wip_state state = readbuf(&icmp->io, buf, n, icmp);
if (state)
return state;
else
{
struct wip_sm_io io = {0};
io.buf = &icmp->seqnum;
io.n = sizeof icmp->seqnum;
icmp->io = io;
}
wip_log("got id: %#x\n", wip_be16(&icmp->id));
icmp->checksum += wip_be16(&icmp->id);
icmp->next = get_seqnum;
*r = sizeof icmp->id;
return WIP_AGAIN;
}
enum wip_state get_checksum(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
const enum wip_state state = readbuf(&icmp->io, buf, n, icmp);
if (state)
return state;
else
{
struct wip_sm_io io = {0};
io.buf = &icmp->id;
io.n = sizeof icmp->id;
icmp->io = io;
}
wip_log("got expected checksum: %#x\n", wip_be16(&icmp->exp_checksum));
icmp->next = get_id;
*r = sizeof icmp->exp_checksum;
return WIP_AGAIN;
}
enum wip_state get_code(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
unsigned char code;
struct wip_sm_io io = {0};
enum wip_state state;
io.buf = &code;
io.n = sizeof code;
if ((state = readbuf(&io, buf, n, icmp)))
return state;
else if (code)
return WIP_INVALID;
else
{
struct wip_sm_io nio = {0};
nio.buf = &icmp->exp_checksum;
nio.n = sizeof icmp->exp_checksum;
icmp->io = nio;
}
wip_log("got code\n");
icmp->checksum += code;
icmp->next = get_checksum;
*r = sizeof code;
return WIP_AGAIN;
}
enum wip_state wip_icmp_rx_start(struct wip *const w, const void *const buf,
const size_t n, struct wip_icmp *const icmp, size_t *const r)
{
unsigned char type;
struct wip_sm_io io = {0};
enum wip_state state;
io.buf = &type;
io.n = sizeof type;
if ((state = readbuf(&io, buf, n, icmp)))
return state;
else if (type != ICMP_ECHO_REQUEST)
return WIP_INVALID;
wip_log("got echo request\n");
icmp->checksum += type;
icmp->type = type;
icmp->next = get_code;
*r = sizeof type;
return WIP_AGAIN;
}
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