First commitHEADmaster

1 files changed, 205 insertions, 0 deletions

diff --git a/src/protocol/icmp/start.c b/src/protocol/icmp/start.c
new file mode 100644
index 0000000..f50052e
--- /dev/null
+++ b/src/protocol/icmp/start.c
@@ -0,0 +1,205 @@
+/*
+ * 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;
+}