First commitHEADmaster

2 files changed, 457 insertions, 0 deletions

diff --git a/src/routines/CMakeLists.txt b/src/routines/CMakeLists.txt
new file mode 100644
index 0000000..aa69a13
--- /dev/null
+++ b/src/routines/CMakeLists.txt
@@ -0,0 +1,10 @@
+# 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/.
+
+target_sources(${PROJECT_NAME} PRIVATE
+    rx.c
+)
diff --git a/src/routines/rx.c b/src/routines/rx.c
new file mode 100644
index 0000000..b031d14
--- /dev/null
+++ b/src/routines/rx.c
@@ -0,0 +1,447 @@
+/*
+ * 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/tcp.h>
+#include <wip/prv/udp.h>
+#include <wip/prv/routines.h>
+#include <stddef.h>
+
+#include <time.h>
+
+unsigned valid_packets;
+
+enum {MIN_HEADER_SZ = 20};
+
+static const struct wip_prot_ops protocols[] =
+{
+    {
+        WIP_P_ICMP,
+        wip_icmp_alloc,
+        wip_icmp_free,
+        wip_icmp_rx,
+        wip_icmp_tx
+    },
+
+    {
+        WIP_P_TCP,
+        wip_tcp_alloc,
+        wip_tcp_free,
+        wip_tcp_rx,
+        wip_tcp_tx
+    },
+
+    {
+        WIP_P_UDP,
+        wip_udp_alloc,
+        wip_udp_free,
+        wip_udp_rx,
+        wip_udp_tx
+    }
+};
+
+static enum wip_state get_data(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io *const io = &h->io;
+    const unsigned short dlen = wip_be16(&h->len) - h->header_sz;
+    const struct wip_prot_ops *const p = h->prot;
+    enum wip_state n;
+
+    if ((n = wip_io_read(w, io)))
+        return n;
+    else if (p && (n = p->rx(w, rx->buf, io->n, h->args)))
+        return n;
+
+#if 0
+    wip_log("got new data, h->i=%lu, io->n=%lu, dlen=%u\n",
+        (unsigned long)h->i, (unsigned long)io->n, dlen);
+#endif
+
+    if ((h->i += io->n) >= dlen)
+    {
+#if 1
+        wip_log("finished getting data (%u bytes)\n", (unsigned)dlen);
+#endif
+        if (h->prot)
+        {
+            h->prot->free(w, h->args);
+            h->prot = h->args = NULL;
+        }
+
+        wip_rx(w);
+        valid_packets++;
+    }
+    else
+    {
+        struct wip_sm_io nio = {0};
+        const size_t n = dlen - h->i;
+
+#if 0
+        wip_log("still need more data! (%u bytes)\n", n);
+#endif
+
+        nio.buf = rx->buf;
+        nio.n = n > sizeof rx->buf ? sizeof rx->buf : n;
+        *io = nio;
+    }
+
+    return WIP_OK;
+}
+
+static enum wip_state get_options(struct wip *const w)
+{
+    unsigned char b;
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io io = {0};
+    enum wip_state n;
+
+    io.buf = &b;
+    io.n = sizeof b;
+
+    if ((n = wip_io_read(w, &io)))
+        return n;
+    else if (++h->i >= h->header_sz - MIN_HEADER_SZ)
+    {
+        struct wip_sm_io nio = {0};
+        const unsigned short dlen = wip_be16(&h->len);
+        const size_t n = dlen - h->i;
+
+        nio.buf = rx->buf;
+        nio.n = n > sizeof rx->buf ? sizeof rx->buf : n;
+        h->io = nio;
+        h->i = 0;
+#if 0
+        wip_log("%s: will read %lu bytes of data\n", __func__, (unsigned long)h->io.n);
+#endif
+        rx->next = get_data;
+    }
+
+    h->chksum += b;
+    return WIP_OK;
+}
+
+static enum wip_state get_dst(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    if (n)
+        return n;
+
+#if 0
+    wip_log("got dst address=%hhu.%hhu.%hhu.%hhu\n",
+        h->src.v[0], h->src.v[1], h->src.v[2], h->src.v[3]);
+#endif
+    h->chksum += wip_be32(&h->dst);
+
+    if (h->header_sz > MIN_HEADER_SZ)
+    {
+#if 0
+        wip_log("will parse options\n");
+#endif
+        rx->next = get_options;
+    }
+    else
+    {
+        struct wip_sm_io io = {0};
+        const size_t n = wip_be16(&h->len) - h->header_sz;
+
+        io.buf = rx->buf;
+        io.n = n >= sizeof rx->buf ? sizeof rx->buf : n;
+#if 0
+        wip_log("%s: expecting %lu bytes of data\n", __func__, (unsigned long)io.n);
+#endif
+        h->i = 0;
+        h->io = io;
+        rx->next = get_data;
+    }
+
+    return WIP_OK;
+}
+
+static enum wip_state get_src(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    if (n)
+        return n;
+    else
+    {
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->dst;
+        io.n = sizeof h->dst;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got source address=%hhu.%hhu.%hhu.%hhu\n",
+        h->src.v[0], h->src.v[1], h->src.v[2], h->src.v[3]);
+#endif
+    h->chksum += wip_be32(&h->src);
+    rx->next = get_dst;
+    return WIP_OK;
+}
+
+static enum wip_state get_chksum(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    if (n)
+        return n;
+    else
+    {
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->src;
+        io.n = sizeof h->src;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got expected checksum=%hu\n", wip_be16(&h->rchksum));
+#endif
+    rx->next = get_src;
+    return WIP_OK;
+}
+
+static const struct wip_prot_ops *get_ops(const unsigned char protocol)
+{
+    size_t i;
+
+    for (i = 0; i < sizeof protocols / sizeof *protocols; i++)
+    {
+        const struct wip_prot_ops *const p = &protocols[i];
+
+        if (protocol == p->id)
+            return p;
+    }
+
+    return NULL;
+}
+
+static enum wip_state get_protocol(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io io = {0};
+    enum wip_state n;
+
+    io.buf = &h->protocol;
+    io.n = sizeof h->protocol;
+
+    if ((n = wip_io_read(w, &io)))
+        return n;
+    else
+    {
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->rchksum;
+        io.n = sizeof h->rchksum;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got protocol: %#hhx\n", h->protocol);
+#endif
+    if ((h->prot = get_ops(h->protocol))
+        && !(h->args = h->prot->alloc(w)))
+        return WIP_FATAL;
+
+    h->chksum += h->protocol;
+    rx->next = get_chksum;
+    return WIP_OK;
+}
+
+static enum wip_state get_ttl(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io io = {0};
+    enum wip_state n;
+
+    io.buf = &h->ttl;
+    io.n = sizeof h->ttl;
+
+    if ((n = wip_io_read(w, &io)))
+        return n;
+
+#if 0
+    wip_log("got TTL\n");
+#endif
+    h->chksum += h->ttl;
+    rx->next = get_protocol;
+    return WIP_OK;
+}
+
+static enum wip_state get_flags_offset(struct wip *const w)
+{
+    unsigned char flags;
+    unsigned short fl_off;
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    if (n)
+        return n;
+
+    fl_off = wip_be16(&h->fl_off);
+
+    if ((flags = fl_off >> 13) & 1)
+        return WIP_INVALID;
+
+#if 0
+    wip_log("got flags offset: %hu\n", fl_off);
+#endif
+    h->chksum += fl_off;
+    rx->next = get_ttl;
+    return WIP_OK;
+}
+
+static enum wip_state get_id(struct wip *const w)
+{
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    /* TODO: use ID? */
+    if (n)
+        return n;
+    else
+    {
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->fl_off;
+        io.n = sizeof h->fl_off;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got id: %hu\n", wip_be16(&h->id));
+#endif
+    h->chksum += wip_be16(&h->id);
+    rx->next = get_flags_offset;
+    return WIP_OK;
+}
+
+static enum wip_state get_len(struct wip *const w)
+{
+    unsigned short len;
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    const enum wip_state n = wip_io_read(w, &h->io);
+
+    if (n)
+        return n;
+    else if ((len = wip_be16(&h->len)) < MIN_HEADER_SZ)
+        return WIP_INVALID;
+    else if (len > sizeof rx->buf)
+    {
+#if 0
+        wip_log("data too big: %hu (max %lu)\n", len,
+            (unsigned long)sizeof rx->buf);
+#endif
+        return WIP_INVALID;
+    }
+    else
+    {
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->id;
+        io.n = sizeof h->id;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got length: %hu\n", len);
+#endif
+    h->chksum = len;
+    rx->next = get_id;
+    return WIP_OK;
+}
+
+static enum wip_state get_dscp_ecn(struct wip *const w)
+{
+    unsigned char b;
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io io = {0};
+    enum wip_state n;
+
+    io.buf = &b;
+    io.n = sizeof b;
+
+    /* TODO: support DSCP and ECN? */
+    if ((n = wip_io_read(w, &io)))
+        return n;
+    else
+    {
+        struct wip_rx_sm_h *const h = &rx->sm.h;
+        struct wip_sm_io io = {0};
+
+        io.buf = &h->len;
+        io.n = sizeof h->len;
+        h->io = io;
+    }
+
+#if 0
+    wip_log("got DSCP and ECN\n");
+#endif
+    h->chksum += b;
+    rx->next = get_len;
+    return WIP_OK;
+}
+
+static enum wip_state get_version_ihl(struct wip *const w)
+{
+    enum {VERSION = 4};
+    unsigned char b, version, ihl;
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const h = &rx->sm.h;
+    struct wip_sm_io io = {0};
+    enum wip_state n;
+
+    io.buf = &b;
+    io.n = sizeof b;
+
+    if ((n = wip_io_read(w, &io)))
+        return n;
+    else if ((version = b >> 4) != 4
+        || (ihl = b & 0xf) < MIN_HEADER_SZ / 4)
+        return WIP_INVALID;
+
+#if 0
+    wip_log("got IPv4 header, length=%u\n", ihl * 4);
+#endif
+    h->chksum += b;
+    h->header_sz = ihl * 4;
+    rx->next = get_dscp_ecn;
+    return WIP_OK;
+}
+
+void wip_rx(struct wip *const w)
+{
+    const struct wip_rx_sm_h h = {0};
+    struct wip_rx *const rx = &w->rx;
+    struct wip_rx_sm_h *const ph = &rx->sm.h;
+
+    *ph = h;
+    rx->next = get_version_ihl;
+}