From b130e0e745ce3be4e28fc0eb50011f931157b49a Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 16 Jun 2025 01:34:26 -0400
Subject: kernel: net: Implement IEEE 802.3 + ARP requests

Introduce IEEE 802.3 related headers such as ones containing the
structure of an ethernet frame as well as its types. This commit
additionally introduces ARP request logic.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/netinet/if_ether.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 sys/netinet/if_ether.c

(limited to 'sys/netinet/if_ether.c')

diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
new file mode 100644
index 0000000..0c458a4
--- /dev/null
+++ b/sys/netinet/if_ether.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/endian.h>
+#include <sys/errno.h>
+#include <vm/dynalloc.h>
+#include <net/ethertypes.h>
+#include <netinet/if_ether.h>
+#include <string.h>
+
+struct arp_pkt {
+    struct ether_frame ehfr;
+    struct ether_arp payload;
+};
+
+static void
+set_hwaddr(struct netif_addr *addrp, char addr[ETHER_ADDR_LEN])
+{
+    uint16_t *psrc, *p;
+
+    psrc = (uint16_t *)&addrp->data[0];
+    p = (uint16_t *)addr;
+
+    p[0] = swap16(psrc[0]);
+    p[1] = swap16(psrc[1]);
+    p[2] = swap16(psrc[2]);
+}
+
+static struct arp_pkt *
+arp_create(struct netif *nifp, uint32_t *sproto, uint32_t *tproto, uint16_t op)
+{
+    struct arp_pkt *packet;
+    struct arp_hdr *hdrp;
+    struct ether_frame *frp;
+    struct ether_arp *payload;
+
+    packet = dynalloc(sizeof(*packet));
+    if (packet == NULL) {
+        return NULL;
+    }
+
+    frp = &packet->ehfr;
+    payload = &packet->payload;
+    hdrp = &payload->hdr;
+
+    /* Ethernet frame, from source to all */
+    set_hwaddr(&nifp->addr, frp->ether_saddr);
+    memset(frp->ether_daddr, 0xFF, ETHER_ADDR_LEN);
+    frp->ether_type = swap16(ETHERTYPE_ARP);
+
+    /* Now for the ARP header */
+    hdrp->hw_type = swap16(ARP_HWTYPE_ETHER);
+    hdrp->proto_type = swap16(ETHERTYPE_IPV4);
+    hdrp->hw_len = ETHER_ADDR_LEN;
+    hdrp->proto_len = 4;
+    hdrp->op_type = swap16(op);
+
+    memcpy(payload->sha, frp->ether_saddr, ETHER_ADDR_LEN);
+    memset(payload->tha, 0xFF, ETHER_ADDR_LEN);
+
+    /* Protocol source address */
+    *((uint32_t *)payload->spa) = *sproto;
+    *((uint32_t *)payload->tpa) = *tproto;
+    return packet;
+}
+
+int
+arp_request(struct netif *nifp, uint8_t *sproto, uint8_t *tproto)
+{
+    struct arp_pkt *packet;
+    struct netbuf nb;
+    uint32_t *src_tmp, *targ_tmp;
+
+    if (nifp->tx_enq == NULL) {
+        return -ENOTSUP;
+    }
+    if (nifp->tx_start == NULL) {
+        return -ENOTSUP;
+    }
+
+    src_tmp = (uint32_t *)sproto;
+    targ_tmp = (uint32_t *)tproto;
+
+    packet = arp_create(nifp, src_tmp, targ_tmp, ARP_REQUEST);
+    if (packet == NULL) {
+        return -ENOMEM;
+    }
+
+    nb.len = sizeof(*packet);
+    memcpy(nb.data, packet, nb.len);
+
+    nifp->tx_enq(nifp, &nb, NULL);
+    nifp->tx_start(nifp);
+    dynfree(packet);
+    return 0;
+}
-- 
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