Add ARP stub

etc/make/conf.mk

@@ -95,7 +95,10 @@ DIRS+=$(O)/drivers/pci \
 OBJS+=$(O)/drivers/net/rtl8139.o
 DIRS+=$(O)/drivers/net
 
-OBJS+=$(O)/net/net.o
+OBJS+=$(O)/net/net.o \
+	  $(O)/net/eth.o \
+	  $(O)/net/arp.o \
+	  $(O)/net/util.o
 DIRS+=$(O)/net
 
 ifeq ($(DEBUG_COUNTERS),1)

include/net/arp.h

@@ -0,0 +1,21 @@
+#pragma once
+#include "sys/types.h"
+
+#define ARP_H_ETH           1
+#define ARP_P_IP            0x0800
+
+struct arp_frame {
+    uint16_t htype;
+    uint16_t ptype;
+    uint8_t hlen;
+    uint8_t plen;
+    uint16_t oper;
+    // INET only
+    uint8_t sha[6];
+    uint32_t spa;
+    uint8_t tha[6];
+    uint32_t tpa;
+} __attribute__((packed));
+
+struct packet;
+void arp_handle_frame(struct packet *packet, void *data, size_t len);

include/net/eth.h

@@ -0,0 +1,15 @@
+#pragma once
+#include "sys/types.h"
+
+#define ETH_T_IP            0x0800
+#define ETH_T_IPv6          0x86DD
+#define ETH_T_ARP           0x0806
+
+struct eth_frame {
+    uint8_t dst_hwaddr[6];
+    uint8_t src_hwaddr[6];
+    uint16_t ethertype;
+} __attribute__((packed));
+
+struct packet;
+void eth_handle_frame(struct packet *p);

include/net/packet.h

@@ -0,0 +1,11 @@
+#pragma once
+#include "sys/types.h"
+
+// Takes up a single page
+#define PACKET_DATA_MAX         (4064)
+struct packet {
+    size_t size;
+    struct packet *prev, *next;
+    void *source_if;
+    char data[PACKET_DATA_MAX];
+};

include/net/util.h

@@ -0,0 +1,8 @@
+#pragma once
+#include "sys/types.h"
+
+void strmac(char *dst, const uint8_t *hw);
+
+static inline uint16_t ntohs(uint16_t w) {
+    return (w >> 8) | (w << 8);
+}

net/arp.c

@@ -0,0 +1,50 @@
+#include "sys/debug.h"
+#include "net/util.h"
+#include "net/arp.h"
+
+
+/*
+?Do I have the hardware type in ar$hrd?
+Yes: (almost definitely)
+  [optionally check the hardware length ar$hln]
+  ?Do I speak the protocol in ar$pro?
+  Yes:
+    [optionally check the protocol length ar$pln]
+    Merge_flag := false
+    If the pair <protocol type, sender protocol address> is
+        already in my translation table, update the sender
+        hardware address field of the entry with the new
+        information in the packet and set Merge_flag to true.
+    ?Am I the target protocol address?
+    Yes:
+      If Merge_flag is false, add the triplet <protocol type,
+          sender protocol address, sender hardware address> to
+          the translation table.
+      ?Is the opcode ares_op$REQUEST?  (NOW look at the opcode!!)
+      Yes:
+        Swap hardware and protocol fields, putting the local
+            hardware and protocol addresses in the sender fields.
+        Set the ar$op field to ares_op$REPLY
+        Send the packet to the (new) target hardware address on
+            the same hardware on which the request was received.
+*/
+
+
+void arp_handle_frame(struct packet *p, void *data, size_t len) {
+    if (len < sizeof(struct arp_frame)) {
+        kwarn("Dropping undersized frame: %u\n", len);
+        return;
+    }
+
+    struct arp_frame *arp = data;
+
+    if (ntohs(arp->htype) != ARP_H_ETH) {
+        kwarn("Dropping non-ethernet packet\n");
+        return;
+    }
+    if (ntohs(arp->ptype) != ARP_P_IP) {
+        kwarn("Dropping non-IP packet\n");
+        return;
+    }
+
+}

net/eth.c

@@ -0,0 +1,28 @@
+#include "net/packet.h"
+#include "sys/debug.h"
+#include "net/util.h"
+#include "net/eth.h"
+
+#include "net/arp.h"
+
+void eth_handle_frame(struct packet *p) {
+    struct eth_frame *eth = (struct eth_frame *) p->data;
+
+    if (p->size < sizeof(struct eth_frame)) {
+        kwarn("Dropping undersized packet: %u\n", p->size);
+        return;
+    }
+
+    switch (ntohs(eth->ethertype)) {
+    case ETH_T_ARP:
+        arp_handle_frame(p, p->data + sizeof(struct eth_frame), p->size - sizeof(struct eth_frame));
+        break;
+    case ETH_T_IP:
+    case ETH_T_IPv6:
+        // Silently drop
+        break;
+    default:
+        kwarn("Dropping unknown packet: %04x\n", ntohs(eth->ethertype));
+        break;
+    }
+}

net/net.c

@@ -8,14 +8,8 @@
 #include "sys/debug.h"
 #include "sys/spin.h"
 
-// Takes up a single page
-#define PACKET_DATA_MAX         (4064)
-struct packet {
-    size_t size;
-    struct packet *prev, *next;
-    void *source_if;
-    char data[PACKET_DATA_MAX];
-};
+#include "net/packet.h"
+#include "net/eth.h"
 
 static struct thread netd_thread = {0};
 static spin_t g_rxq_lock = 0;
@@ -24,9 +18,9 @@ static struct packet *g_rxq_head, *g_rxq_tail;
 static struct packet *packet_create(void);
 static void packet_free(struct packet *p);
 
-static void net_handle_packet(struct packet *p) {
-    kdebug("Packet:\n");
-    debug_dump(DEBUG_DEFAULT, p->data, p->size);
+static inline void net_handle_packet(struct packet *p) {
+    // TODO: check if interface sends packet not in ethernet format
+    eth_handle_frame(p);
 }
 
 static void net_daemon(void) {
@@ -80,6 +74,8 @@ int net_receive(/* TODO: replace with struct netdev * */ void *ctx, const void *
     }
     struct packet *p = packet_create();
 
+    // TODO: maybe information like "Physical match", "Multicast" or "Broadcast"
+    //       would be useful to store in packet
     memcpy(p->data, data, len);
     p->size = len;
     p->source_if = ctx;

net/util.c

@@ -0,0 +1,11 @@
+#include "net/util.h"
+
+void strmac(char *dst, const uint8_t *hw) {
+    static const char hex_digits[] = "0123456789abcdef";
+    // I don't have snprintf, lol
+    for (size_t i = 0; i < 6; ++i) {
+        dst[i * 3 + 0] = hex_digits[hw[i] >> 4];
+        dst[i * 3 + 1] = hex_digits[hw[i] & 0xF];
+        dst[i * 3 + 2] = i == 5 ? 0 : ':';
+    }
+}