Add ARP tables and reply function

drivers/net/rtl8139.c

@@ -56,8 +56,10 @@ static void rtl8139_reset(struct rtl8139 *rtl) {
     while (inb(rtl->iobase + REG_CR) & CR_RST);
 }
 
-static int rtl8139_netdev_send(struct netdev *net, const void *date, size_t len) {
+static int rtl8139_netdev_send(struct netdev *net, const void *data, size_t len) {
     // TODO
+    kdebug("%s: send stub:\n", net->name);
+    debug_dump(DEBUG_DEFAULT, data, len);
     return -1;
 }
 

include/net/arp.h

@@ -4,6 +4,9 @@
 #define ARP_H_ETH           1
 #define ARP_P_IP            0x0800
 
+#define ARP_OP_REQUEST      1
+#define ARP_OP_REPLY        2
+
 struct arp_frame {
     uint16_t htype;
     uint16_t ptype;

include/net/eth.h

@@ -11,5 +11,8 @@ struct eth_frame {
     uint16_t ethertype;
 } __attribute__((packed));
 
+struct netdev;
 struct packet;
 void eth_handle_frame(struct packet *p);
+
+int eth_send_wrapped(struct netdev *src, const uint8_t *dst, uint16_t et, void *data, size_t len);

include/net/if.h

@@ -6,6 +6,7 @@
 #define IF_T_ETH        1
 
 struct netdev;
+struct arp_ent;
 
 typedef int (*netdev_send_func_t) (struct netdev *, const void *, size_t);
 
@@ -17,7 +18,8 @@ struct netdev {
     uint32_t flags;
     int type;
 
-    // TODO: arp table here?
+    // ARP entry list
+    struct arp_ent *arp_ent_head;
 
     netdev_send_func_t send;
 

include/net/util.h

@@ -9,6 +9,14 @@
 
 void strmac(char *dst, const uint8_t *hw);
 
+static inline uint32_t ntohl(uint32_t w) {
+    uint8_t *s = (uint8_t *)&w;
+    return (uint32_t) (s[0] << 24 | s[1] << 16 | s[2] << 8 | s[3]);
+}
+
 static inline uint16_t ntohs(uint16_t w) {
     return (w >> 8) | (w << 8);
 }
+static inline uint16_t htons(uint16_t w) {
+    return (w >> 8) | (w << 8);
+}

net/arp.c

@@ -1,9 +1,45 @@
 #include "net/packet.h"
+#include "sys/assert.h"
+#include "sys/string.h"
 #include "sys/debug.h"
+#include "sys/heap.h"
 #include "net/util.h"
 #include "net/arp.h"
+#include "net/eth.h"
 #include "net/if.h"
 
+struct arp_ent {
+    uint32_t inaddr;
+    uint8_t hwaddr[6];
+    int resolved;
+    struct arp_ent *prev, *next;
+};
+
+static struct arp_ent *arp_find_inaddr(struct netdev *dev, uint32_t inaddr) {
+    for (struct arp_ent *ent = dev->arp_ent_head; ent; ent = ent->next) {
+        if (ent->inaddr == inaddr) {
+            return ent;
+        }
+    }
+    return NULL;
+}
+
+static void arp_add_entry(struct netdev *dev, uint32_t inaddr, const uint8_t *hw) {
+    struct arp_ent *ent = kmalloc(sizeof(struct arp_ent));
+    _assert(ent);
+
+    ent->inaddr = inaddr;
+    memcpy(ent->hwaddr, hw, 6);
+    ent->resolved = 1;
+
+    ent->next = dev->arp_ent_head;
+    ent->prev = NULL;
+    dev->arp_ent_head = ent;
+
+    char mac[24];
+    strmac(mac, hw);
+    kdebug("%s: add arp entry: " FMT_INADDR " -> %s\n", dev->name, VA_INADDR(inaddr), mac);
+}
 
 /*
 ?Do I have the hardware type in ar$hrd?
@@ -31,6 +67,25 @@ Yes: (almost definitely)
             the same hardware on which the request was received.
 */
 
+static void arp_send_reply(struct netdev *src, struct arp_frame *req) {
+    char reply[sizeof(struct eth_frame) + sizeof(struct arp_frame)];
+    struct arp_frame *arp = (struct arp_frame *) &reply[sizeof(struct eth_frame)];
+
+    memcpy(arp->tha, req->sha, 6);
+    memcpy(arp->sha, src->hwaddr, 6);
+
+    arp->spa = req->tpa;
+    arp->tpa = req->spa;
+
+    arp->hlen = req->hlen;
+    arp->plen = req->plen;
+    arp->htype = req->htype;
+    arp->ptype = req->ptype;
+
+    arp->oper = htons(ARP_OP_REPLY);
+
+    eth_send_wrapped(src, arp->tha, ETH_T_ARP, reply, sizeof(reply));
+}
 
 void arp_handle_frame(struct packet *p, void *data, size_t len) {
     if (len < sizeof(struct arp_frame)) {
@@ -39,6 +94,9 @@ void arp_handle_frame(struct packet *p, void *data, size_t len) {
     }
 
     struct arp_frame *arp = data;
+    struct arp_ent *ent;
+    struct netdev *dev = p->dev;
+    int merge = 0;
 
     if (ntohs(arp->htype) != ARP_H_ETH) {
         kwarn("%s: dropping non-ethernet packet\n", p->dev->name);
@@ -48,4 +106,20 @@ void arp_handle_frame(struct packet *p, void *data, size_t len) {
         kwarn("%s: dropping non-IP packet\n", p->dev->name);
         return;
     }
+
+    if ((ent = arp_find_inaddr(dev, ntohl(arp->spa))) != NULL) {
+        merge = 1;
+        kinfo("Found source addr\n");
+    }
+
+    if ((dev->flags & IF_F_HASIP) &&
+        dev->inaddr == ntohl(arp->tpa)) {
+        if (!merge) {
+            arp_add_entry(dev, ntohl(arp->spa), arp->sha);
+        }
+
+        if (htons(arp->oper) == ARP_OP_REQUEST) {
+            arp_send_reply(dev, arp);
+        }
+    }
 }

net/eth.c

@@ -1,4 +1,6 @@
 #include "net/packet.h"
+#include "sys/assert.h"
+#include "sys/string.h"
 #include "sys/debug.h"
 #include "net/util.h"
 #include "net/eth.h"
@@ -6,6 +8,17 @@
 
 #include "net/arp.h"
 
+int eth_send_wrapped(struct netdev *src, const uint8_t *hwaddr, uint16_t et, void *data, size_t len) {
+    struct eth_frame *eth = data;
+
+    memcpy(eth->dst_hwaddr, hwaddr, 6);
+    memcpy(eth->src_hwaddr, src->hwaddr, 6);
+    eth->ethertype = htons(et);
+
+    _assert(src->send);
+    return src->send(src, data, len);
+}
+
 void eth_handle_frame(struct packet *p) {
     if (p->size < sizeof(struct eth_frame)) {
         kwarn("%s: dropping undersized packet: %u\n", p->dev->name, p->size);

net/if.c

@@ -17,6 +17,7 @@ struct netdev *netdev_create(int type) {
     net->inaddr = 0;
     net->flags = 0;
     net->type = type;
+    net->arp_ent_head = NULL;
 
     switch (type) {
     case IF_T_ETH: