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#include "proto.h"
#include "util.h"
#include <assert.h>
#include <camellia/syscalls.h>
#include <string.h>
enum {
HdrType = 0,
HdrTypeEther = 1,
ProtoType = 2,
HdrALen = 4,
ProtoALen = 5,
Operation = 6,
OpReq = 1,
OpReply = 2,
};
struct arpc {
struct arpc *next;
uint32_t ip;
mac_t mac;
};
static struct arpc *arpcache;
static void arpcache_put(uint32_t ip, mac_t mac);
void arp_parse(const uint8_t *buf, size_t len) {
if (len < Operation + 2) return;
uint16_t htype = nget16(buf + HdrType);
uint16_t ptype = nget16(buf + ProtoType);
uint16_t op = nget16(buf + Operation);
if (!(htype == HdrTypeEther && ptype == ET_IPv4)) return;
enum { /* only valid for this combination of header + proto */
SrcMAC = 8,
SrcIP = 14,
DstMAC = 18,
DstIP = 24,
};
if (len < DstIP + 4) return;
arpcache_put(nget32(buf + SrcIP), *(mac_t*)buf + SrcMAC);
if (op == OpReq) {
uint32_t daddr = nget32(buf + DstIP);
if (daddr == state.ip) {
uint8_t *pkt = ether_start(30, (struct ethernet){
.dst = (void*)(buf + SrcMAC),
.type = ET_ARP,
});
nput16(pkt + HdrType, 1);
nput16(pkt + ProtoType, ET_IPv4);
pkt[HdrALen] = 6;
pkt[ProtoALen] = 4;
nput16(pkt + Operation, OpReply);
memcpy(pkt + SrcMAC, state.mac, 6);
nput32(pkt + SrcIP, state.ip);
memcpy(pkt + DstMAC, buf + SrcMAC, 10); /* sender's MAC and IP */
ether_finish(pkt);
}
}
}
static void arpcache_put(uint32_t ip, mac_t mac) {
for (struct arpc *iter = arpcache; iter; iter = iter->next) {
if (memcmp(iter->mac, mac, 6) == 0) {
if (iter->ip == ip) return; /* cache entry correct */
else break; /* cache entry needs updating */
}
}
struct arpc *e = malloc(sizeof *e);
e->next = arpcache;
e->ip = ip;
memcpy(e->mac, mac, 6);
arpcache = e;
}
int arpcache_get(uint32_t ip, mac_t *mac) {
for (struct arpc *iter = arpcache; iter; iter = iter->next) {
if (iter->ip == ip) {
if (mac) memcpy(mac, iter->mac, 6);
return 0;
}
}
return -1;
}
void arp_fsread(handle_t h, long offset) {
const char *fmt = "%08x\t%02x:%02x:%02x:%02x:%02x:%02x\n";
long linelen = snprintf(NULL, 0, fmt, 0, 1, 2, 3, 4, 5, 6) + 1;
char buf[28];
assert(linelen <= (long)sizeof(buf));
if (offset < 0) goto err;
struct arpc *cur = arpcache;
if (!cur) goto err;
for (; linelen <= offset; offset -= linelen) {
cur = cur->next;
if (!cur) goto err;
}
assert(0 <= offset && offset < linelen);
snprintf(buf, sizeof buf, fmt, cur->ip,
cur->mac[0],
cur->mac[1],
cur->mac[2],
cur->mac[3],
cur->mac[4],
cur->mac[5]);
_syscall_fs_respond(h, buf + offset, linelen - offset, 0);
return;
err:
_syscall_fs_respond(h, NULL, -1, 0);
}
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