3 files changed, 68 insertions, 2 deletions

diff --git a/src/user/app/netstack/arp.c b/src/user/app/netstack/arp.c
index 9eab8e3..b43b7e8 100644
--- a/src/user/app/netstack/arp.c
+++ b/src/user/app/netstack/arp.c
@@ -1,5 +1,7 @@
 #include "proto.h"
 #include "util.h"
+#include <assert.h>
+#include <camellia/syscalls.h>
 #include <string.h>
 
 enum {
@@ -13,8 +15,16 @@ enum {
 		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) {
-	// TODO no bound checks
+	if (len < Operation + 2) return;
 	uint16_t htype = nget16(buf + HdrType);
 	uint16_t ptype = nget16(buf + ProtoType);
 	uint16_t op = nget16(buf + Operation);
@@ -26,6 +36,8 @@ void arp_parse(const uint8_t *buf, size_t len) {
 		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);
@@ -46,3 +58,45 @@ void arp_parse(const uint8_t *buf, size_t len) {
 		}
 	}
 }
+
+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;
+}
+
+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);
+}
diff --git a/src/user/app/netstack/fs.c b/src/user/app/netstack/fs.c
index 52d6038..dc6db04 100644
--- a/src/user/app/netstack/fs.c
+++ b/src/user/app/netstack/fs.c
@@ -2,6 +2,8 @@
  * path format:
  * /net/raw
  *   raw ethernet frames (read-write)
+ * /net/arp
+ *   ARP cache (currently read-only)
  * /net/0.0.0.0/connect/1.2.3.4/udp/53
  *   connect from 0.0.0.0 (any ip) to 1.2.3.4 on udp port 53
  * /net/0.0.0.0/listen/udp/53
@@ -9,6 +11,7 @@
  *   open() returns once a connection to ip 0.0.0.0 on udp port 53 is received
  */
 #include "proto.h"
+#include "util.h"
 #include <camellia/syscalls.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -17,6 +20,7 @@
 enum handle_type {
 	H_ETHER,
 	H_UDP,
+	H_ARP,
 };
 
 struct strqueue {
@@ -79,7 +83,7 @@ static void udp_recv_enqueue(struct handle *h, handle_t reqh) {
 }
 
 static void fs_open(handle_t reqh, char *path) {
-#define respond(buf, val) do{ _syscall_fs_respond(reqh, NULL, -1, 0); return; }while(0)
+#define respond(buf, val) do{ _syscall_fs_respond(reqh, buf, val, 0); return; }while(0)
 	struct handle *h;
 	if (*path != '/') respond(NULL, -1);
 	path++;
@@ -88,6 +92,10 @@ static void fs_open(handle_t reqh, char *path) {
 		h = malloc(sizeof *h);
 		h->type = H_ETHER;
 		respond(h, 0);
+	} else if (strcmp(path, "arp") == 0) {
+		h = malloc(sizeof *h);
+		h->type = H_ARP;
+		respond(h, 0);
 	}
 
 	char *save;
@@ -147,6 +155,9 @@ void fs_thread(void *arg) { (void)arg;
 					case H_UDP:
 						udp_recv_enqueue(h, reqh);
 						break;
+					case H_ARP:
+						arp_fsread(reqh, res.offset);
+						break;
 					default:
 						_syscall_fs_respond(reqh, NULL, -1, 0);
 				}
diff --git a/src/user/app/netstack/proto.h b/src/user/app/netstack/proto.h
index 106f286..864f1c1 100644
--- a/src/user/app/netstack/proto.h
+++ b/src/user/app/netstack/proto.h
@@ -46,6 +46,7 @@ struct ethq {
 extern struct ethq *ether_queue;
 
 void arp_parse(const uint8_t *buf, size_t len);
+void arp_fsread(handle_t h, long offset);
 
 void icmp_parse(const uint8_t *buf, size_t len, struct ipv4 ip);
 void icmp_send(const void *payload, size_t len, struct icmp i);