user/net: respond to pings

1 files changed, 32 insertions, 3 deletions

diff --git a/src/user/app/ethdump/icmp.c b/src/user/app/ethdump/icmp.c
index 9c80a2d..3f10ae8 100644
--- a/src/user/app/ethdump/icmp.c
+++ b/src/user/app/ethdump/icmp.c
@@ -1,8 +1,37 @@
 #include "proto.h"
 #include "util.h"
+#include <string.h>
 
-void icmp_parse(const uint8_t *buf, size_t len) {
-	if (len < 4) return;
-	uint8_t type = buf[0];
+enum {
+	Type     = 0,
+	Code     = 1,
+	Checksum = 2,
+	Payload  = 4,
+};
+
+void icmp_parse(const uint8_t *buf, size_t len, struct ipv4 ip) {
+	if (len < Payload) return;
+	uint8_t type = buf[Type];
 	printf("ICMP type %u\n", type);
+	if (type == 8 && ip.dst == state.ip) {
+		uint8_t *pkt = icmp_start(len - Payload, (struct icmp){
+			.type = 0,
+			.ip.dst = ip.src,
+			.ip.e.dst = ip.e.src,
+		});
+		memcpy(pkt, buf + Payload, len - Payload);
+		icmp_finish(pkt);
+	}
+}
+
+uint8_t *icmp_start(size_t len, struct icmp i) {
+	i.ip.proto = 1;
+	uint8_t *pkt = ipv4_start(Payload + len, i.ip);
+	pkt[Type] = i.type;
+	pkt[Code] = i.code;
+	nput16(pkt + Checksum, ip_checksum(pkt, Payload + len));
+	return pkt + Payload;
+}
+void icmp_finish(uint8_t *pkt) {
+	ipv4_finish(pkt - Payload);
 }