1 files changed, 48 insertions, 0 deletions
diff --git a/mbd/derpspan.c b/mbd/derpspan.c
new file mode 100644
index 0000000..b9fb362
--- /dev/null
+++ b/mbd/derpspan.c
@@ -0,0 +1,48 @@
+// gcc -O2 -o derspan derspan.c -lpcap -std=gnu99 -Wall
+
+#include <pcap.h>
+#include <stdlib.h>
+#include <netinet/ip.h>
+#include <stdint.h>
+#include <stdio.h>
+
+int rawsock;
+
+void my_callback(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
+{
+	int len = h->caplen;
+	if (len < 40) {
+		//printf("skipped short packet\n");
+		return;
+	}
+	if (bytes[14] != 0x88 || bytes[15] != 0xbe) {
+		//printf("skipped non-ethernet packet\n");
+		return;
+	}
+	if (bytes[36] != 0x08 || bytes[37] != 0x00) {
+		//printf("skipped non-IPv4 packet\n");
+		return;
+	}
+
+	struct sockaddr_in self;
+	self.sin_family = AF_INET;
+	self.sin_addr.s_addr = htonl(0x7f000001);  // localhost
+	self.sin_port = htons(1337);
+
+	sendto(rawsock, bytes + 38, len - 38, 0, (struct sockaddr *)&self, sizeof(self));
+}
+
+int main(int argc, char **argv)
+{
+	rawsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
+	if (rawsock == -1) {
+		perror("socket");
+		exit(0);
+	}
+
+	pcap_t *pcap = pcap_open_live(argv[1], 1500, 1, 1000, NULL);
+	pcap_activate(pcap);
+	pcap_loop(pcap, -1, my_callback, NULL);
+	return 0;
+}
+