Initial version

Working ping back and forth with specified data, and data
arrives at the other party.

Currently, the server uses nflog to get the pings, which:
1. requires iptables settings to work;
2. buffers and collects messages for a second.
Both are suboptimal, and I believe raw sockets can improve
on this.

1 files changed, 30 insertions, 0 deletions

diff --git a/util.c b/util.c
new file mode 100644
index 0000000..be7083c
--- /dev/null
+++ b/util.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <ctype.h>
+#include "util.h"
+
+
+void xxd(const void *buf_, size_t length) {
+	unsigned char *buf = (unsigned char*)buf_;
+
+	for (size_t cursor = 0; cursor < length;) {
+		printf("%08zx:", cursor);
+
+		for (int i = 0; i < 16; i++) {
+			if (i % 2 == 0) printf(" ");
+			if (i % 8 == 0) printf(" ");
+			if (cursor + i < length) printf("%02x", (unsigned)buf[cursor + i]);
+			else printf("  ");
+		}
+
+		printf("  |");
+
+		for (int i = 0; i < 16 && cursor + i < length; i++) {
+			if (isprint(buf[cursor + i])) printf("%c", buf[cursor + i]);
+			else printf(".");
+		}
+
+		printf("|\n");
+
+		cursor += 16;
+	}
+}