added little utility to mark all outgoing packets of a program with a FW mark

.gitignore

@@ -1,2 +1,3 @@
 *.o
 *~
+mark.so

project/mark.c

@@ -0,0 +1,49 @@
+/** Wrapper utility to mark all sockets of a program
+ *
+ * Compile:
+ *  gcc -fPIC -c -o mark.o mark.c
+ *  gcc -shared -o mark.so mark.o -ldl
+ *
+ * Use:
+ *  LD_PRELOAD="./soft_atimes.so" command
+ *
+ * @author Steffen Vogel <post@steffenvogel.de>
+ * @authir D.J. Capelis
+ * @copyright 2014-2015, Steffen Vogel
+ * @copyright 2007, Regents of the University of California
+ * @license GPLv3
+ *********************************************************************************/
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+typedef int (*socket_t)(int domain, int type, int protocol);
+
+static socket_t _socket;
+
+int socket(int domain, int type, int protocol)
+{	
+	if (!_socket)
+		_socket = (socket_t) dlsym(RTLD_NEXT, "socket");
+
+	int sd = _socket(domain, type, protocol);
+
+	if (sd >= 0) {
+		if (domain == AF_INET || domain == AF_INET6) {
+			char * env = getenv("MARK");
+			int mark = env ? atoi(env) : 0xCD;
+			
+			printf("Setting SO_MARK for fd=%u to %#x\n", sd, mark);
+		
+			setsockopt(sd, SOL_SOCKET, SO_MARK, &mark, sizeof(mark));
+		}
+	}
+	
+	return sd;
+}