added more information to the remade

README.md

@@ -1,34 +1,63 @@
 # Netem Tool
 
-This tool uses the 3-way TCP handshake to measure the real RTT of a TCP connection.
+This tool uses a 3-way TCP handshake to measure the real RTT of a TCP connection.
+The gathered information can be used to configure the Linux network emulation queing discipline (see tc-netem(8)).
+
+It is possible to directly pass the results of the RTT probes to the Kernel.
+Therefore it allows to simulate an existing network connection in realtime.
+Alternatively, the measurements can be stored and replayed later.
+
+One use case might be to test your application, equipement, protocols against sudden changes of the link quality.
+It also allows to generate custom delay distributions which can be used with tc-netem(8).
 
 ### Usage
 
-###### Use case 1: collect probing measurements
+###### Use case 1: collect RTT measurements
 
 Run TCP SYN/ACK probes to measure round-trip-time (RTT):
 
-    ./netem probe 8.8.8.8 > probing.dat
+    ./netem probe 8.8.8.8 53 > measurements.dat
 
-###### Use case 2: convert measurements into delay distribution table
+###### Use case 2a: convert measurements into delay distribution table
 
 Collect measurements to build a tc-netem(8) delay distribution table
 
-###### Use case 3
+    ./netem dist generate < measurements.dat > google_dns.dist
+
+###### Use case 2b: generate distribution from measurements and load it to the Kernel
+
+    ./netem dist load < probing.dat
+
+###### Use case 3: on-the-fly link simulation
 
 The output of this command and be stored in a file or directly passed to the `emulate` subcommand:
 
-    ./netem probe 8.8.8.8 | ./netem emulate
-    ./netem emulate < probing.dat
+    ./netem probe 8.8.8.8 53 | ./netem emulate
+
+or
+
+    ./netem emulate < measurements.dat
+
+###### Use case 4: Limit the effect of the network emulation to a specific application
 
 To apply the network emulation only to a limit stream of packets, you can use the `mark` tool:
 
+    ./netem -m 0xCD dist load < measurements.dat
     sudo LD_PRELOAD=${PWD}/mark.so MARK=0xCD ping google.de
 
 Please make sure the specify the environmental variables after the sudo command!
 This is necessary, as `ping` is a SUID program.
 The dynamic linker strips certain enviromental variables (as `LD_PRELOAD`) for security reasons!
 
+### ToDo
+
+Add more metrics:
+
+  - loss
+  - duplication
+  - corruption
+  - reordering
+
 ### Building
 
 ##### Install libnl

config.h

@@ -14,9 +14,8 @@ struct config {
 	int mark;
 	int mask;
 	int interval;
-	int rate;
 	int limit;
-	
+	double rate;
 	char *dev;
 };
 

main.c

@@ -26,6 +26,7 @@ int running = 1;
 /* Default settings */
 struct config cfg = {
 	.limit = 100,
+	.rate = 1,
 	.mark = 0xCD,
 	.mask = 0xFFFFFFFF,
 	.dev = "eth0"
@@ -45,15 +46,14 @@ int main(int argc, char *argv[])
 	if (argc < 2) {
 		printf("usage: %s CMD [OPTIONS]\n", argv[0]);
 		printf("  CMD     can be one of:\n");
-		printf("    live          \n");
-		printf("    probe         \n");
-		printf("    emulate       \n");		
+		printf("    probe IP PORT\n");
+		printf("    emulate\n");		
 		printf("\n");
 		printf("  OPTIONS:\n");
 		printf("    -m --mark N      apply emulation only to packet buffers with mark N\n");
 		printf("    -M --mask N      an optional mask for the fw mark\n");
 		printf("    -i --interval N  update the emulation parameters every N seconds\n");
-		printf("    -r --rate        the packet rate used for measurements\n");
+		printf("    -r --rate        rate limit used for measurements and updates of network emulation\n");
 		printf("    -l --limit       how many probes should we sent\n");
 		printf("    -d --dev         network interface\n");
 		
@@ -82,7 +82,7 @@ int main(int argc, char *argv[])
 	
 	/* Parse Arguments */
 	char c, *endptr;
-	while ((c = getopt (argc-1, argv+1, "h:m:M:i:l:d:")) != -1) {
+	while ((c = getopt (argc-1, argv+1, "h:m:M:i:l:d:r:")) != -1) {
 		switch (c) {
 			case 'm':
 				cfg.mark = strtoul(optarg, &endptr, 0);
@@ -94,7 +94,7 @@ int main(int argc, char *argv[])
 				cfg.interval = strtoul(optarg, &endptr, 10);
 				goto check;
 			case 'r':
-				cfg.rate = strtoul(optarg, &endptr, 10);
+				cfg.rate = strtof(optarg, &endptr);
 				goto check;
 			case 'l':
 				cfg.limit = strtoul(optarg, &endptr, 10);

timing.c

@@ -5,6 +5,13 @@
  * @license GPLv3
  *********************************************************************************/
 
+#define _POSIX_C_SOURCE 199309L
+
+#include <unistd.h>
+	
+#include <time.h>
+#include <sys/timerfd.h>
+
 #include "timing.h"
 
 uint64_t timerfd_wait(int fd)

timing.h

@@ -5,17 +5,11 @@
  * @license GPLv3
  *********************************************************************************/
 
-#ifndef _TIME_H_
-#define _TIME_H_
+#ifndef _TIMING_H_
+#define _TIMING_H_
 
-#define _POSIX_C_SOURCE 199309L
-
-#include <unistd.h>
 #include <stdio.h>
 #include <stdint.h>
-	
-#include <time.h>
-#include <sys/timerfd.h>
 
 /** Wait until timer elapsed
  *