Add more improvements inspired by the #232 review

Includes

- A fix to the 6791 pool: was always using host addresses,
  regardless of whether the pool had elements or not.
- More graybox improvements.
- More comments.

include/nat64/mod/common/log.h

@@ -15,12 +15,12 @@
  * (bad checksums, bogus addresses, etc) and some failed memory allocations
  * (because the kernel already prints those).
  */
-#define log_debug(text, ...) pr_debug(text "\n", ##__VA_ARGS__)
+#define log_debug(text, ...) pr_debug("%s: " text "\n", xlat_get_name(), ##__VA_ARGS__)
 /**
  * Responses to events triggered by the user, which might not show signs of life
  * elsehow.
  */
-#define log_info(text, ...) pr_info(text "\n", ##__VA_ARGS__)
+#define log_info(text, ...) pr_info("%s: " text "\n", xlat_get_name(), ##__VA_ARGS__)
 /**
  * "I'm not going to translate this because the config's not right."
  * These rate limit themselves so the log doesn't get too flooded.

mod/common/rfc6145/4to6.c

@@ -36,10 +36,12 @@ verdict ttp46_create_skb(struct xlation *state)
 	 * The subpayload might get truncated to maximize delivery probability.
 	 */
 	l3_hdr_len = sizeof(struct ipv6hdr);
-	if (will_need_frag_hdr(pkt_ip4_hdr(in)))
+	if (will_need_frag_hdr(pkt_ip4_hdr(in))) {
 		l3_hdr_len += sizeof(struct frag_hdr);
-	else
+	} else {
+		/* The kernel might want to fragment this so leave room.*/
 		reserve += sizeof(struct frag_hdr);
+	}
 
 	total_len = l3_hdr_len + pkt_l3payload_len(in);
 	if (is_first_frag4(pkt_ip4_hdr(in)) && pkt_is_icmp4_error(in)) {

mod/stateless/rfc6791.c

@@ -95,7 +95,7 @@ static int get_rfc6791_address(struct xlation *state, unsigned int count,
 		done = pool_foreach(state->jool.siit.pool6791, find_nth_addr,
 				&args, NULL);
 		if (done)
-			return done;
+			return 0;
 
 		if (args.flushed)
 			return -ESRCH;

test/graybox/README.md

@@ -31,77 +31,75 @@ See the content of `run.sh` for more versatility.
 
 Please [report](https://github.com/NICMx/Jool/issues) any errors or queued packets you find. Please include your distro, kernel version (`uname -r`) and the tail of `dmesg` (after the "SIIT/NAT64 Jool vX.Y.Z.W module inserted" caption).
 
-That's everything most users need to know. See below if you want to add tests to the suite.
+That's everything you need to know if you just want to run the tests. See below if you'd like to add tests to the suite.
 
 ## Preparing tests
 
 This is what you need to know:
 
-Adding tests to the suite right away is cumbersome; you don't want to run the entire suite when you're testing your *test*. To speed things up, you can run improvised standalone packet exchanges with the suite's translators by interacting with the following scripts (attached):
+Adding tests to the suite right away is cumbersome; you don't want to run the entire thing when you're just testing your *test*. To speed things up, you can run improvised standalone packet exchanges with the suite's translators by interacting with the following scripts (in the `test-suite` folder):
 
-	test-suite/namespace-create.sh
+	namespace-create.sh
 		Creates a network namespace where the translator will be
 		enclosed and the relevant virtual interfaces.
-	test-suite/namespace-destroy.sh
-		Cleans up whatever namespace-crete.sh did.
-	test-suite/network-create.sh <translator>
+		See the output of `ip netns` and `ip link` to take a peek
+		to the results.
+	namespace-destroy.sh
+		Reverts whatever namespace-create.sh did.
+	network-create.sh <translator>
 		Prepares the test network for the relevant translator.
 		<translator> can be either "siit" or "nat64".
-	test-suite/network-destroy.sh <translator>
-		Cleans up whatever network-crete.sh did.
+		See the output of `ip addr` to take a peek to the
+		results.
+	network-destroy.sh <translator>
+		Reverts whatever network-create.sh did.
 
 So, for example, to prepare an environment to send some improvised packets to the SIIT translator, run
 
 ```bash
-test-suite/namespace-create.sh
-test-suite/network-create.sh siit
+cd test-suite
+sudo ./namespace-create.sh
+sudo ./network-create.sh siit
+cd ..
 ```
 
-A description of the network we just created can be found in `test-suite/siit network.txt`. (TODO we need a NAT64 version too.)
-
-You can run `ip address` here to see your channels to your "improvised" translator.
+A description of the network you just created can be found in `test-suite/siit network.txt`. (TODO we need a NAT64 version too.) See `ip address` too.
 
-Then send some packets and see how Jool behaves (via `tcpdump`, `dmesg` and stuff):
+Then send some test packets. Evaluate results via tools such as `dmesg` (if you enabled [debug](https://github.com/NICMx/Jool/wiki/Jool's-Compilation-Options#-ddebug)) and `tcpdump`. Graybox expects test packets to be contained verbatim (from layer 3 header onwards) in a file. See examples in `test-suite/client/siit/manual`.
 
 ```bash
-usr/graybox send some-packet-1.pkt
-usr/graybox send some-packet-2.pkt
-usr/graybox send some-packet-3.pkt
+usr/graybox send /path/to/some-packet-1.pkt
+usr/graybox send /path/to/some-packet-2.pkt
+usr/graybox send /path/to/some-packet-3.pkt
 ```
 
 See `man usr/graybox.7` for more documentation on what `usr/graybox` can do.
 
 Finally, when you're done, issue the following commands to clean up:
 
 ```bash
-test-suite/network-destroy.sh siit
-test-suite/namespace-destroy.sh
+cd test-suite
+sudo ./network-destroy.sh siit
+sudo ./namespace-destroy.sh
+cd ..
 ```
 
-## Adding improvised tests to the suite
-
-(TODO now that I added the previous section, this is kind of obsolete and should become "how to add your improvised test to the suite.")
+## Adding your "improvised" test to the suite
 
-You need to provide:
+For every test, you need to provide:
 
-- A "test" packet. (A packet that is sent to the translator.)
+- A "test" packet. (A packet that is sent to the translator. It's the one you generated during the previous step.)
 - An "expected" packet. (The packet that we expect the translator to turn the "test" packet into.)
 
-The framework expects each packet to be found verbatim (layer 3 header, layer 4 header, payload) in a dedicated file. See examples in `test-suite/client/siit/manual`.
-
-Assuming that there is a translator available, and the packets' addresses will be routed towards and back from it, a standalone test can be pulled off as follows:
+Test "expected" by doing something like (assuming the namespace and the network are set)
 
 ```bash
-# Start graybox.
-insmod mod/graybox.ko
 # Tell graybox to "expect" packet foo.pkt
-usr/graybox expect add foo.pkt
-# Tell graybox to send "test" packet bar.pkt
-usr/graybox send bar.pkt
+usr/graybox expect add /path/to/foo.pkt
+# Ask graybox to send "test" packet bar.pkt
+usr/graybox send /path/to/bar.pkt
 # Wait. Jool translates bar.pkt and graybox validates the response.
 # Hopefully this should happen in less than a tenth of a second.
-# I wish I had a more bulletproff and less wasteful way to do this.
-# Maybe later.
 # This is only for scripts. If you're typing this, you obviously don't need this
 # unless you can type faster than the kernel can send packets.
 sleep 0.1
@@ -111,10 +109,12 @@ sleep 0.1
 usr/graybox expect flush
 # Print the results.
 usr/graybox stats display
-# Stop graybox.
-rmmod graybox
 ```
 
+Place both the expected and test packets in `test-suite/client/<translator>/manual` and register them in `test-suite/client/<translator>/manual.sh`.
+
+Test the full suite and you're done. Might want to commit and upload your work to the repository.
+
 ## Some notes
 
 - I don't know if the graybox kernel module is a very elegant way to do this. Perhaps raw sockets would get the job done just fine.

test/graybox/test-suite/client/siit/manual.sh

@@ -1,22 +1,21 @@
 #!/bin/bash
 
 
+GRAYBOX=`dirname $0`/../../../usr/graybox
+
+
 function test-single {
-	graybox expect add $2-nofrag.pkt $3
-	graybox send $1-nofrag.pkt
+	$GRAYBOX expect add $2-expected.pkt $3
+	$GRAYBOX send $1-test.pkt
 	sleep 0.1
-	graybox expect flush
+	$GRAYBOX expect flush
 }
 
 
-# test-frags 4-udp-csumok-nodf 6-udp-csumok-nodf
-# test-frags 4-udp-csumfail-nodf 6-udp-csumfail-nodf
-
-test-single manual/igmp6-sender manual/igmp4-receiver 4,5,10,11
-test-single manual/igmp4-sender manual/igmp6-receiver
+test-single manual/igmp64 4,5,10,11
+test-single manual/igmp46
+test-single manual/6791 4,5,10,11,32,33,38,39
 
-#NAT64/tests/graybox/usr/graybox -sa --pkt manual/error-addresses-test.pkt
-#NAT64/tests/graybox/usr/graybox -sa --pkt manual/loop.pkt
 
 graybox stats display
 graybox stats flush