trafgen: fix checksumming in trafgen example config

Took quite a while to git bisect the cause for the wrong TCP checksum
in the -e example. It turned out that commit bf43e1993c7037 ("trafgen:
lexer: return original string if no shellcode") "broke" it, since
before that commit the TCP checksum from -e example was correct and
afterwards not anymore. Well, it didn't break it. What was happening
here is that with this fix above, the packet got 1 byte longer since
the first character of the example string is not omitted anymore,
therefore the checksum got wrong. Fix this by fixing the IP total
length of the packet in the -e and man page example. The UDP example
from the man page still works well if csumudp() is used, so not
affected of this.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/trafgen.8 b/trafgen.8
index f45a0c5..fb08cc0 100644
--- a/trafgen.8
+++ b/trafgen.8
@@ -257,7 +257,7 @@ taste of a more advanced example, run ''trafgen \-e'', fields are commented:
      /* IPv4 Version, IHL, TOS */
      0b01000101, 0,
      /* IPv4 Total Len */
-     c16(58),
+     c16(59),
      /* IPv4 Ident */
      drnd(2),
      /* IPv4 Flags, Frag Off */
diff --git a/trafgen.c b/trafgen.c
index ce2967d..762d0f9 100644
--- a/trafgen.c
+++ b/trafgen.c
@@ -240,7 +240,7 @@ static void __noreturn example(void)
 	"  /* IPv4 Version, IHL, TOS */\n"
 	"  0b01000101, 0,\n"
 	"  /* IPv4 Total Len */\n"
-	"  c16(58),\n"
+	"  c16(59),\n"
 	"  /* IPv4 Ident */\n"
 	"  drnd(2),\n"
 	"  /* IPv4 Flags, Frag Off */\n"