[docs] add knet packet layout

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>
kronosnet · Aug 21, 2019 · b7d0f70 · b7d0f70
1 parent 2e433d3
commit b7d0f70
Showing 1 changed file with 22 additions and 0 deletions.
diff --git a/libknet/threads_pmtud.c b/libknet/threads_pmtud.c
@@ -91,6 +91,28 @@ static int _handle_check_link_pmtud(knet_handle_t knet_h, struct knet_host *dst_
 		failsafe++;
 	}
 
+	/*
+	 * unencrypted packet looks like:
+	 *
+	 * | ip | protocol | knet_header | unencrypted data                                  |
+	 * | onwire_len                                                                      |
+	 * | overhead_len  |
+	 *                 | data_len                                                        |
+	 *                               | app MTU                                           |
+	 *
+	 * encrypted packet looks like (not to scale):
+	 *
+	 * | ip | protocol | salt | crypto(knet_header | data)      | crypto_data_pad | hash |
+	 * | onwire_len                                                                      |
+	 * | overhead_len  |
+	 *                 | data_len                                                        |
+	 *                                             | app MTU    |
+	 *
+	 * knet_h->sec_block_size is >= 0 if encryption will pad the data
+	 * knet_h->sec_salt_size is >= 0 if encryption is enabled
+	 * knet_h->sec_hash_size is >= 0 if signing is enabled
+	 */
+
 	data_len = onwire_len - overhead_len;
 
 	if (knet_h->crypto_instance) {