PPI: Add specification, update summary, add some comments

[skip ci]

diff --git a/print-ppi.c b/print-ppi.c
index fe85fa51e699136d760f8bf131686ee0ec9c6606..6d901a20717f5da2b3e3cb9da2ee22d90db6c50c 100644 (file)
--- a/print-ppi.c
+++ b/print-ppi.c
@@ -2,7 +2,12 @@
  * Oracle
  */
 
-/* \summary: Oracle DLT_PPI printer */
+/* \summary: Per-Packet Information (DLT_PPI) printer */
+
+/* Specification:
+ * Per-Packet Information Header Specification - Version 1.0.7
+ * https://web.archive.org/web/20160328114748/http://www.cacetech.com/documents/PPI%20Header%20format%201.0.7.pdf
+ */
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
@@ -15,10 +20,12 @@
 
 
 typedef struct ppi_header {
-       nd_uint8_t      ppi_ver;
-       nd_uint8_t      ppi_flags;
-       nd_uint16_t     ppi_len;
-       nd_uint32_t     ppi_dlt;
+       nd_uint8_t      ppi_ver;        /* Version.  Currently 0 */
+       nd_uint8_t      ppi_flags;      /* Flags. */
+       nd_uint16_t     ppi_len;        /* Length of entire message, including
+                                        * this header and TLV payload. */
+       nd_uint32_t     ppi_dlt;        /* Data Link Type of the captured
+                                        * packet data. */
 } ppi_header_t;
 
 #define        PPI_HDRLEN      8