Remove `struct ndpi_packet_struct` from `struct ndpi_flow_struct` (#1319)

There are no real reasons to embed `struct ndpi_packet_struct` (i.e. "packet")
in `struct ndpi_flow_struct` (i.e. "flow"). In other words, we can avoid
saving dissection information of "current packet" into the "flow" state,
i.e. in the flow management table.

The nDPI detection module processes only one packet at the time, so it is
safe to save packet dissection information in `struct ndpi_detection_module_struct`,
reusing always the same "packet" instance and saving a huge amount of memory.
Bottom line: we need only one copy of "packet" (for detection module),
not one for each "flow".

It is not clear how/why "packet" ended up in "flow" in the first place.
It has been there since the beginning of the GIT history, but in the original
OpenDPI code `struct ipoque_packet_struct` was embedded in
`struct ipoque_detection_module_struct`, i.e. there was the same exact
situation this commit wants to achieve.

Most of the changes in this PR are some boilerplate to update something
like "flow->packet" into something like "module->packet" throughout the code.
Some attention has been paid to update `ndpi_init_packet()` since we need
to reset some "packet" fields before starting to process another packet.

There has been one important change, though, in ndpi_detection_giveup().
Nothing changed for the applications/users, but this function can't access
"packet" anymore.
The reason is that this function can be called "asynchronously" with respect
to the data processing, i.e in context where there is no valid notion of
"current packet"; for example ndpiReader calls it after having processed all
the traffic, iterating the entire session table.

Mining LRU stuff seems a bit odd (even before this patch): probably we need
to rethink it, as a follow-up.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/lib/protocols/irc.c b/src/lib/protocols/irc.c
index a6ed0466b..bb1b65929 100644
--- a/src/lib/protocols/irc.c
+++ b/src/lib/protocols/irc.c
@@ -64,7 +64,7 @@ u_int8_t ndpi_is_duplicate(struct ndpi_id_struct *id_t, u_int16_t port)
 static u_int8_t ndpi_check_for_NOTICE_or_PRIVMSG(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
 
-  struct ndpi_packet_struct *packet = &flow->packet;
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
   //
   u_int16_t i;
   u_int8_t number_of_lines_to_be_searched_for = 0;
@@ -88,7 +88,7 @@ static u_int8_t ndpi_check_for_NOTICE_or_PRIVMSG(struct ndpi_detection_module_st
 
 static u_int8_t ndpi_check_for_Nickname(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
-  struct ndpi_packet_struct *packet = &flow->packet;
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
   u_int16_t i, packetl = packet->payload_packet_len;
 
   if (packetl < 4) {
@@ -110,7 +110,7 @@ static u_int8_t ndpi_check_for_Nickname(struct ndpi_detection_module_struct *ndp
 
 static u_int8_t ndpi_check_for_cmd(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
-  struct ndpi_packet_struct *packet = &flow->packet;
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
   u_int16_t i;
 
   if (packet->payload_packet_len < 4) {
@@ -150,7 +150,7 @@ static u_int8_t ndpi_check_for_IRC_traces(const u_int8_t * ptr, u_int16_t len)
 u_int8_t ndpi_search_irc_ssl_detect_ninety_percent_but_very_fast(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
 
-  struct ndpi_packet_struct *packet = &flow->packet;
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
 	
 
   NDPI_LOG_DBG(ndpi_struct, "start fast detect\n");
@@ -367,7 +367,7 @@ u_int8_t ndpi_search_irc_ssl_detect_ninety_percent_but_very_fast(struct ndpi_det
 
 void ndpi_search_irc_tcp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
 {
-  struct ndpi_packet_struct *packet = &flow->packet;
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
 	
   struct ndpi_id_struct *src = flow->src;
   struct ndpi_id_struct *dst = flow->dst;