Tap api. tap is a simple api that can be used for arbitrary extensions.

One example extension is rpcstat.

Try -Z rpc,rtt,100003,3 as argument to tethereal when reading a capture
containing NFSv3 packets.

tap-rpcstat.[ch] is intended to demonstrate the api and can be used to
base other extensions on.

svn path=/trunk/; revision=6175

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+/* tap-rpcstat.c
+ * rpcstat   2002 Ronnie Sahlberg
+ *
+ * $Id: tap-rpcstat.c,v 1.1 2002/09/04 09:40:24 sahlberg Exp $
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ * Copyright 1998 Gerald Combs
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+/* This module provides rpc call/reply RTT statistics to tethereal.
+ * It is only used by tethereal and not ethereal
+ *
+ * It serves as an example on how to use the tap api.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdio.h>
+
+#ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+
+#include <string.h>
+#include "epan/packet_info.h"
+#include "tap.h"
+#include "tap-rpcstat.h"
+#include "packet-rpc.h"
+
+
+/* used to keep track of statistics for a specific procedure */
+typedef struct _rpc_procedure_t {
+	char *proc;
+	int num;
+	nstime_t min;
+	nstime_t max;
+	nstime_t tot;
+} rpc_procedure_t;
+
+/* used to keep track of the statistics for an entire program interface */
+typedef struct _rpcstat_t {
+	char *prog;
+	guint32 program;
+	guint32 version;
+	guint32 num_procedures;
+	rpc_procedure_t *procedures;
+} rpcstat_t;
+
+
+
+/* This callback is never used by tethereal but it is here for completeness.
+ * When registering below, we could just have left this function as NULL.
+ *
+ * When used by ethereal, this function will be called whenever we would need
+ * to reset all state. Such as when ethereal opens a new file, when it
+ * starts a new capture, when it rescans the packetlist after some prefs have
+ * changed etc.
+ * So if your aplication has some state it needs to clean up in those
+ * situations, here is a good place to put that code.
+ */
+static void
+rpcstat_reset(rpcstat_t *rs)
+{
+	guint32 i;
+
+	for(i=0;i<rs->num_procedures;i++){
+		rs->procedures[i].num=0;	
+		rs->procedures[i].min.secs=0;
+		rs->procedures[i].min.nsecs=0;
+		rs->procedures[i].max.secs=0;
+		rs->procedures[i].max.nsecs=0;
+		rs->procedures[i].tot.secs=0;
+		rs->procedures[i].tot.nsecs=0;
+	}
+}
+
+
+/* This callback is invoked whenever the tap system has seen a packet
+ * we might be interested in.
+ * The function is to be used to only update internal state information
+ * in the *tapdata structure, and if there were state changes which requires
+ * the window to be redrawn, return 1 and (*draw) will be called sometime
+ * later.
+ *
+ * This function should be as lightweight as possible since it executes together
+ * with the normal ethereal dissectors. Try to push as much processing as
+ * possible into (*draw) instead since that function executes asynchronously
+ * and does not affect the main threads performance.
+ *
+ * If it is possible, try to do all "filtering" explicitely as we do below in 
+ * this example since you will get MUCH better performance than applying
+ * a similar display-filter in the register call.
+ *
+ * The third parameter is tap dependant. Since we register this one to the "rpc"
+ * tap the third parameters type is rpc_call_info_value.
+ *
+ *
+ * The filtering we do is just to check the rpc_call_info_value struct that
+ * we were called for the proper program and version. We didnt apply a filter
+ * when we registered so we will be called for ALL rpc packets and not just
+ * the ones we are collecting stats for.
+ * 
+ *
+ * function returns :
+ *  0: no updates, no need to call (*draw) later
+ * !0: state has changed, call (*draw) sometime later
+ */
+static int
+rpcstat_packet(rpcstat_t *rs, packet_info *pinfo, rpc_call_info_value *ri)
+{
+	nstime_t delta;
+	rpc_procedure_t *rp;
+
+	if(ri->proc>=rs->num_procedures){
+		/* dont handle this since its outside of known table */
+		return 0;
+	}
+	/* we are only interested in reply packets */
+	if(ri->request){
+		return 0;
+	}
+	/* we are only interested in certain program/versions */
+	if( (ri->prog!=rs->program) || (ri->vers!=rs->version) ){
+		return 0;
+	}
+
+	rp=&(rs->procedures[ri->proc]);
+
+	/* calculate time delta between request and reply */
+	delta.secs=pinfo->fd->abs_secs-ri->req_time.secs;
+	delta.nsecs=pinfo->fd->abs_usecs*1000-ri->req_time.nsecs;
+	if(delta.nsecs<0){
+		delta.nsecs+=1000000000;
+		delta.secs--;
+	}
+
+	if((rp->max.secs==0)
+	&& (rp->max.nsecs==0) ){
+		rp->max.secs=delta.secs;
+		rp->max.nsecs=delta.nsecs;
+	}
+
+	if((rp->min.secs==0)
+	&& (rp->min.nsecs==0) ){
+		rp->min.secs=delta.secs;
+		rp->min.nsecs=delta.nsecs;
+	}
+
+	if( (delta.secs<rp->min.secs)
+	||( (delta.secs==rp->min.secs)
+	  &&(delta.nsecs<rp->min.nsecs) ) ){
+		rp->min.secs=delta.secs;
+		rp->min.nsecs=delta.nsecs;
+	}
+
+	if( (delta.secs>rp->max.secs)
+	||( (delta.secs==rp->max.secs)
+	  &&(delta.nsecs>rp->max.nsecs) ) ){
+		rp->max.secs=delta.secs;
+		rp->max.nsecs=delta.nsecs;
+	}
+	
+	rp->tot.secs += delta.secs;
+	rp->tot.nsecs += delta.nsecs;
+	if(rp->tot.nsecs>1000000000){
+		rp->tot.nsecs-=1000000000;
+		rp->tot.secs++;
+	}
+	rp->num++;
+
+	return 1;
+}
+
+/* This callback is used when tethereal wants us to draw/update our
+ * data to the output device. Since this is tethereal only output is
+ * stdout.
+ * Tethereal will only call this callback once, which is when tethereal has
+ * finished reading all packets and exists.
+ * If used with ethereal this may be called any time, perhaps once every 3 
+ * seconds or so.
+ * This function may even be called in parallell with (*reset) or (*draw)
+ * so make sure there are no races. The data in the rpcstat_t can thus change
+ * beneath us. Beware.
+ */
+static void
+rpcstat_draw(rpcstat_t *rs)
+{
+	guint32 i;
+#ifdef G_HAVE_UINT64
+	guint64 td;
+#else
+	guint32 td;
+#endif
+	printf("\n");
+	printf("===================================================================\n");
+	printf("%s Version %d RTT Statistics:\n", rs->prog, rs->version);
+	printf("Procedure        Calls   Min RTT   Max RTT   Avg RTT\n");
+	for(i=0;i<rs->num_procedures;i++){
+		/* scale it to units of 10us.*/
+		/* for long captures with a large tot time, this can overflow on 32bit */
+		td=(int)rs->procedures[i].tot.secs;
+		td=td*100000+(int)rs->procedures[i].tot.nsecs/10000;
+		if(rs->procedures[i].num){
+			td/=rs->procedures[i].num;
+		} else {
+			td=0;
+		}
+
+		printf("%-15s %6d %3d.%05d %3d.%05d %3d.%05d\n",
+			rs->procedures[i].proc,
+			rs->procedures[i].num,
+			(int)rs->procedures[i].min.secs,rs->procedures[i].min.nsecs/10000,
+			(int)rs->procedures[i].max.secs,rs->procedures[i].max.nsecs/10000,
+			td/100000, td%100000
+		);
+	}
+	printf("===================================================================\n");
+}
+
+static guint32 rpc_program=0;
+static guint32 rpc_version=0;
+static gint32 rpc_min_proc=-1;
+static gint32 rpc_max_proc=-1;
+
+static void *
+rpcstat_find_procs(gpointer *key, gpointer *value _U_, gpointer *user_data _U_)
+{
+	rpc_proc_info_key *k=(rpc_proc_info_key *)key;
+
+	if(k->prog!=rpc_program){
+		return NULL;
+	}
+	if(k->vers!=rpc_version){
+		return NULL;
+	}
+	if(rpc_min_proc==-1){
+		rpc_min_proc=k->proc;
+		rpc_max_proc=k->proc;
+	}
+	if((gint32)k->proc<rpc_min_proc){
+		rpc_min_proc=k->proc;
+	}
+	if((gint32)k->proc>rpc_max_proc){
+		rpc_max_proc=k->proc;
+	}
+
+	return NULL;
+}
+
+
+/* When called, this function will create a new instance of rpcstat.
+ * program and version are whick onc-rpc program/version we want to
+ * collect statistics for.
+ * This function is called from tethereal when it parses the -Z rpc, arguments
+ * and it creates a new instance to store statistics in and registers this
+ * new instance for the rpc tap.
+ */
+void
+rpcstat_init(guint32 program, guint32 version)
+{
+	rpcstat_t *rs;
+	guint32 i;
+/*	char filter[256];*/
+
+
+	rs=g_malloc(sizeof(rpcstat_t));
+	rs->prog=rpc_prog_name(program);
+	rs->program=program;
+	rs->version=version;
+
+	rpc_program=program;
+	rpc_version=version;
+	rpc_min_proc=-1;
+	rpc_max_proc=-1;
+	g_hash_table_foreach(rpc_procs, (GHFunc)rpcstat_find_procs, NULL);
+	if(rpc_min_proc==-1){
+		fprintf(stderr,"tethereal: Invalid -Z rpc,rrt,%d,%d\n",rpc_program,rpc_version);
+		fprintf(stderr,"   Program:%d version:%d is not supported by tethereal.\n", rpc_program, rpc_version);
+		exit(1);
+	}
+
+
+	rs->num_procedures=rpc_max_proc+1;
+	rs->procedures=g_malloc(sizeof(rpc_procedure_t)*(rs->num_procedures+1));
+	for(i=0;i<rs->num_procedures;i++){
+		rs->procedures[i].proc=rpc_proc_name(program, version, i);
+		rs->procedures[i].num=0;	
+		rs->procedures[i].min.secs=0;
+		rs->procedures[i].min.nsecs=0;
+		rs->procedures[i].max.secs=0;
+		rs->procedures[i].max.nsecs=0;
+		rs->procedures[i].tot.secs=0;
+		rs->procedures[i].tot.nsecs=0;
+	}
+
+/* It is possible to create a filter and attach it to the callbacks. Then the
+ * callbacks would only be invoked if the filter matched.
+ * Evaluating filters is expensive and if we can avoid it and not use them
+ * we gain performance. Here we just tap everything from rpc without
+ * filtering and we do the filtering we need explicitely inside the callback
+ * itself (*packet) instead with a few if()s.
+ *
+ * This is what it would look like IF we wanted to use a filter when attaching
+ * it to the tap.
+	snprintf(filter, 255, "(rpc.msgtyp==1) && (rpc.program==%d) && (rpc.programversion==%d)",program,version);
+	register_tap_listener("rpc", rs, filter, (void*)rpcstat_reset, (void*)rpcstat_packet, (void*)rpcstat_draw);
+ */
+
+	if(register_tap_listener("rpc", rs, NULL, (void*)rpcstat_reset, (void*)rpcstat_packet, (void*)rpcstat_draw)){
+		/* error, we failed to attach to the tap. clean up */
+		g_free(rs->procedures);
+		g_free(rs);
+
+		fprintf(stderr,"tethereal: rpcstat_init() failed to attach to tap.\n");
+		exit(1);
+	}
+}
+
+
+
+