[patch] Filtering VLANs in sflowtool

Hello

Neil from inmon.com asked me to send this patch to the mailing list
to estimate if there's interest in including it into his sflowtool.

> On Jan 23, 2006, at 3:07 AM, Christian Hammers wrote:
> >Attached you'll find a little patch that we use to filter some VLANs
> >which should not be accounted. It still contains some comment lines
> >and may be not the best C but feel free to use it.

bye,

-christian-

-- 
Christian Hammers             WESTEND GmbH  |  Internet-Business-Provider
Technik                       CISCO Systems Partner - Authorized Reseller
                              L|tticher Stra_e 10      Tel 0241/701333-11
ch@westend.com                D-52064 Aachen              Fax 0241/911879
--- sflowtool-3.9/src/sflowtool.c	Mon Sep 19 20:08:45 2005
+++ oldsflowtool-3.9/src/sflowtool.c	Mon Jan 23 12:46:13 2006
@@ -138,6 +138,8 @@
 
 typedef enum { SFLFMT_FULL=0, SFLFMT_PCAP, SFLFMT_LINE } EnumSFLFormat;
 
+#define SFCONFIG_FILTER_IN_VLANS_NUM 100
+
 typedef struct _SFConfig {
   /* sflow options */
   u_int16_t sFlowInputPort;
@@ -165,6 +167,9 @@
 #endif
 
   SFForwardingTarget *forwardingTargets;
+
+  unsigned int filterInVlansNum;
+  u_int32_t filterInVlans[SFCONFIG_FILTER_IN_VLANS_NUM];
 } SFConfig;
 
 /* make the options structure global to the program */
@@ -1869,6 +1874,7 @@
 
 static void readFlowSample_v2v4(SFSample *sample)
 {
+  int i;
   sf_log("sampleType FLOWSAMPLE\n");
 
   sample->samplesGenerated = getData32(sample);
@@ -1927,6 +1933,14 @@
     }
   }
   
+  /* #42#WESTEND# VLAN-Filterung */
+  for (i=0; i<sfConfig.filterInVlansNum; i++) {
+    if (sample->in_vlan == sfConfig.filterInVlans[i]) {
+      sf_log("skipping vlan #%d %u\n", i, sfConfig.filterInVlans[i]);
+      return;
+    }
+  }
+  
   /* if we are exporting netflow and we have an IPv4 layer, compose the datagram now */
   if(sfConfig.netFlowOutputSocket && sample->gotIPV4) sendNetFlowDatagram(sample);
   /* if we are writing tcpdump format, write the next packet record now */
@@ -2583,6 +2597,9 @@
   fprintf(stderr,"\n");
   fprintf(stderr,"%s version: %s\n", command, VERSION);
   fprintf(stderr,"\n");
+  fprintf(stderr,"filtering:\n");
+  fprintf(stderr, "   -x vlan1,vlan2,... -  Discard packets from specified VLANs\n");
+  fprintf(stderr,"\n");
   fprintf(stderr,"forwarding:\n");
   fprintf(stderr, "   -f host/port       -  (forward sflow to another collector\n");
   fprintf(stderr, "                      -   ...repeat for multiple collectors)\n");
@@ -2618,6 +2635,10 @@
   /* set defaults */
   sfConfig.sFlowInputPort = 6343;
   
+
+  /* #42#WESTEND# */
+  sfConfig.filterInVlansNum = 0;
+  bzero(sfConfig.filterInVlans, sizeof(sfConfig.filterInVlans));
   /* walk though the args */
   while (arg < argc) {
     if(argv[arg][0] != '-') instructions(*argv);
@@ -2645,6 +2666,25 @@
     case 'S': sfConfig.spoofSource = YES; break;
 #endif
     case 'f': if(addForwardingTarget(argv[arg++]) == NO) exit(-35); break;
+    /* #42#WESTEND# */
+    case 'x': 
+      {
+        /* parse argument string to '-x' to array of integer */
+	/* #42#WESTEND# FIXME: manpage discouraged using strtok() but did not suggest a replacement. */
+        int i;
+        char *vlan_id = strtok(argv[arg++], ",");
+        while (vlan_id != NULL) {
+          if (sfConfig.filterInVlansNum < SFCONFIG_FILTER_IN_VLANS_NUM) {
+            sfConfig.filterInVlans[sfConfig.filterInVlansNum++] = atoi(vlan_id);      
+          }
+          vlan_id = strtok(NULL, ",");
+        }
+        /* show array contents */
+        for (i=0; i<sfConfig.filterInVlansNum; i++) {
+           fprintf(stderr, "Filtering VLAN %u\n", sfConfig.filterInVlans[i]);
+        }
+      }
+      break;
     case '?':
     case 'h':
     default: instructions(*argv);