Diff: main.cpp

Revision:

25:0b0450e1b08b

Parent:

24:9f3db3bf7f9c

Child:

26:11f4eb2663a7

--- a/main.cpp	Mon Jan 02 18:43:15 2017 +0000
+++ b/main.cpp	Mon Jan 02 19:36:21 2017 +0000
@@ -196,15 +196,14 @@
 
 int dataCheckSum(char * ptr, int len) {
     int sum=0; int placeHolder;
-    if (len&1) { placeHolder = ptr[len-1]; ptr[len-1]=0; } // case where length is odd
+    if (len&1) { placeHolder = ptr[len-1]; ptr[len-1]=0; } // when length is odd zero stuff
     for (int i=0;i<len/2;i++) {
-        int hi = *ptr; ptr++;
-        int lo = *ptr; ptr++;
+        int hi = *ptr; ptr++; int lo = *ptr; ptr++;
         int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
         sum = sum + val;
     }
     sum = sum + (sum>>16);
-    if (len&1) { ptr[len-1] = placeHolder; } // for odd lengths restore the last byte
+    if (len&1) { ptr[len-1] = placeHolder; } // restore the last byte for odd lengths 
     return ~sum;
 }    
 
@@ -241,7 +240,8 @@
         char * dstAdr = ipPkt+16;
         int icmpIdent = (icmpType[4]<<8)|icmpType[5];
         int icmpSequence = (icmpType[6]<<8)|icmpType[7];     
-        debug(("ICMP PING %d.%d.%d.%d %d.%d.%d.%d Ident %04x Sequence %04d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3],icmpIdent,icmpSequence));
+        debug(("ICMP PING %d.%d.%d.d %d.%d.%d.%d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]));
+        debug(("Ident %04x Sequence %04d ",icmpIdent,icmpSequence));
         char src[4]; char dst[4];
         memcpy(src, srcAdr,4);
         memcpy(dst, dstAdr,4);
@@ -258,11 +258,13 @@
         icmpSum[0]=sum>>8; icmpSum[1]=sum; // new checksum for ICMP data portion
 
         int printSize = icmpLength-8; // exclude size of icmp header
-        char * icmpData = icmpType+8; // the actual data is after the header
-        if (printSize > 10) printSize = 10; // print only first 20 characters
-        if (printSize >0) for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("%c",'_')); }}
-        debug(("%c",'\n'));
+        char * icmpData = icmpType+8; // the actual payload data is after the header
+        if (printSize > 10) printSize = 10; // print up to 20 characters
+        for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("_")); }}
+        debug(("\n"));
+        
         sendFrame(); // reply to the ping
+        
     } else {
         debug(("ICMP type=%d \n", icmpType[0])); 
     }