Topic (netsniff-ng-0.5.9-rc4):
Using the option -F with mausezahn, to read input out of a hexfile, results in
corrupt data transmitted (first byte will always be 0).
in Detail:
1) netsniff-ng-0.5.9-rc4\staging\mausezahn.c adds ",p=" in front of the hex
payload.
//<...>
case 'F': // HEX payload in FILE
afp = fopen(optarg, "r");
i=0;
while ( (hexpld[i]=fgetc(afp))!=EOF ) {
if (isspace(hexpld[i])) {
hexpld[i]=':';
}
i++;
}
hexpld[i]='\0';
fclose(afp);
hexpld_specified=1;
break;
//<...>
if (hexpld_specified) {
strcat(tx.arg_string, ",p=");
strcat(tx.arg_string, hexpld);
}
//<...>
2) netsniff-ng-0.5.9-rc4\staging\layer1.c has the need to convert the hexdata
to binary, using the function str2hex().
//<...>
bytestring_s = str2hex (tx.arg_string, bytestring, MAX_PAYLOAD_SIZE);
//<...>
3) netsniff-ng-0.5.9-rc4\staging\str2hex.c uses the function strtok() and
strtol() to separate and convert the hex data.
//<...>
hs=(char*)strtok(tmp,"-:., ");
i=0;
do
{ n--;
curval=strtol(hs,NULL,16);
if (curval>0xff) return -1;
hp[i]=(u_int8_t) curval;
i++;
}
while ((n) && ((hs=(char*)strtok(NULL,"-:., "))!= NULL));
//<...>
As the first token consists of ",p=" and the hex chars, strtol() can't convert
this. Therefor strtol() always returns 0 for this first value.
Solution:
(I have to admit that I don't fully read all code, it's only a copy&paste
solution from netsniff-ng-0.5.9-rc4\staging\layer3.c or
netsniff-ng-0.5.9-rc4\staging\layer4.c and so on)
diff -urN netsniff-ng-0.5.9-rc4.orig/staging/layer1.c
netsniff-ng-0.5.9-rc4/staging/layer1.c
--- netsniff-ng-0.5.9-rc4.orig/staging/layer1.c 2014-09-01 11:43:50.000000000
+0200
+++ netsniff-ng-0.5.9-rc4/staging/layer1.c 2015-02-18 10:34:17.311806118
+0100
@@ -58,7 +58,8 @@
j=0;
char
err_buf[LIBNET_ERRBUF_SIZE],
- message[MAX_PAYLOAD_SIZE*3];
+ message[MAX_PAYLOAD_SIZE*3],
+ argval[MAX_PAYLOAD_SIZE*2];
u_int8_t bytestring[MAX_PAYLOAD_SIZE];
libnet_ptag_t t;
@@ -100,7 +101,10 @@
// Create a temporal, local bytestring:
//
for (i=0; i<MAX_PAYLOAD_SIZE; i++) bytestring[i]=0x00;
- bytestring_s = str2hex (tx.arg_string, bytestring, MAX_PAYLOAD_SIZE);
+ if ( (getarg(tx.arg_string,"payload", argval)==1) ||
(getarg(tx.arg_string,"p", argval)==1))
+ {
+ bytestring_s = str2hex (argval, bytestring, MAX_PAYLOAD_SIZE);
+ }
// Set the flags to shorten subsequent decisions:
src = strlen(tx.eth_src_txt);
--
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