hallo,
i would like to add a disable checksum flag to tcpdump.
i assume this will affect ip, tcp, udp, icmp, icmp6, isoclns, igmp, vrrp,
mobile printers, and tcpdump.c file (is it all?)
proposed change:
add a global int cksumflag=1 in tcpdump.c :)
add a command line flag: k (?),
which when specified disables the checksum calculation (cksumflag=0);
check cksumflag before calculating checksums in printers.
i attached the patch against today's cvs, which worked on my setup,
but i have no idea what some printers do, so, please, let me know
if there is more changes needed or things should be done differently.
???
thanks,
-alexm
--
001, 010, 011, 100, 101 - ����� ������ ��������
diff -urN tcpdump.orig/print-icmp.c tcpdump/print-icmp.c
--- tcpdump.orig/print-icmp.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-icmp.c Fri Jul 18 12:39:34 2003
@@ -41,6 +41,8 @@
#include "udp.h"
#include "ipproto.h"
+extern int cksumflag;
+
/*
* Interface Control Message Protocol Definitions.
* Per RFC 792, September 1981.
@@ -477,7 +479,7 @@
break;
}
(void)printf("icmp %d: %s", plen, str);
- if (vflag && !fragmented) { /* don't attempt checksumming if this is a frag */
+ if (vflag && !fragmented && cksumflag) { /* don't attempt checksumming if this
is a frag */
u_int16_t sum, icmp_sum;
if (TTEST2(*bp, plen)) {
sum = in_cksum((u_short*)dp, plen, 0);
diff -urN tcpdump.orig/print-icmp6.c tcpdump/print-icmp6.c
--- tcpdump.orig/print-icmp6.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-icmp6.c Fri Jul 18 12:39:34 2003
@@ -46,6 +46,8 @@
#include "udp.h"
#include "ah.h"
+extern int cksumflag;
+
static const char *get_rtpref(u_int);
static const char *get_lifetime(u_int32_t);
static void print_lladdr(const u_char *, size_t);
@@ -171,7 +173,7 @@
TCHECK(dp->icmp6_cksum);
- if (vflag && !fragmented) {
+ if (vflag && !fragmented && cksumflag) {
int sum = dp->icmp6_cksum;
if (TTEST2(bp[0], icmp6len)) {
diff -urN tcpdump.orig/print-igmp.c tcpdump/print-igmp.c
--- tcpdump.orig/print-igmp.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-igmp.c Fri Jul 18 12:39:34 2003
@@ -41,6 +41,8 @@
#define IN_CLASSD(i) (((int32_t)(i) & 0xf0000000) == 0xe0000000)
#endif
+extern int cksumflag;
+
/* (following from ipmulti/mrouted/prune.h) */
/*
@@ -319,7 +321,7 @@
break;
}
- if (vflag && TTEST2(bp[0], len)) {
+ if (vflag && cksumflag && TTEST2(bp[0], len)) {
/* Check the IGMP checksum */
if (in_cksum((const u_short*)bp, len, 0))
printf(" bad igmp cksum %x!", EXTRACT_16BITS(&bp[2]));
diff -urN tcpdump.orig/print-ip.c tcpdump/print-ip.c
--- tcpdump.orig/print-ip.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-ip.c Fri Jul 18 12:39:34 2003
@@ -41,6 +41,8 @@
#include "ip.h"
#include "ipproto.h"
+extern int cksumflag;
+
/*
* print the recorded route in an IP RR, LSRR or SSRR option.
*/
@@ -434,7 +436,7 @@
printf(" )");
}
- if ((u_char *)ip + hlen <= snapend) {
+ if ((u_char *)ip + hlen <= snapend && cksumflag) {
sum = in_cksum((const u_short *)ip, hlen, 0);
if (sum != 0) {
ip_sum = EXTRACT_16BITS(&ip->ip_sum);
diff -urN tcpdump.orig/print-isoclns.c tcpdump/print-isoclns.c
--- tcpdump.orig/print-isoclns.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-isoclns.c Fri Jul 18 12:39:34 2003
@@ -45,6 +45,8 @@
#include "extract.h"
#include "gmpls.h"
+extern int cksumflag;
+
#define NLPID_CLNS 129 /* 0x81 */
#define NLPID_ESIS 130 /* 0x82 */
#define NLPID_ISIS 131 /* 0x83 */
@@ -545,7 +547,7 @@
if(vflag < 1)
return;
- if (vflag && osi_cksum(p, li)) {
+ if (vflag && cksumflag && osi_cksum(p, li)) {
printf(" bad cksum (got 0x%02x%02x)",
eh->cksum[1], eh->cksum[0]);
default_print(p, length);
diff -urN tcpdump.orig/print-mobile.c tcpdump/print-mobile.c
--- tcpdump.orig/print-mobile.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-mobile.c Fri Jul 18 12:39:34 2003
@@ -55,6 +55,8 @@
#define MOBILE_SIZE (8)
+extern int cksumflag;
+
struct mobile_ip {
u_int16_t proto;
u_int16_t hcheck;
@@ -101,7 +103,7 @@
(void)printf("> %s ",ipaddr_string(&mob->odst));
(void)printf("(oproto=%d)",proto>>8);
}
- if (in_cksum((u_short *)mob, osp ? 12 : 8, 0)!=0) {
+ if (cksumflag && in_cksum((u_short *)mob, osp ? 12 : 8, 0)!=0) {
(void)printf(" (bad checksum %d)",crc);
}
diff -urN tcpdump.orig/print-tcp.c tcpdump/print-tcp.c
--- tcpdump.orig/print-tcp.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-tcp.c Fri Jul 18 12:39:34 2003
@@ -50,6 +50,8 @@
#include "nameser.h"
+extern int cksumflag;
+
static void print_tcp_rst_data(register const u_char *sp, u_int length);
#define MAX_RST_DATA_LEN 30
@@ -398,7 +400,7 @@
return;
}
- if (IP_V(ip) == 4 && vflag && !fragmented) {
+ if (IP_V(ip) == 4 && vflag && !fragmented && cksumflag) {
u_int16_t sum, tcp_sum;
if (TTEST2(tp->th_sport, length)) {
sum = tcp_cksum(ip, tp, length);
@@ -411,7 +413,7 @@
}
}
#ifdef INET6
- if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
+ if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented && cksumflag) {
int sum;
if (TTEST2(tp->th_sport, length)) {
sum = tcp6_cksum(ip6, tp, length);
diff -urN tcpdump.orig/print-udp.c tcpdump/print-udp.c
--- tcpdump.orig/print-udp.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-udp.c Fri Jul 18 12:39:34 2003
@@ -57,6 +57,8 @@
#include "nfs.h"
#include "bootp.h"
+extern int cksumflag;
+
struct rtcphdr {
u_int16_t rh_flags; /* T:2 P:1 CNT:5 PT:8 */
u_int16_t rh_len; /* length of message (in words) */
@@ -575,7 +577,7 @@
}
udpipaddr_print(ip, sport, dport);
- if (IP_V(ip) == 4 && vflag && !fragmented) {
+ if (IP_V(ip) == 4 && vflag && !fragmented && cksumflag) {
int sum = up->uh_sum;
if (sum == 0) {
(void)printf("[no cksum] ");
@@ -588,7 +590,7 @@
}
}
#ifdef INET6
- if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
+ if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented && cksumflag) {
int sum = up->uh_sum;
/* for IPv6, UDP checksum is mandatory */
if (TTEST2(cp[0], length)) {
diff -urN tcpdump.orig/print-vrrp.c tcpdump/print-vrrp.c
--- tcpdump.orig/print-vrrp.c Fri Jul 18 12:39:24 2003
+++ tcpdump/print-vrrp.c Fri Jul 18 12:39:34 2003
@@ -41,6 +41,8 @@
#include "extract.h"
#include "addrtoname.h"
+extern int cksumflag;
+
/*
* RFC 2338:
* 0 1 2 3
@@ -110,7 +112,7 @@
int i;
char c;
- if (TTEST2(bp[0], len) && in_cksum((const u_short*)bp, len, 0))
+ if (cksumflag && TTEST2(bp[0], len) && in_cksum((const u_short*)bp,
len, 0))
printf(" (bad vrrp cksum %x!)",
EXTRACT_16BITS(&bp[6]));
printf(" addrs");
diff -urN tcpdump.orig/tcpdump.c tcpdump/tcpdump.c
--- tcpdump.orig/tcpdump.c Fri Jul 18 12:39:24 2003
+++ tcpdump/tcpdump.c Fri Jul 18 12:39:34 2003
@@ -69,6 +69,8 @@
#include "gmt2local.h"
#include "pcap-missing.h"
+int cksumflag = 1;
+
int aflag; /* translate network and broadcast addresses */
int dflag; /* print filter code */
int eflag; /* print ethernet header */
@@ -334,6 +336,7 @@
infile = NULL;
RFileName = NULL;
WFileName = NULL;
+
if ((cp = strrchr(argv[0], '/')) != NULL)
program_name = cp + 1;
else
@@ -348,7 +351,7 @@
opterr = 0;
while (
- (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG
"eE:fF:i:lLm:nNOpqr:Rs:StT:u" U_FLAG "vw:xXy:Y")) != -1)
+ (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG
"eE:fF:i:klLm:nNOpqr:Rs:StT:u" U_FLAG "vw:xXy:Y")) != -1)
switch (op) {
case 'a':
@@ -401,6 +404,10 @@
return 0;
#endif /* HAVE_PCAP_FINDALLDEVS */
+ case 'k':
+ cksumflag = 0;
+ break;
+
case 'L':
Lflag++;
break;
@@ -753,6 +760,9 @@
(void)fprintf(stderr, "%s: ", program_name);
(void)fprintf(stderr, "listening on %s, link-type %u, capture size %u
bytes\n",
device, pcap_datalink(pd), snaplen);
+#ifdef _AIX /* no checksum on AIX loopback */
+ if (pcap_datalink(pd) == 0) cksumflag = 0;
+#endif /* _AIX */
(void)fflush(stderr);
}
#endif /* WIN32 */
@@ -1032,7 +1042,7 @@
#endif /* WIN32 */
#endif /* HAVE_PCAP_LIB_VERSION */
(void)fprintf(stderr,
-"Usage: %s [-aAd" D_FLAG "eflLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [-c count] [ -C
file_size ]\n", program_name);
+"Usage: %s [-aAd" D_FLAG "efklLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [-c count] [
-C file_size ]\n", program_name);
(void)fprintf(stderr,
"\t\t[ -E algo:secret ] [ -F file ] [ -i interface ] [ -r file ]\n");
(void)fprintf(stderr,
